Dysuria, Urinary Frequency
Dysuria is painful or burning sensation during urination, and urinary frequency is the need to urinate more often than normal, both commonly indicating lower urinary tract irritation or infection.
Dysuria literally means "dys-" (difficult/painful, from Greek) + "-uria" (urination). Clinically, it refers to painful urination, usually described as burning, scalding, or stinging [1][2]. It is often associated with suprapubic pain and often associated with other lower urinary tract symptoms (LUTS), e.g. frequency, urgency, incomplete emptying [2].
Urinary frequency means the patient's perception that they are voiding too often during the day (typically > 7 voids/day). It is a storage (irritative) symptom and may or may not coexist with dysuria [2][3].
These two symptoms together form one of the most common presenting complaints in primary care and emergency medicine, and their combined presence strongly suggests a lower urinary tract process — most commonly urinary tract infection (UTI), but the differential is broader than that [1][2].
Key Conceptual Point
Dysuria indicates ongoing infection or inflammation of the lower urinary tract and is NOT grouped under obstructive or irritative LUTS headings — it is a separate, distinct symptom [2]. Meanwhile, urinary frequency IS a storage (irritative) LUTS. Their coexistence narrows the differential to conditions that both irritate the bladder/urethral mucosa AND increase the urge to void.
Epidemiology
- UTI (the most common cause of dysuria and frequency) is one of the commonest bacterial infections, accounting for 1–3% of GP consultations [4].
- 30% of women will have a symptomatic UTI by age 24; 50% of women will have at least one UTI during their lifetime [4].
- Females >>> Males — this ratio is approximately 30:1 for bacteriuria in young adults. UTI is rare in males except at the extremes of age: 0–1 years (boys with urinary tract anomalies) or > 60 years (men with BPH causing stasis) [4].
- Incidence increases with age — in women, there is a sharp increase after onset of sexual activity (hence the classic term "honeymoon cystitis") [4].
- In Hong Kong specifically, UTI is an extremely common emergency department and outpatient presentation. Antibiotic resistance patterns (especially fluoroquinolone-resistant E. coli) are a significant local concern, with Hong Kong reporting E. coli fluoroquinolone resistance rates exceeding 30% in community-acquired UTI.
| Feature | Female | Male |
|---|---|---|
| Lifetime UTI risk | ~50% | Much lower (~5%) |
| Peak incidence | Onset of sexual activity, pregnancy, postmenopause | Extremes of age (infancy, > 60y) |
| Common cause of dysuria | UTI, vaginitis, urethral syndrome | UTI, prostatitis, urethritis |
| Anatomical predisposition | Short urethra (~4 cm), close to anus | Longer urethra (~20 cm), prostate acts as barrier (but also source of pathology) |
Risk Factors for UTI (the Most Common Cause)
Understanding risk factors requires understanding the pathogenesis of ascending infection: bacteria must colonize the periurethral area → ascend the urethra → adhere to bladder urothelium → overcome host defenses. Anything that facilitates any of these steps is a risk factor.
Female Sex [3][4]
- Shorter urethral length (~4 cm in females vs ~20 cm in males) → shorter distance for bacteria to travel from perineum to bladder.
- Proximity of urethral meatus to anus → easier fecal-to-urethral bacterial transfer.
Sexual Activity [3][4]
- Mechanical introduction of periurethral bacteria into the bladder during intercourse ("honeymoon cystitis" [4]).
- New sexual partners → altered vaginal flora.
- Use of spermicides and diaphragm → spermicides disrupt the normal Lactobacillus-dominant vaginal flora (by killing Lactobacilli, raising vaginal pH, and facilitating E. coli colonization) [4].
Lack of Circumcision [3]
- The mucosal surface of uncircumcised foreskin is more likely to bind uropathogenic bacterial species than keratinized skin on a circumcised penis.
- Partial obstruction of the urethral meatus by a tight foreskin.
Vesicoureteral Reflux (VUR) [3]
- Retrograde passage of urine from bladder into upper urinary tract → allows bacteria to ascend to the kidneys.
- Important risk factor for renal scarring, especially in children.
Urinary Obstruction [3][4]
- Stagnancy of urine → bacteria have more time to multiply and adhere.
- Anatomical: BPH, urethral strictures, posterior urethral valves, ureteropelvic junction obstruction
- Neurological: neurogenic bladder (e.g. myelomeningocele, spinal cord injury, DM neuropathy)
- Functional: bladder and bowel dysfunction
Urinary Instrumentation [3][4]
- Bladder catheterization → direct introduction of bacteria, disruption of mucosal barrier.
- Risk of catheter-associated UTI (CAUTI) increases approximately 3–7% per day of catheterization.
Hormonal Factors [3][4]
- Oestrogen deficiency (postmenopausal): loss of oestrogen → loss of Lactobacilli → ↑vaginal pH → ↑colonization by uropathogens.
- This is why topical oestrogen reduces recurrent UTI by ~75% in RCTs [4].
Other Risk Factors
- Recurrent antimicrobial use → alteration of normal vaginal flora [3].
- Diabetes mellitus → glucosuria provides a rich bacterial growth medium; autonomic neuropathy can impair bladder emptying [5].
- Pregnancy → progesterone-mediated ureteral smooth muscle relaxation → ureteral dilatation and stasis; mechanical compression by the gravid uterus.
- Immunosuppression → reduced immune clearance.
Risk Factors for Recurrent UTI (≥2 per 6 months or ≥3 per 12 months) [3][4]
| Pre-menopausal | Post-menopausal |
|---|---|
| ↑Frequency of sexual intercourse | Oestrogen deficiency |
| New sexual partners | Urinary incontinence |
| Spermicide/diaphragm use | Post-voiding residual urine |
| ↓Urethra-to-anus distance | Presence of cystocele |
| Genetic susceptibility (↑vaginal cell bacterial adherence) | History of UTI before menopause |
| Prior antibiotic use (alters vaginal flora) | Genetic susceptibility |
| ↓Age of first UTI | |
| Family history |
Why Genetics Matter in Recurrent UTI
The intrinsic susceptibility of vaginal epithelial cells to bacterial adherence is genetically determined [4]. Some women express more receptors (e.g. P blood group antigens, Lewis non-secretor phenotype) that allow E. coli to bind more easily. This explains why some women get recurrent UTIs despite perfect hygiene and behaviour — it is fundamentally a host factor, not a hygiene issue.
Anatomy and Function of the Lower Urinary Tract
Understanding dysuria and frequency requires understanding the normal anatomy and physiology of micturition.
Bladder:
- Hollow muscular organ in the pelvis, lined by transitional epithelium (urothelium).
- Wall composed of the detrusor muscle (3 layers of smooth muscle — inner longitudinal, middle circular, outer longitudinal).
- Capacity ~400–600 mL.
- The trigone (triangular area between the two ureteral orifices and the internal urethral orifice) is particularly sensitive to inflammation — this is why cystitis causes suprapubic pain and urgency.
Urethra:
- Female: ~4 cm, straight, opens anterior to the vaginal introitus, close to the anus.
- Male: ~20 cm, divided into prostatic, membranous, bulbar, and penile segments. The prostate surrounds the prostatic urethra.
Prostate (Male):
- Walnut-sized gland surrounding the prostatic urethra, just below the bladder neck.
- Contains the transitional zone (where BPH arises) and peripheral zone (where prostate cancer arises).
- Enlargement of the transitional zone compresses the urethra → obstructive LUTS.
Sphincters:
- Internal urethral sphincter (smooth muscle, involuntary, sympathetic α₁-adrenergic control) at the bladder neck.
- External urethral sphincter (striated muscle, voluntary, somatic pudendal nerve S2–S4 control) at the membranous urethra.
Normal voiding involves a coordinated interplay between the pontine micturition centre (PMC), the sacral micturition centre (S2–S4), and the cortex:
-
Storage phase (sympathetic dominance):
- Sympathetic (T10–L2, hypogastric nerve):
- β₃-adrenergic receptors on detrusor → detrusor relaxation (bladder fills)
- α₁-adrenergic receptors on internal sphincter → sphincter contraction (continence)
- Somatic (S2–S4, pudendal nerve): tonic contraction of external sphincter
- Parasympathetic activity suppressed
- Sympathetic (T10–L2, hypogastric nerve):
-
Voiding phase (parasympathetic dominance):
- When bladder volume reaches ~200–300 mL, stretch receptors fire → signals via pelvic nerve to sacral cord → ascending signals to PMC → PMC activates voiding:
- Parasympathetic (S2–S4, pelvic nerve): muscarinic M₃ receptors on detrusor → detrusor contraction
- Sympathetic inhibited → internal sphincter relaxes
- Somatic pudendal nerve inhibited → external sphincter relaxes
- Coordinated: detrusor contracts while sphincters relax → urine expelled
- When bladder volume reaches ~200–300 mL, stretch receptors fire → signals via pelvic nerve to sacral cord → ascending signals to PMC → PMC activates voiding:
Why does this matter clinically?
- Drugs that block M₃ receptors (anticholinergics like oxybutynin) → reduce detrusor overactivity → treat urgency/frequency.
- Drugs that block α₁ receptors (like tamsulosin) → relax internal sphincter and prostatic smooth muscle → relieve obstruction in BPH.
- Drugs that stimulate β₃ receptors (like mirabegron) → relax detrusor → treat overactive bladder.
When the bladder mucosa (urothelium) or urethral mucosa is inflamed (by infection, chemical irritation, or mechanical injury):
- Dysuria: inflammatory mediators (prostaglandins, bradykinin, histamine) activate nociceptors in the urothelium and submucosal nerve endings → pain signals via pelvic nerve (Aδ and C fibres) to the sacral cord → perceived as burning/stinging during micturition, when the inflamed mucosa is stretched and contacted by urine.
- Frequency: inflammation lowers the sensory threshold for detrusor afferents → the brain receives "bladder full" signals at much lower volumes → patient voids small volumes frequently. Inflammatory mediators also stimulate local release of ATP and acetylcholine from the urothelium → premature detrusor contractions (detrusor overactivity) → urgency and frequency.
Etiology (Focus on Hong Kong)
The probability diagnosis for dysuria is UTI (especially cystitis), urethritis, urethral syndrome (abacterial cystitis in females), and vaginitis. [1]
The causes differ between sexes [1][2]:
| Female | Male |
|---|---|
| UTI (esp. cystitis) | UTI |
| Sexually transmitted diseases: vaginitis, urethritis | Urethritis: due to STD |
| Pelvic inflammatory disease | Acute/chronic prostatitis |
| Interstitial cystitis (painful bladder syndrome) | Bladder stones |
| Bladder stones | Epididymitis |
Neoplasia:
- Bladder cancer
- Prostate cancer
- Urethral cancer
Infection:
- Gonorrhoea
- Chlamydia/others
- Genital herpes
- Prostatitis
Other:
- Reactive arthritis (formerly Reiter's syndrome — the classic triad of urethritis + conjunctivitis + arthritis, often following urogenital Chlamydia or enteric infection)
- Calculi (e.g. bladder)
- Menopause syndrome — atrophic urethritis/vaginitis from oestrogen deficiency
- Adenovirus urethritis
- Prostatitis (especially chronic prostatitis, which can be very subtle)
- Foreign bodies in lower urinary tract
- Acidic urine (dietary causes — high-dose vitamin C, cranberry juice)
- Acute fever (can cause dysuria without UTI)
- Interstitial cystitis [1]
- Urethral caruncle/diverticuli [1]
- Vaginal prolapse [1]
Obstruction: [1]
- Benign prostatic hyperplasia
- Urethral stricture
- Phimosis
- Meatal stenosis
- Depression
- Diabetes (glucosuria → irritation; autonomic neuropathy → incomplete emptying → secondary UTI)
- Drugs (e.g. cyclophosphamide → haemorrhagic cystitis; SGLT2 inhibitors → glucosuria → genital infections)
- UTI
Is the patient trying to tell me something? [1]
- Consider psychosexual problems, anxiety and hypochondriasis.
Hong Kong Context
In Hong Kong:
- E. coli is the predominant uropathogen (~75% of uncomplicated UTI) but fluoroquinolone resistance is > 30% in community isolates — hence empirical fluoroquinolone use is increasingly problematic.
- ESBL-producing Enterobacteriaceae are increasingly common in complicated UTI, particularly in institutionalized elderly.
- Aristolochic acid exposure from certain traditional Chinese medicines is a recognized cause of chronic urothelial changes and urothelial carcinoma — always ask about TCM use.
- BPH is extremely common in the ageing male Hong Kong population and is a leading cause of frequency and secondary UTI.
- TB of the urinary tract should always be considered in Hong Kong (endemic area) — sterile pyuria with frequency and haematuria = TB until proven otherwise.
Etiology: Detailed Pathophysiology of Each Major Cause
1. Urinary Tract Infection (UTI) — The Most Common Cause
UTI = inflammatory response of the urothelium to invasion by bacteria or other pathogens, usually associated with bacteriuria and pyuria [4].
Important distinctions [4]:
| Term | Meaning | Pitfall |
|---|---|---|
| Bacteriuria | Presence of bacteria in urine | Does NOT equate infection — d/dx includes colonization and contamination |
| Pyuria | Presence of WBCs in urine | Indicative of infection/inflammation but does NOT equate infection — d/dx includes stones, cancer, TB, interstitial nephritis |
Common Exam Mistake
Students often equate bacteriuria with UTI. A positive urine culture alone does NOT mean UTI — you need clinical symptoms + significant bacteriuria + pyuria to diagnose UTI. Asymptomatic bacteriuria should NOT be treated except in pregnancy and before urological procedures.
| Uncomplicated UTI | Complicated UTI | Nosocomial UTI |
|---|---|---|
| E. coli (75%) | E. coli (65%) | E. coli (50%) |
| S. saprophyticus (6%) | Enterococcus spp (11%) | Pseudomonas spp |
| Klebsiella pneumoniae (6%) | Klebsiella pneumoniae (8%) | Citrobacter, Providencia, Serratia |
| Enterococcus spp (5%) | Candida spp (7%) | Enterobacter spp |
| S. agalactiae (3%) | S. aureus (3%) | CoNS |
| Proteus mirabilis (2%) | S. agalactiae, Proteus (2% each) | Can be polymicrobial |
| P. aeruginosa, S. aureus, Candida | P. aeruginosa (2%) |
Other organisms [3]:
- Viruses: Adenovirus (haemorrhagic cystitis, esp. in children and immunosuppressed), Enterovirus, Echovirus, Coxsackievirus
- Fungi: Candida (esp. catheterized/diabetic/immunosuppressed), Aspergillus, Cryptococcus neoformans
- Mycobacteria: M. tuberculosis (consider in sterile pyuria in Hong Kong!)
Route of infection:
- Ascending (commonest): rectum → periurethral area → urethra → bladder ± kidney [4]
- Facilitated by: indwelling catheter, vesicoureteral reflux, ureteral obstruction
- Haematogenous (uncommon): extrarenal source of bacteraemia (e.g. S. aureus endocarditis) → secondary infection of kidney [4]
- Examples: renal abscess from septic emboli, genitourinary TB
- Direct extension (unusual): spread from neighbouring suppurative infections (e.g. diverticulitis) [4]
- Uncommon because of the thick Gerota's fascia
Bacterial virulence factors (using E. coli as the prototype) [4]:
- Adhesins (pili/fimbriae): critical for mucosal adherence
- Type 1 (mannose-sensitive) pili (FimH): commonly expressed, found in majority of acute cystitis isolates → bind to mannose residues on bladder urothelium
- P pili (mannose-resistant, PapG): bind preferentially to upper tract urothelium → found in 80% of acute pyelonephritis isolates (this explains why some E. coli strains cause cystitis while others cause pyelonephritis)
- Type S pili: both bladder and kidney infection
- Dr adhesins: bind to complement regulatory protein DAF
- Toxins: haemolysin (HlyA) → forms pores in host cell membrane and RBC lysis
- Urease: breaks down urea → ammonia → alkalinizes urine → promotes struvite stone formation (classic for Proteus)
- Others: IgA-inactivating proteins, phasic variation of piliated state (immune evasion), siderophores (iron acquisition)
Host defense mechanisms [4]:
| Defense | Mechanism | What disrupts it |
|---|---|---|
| Normal vaginal flora (Lactobacilli) | Glycogen → lactic acid → low vaginal pH → hostile to uropathogens | Hypoestrogen, spermicides, antibiotics |
| Anterograde urine flow | Physical washout of bacteria | Obstruction, reflux |
| Urine characteristics | Normal pH, high osmolality, Tamm-Horsfall protein (saturates mannose-binding sites of type 1 pili) | Alkaline urine, dilute urine |
| Normal bladder emptying | Regular emptying prevents bacterial multiplication | BOO, neurogenic bladder, VUR |
| Urothelial innate immunity | Urothelial TLR4 recognizes LPS → activates innate immunity → ↑local PMNs, macrophages | Immunosuppression, catheter disruption |
| Exfoliation of urothelial cells | Infected superficial cells are shed into urine | Catheter biofilm |
| Feature | Uncomplicated UTI | Complicated UTI |
|---|---|---|
| Definition | UTI in a host with structurally + functionally normal urinary tract | UTI in a structurally/functionally abnormal urinary tract ± immunocompromised |
| Organisms | Usual uropathogens (70–95% E. coli) | Broader spectrum, often Rx-resistant |
| Treatment | Standard short-course antibiotics | Longer course, broader spectrum; must address the complicating factor |
| Examples of complicating factors | — | Obstruction (BPH, stones), catheter, VUR, neurogenic bladder, renal transplant, pregnancy, immunosuppression, DM |
- Isolated UTI: UTI separated from last episode by > 6 months
- Recurrent UTI: ≥2 per 6 months or ≥3 per 12 months, documented by negative culture between episodes
- Bacterial re-infection ( > 95% of recurrent UTIs in women): different organism each time; due to underlying host susceptibility (genetically determined → not amenable to correction)
- Bacterial persistence (rare but important): same organism persisting from a focus within the urinary tract (e.g. infected stone, diverticulum) → potentially correctable by removing the focus
- Asymptomatic bacteriuria
- Acute bacterial infections:
- Upper tract: pyelonephritis, pyonephrosis, renal abscess
- Lower tract: cystitis, prostatitis, epididymo-orchitis, urethritis/STDs
- Other infections: mycobacterial (TB), parasitic (schistosomiasis), fungal
Urethritis = inflammation of the urethra, most commonly caused by sexually transmitted organisms.
- Gonococcal urethritis (Neisseria gonorrhoeae): typically causes purulent urethral discharge + dysuria 2–5 days after exposure
- Non-gonococcal urethritis (Chlamydia trachomatis — most common; also Mycoplasma genitalium, Ureaplasma urealyticum): mucopurulent or clear discharge + dysuria, often more subtle
- Pathophysiology: organisms directly infect the urethral epithelium → mucosal inflammation → dysuria (pain as urine passes over inflamed mucosa) + discharge (from purulent exudate)
Diagnostic tip from Murtagh: "Urethritis causes pain at the onset of micturition and cystitis at the end" [1]. This is because in urethritis, the inflamed anterior urethra is the first structure contacted by the urine stream; in cystitis, it is the contraction of the inflamed bladder wall at the end of voiding that causes pain.
- Causes: Candida albicans (vulvovaginal candidiasis), Trichomonas vaginalis, bacterial vaginosis (Gardnerella vaginalis + anaerobes)
- External dysuria: urine passes over inflamed vulvar/vaginal mucosa → burning sensation that is external rather than internal (suprapubic)
- Clue: vaginal pruritus and discharge are prominent; true LUTS (frequency, urgency) are usually absent
- Acute bacterial prostatitis: systemic disturbance (fever, chills, malaise), deep pelvic/perineal pain ± obstructive symptoms (swollen inflamed prostate compresses urethra). The prostate is exquisitely tender on DRE (but vigorous prostatic massage is contraindicated in acute prostatitis → risk of bacteraemia) [2].
- Chronic bacterial prostatitis: can be subtle; recurrent UTI symptoms, low-grade fever, deep pain (pelvis, perineum, scrotum, especially during ejaculation), haematospermia ± obstructive symptoms [2].
- Chronic pelvic pain syndrome (CPPS, formerly "chronic non-bacterial prostatitis"): the most common form; pelvic pain without proven infection; poorly understood pathophysiology involving possible neurogenic inflammation, pelvic floor dysfunction.
Interstitial cystitis is a diagnosis of exclusion → chronic, refractory bladder symptoms and pain [2].
- Refers to chronic bladder pain without identifiable aetiology [2].
- Pathophysiology: poorly understood, likely multifactorial — defective glycosaminoglycan (GAG) layer on urothelium → increased urothelial permeability → urinary solutes (especially potassium) penetrate submucosal nerve endings → chronic pain and frequency.
- Predominantly affects women (9:1 F:M).
Definition: proliferation of stromal component in the transitional zone of the prostate [5].
Prostate starts to increase in size at age 40, usually becoming symptomatic at ~50 years old [5].
Pathophysiology [5]:
- Static component: stromal hyperplasia mediated by dihydrotestosterone (DHT) via 5α-reductase → physical compression of urethra → obstruction. This is the target of 5α-reductase inhibitors (5ARI, e.g. finasteride, dutasteride).
- Dynamic component: smooth muscle hypertrophy and contraction via α₁-adrenergic receptors → functional narrowing of prostatic urethra. This is the target of α₁-blockers (e.g. tamsulosin).
- Irritative component: detrusor instability/overactive bladder secondary to chronic obstruction (30–60% of BOO patients develop detrusor overactivity, likely due to ↑intravesical pressure → tissue ischaemia → smooth muscle injury and cholinergic denervation supersensitivity [2]).
Why BPH causes dysuria: obstruction leads to urinary stasis → ↑risk of secondary UTI → inflammation → dysuria. BPH can also cause mucosal inflammation from chronic distension.
Stones sitting in the bladder or lodged at the ureterovesical junction irritate the trigone and bladder mucosa → intense frequency, urgency, and dysuria. Terminal haematuria is classic (stone scrapes the bladder neck during voiding).
Classification
The traditional LUTS mnemonic is "FUN DISH" [3]:
| Phase | Type | Symptoms | Common Causes |
|---|---|---|---|
| Storage | Irritative | Frequency (尿频), Urgency (尿急) ± urge incontinence, Nocturia (夜尿) | Local: stone, UTI, tumour, post-RT; Regional: detrusor overactivity; Systemic: polyuria (DM, DI), ↑fluid intake |
| Voiding | Obstructive | Dribbling (尿末滴漏), Incomplete emptying (尿意未盡), Straining (谷), Hesitancy (等尿), Intermittent and weak stream (尿流斷續) | Outflow: BPH, CA prostate, urethral stricture; Bladder: hypocontractility (nerve/detrusor) |
The Hald Diagram
Three commonly confused concepts [2]:
- Bladder outlet obstruction (BOO): defined urodynamically (high detrusor pressure + low flow rate)
- LUTS: defined clinically (symptoms above) — can occur in females! LUTS ≠ BPH
- Benign prostatic enlargement (BPE): LUTS + clinically enlarged prostate on DRE
These three overlap but are NOT synonymous. Different treatments target different components. A man with a small prostate can still have BOO, and a man with a large prostate may not have significant symptoms.
Clinical Features
A. Symptoms (with Pathophysiological Basis)
- Description: burning, scalding, or stinging pain during urination
- Mechanism: inflammation of the urothelium/urethral mucosa → inflammatory mediators (PGE₂, bradykinin) sensitize submucosal nociceptors (C-fibres, Aδ-fibres) → pain is triggered when urine flow mechanically stretches the inflamed mucosa and/or when acidic/hyperosmolar urine contacts denuded epithelium
- Timing of pain matters [1]:
- "Urethritis causes pain at the onset of micturition and cystitis at the end" → because in urethritis the inflamed anterior urethra is the first structure contacted; in cystitis, detrusor contraction squeezing the inflamed bladder wall at the end of micturition causes terminal dysuria
- External dysuria: in vaginitis, the pain is perceived externally as urine splashes over inflamed vulvar mucosa — patients may describe it as "burning on the outside"
- Definition: patient's perception that they void too often during the day (typically > 7 voids/day)
- Mechanism in UTI/inflammation: mucosal inflammation → lowered sensory threshold of bladder afferents → brain receives "bladder full" signals at much smaller volumes → frequent voiding of small volumes. Also: inflammatory mediators stimulate local release of ATP from urothelium → premature detrusor contractions.
- Mechanism in BPH: incomplete emptying → large post-void residual → functional capacity reduced → frequent re-filling to sensation threshold. Also secondary detrusor overactivity from chronic obstruction.
- Mechanism in polyuria (DM/DI): increased urine production → bladder fills faster → frequency, but each void is a normal or large volume (distinguish from "true frequency" where each void is a small volume)
- Definition: sudden, compelling desire to pass urine that is difficult to defer
- Mechanism: identical to frequency — low threshold for sensory afferents + premature detrusor contractions from inflammation or detrusor overactivity → overwhelming sensation of needing to void immediately
- ± Urge incontinence: if detrusor contraction overwhelms sphincter resistance
- Definition: need to wake at night ≥1 time to void
- Mechanism: multifactorial —
- Nocturnal polyuria (loss of circadian ADH → excessive nocturnal urine production — especially in elderly, OSA, CHF)
- Reduced nocturnal bladder capacity (detrusor overactivity, BPH)
- Sleep disturbance (primary insomnia → patient notices bladder sensation)
- Peripheral oedema redistribution (CHF, venous insufficiency → lying supine → fluid mobilized → ↑renal perfusion → ↑nocturnal urine output)
- "Suprapubic discomfort is a feature of bladder infection (cystitis)" [1]
- Mechanism: inflammation of the bladder wall (especially the trigone) → visceral pain transmitted via pelvic nerve (S2–S4) → referred to the suprapubic region (dermatome overlap)
- Suggests upper tract involvement (pyelonephritis, ureteric colic)
- Mechanism: renal capsule distension from inflammation/obstruction → pain via sympathetic afferents → referred to the T10–L1 dermatomal distribution (loin, flank)
- Mechanism: inflammation → mucosal hyperaemia and erosion → bleeding from the richly vascularized submucosal plexus
- In BPH: ruptured dilated bladder neck veins [5]
- Gross or microscopic
- Mechanism: cloudiness = pyuria (WBCs) + bacteria; foul smell = bacterial metabolism of urea → ammonia + other volatile compounds
- Suggests STD (urethritis) or vaginitis rather than UTI
- Clinical pointer: +ve sexual history, discharge especially during morning void [2]
- Mechanism: in upper tract UTI (pyelonephritis), bacteria enter the renal parenchyma → activate systemic inflammatory response → cytokine release (IL-1, IL-6, TNF-α) → fever, rigors
- Cystitis should NOT cause fever or systemic upset — if present, think pyelonephritis, prostatitis, or epididymitis [4]
- "Strangury" = painful, frequent urination of small volumes expelled slowly only by straining despite severe urgency with a feeling of incomplete emptying
- Classic for bladder/urethral stones
B. Signs (with Pathophysiological Basis)
- Vital signs: fever (upper tract UTI, prostatitis, epididymitis), tachycardia (sepsis)
- General appearance: well (simple cystitis) vs toxic (pyelonephritis, urosepsis)
- Suprapubic tenderness: bladder wall inflammation (cystitis) or distended bladder (retention)
- Palpable bladder: suggests urinary retention (AROU or CROU)
- Renal angle/loin tenderness (Murphy's kidney punch): pyelonephritis, renal abscess, obstructed infected kidney
- Female:
- Dry atrophic urethral opening → atrophic urethritis/vaginitis (menopause) [1]
- Urethral caruncle (small, red, fleshy mass at urethral meatus) → can cause dysuria [1]
- Urethral prolapse [1]
- Vaginal discharge → vaginitis/STD
- Cystocele → prolapse of bladder into vagina → incomplete emptying → recurrent UTI
- Male:
This is essential in any male with LUTS:
| Finding | Suggests |
|---|---|
| Smooth, symmetrically enlarged > 3 finger-breadths, non-tender, median sulcus present, anal tone intact | BPH [5] |
| Asymmetrically enlarged, irregular, hard nodule, median sulcus lost | Prostate cancer [5] |
| Exquisitely tender, boggy, swollen prostate | Acute prostatitis (vigorous massage contraindicated) |
| Mildly tender prostate | Chronic prostatitis |
| Normal prostate | Does not exclude BOO (small prostate can still obstruct) |
| Reduced anal tone | Neurogenic cause (cauda equina, sacral nerve lesion) |
Key history questions [1]:
- "Could you describe the discomfort?" — burning, stinging, external vs internal
- "What colour is your urine?" — cloudy (pyuria), red/pink (haematuria)
- "Does it have a particular odour?" — foul-smelling (bacterial UTI)
- "Have you noticed a discharge?" — urethral/vaginal discharge → STD
- "If so, could it be sexually acquired?"
- "Do you find intercourse painful or uncomfortable (women)?" — vaginitis, interstitial cystitis
- "Have you any fever, sweats or chills?" — upper tract infection, prostatitis
Additional important questions:
- Onset, duration, severity of symptoms
- LUTS symptoms: obstructive (DISH) + irritative (FUN) [2]
- Previous episodes: recurrent UTI? Pattern?
- Sexual history: new partner, unprotected intercourse, number of partners
- Menstrual/menopausal status: atrophic changes in postmenopausal
- PMHx: DM, neurological diseases, stones, previous urological surgery
- Drug history: anticholinergics, sympathomimetics, recent antibiotics, SGLT2 inhibitors
- Bladder diary for ≥3 days if frequency/nocturia is prominent [2][5]
Key examination [1]:
- General inspection looking for evidence of kidney disease and vital signs
- Abdominal palpation to focus on the loins and suprapubic areas
- The possibility of STIs should be considered and this includes vaginal examination in the female and rectal and genital examination in the male
- In the menopausal female, the cause may be evident from a dry atrophic urethral opening, a urethral caruncle, or urethral prolapse
High Yield Diagnostic Tips from Murtagh [1]:
- "Urethritis causes pain at the onset of micturition and cystitis at the end."
- "Suprapubic discomfort is a feature of bladder infection (cystitis)."
- "Unexplained dysuria could be a pointer to chlamydia urethritis."
High Yield Summary
-
Dysuria = painful urination (burning/scalding/stinging); frequency = voiding too often. Together they strongly suggest lower urinary tract inflammation, most commonly UTI (esp. cystitis).
-
Dysuria is NOT grouped under LUTS headings — it indicates infection/inflammation specifically, while frequency is a storage (irritative) LUTS.
-
UTI is the result of host-pathogen interaction: ascending route is commonest; E. coli causes 75% of uncomplicated UTI; virulence factors (Type 1 pili for cystitis, P pili for pyelonephritis) determine clinical syndrome.
-
Probability diagnoses: UTI, urethritis, urethral syndrome (abacterial cystitis), vaginitis.
-
Serious disorders not to be missed: bladder/prostate/urethral cancer, gonorrhoea, chlamydia, genital herpes, prostatitis, reactive arthritis, calculi.
-
Pitfalls: menopause syndrome, adenovirus urethritis, chronic prostatitis, foreign bodies, acidic urine, interstitial cystitis.
-
Female vs Male differential: Female → UTI, vaginitis, PID, interstitial cystitis, stones. Male → UTI, STD urethritis, prostatitis (acute/chronic), stones, epididymitis.
-
DRE is essential in males: smooth enlarged prostate = BPH; hard irregular nodule = cancer; tender boggy = acute prostatitis.
-
BPH pathophysiology: static (DHT-mediated stromal hyperplasia → 5ARI) + dynamic (α₁-receptor smooth muscle → α₁-blockers) + irritative (secondary detrusor overactivity).
-
Timing of dysuria: onset = urethritis; terminal = cystitis. Unexplained dysuria → think Chlamydia.
-
Cystitis should NOT cause fever — fever with dysuria = think upper tract (pyelonephritis) or prostatitis.
Active Recall - Dysuria and Urinary Frequency
[1] Lecture slides: murtagh merge.pdf (p40–42, Dysuria) [2] Senior notes: Ryan Ho Urogenital.pdf (p121–126, Dysuria and UTI sections) [3] Senior notes: felixlai.md (UTI, LUTS, AROU sections) [4] Senior notes: Ryan Ho Urogenital.pdf (p122–126, UTI pathogenesis, microbiology, classification) [5] Senior notes: maxim.md (LUTS and BPH section)
Differential Diagnosis of Dysuria and Urinary Frequency
The differential diagnosis of dysuria and frequency is best organised by asking three sequential questions:
- Is this infective or non-infective? — most cases are infective (UTI, STD, prostatitis).
- Where is the pathology? — lower urinary tract (bladder, urethra, prostate) vs upper tract (kidney, ureter) vs extra-urinary (vagina, pelvis).
- Is there a structural or functional abnormality? — obstruction (BPH, stricture, stone), neurogenic (OAB, neurogenic bladder), or mucosal disease (interstitial cystitis, malignancy, atrophy).
This framework ensures you don't miss anything — from the common to the dangerous.
Master Differential Diagnosis Table
The following table integrates the Murtagh's diagnostic strategy [1] with the senior notes differentials [2][3][4][5]:
| Female | Male |
|---|---|
| UTI (esp. cystitis) [1][2] | UTI [1][2] |
| Sexually transmitted diseases: vaginitis, urethritis [1][2] | Urethritis: due to STD [1][2] |
| Pelvic inflammatory disease [1][2] | Acute/chronic prostatitis [1][2] |
| Interstitial cystitis (painful bladder syndrome) [1][2] | Bladder stones [1][2] |
| Bladder stones [1][2] | Epididymitis [2] |
| Category | Differentials | Why it causes dysuria/frequency |
|---|---|---|
| Probability diagnosis | UTI (esp. cystitis) | Bacterial invasion of urothelium → inflammation → nociceptor activation during voiding; ↓sensory threshold → frequency |
| Urethritis | Urethral mucosal inflammation (gonococcal or non-gonococcal) → pain on urine contact; "urethritis causes pain at the onset of micturition" [1] | |
| Urethral syndrome — abacterial cystitis (female) | Irritative urethral/bladder symptoms with sterile cultures; poorly understood — may involve subclinical infection (Chlamydia, Ureaplasma), local inflammation, or pelvic floor dysfunction | |
| Vaginitis | External dysuria — urine splashes over inflamed vulvar/vaginal mucosa (Candida, Trichomonas, BV); vaginal pruritus and discharge distinguish this from true UTI | |
| Serious disorders not to be missed | Neoplasia: bladder, prostate, urethra | Tumour erodes urothelium → chronic irritation and inflammation → frequency, dysuria, haematuria. Bladder cancer classically presents with painless haematuria but can cause irritative LUTS [4][6] |
| Infection: gonorrhoea, chlamydia/others, genital herpes, prostatitis | Direct mucosal infection → inflammation; genital herpes causes vesicular lesions on urethral/vulvar mucosa → exquisite pain on urine contact | |
| Reactive arthritis | Post-infectious immune-mediated sterile urethritis (typically post-Chlamydia or enteric infection) → dysuria occurs as part of the classic triad: urethritis + conjunctivitis + arthritis | |
| Calculi (e.g. bladder) | Stone mechanically irritates trigone/bladder mucosa → frequency, urgency, dysuria, terminal haematuria; VUJ stones trigger irritative LUTS by stimulating bladder afferents [3][5] | |
| Pitfalls (often missed) | Menopause syndrome | Oestrogen deficiency → urethral/vaginal mucosal atrophy → dry, friable tissue → chronic irritation and dysuria; "In the menopausal female the cause may be evident from a dry atrophic urethral opening, a urethral caruncle or urethral prolapse" [1] |
| Adenovirus urethritis | Viral urethritis — particularly in children and immunosuppressed; haemorrhagic cystitis with adenovirus types 11 and 21 | |
| Prostatitis | Especially chronic prostatitis which is subtle — "can be subtle, a/w recurrent UTI symptoms, low-grade fever, deep pain (in pelvis, perineum, scrotum, and esp if during ejaculation), haematospermia ± obstructive symptoms" [2] | |
| Foreign bodies in lower urinary tract | Mechanical irritation of urothelium → chronic inflammation → frequency, dysuria; think forgotten stent, retained catheter fragment, deliberate insertion | |
| Acidic urine | Low urinary pH (dietary: high-dose vitamin C, cranberry juice) → chemical irritation of urothelium | |
| Acute fever | Concentrated, acidic urine in febrile illness → transient dysuria without true UTI | |
| Interstitial cystitis | Dx of exclusion → chronic, refractory bladder symptoms and pain [2]; defective GAG layer → urinary solutes penetrate submucosa → chronic pain | |
| Urethral caruncle/diverticuli | Caruncle: vascular, polyp-like growth at urethral meatus (postmenopausal women) → tender, bleeds on contact; diverticulum: outpouching of urethra → collects urine → secondary infection → dysuria and post-void dribbling | |
| Vaginal prolapse | Cystocele → incomplete bladder emptying → stasis → secondary UTI → frequency and dysuria | |
| Obstruction | Benign prostatic hyperplasia | Static (DHT-mediated stromal compression) + dynamic (α₁-receptor smooth muscle tone) → BOO → stasis → secondary UTI → dysuria; also secondary detrusor overactivity → frequency [5] |
| Urethral stricture | Fibrotic narrowing of urethra (post-instrumentation, post-infection, post-trauma) → obstructive symptoms + stasis → secondary infection | |
| Phimosis | Tight foreskin → partial urethral obstruction + difficult hygiene → ↑bacterial colonization | |
| Meatal stenosis | Narrowed urethral meatus (post-circumcision in boys, post-catheterisation) → obstructive symptoms | |
| Masquerades checklist | Depression | Somatisation of psychiatric distress as urinary symptoms |
| Diabetes | Glucosuria → osmotic diuresis → polyuria/frequency; also rich growth medium for bacteria → recurrent UTI; autonomic neuropathy → incomplete emptying → stasis | |
| Drugs | Cyclophosphamide → haemorrhagic cystitis (acrolein metabolite); SGLT2 inhibitors → glucosuria → genital candidiasis; anticholinergics → retention → secondary UTI; α-agonists → ↑sphincter tone → retention | |
| UTI | Always reconsider UTI as the underlying cause | |
| Psychosocial | Psychosexual problems, anxiety, hypochondriasis | "Is the patient trying to tell me something? Consider psychosexual problems, anxiety and hypochondriasis." [1] |
Key Principle
"It is important to determine whether dysuria is really genitourinary in origin and not attributable to functional disorders, such as psychosexual problems. Disturbances of micturition are uncommon in the young male and if present suggest sexually transmitted infection (STIs)." [1]
Expanded Differential of Frequency (with or without dysuria)
| Category | Differentials | Why |
|---|---|---|
| Bladder outlet obstruction (predominantly voiding symptoms) | BPH, CA prostate, urethral stricture, bladder neck contracture, bladder stones, bladder cancer, interstitial cystitis, ketamine cystitis [3] | Physical or dynamic obstruction → incomplete emptying → ↓functional capacity → frequency; stasis → secondary UTI → dysuria |
| Overactive bladder (predominantly storage symptoms) | Neurogenic: stroke, PD, MS, SCI, TBI, NPH [3] | Loss of cortical/pontine inhibition of sacral micturition reflex → uninhibited detrusor contractions |
| Non-neurogenic: idiopathic, secondary to BOO, bladder pathology (cystitis, tumour, stones, FB), drugs [3][2] | Chronic BOO → ↑intravesical pressure → tissue ischaemia → smooth muscle injury and cholinergic denervation supersensitivity → detrusor overactivity [2] | |
| Polyuria | DM (osmotic diuresis), DI (↓ADH or renal insensitivity), polydipsia, hypercalcaemia, CKD (loss of concentrating ability) | Increased urine production → bladder fills faster → frequency with normal or large volume per void (unlike "true frequency" where volumes are small) |
| System | Cause | Mechanism |
|---|---|---|
| Respiratory | Obstructive sleep apnoea | Difficulty with sleep maintenance + loss of diurnal variation in ADH release → nocturnal polyuria |
| Cardiovascular | Hypertension, CHF, peripheral oedema | Supine position → mobilisation of peripheral oedema → ↑venous return → ↑renal perfusion → ↑nocturnal urine output; also ↑ANP release → natriuresis |
| Urological | UTI, BPH, CA prostate | Inflammation → ↓bladder capacity; obstruction → incomplete emptying; same mechanisms as above |
| Endocrine | DM, DI | DM: osmotic diuresis from glucosuria; DI: loss of diurnal variation or deficiency of vasopressin (ADH) → nocturnal polyuria |
This is critical for exams. When a patient presents with dysuria ± frequency, the associated features point you to the diagnosis [1][2][6]:
| Diagnosis | Key Clinical Pointers |
|---|---|
| UTI (cystitis) | Storage LUTS, turbid/bloody urine, suprapubic pain ± loin pain, fever, chills (if upper tract) [2]; "Suprapubic discomfort is a feature of bladder infection (cystitis)" [1]; cystitis should NOT cause fever/systemic upset — if present, think pyelonephritis [4] |
| STDs (urethritis/vaginitis) | +ve sexual Hx, urethral/vaginal discharge (esp during morning void) [2]; "Unexplained dysuria could be a pointer to chlamydia urethritis" [1] |
| Acute prostatitis | Systemic disturbance (fever, chills, malaise), deep pelvic/perineal pain ± obstructive symptoms (with acute swollen prostate) [2]; DRE: exquisitely tender, boggy prostate |
| Chronic prostatitis | Subtle, a/w recurrent UTI symptoms, low-grade fever, deep pain (in pelvis, perineum, scrotum, and esp if during ejaculation), haematospermia ± obstructive symptoms [2] |
| Acute epididymitis | Storage LUTS + unilateral testicular pain + high fever/rigors [2] |
| Interstitial cystitis | Dx of exclusion → chronic, refractory bladder symptoms and pain [2]; middle-aged women, symptoms worsened by bladder filling and relieved by voiding |
| Bladder stone | Frequency, urgency, dysuria with terminal haematuria; symptoms worse with movement/exercise (stone shifts and irritates trigone); strangury (painful, frequent small-volume voids with straining) [2][5] |
| BPH | Typical age 50-80; LUTS with obstructive > > irritative symptoms [5]; DRE: smooth enlarged > 3FB, non-tender, median sulcus present |
| CA prostate | Obstructive LUTS (late — arises in peripheral zone so doesn't obstruct early); hard, irregular prostate with loss of median sulcus on DRE; ↑PSA; bone pain if metastatic [5][6] |
| CA bladder | Painless haematuria (classic); irritative LUTS; constitutional symptoms; risk factors: smoking, occupational exposure, aristolochic acid (TCM) [4][6] |
| Pyelonephritis | Systemic upset (high fever > 39°C, rigors), flank pain, renal angle tenderness, Murphy's kidney punch +ve; preceded by irritative urinary symptoms [4][7] |
| Urolithiasis at VUJ | Colicky loin-to-groin pain + irritative LUTS (frequency, urgency, dysuria) when stone is at the vesicoureteric junction → stone irritates bladder trigone afferents [3][5] |
| Atrophic urethritis/vaginitis | Postmenopausal woman; dry, atrophic urethral opening; ± urethral caruncle; chronic low-grade dysuria and frequency [1] |
| Colovesical fistula | Pneumaturia, fecaluria, dysuria (recurrent UTI); history of diverticular disease or colorectal malignancy [7][8] |
| Gonococcal vs non-gonococcal urethritis | GC: profuse, purulent discharge, dysuria within 4 days, greater extent; NGC: mucoid, scanty discharge, dysuria over 1–5 weeks (peak 2–3 weeks), lesser extent [6] |
Exam Pearl: Gonococcal vs Non-Gonococcal Urethritis
The character and timing of discharge is the key differentiator [6]:
- Gonococcal: profuse, purulent, rapid onset (within 4 days), more severe dysuria
- Non-gonococcal (Chlamydia): mucoid, scanty, slower onset (1–5 weeks, peak at 2–3 weeks), milder dysuria
Remember: "Unexplained dysuria could be a pointer to chlamydia urethritis" [1] — Chlamydia is easily missed because the discharge is subtle and the patient may not notice it.
| Category | Causes |
|---|---|
| Physiological | Sexual arousal, prostatorrhoea/spermatorrhoea, phosphaturia |
| STDs | Gonorrhoea; Non-gonococcal: Chlamydia trachomatis, Mycoplasma genitalium, Ureaplasma urealyticum, Trichomonas vaginalis, Candida, HSV; or BOTH |
| Non-STDs | Bacterial urethritis/prostatitis; phimosis with poor hygiene; catheterisation and instrumentation; allergy (SJS); irritants (alcohol, caffeine, physical trauma); foreign bodies |
Don't forget causes outside the urinary tract that can mimic or cause dysuria/frequency:
| Source | Condition | Mechanism |
|---|---|---|
| GI tract | Acute diverticulitis adjacent to bladder | Pericolic inflammation irritates bladder serosa → frequency, urgency, dysuria; if fistula forms (colovesical) → pneumaturia, fecaluria, recurrent UTI [7][8] |
| GI tract | Acute appendicitis (pelvic appendix) | Inflamed appendix lying on bladder → referred frequency and dysuria [7] |
| Gynaecological | PID, endometriosis | Pelvic inflammation → irritation of bladder peritoneum; endometriotic implants on bladder → cyclical dysuria |
| Gynaecological | Ectopic pregnancy | Pelvic haematoma → bladder irritation |
| Neurological | MS, spinal cord lesion, stroke | Loss of supraspinal inhibition → neurogenic detrusor overactivity → frequency, urgency |
| Drug-related | Cyclophosphamide, ifosfamide | Acrolein metabolite → haemorrhagic cystitis → severe dysuria, frequency, haematuria [4] |
| Drug-related | SGLT2 inhibitors | Glucosuria → genital candidiasis → external dysuria; osmotic diuresis → frequency |
| Radiation | Post-pelvic RT (cervix, rectum, prostate) | Radiation cystitis → chronic mucosal inflammation and fibrosis → frequency, dysuria, haematuria [4] |
| Patient Profile | Most Likely | Don't Miss |
|---|---|---|
| Young woman (18–35), sexually active | Acute cystitis, vaginitis | Chlamydia urethritis, PID |
| Postmenopausal woman | UTI (recurrent), atrophic urethritis | CA bladder, interstitial cystitis |
| Young man (18–35) | STD urethritis (GC/NGC) | Reactive arthritis, acute prostatitis |
| Older man ( > 50) | BPH with secondary UTI | CA prostate, CA bladder |
| Child | UTI (esp. if febrile without focus) | VUR, posterior urethral valves, neurogenic bladder |
| Immunocompromised/catheterised | Complicated UTI (broad-spectrum organisms) | Fungal UTI (Candida), adenoviral haemorrhagic cystitis |
| History of TCM use (Hong Kong) | UTI | Urothelial carcinoma (aristolochic acid nephropathy) |
| Ketamine user (Hong Kong) | Ketamine cystitis [3] | Contracted bladder, upper tract damage |
Ketamine Cystitis — Hong Kong-Specific Pitfall
Ketamine abuse is a significant problem in Hong Kong. Ketamine and its metabolites (norketamine) are directly toxic to the urothelium → severe chemical cystitis → markedly contracted bladder (capacity may drop to < 50 mL) → extreme frequency (voiding every 15–30 minutes), severe dysuria, haematuria. In advanced cases, upper tract involvement with hydronephrosis and renal impairment occurs. Always ask about recreational drug use in young patients with refractory frequency.
The key discriminating features when facing dysuria ± frequency:
| Feature | Think... |
|---|---|
| Discharge (urethral/vaginal) | STD / vaginitis |
| Fever + systemic upset | Upper tract (pyelonephritis) or prostatitis |
| Suprapubic pain, no fever | Cystitis [1] |
| Loin pain | Pyelonephritis, ureteric stone |
| Terminal haematuria + movement-related symptoms | Bladder stone |
| Obstructive LUTS | BPH, CA prostate, urethral stricture |
| Painless haematuria + irritative LUTS + age > 35 | CA bladder — until proven otherwise |
| Chronic refractory symptoms, cultures negative | Interstitial cystitis, TB, ketamine cystitis |
| Postmenopausal, dry atrophic mucosa | Atrophic urethritis/vaginitis |
| Perineal pain, tender prostate | Prostatitis |
| Pneumaturia, fecaluria | Colovesical fistula (diverticular disease/CRC) |
| Sterile pyuria | TB of urinary tract, interstitial nephritis, stones, cancer |
Sterile Pyuria — Always Think TB in Hong Kong
Sterile pyuria (WBCs in urine but negative standard culture) is a classic finding in genitourinary tuberculosis. In Hong Kong, an endemic area, always send 3 early morning urine specimens for AFB smear and mycobacterial culture when you see persistent sterile pyuria with frequency/dysuria/haematuria that doesn't respond to standard antibiotics.
High Yield Summary
Probability diagnoses for dysuria: UTI (cystitis), urethritis, urethral syndrome, vaginitis.
Serious disorders not to miss: CA bladder/prostate/urethra, gonorrhoea, chlamydia, genital herpes, prostatitis, reactive arthritis, calculi.
Pitfalls: menopause syndrome, adenovirus urethritis, chronic prostatitis, foreign bodies, acidic urine, acute fever, interstitial cystitis, urethral caruncle, vaginal prolapse.
Sex-specific DDx: Female → UTI, vaginitis, PID, interstitial cystitis, stones. Male → UTI, STD urethritis, prostatitis, stones, epididymitis.
Key clinical discriminators: Discharge = STD; Fever = upper tract/prostatitis; Suprapubic pain without fever = cystitis; Obstructive LUTS = BPH/prostate cancer/stricture; Chronic refractory + sterile cultures = interstitial cystitis/TB/ketamine cystitis; Painless haematuria + age > 35 = malignancy until proven otherwise.
Timing of dysuria: Onset = urethritis; Terminal = cystitis.
Gonococcal vs NGC: Profuse purulent rapid = GC; Mucoid scanty slow = NGC (Chlamydia).
Hong Kong specifics: Ketamine cystitis in young recreational drug users; genitourinary TB with sterile pyuria; aristolochic acid urothelial CA from TCM; high fluoroquinolone resistance in community E. coli.
Active Recall - Differential Diagnosis of Dysuria and Frequency
References
[1] Lecture slides: murtagh merge.pdf (p40–42, Dysuria) [2] Senior notes: Ryan Ho Fundamentals.pdf (p346, Dysuria; p354–355, LUTS) [3] Senior notes: felixlai.md (LUTS differential diagnosis, nocturia differential, urolithiasis) [4] Senior notes: Ryan Ho Urogenital.pdf (p121–128, Dysuria and UTI sections; p130–132, Haematuria approach) [5] Senior notes: maxim.md (LUTS and BPH section, urolithiasis, irritative LUTS approach) [6] Senior notes: Ryan Ho Urogenital.pdf (p248, Urethritis differential and approach) [7] Senior notes: Ryan Ho GI.pdf (p151, Appendicitis DDx; p157, Acute diverticulitis) [8] Senior notes: felixlai.md (Diverticulitis complications — colovesical fistula)
Diagnostic Criteria
UTI is fundamentally a clinical diagnosis supported by laboratory confirmation. There is no single pathognomonic test. The diagnosis requires the combination of [4][9]:
- Clinical symptoms and signs (dysuria, frequency, urgency, suprapubic pain, ± systemic upset)
- Urinalysis (gross inspection, dipstick, microscopy)
- Urine culture and sensitivity (C/ST) — the definitive confirmatory test
The reason you need all three is that each component alone has limitations:
- Symptoms alone → other conditions mimic UTI (vaginitis, urethritis, interstitial cystitis)
- Positive dipstick alone → can be contamination or asymptomatic bacteriuria
- Positive culture alone → asymptomatic bacteriuria (not UTI unless symptomatic)
The threshold for "significant bacteriuria" depends on the method of urine collection and the clinical context — this is because different collection methods have different contamination risks [3][4]:
| Collection Method | Threshold for Significant Bacteriuria | Rationale |
|---|---|---|
| Midstream urine (MSU) — Female | ≥ 10⁵ CFU/mL (≥ 100,000) of a single organism | Higher threshold needed because MSU in females is prone to contamination from vaginal/perineal flora |
| MSU — Male | ≥ 10³ CFU/mL (≥ 1,000) | Lower threshold because contamination is less common in males; UTI in males is unusual and warrants attention [4] |
| Catheter specimen | ≥ 10² CFU/mL (≥ 100) | Direct bladder sampling reduces contamination risk |
| Suprapubic aspiration (SPA) | Any growth (even 1 CFU/mL) | SPA bypasses all potential contamination sources — any bacteria found must have come from the bladder [3] |
Why Different Thresholds?
The concept of "significant bacteriuria" was established by Kass in the 1950s. The ≥10⁵ threshold for MSU in women was chosen because it best discriminated true bladder infection from perineal contamination (sensitivity ~95%, specificity ~95% for a single specimen). However, in symptomatic women, as few as 10² CFU/mL may represent true infection — the EAU and IDSA guidelines accept ≥10³ CFU/mL in symptomatic acute uncomplicated cystitis. The key message: always interpret culture results in the clinical context.
- Pyuria = > 5 WBC per high-power field (HPF) on centrifuged urine microscopy, OR > 10 WBC/mm³ on uncentrifuged urine [4][9]
- Pyuria is present in virtually all symptomatic UTI — absence of pyuria strongly argues against UTI
- However, pyuria does NOT equate infection — other causes include stones, cancer, TB, interstitial nephritis, and any urinary tract inflammation [4]
- Urethral swab Gram stain: urethritis diagnosed when ≥ 5 PMN per HPF (examine 5 fields of most PMN under HPF, average the count) [6]
- ± Intracellular Gram-negative diplococci = diagnostic of gonorrhoea [6]
- First-catch urine microscopy: urethritis diagnosed if centrifuged sediment > 10 WBC per HPF [6]
- NAAT for Chlamydia trachomatis and Neisseria gonorrhoeae on first-catch urine or urethral swab is the confirmatory test
Overactive bladder (OAB) is a clinical diagnosis made after excluding infection, stones, and tumour [5]:
- Bladder diary: frequent voiding of small volumes (typically > 8 voids/day, each < 200 mL)
- Normal prostate on DRE
- Good flow rate on uroflowmetry (excludes BOO as the cause)
- Exclude infection (negative urine C/ST), stone, and tumour
BPH is diagnosed by a combination of:
- Clinical: LUTS (obstructive > > irritative) in a male aged 50–80 [5]
- DRE: smooth, enlarged > 3 finger-breadths, non-tender, median sulcus present, anal tone intact [5]
- IPSS: quantifies severity — mild (1–7), moderate (8–19), severe (20–35) [2][3]
- Uroflowmetry: peak flow rate (Qmax) < 15 mL/sec is diagnostic of obstruction; < 10 mL/sec is prognostic (better outcome after TURP) [5]
- Post-void residual volume: < 150 mL [5]
Diagnostic Algorithm
| Clinical Scenario | Investigations Needed | Why |
|---|---|---|
| Uncomplicated cystitis in young woman | Dipstick ± microscopy; C/ST optional (empirical Rx acceptable) | Predictable microbiology (E. coli 75%); short-course antibiotics highly effective; culture reserved for treatment failure or recurrence [4] |
| Complicated UTI / Male UTI | Dipstick + microscopy + C/ST mandatory | Broader spectrum of organisms, ↑resistance risk; need sensitivity data to guide therapy [4] |
| Recurrent UTI | C/ST + imaging (USG ± CT) ± cystoscopy | Must r/o focus of bacterial persistence (stone, diverticulum), obstruction, or anatomical abnormality [4][5] |
| Suspected STD | Urethral swabs or first-pass urine for STIs [1]; NAAT for GC + CT | Urine C/ST will be negative; need specific STD testing |
| Male with LUTS | IPSS + voiding diary + DRE + urinalysis + C/ST + uroflowmetry + RFT + PSA | Comprehensive evaluation because LUTS ≠ BPH; must exclude cancer, infection, neurogenic causes [2] |
| Sterile pyuria | EMU × AFB (3 early morning urines for mycobacterial culture), urine cytology, cystoscopy | Must r/o TB (especially in Hong Kong), cancer, interstitial nephritis [9] |
| Suspected pyelonephritis | Bloods (CBC, RFT, CRP/ESR, blood cultures), urine C/ST, imaging (USG ± CT) | Assess systemic severity; r/o obstruction (pyonephrosis) which requires urgent drainage |
Investigation Modalities — Detailed
Key investigations: dipstick testing of the urine [1]
| Parameter | What it Detects | Interpretation | Mechanism of Test |
|---|---|---|---|
| Leukocyte esterase | WBCs (pyuria) | Sensitivity ~75–96%, Specificity ~94–98% for UTI | Enzyme released from lysed neutrophils → reacts with substrate on dipstick → colour change |
| Nitrite | Gram-negative bacteria (especially Enterobacteriaceae) | Sensitivity ~22–44% (many false negatives!), Specificity ~92–100% | Bacteria reduce dietary nitrate to nitrite; requires ≥4 hours urine dwell time in bladder for conversion; NOT all organisms produce nitrite — Enterococcus, S. saprophyticus, and many others do NOT |
| Blood (haemoglobin) | RBCs, free haemoglobin, myoglobin | Present in UTI, stones, cancer, glomerular disease | Peroxidase activity of haemoglobin catalyses oxidation of chromogen |
| Protein | Albuminuria | If significant → think glomerular disease, not simple UTI | Tetrabromophenol blue indicator |
| Glucose | Glucosuria | Suggests diabetes (osmotic diuresis → frequency) | Glucose oxidase reaction |
| pH | Urine acidity/alkalinity | Alkaline urine with UTI → think Proteus (urease-producing organism); acidic urine → chemical irritation as cause of dysuria | pH indicator |
Dipstick Pearl
A negative nitrite does NOT exclude UTI. Nitrite is only produced by Gram-negative bacteria that possess nitrate reductase (e.g. E. coli, Klebsiella, Proteus). Enterococcus, S. saprophyticus, Candida, and Pseudomonas do NOT produce nitrite. Also, if the patient is voiding frequently (urine doesn't dwell ≥4 hours), there is insufficient time for nitrate-to-nitrite conversion → false negative. The most useful dipstick parameter is leukocyte esterase — if both LE and nitrite are negative, the negative predictive value for UTI is very high ( > 95%).
Key investigations: microscopy or culture (midstream specimen of urine or suprapubic puncture in children) [1]
| Finding | Significance | Threshold |
|---|---|---|
| WBC (pyuria) | Inflammation/infection of urinary tract | > 5 WBC/HPF on centrifuged specimen, or > 10 WBC/mm³ on uncentrifuged [4][9] |
| RBC | Haematuria — UTI, stone, cancer, glomerular disease | ≥ 3 RBC/HPF in 2 of 3 properly collected specimens = microscopic haematuria [5] |
| RBC morphology | Dysmorphic RBCs / RBC casts → glomerular origin; Isomorphic RBCs → urological origin (post-renal) | Key discriminator — glomerular bleeding produces deformed RBCs as they pass through damaged GBM [9] |
| Bacteria | Bacteriuria — but may be contamination | Should prompt culture |
| Epithelial cells | > 5 squamous epithelial cells/HPF → likely contamination | Specimen should be repeated with proper technique |
| Casts | WBC casts → pyelonephritis or interstitial nephritis (localises inflammation to renal tubules); RBC casts → glomerulonephritis | Casts form in renal tubules — their presence localises the pathology to the kidney |
| Crystals | Calcium oxalate (envelope-shaped), uric acid (rhomboid/rosette), struvite (coffin-lid), cystine (hexagonal) | May suggest underlying stone disease |
This is the gold-standard confirmatory test for UTI [3][4].
Interpretation:
- Single organism at significant colony count (see thresholds above) = significant bacteriuria
- Mixed flora (≥ 3 organisms) = contamination → repeat specimen
- No growth with pyuria = sterile pyuria → consider TB, Chlamydia, stones, cancer, interstitial nephritis, or recent antibiotic use [4][9]
Sensitivity testing guides antibiotic choice, critical in:
- Complicated UTI
- Treatment failure
- Recurrent UTI
- Hospital-acquired UTI (↑resistance rates)
This is a high-yield topic — the method of collection determines the validity of the culture result.
| Method | Technique | Use | Advantages | Disadvantages |
|---|---|---|---|---|
| Bag urine | Adhesive bag applied to perineum | Send for urinalysis ONLY (visual + chemical + microscopic) | Non-invasive | Do NOT send for culture — prone to contamination [3] |
| Midstream urine (MSU) | Discard initial stream, collect midstream | Commonest method; can send for urinalysis AND culture | Non-invasive | Prone to contamination, especially in females; NOT applicable in young children [3] |
| Clean-catch urine | Voided urine caught mid-void without interruption | Urinalysis and culture | Less contamination than bag | Still some contamination risk |
| Urethral catheterisation | Sterile catheter passed into bladder | Urinalysis and culture | ↓Contamination | NOT indicated unless patient unable to void; risk of iatrogenic UTI [3] |
| Suprapubic aspiration (SPA) | Needle aspiration directly from bladder through abdominal wall | Urinalysis and culture | Most accurate method — any growth is significant | Invasive; requires distended bladder; indicated in paediatric patients and SCI with paraplegia [3] |
Paediatric Urine Collection
In children [3]:
- Screening: bag urine for urinalysis ONLY (never send bag for culture!)
- Confirmatory (if screening positive):
- < 12 months: SPA, clean-catch, or catheterised urine
- > 12 months: MSU, clean-catch, or catheterised urine This is a commonly tested point. The reason bag urine cannot be cultured is that the bag sits against the perineum for a prolonged period, allowing perineal flora to contaminate the sample → unacceptably high false positive rate for culture.
Key investigations: urethral swabs or first pass urine for STIs [1]
| Test | Specimen | What it Detects | Key Points |
|---|---|---|---|
| Urethral swab — Gram stain | Urethral swab (repeat early morning if negative) [6] | PMN count (≥ 5/HPF = urethritis); intracellular G− diplococci (= gonorrhoea) [6] | Rapid, bedside; if negative, repeat with early morning swab (before first void) [6] |
| GC culture | Urethral swab | Neisseria gonorrhoeae; also gives sensitivity data | Special transport medium and culture medium required (chocolate agar, Thayer-Martin medium, CO₂ incubation) [6] |
| NAAT | First-catch urine (first 20–30 mL of initial stream) or urethral swab [6] | Chlamydia trachomatis + Neisseria gonorrhoeae | Gold-standard for Chlamydia detection; highly sensitive and specific; preferred non-invasive test |
| High vaginal swab (HVS) | Vaginal swab | Candida, Trichomonas, BV (clue cells, whiff test) | For external dysuria with vaginal discharge |
| Test | Purpose | Expected Findings |
|---|---|---|
| CBC | Infection, anaemia | Leukocytosis with neutrophilia in UTI/pyelonephritis [9]; anaemia if chronic disease |
| RFT | Renal impairment from obstructive uropathy or intrinsic renal disease | High serum creatinine can result from bladder outlet obstruction or underlying renal disease — should prompt USG [3] |
| CRP / ESR | Inflammatory markers | ↑ in pyelonephritis, prostatitis, epididymitis; helps differentiate upper from lower tract UTI |
| Blood cultures | Bacteraemia/urosepsis | Indicated in febrile UTI, pyelonephritis, suspected urosepsis |
| Fasting glucose | Screen for diabetes | DM is a risk factor for UTI [2] — glucosuria provides bacterial growth medium |
| PSA | Prostate cancer screening / BPH assessment | Prostate-specific but NOT prostate-cancer specific [3]; PSA > 1.5 ng/mL is a useful marker for prostatic enlargement [3]; PSA ≥ 4 ng/mL = cutoff for diagnostic biopsy; PSA 4–10 = 20% chance of cancer; PSA ≥ 10 = 50% chance of cancer [3] |
Factors Affecting PSA
PSA is organ-specific (made by prostate) but NOT tumour-specific [5]:
- ↑PSA: CA prostate, BPH, AROU, UTI, vigorous cycling, recent ejaculation < 48h, DRE [5]
- ↓PSA: castration, 5α-reductase inhibitors [5]
- Do NOT screen if patients have < 10 years of life expectancy [3]
- EAU recommends: measure PSA if diagnosis of CA prostate will change management [2]
Always interpret PSA in context. A mildly elevated PSA in a man with acute UTI should be repeated after treatment — the UTI itself elevates PSA.
International Prostate Symptom Score (IPSS): a standardised, validated questionnaire [2][3][5]
- Purpose: quantify severity of LUTS, predict treatment response, guide treatment decision, and monitor response to treatment [2]
- Important: NOT a diagnostic tool [2] — it quantifies symptoms but does not tell you the cause
- Components [2]:
- Voiding symptoms: incomplete emptying, intermittency, weak stream, straining
- Storage symptoms: frequency, urgency, nocturia
- Quality of life measure
- Interpretation: mild (1–7), moderate (8–19), severe (20–35) [2]
Voiding diary for at least 3 days, especially if frequency/nocturia is prominent [5][2]
- Records: time and volume of each void, fluid intake, episodes of urgency/incontinence
- Purpose: differentiates:
- Polyuria (high volume per void → look for DM, DI, polydipsia)
- True frequency (low volume per void → detrusor hypersensitivity, reduced capacity)
- Nocturnal polyuria (> 33% of 24h urine output at night in elderly)
Uroflowmetry: screening test for BOO (does not rule out detrusor underactivity!) [2]
- How it works: patient voids into a special toilet with a flow-rate sensor → generates a flow-rate curve
- Key parameters [5]:
- Volume voided must be > 150 mL to be representative of usual voiding habit
- Peak urine flow rate (Qmax):
- Normal: > 15 mL/sec
- < 15 mL/sec: diagnostic of obstruction
- < 10 mL/sec: prognostic — better outcome after TURP [5]
- Abnormal strain pattern (multiple peaks): suggests the patient is straining to void rather than having smooth detrusor contraction [5]
- Post-void residual volume: < 150 mL is acceptable [5]
Normal flow curve: bell-shaped, single smooth peak Obstructive flow curve: flattened, low Qmax, prolonged voiding time Strain pattern: multiple irregular peaks (patient using abdominal muscles)
Urodynamics: gold-standard for diagnosis of BOO [2]
- When indicated: when clinical history and uroflowmetry are equivocal; before invasive treatment (e.g. TURP); to differentiate BOO from detrusor underactivity
- What it measures:
- Filling cystometry: bladder sensation, compliance, detrusor overactivity
- Pressure-flow study: simultaneous measurement of detrusor pressure (Pdet) and urinary flow rate
- BOO defined by: high Pdet + low flow rate [2]
- Detrusor underactivity: low Pdet + low flow rate
- Leak point pressure: for incontinence evaluation
| Modality | Indication | Key Findings |
|---|---|---|
| USG KUB | First-line in complicated UTI, LUTS, recurrent UTI | Hydronephrosis/hydroureter (obstruction), bladder wall thickening (chronic cystitis/BOO), post-void residual volume, prostate size estimation, renal/bladder stones, renal abscess |
| Non-contrast CT KUB | Gold-standard for urolithiasis [5]; suspected renal abscess, obstructive uropathy | Detect urinary stone, urinary tract obstruction (dilated system, perinephric stranding), stone density ( > 1000 HU = hard) [5] |
| CT A+P with contrast | Suspected tumour, complicated pyelonephritis, abscess | Renal/bladder mass, perinephric abscess, ureteric pathology |
| TRUS (transrectal ultrasound) | Assess prostate size (for 5ARI use, surgery planning) [5] | Prostate volume measurement; guide prostate biopsy |
| MCUG (micturating cystourethrogram) | Suspected VUR (especially paediatric) | Grading of VUR (I–V) |
| KUB X-ray | Screening for radio-opaque stones | May miss radiolucent stones (uric acid) and hydronephrosis [5] |
- Indication: persistent haematuria (to r/o bladder cancer), recurrent UTI (to r/o structural abnormality), suspected interstitial cystitis, suspected bladder tumour
- Types:
- Findings in bladder cancer: papillary tumour, flat CIS (erythematous velvety patch), mass
- Findings in interstitial cystitis: Hunner's ulcers, glomerulations (petechial haemorrhages on hydrodistension)
- Fresh urine required; overall sensitivity = 50%, highest for CA bladder [9]
- Can detect high-grade transitional cell carcinoma before gross lesion becomes noticeable (i.e. carcinoma-in-situ of bladder) [9]
- Low detection rate for low-grade cancer [9]
- Findings: normal, atypical, suspicious, malignant [9]
- Precautions: as much volume as possible, sent fresh (cells degrade); avoid first early morning urine (↑↑epithelial cells) — usually send 2nd void in the morning on 3 consecutive days [9]
In the context of sterile pyuria with frequency/dysuria/haematuria not responding to antibiotics, always consider TB (especially in Hong Kong):
- EMU (early morning urine) × AFB: 3 consecutive early morning specimens for acid-fast bacillus smear and mycobacterial culture [9][10]
- Culture sensitivity 10–90%, specificity 100% [10]
- TB-PCR on urine: sensitivity 87–100%, specificity 93–98% [10] — rapid result
- Imaging: asymmetric caliectasis, calcification, hydronephrosis (from downstream strictures), small fibrotic bladder [10]
| Step | Test | Specimen | Action |
|---|---|---|---|
| Screening | Microscopy for pyuria/bacteriuria + Dipstick (LE, nitrite) | Bag urine | ANY positive result → proceed to confirmatory test [3] |
| Confirmatory | Microscopy + LE + Nitrite + C/ST | < 12 mo: SPA / clean-catch / catheterised; > 12 mo: MSU / clean-catch / catheterised [3] | Significant bacteriuria on culture → confirmed UTI |
High Yield Summary
UTI Diagnosis = Clinical symptoms + Urinalysis (dipstick/microscopy) + Urine C/ST
Dipstick: LE (best single parameter), nitrite (specific but insensitive — negative does NOT exclude UTI), blood, pH
Microscopy: pyuria ( > 5 WBC/HPF), bacteriuria, RBC morphology (dysmorphic = glomerular), casts (WBC cast = pyelonephritis), crystals
Culture thresholds: MSU female ≥ 10⁵ (but ≥ 10³ acceptable in symptomatic cystitis); MSU male ≥ 10³; catheter ≥ 10²; SPA = any growth
IPSS: quantifies LUTS severity (mild 1–7, moderate 8–19, severe 20–35) — NOT a diagnostic tool
Uroflowmetry: Qmax < 15 = obstruction, < 10 = surgical benefit; must void > 150 mL; does not r/o detrusor underactivity
Urodynamics: gold-standard for BOO (high Pdet + low flow)
Sterile pyuria: TB (send 3 EMU for AFB), stones, cancer, Chlamydia, interstitial nephritis
Urine cytology: sensitivity 50%, best for high-grade bladder cancer/CIS; send 2nd morning void on 3 consecutive days
PSA: prostate-specific not cancer-specific; ≥ 4 = biopsy cutoff; affected by UTI, BPH, recent ejaculation, cycling
Paediatric: bag urine for screening ONLY (never culture); SPA is most accurate method; any growth on SPA = significant
Active Recall - Diagnosis of Dysuria and Frequency
[1] Lecture slides: murtagh merge.pdf (p40–42, Dysuria) [2] Senior notes: Ryan Ho Fundamentals.pdf (p354–355, LUTS approach and evaluation) [3] Senior notes: felixlai.md (UTI diagnostic approach, urine collection methods, BPH diagnosis, PSA) [4] Senior notes: Ryan Ho Urogenital.pdf (p122–126, UTI diagnostic evaluation, collection methods, classification) [5] Senior notes: maxim.md (BPH investigations, uroflowmetry, urolithiasis investigations, PSA) [6] Senior notes: Ryan Ho Urogenital.pdf (p248, Urethritis investigations) [9] Senior notes: Ryan Ho Urogenital.pdf (p133, Investigations for haematuria; p153, Bladder cancer investigations) and Ryan Ho Fundamentals.pdf (p343, Investigations) [10] Senior notes: Ryan Ho Respiratory.pdf (p78, Genitourinary TB)
The management of dysuria and urinary frequency is cause-directed. There is no single "treatment for dysuria" — you must first identify the underlying aetiology and then treat accordingly. The management framework can be divided into:
- Immediate / Acute management — relieve symptoms, treat infection, decompress if obstructed
- Definitive management — address the underlying cause
- Prevention — particularly for recurrent UTI
Think of it as: Relieve → Treat → Prevent.
A. Management of UTI (The Most Common Cause)
Principle: Predictable microbiology (E. coli ~75%), low complication rate, short-course empirical antibiotics are sufficient [4].
General measures:
- Adequate hydration (aim 2–3 L/day fluid intake) [4]
- Analgesics for dysuria (paracetamol, NSAIDs)
- Urinary alkalinisers (e.g. sodium citrate sachets) may provide symptomatic relief — they raise urine pH, reducing the burning sensation as acidic urine contacts inflamed mucosa
Empirical antibiotic regimens (guided by Hong Kong local resistance patterns):
| Drug | Dose | Duration | Mechanism | Notes |
|---|---|---|---|---|
| Nitrofurantoin (1st line) | 50 mg QID or 100 mg BD (modified release) | 5 days | Reduced by bacterial nitroreductases → reactive intermediates that damage bacterial DNA, ribosomes, and other macromolecules | Excellent for lower UTI; does NOT achieve therapeutic levels in renal parenchyma → not suitable for pyelonephritis; C/I in CrCl < 30 mL/min (insufficient urinary concentration), G6PD deficiency (haemolysis) [3]; avoid in late pregnancy (neonatal haemolysis). Local E. coli resistance only 1–2% |
| Amoxicillin-clavulanate | 375 mg TDS or 1 g BD | 5–7 days | β-lactam + β-lactamase inhibitor | 1st line in Hong Kong guidance; beta-lactams achieve high urinary concentrations even with intermediate susceptibility |
| Cefpodoxime / cefuroxime | Cefpodoxime 100 mg BD; cefuroxime 500 mg BD | 7 days; 5–7 days | Oral cephalosporins | Second-line alternatives when first-line agents are unsuitable; broader spectrum and renal-dose adjustment may be needed |
| Fosfomycin trometamol | 3 g single dose PO | Single dose | Inhibits MurA (first step in peptidoglycan synthesis) | Alternative for suitable premenopausal, non-pregnant women with no known urological abnormalities or co-morbidities; IMPACT notes possibly inferior efficacy vs standard therapy |
| Co-trimoxazole/Septrin | 960 mg BD | 3 days if susceptible | Sequential folate blockade | Not recommended as empiric first-line in HK because local E. coli resistance is 31–32%; C/I in sulfa allergy, G6PD deficiency, pregnancy (1st trimester — teratogenic) |
Must Identify G6PD Deficiency
MUST identify underlying G6PD deficiency before prescribing nitrofurantoin or co-trimoxazole [3]. Both drugs can trigger oxidative haemolysis in G6PD-deficient patients. G6PD deficiency is common in Hong Kong (prevalence ~4.5% in males). Always check G6PD status or ask about known G6PD status before prescribing.
Hong Kong Antibiotic Resistance Context
In Hong Kong, community E. coli fluoroquinolone resistance exceeds 30%, and ampicillin resistance exceeds 50%. Therefore:
- Fluoroquinolones (ciprofloxacin, levofloxacin) should NOT be used as first-line empirical therapy for uncomplicated cystitis
- Nitrofurantoin and amoxicillin-clavulanate are first-line choices in current Hong Kong guidance; fosfomycin remains an alternative for selected uncomplicated cases
- Always check the local antibiogram and adjust based on C/ST results
Principle: broader spectrum of organisms, higher resistance rates, need for longer treatment, and must address the complicating factor [4].
Principle: systemic infection requiring more aggressive treatment; must rule out obstruction (obstructed infected kidney = urological emergency requiring drainage) [4].
| Severity | Management |
|---|---|
| Mild (able to tolerate PO, non-septic) | Urine C/ST first; oral co-amoxiclav or another culture-appropriate oral agent. Avoid empirical fluoroquinolone unless other options are unsuitable and susceptibility/local resistance supports use |
| Moderate-severe (high fever, vomiting, unable to tolerate PO, haemodynamically unstable) | IV antibiotics initially (IMPACT: IV co-amoxiclav; IV piperacillin-tazobactam if Pseudomonas risk; carbapenem if severe/ESBL risk) → step down to PO when afebrile for 24–48h; total usually 10–14 days |
| Obstructed + infected (pyonephrosis) | URGENT drainage (percutaneous nephrostomy or JJ ureteric stent) + IV antibiotics — this is an emergency because pus under pressure in a closed system leads to rapid sepsis and renal destruction |
Imaging: USG kidneys ± CT should be performed in pyelonephritis to rule out obstruction (hydronephrosis), abscess, or other complications.
This is a critical concept. Asymptomatic bacteriuria (ASB) is NOT equivalent to UTI and should NOT be treated in most populations:
| Do NOT treat | Rationale |
|---|---|
| Non-pregnant women (pre- or post-menopausal) | Benign natural history; Rx does not ↓risk of symptomatic UTI |
| Men | Same — no benefit |
| Diabetics | Same — no benefit shown |
| Patients with indwelling catheters | Extremely common (100% with long-term catheters); treatment selects for resistant organisms without benefit |
| Patients with nephrostomy tubes / JJ stents | Same principle |
| Spinal cord injury patients | Same principle |
| TREAT | Rationale |
|---|---|
| Pregnant patients | ↑Risk of ascending infection due to physiological changes → ↑risk of preterm delivery and low birth weight [4] |
| Pending urological procedure where mucosal bleeding is anticipated (e.g. TURP) | A/w ↑risk of infective post-procedure complications; usually require antibiotic prophylaxis [4] |
Common Exam Mistake
Students frequently want to treat positive urine cultures in catheterised elderly patients. Do not treat bacteriuria in catheterised patients unless they are symptomatic (e.g. new fever, rigors, delirium, haematuria) [4]. Treatment of asymptomatic bacteriuria in catheterised patients only selects for resistant organisms and causes antibiotic-related side effects (e.g. C. difficile colitis).
20% of women with UTI will recur within 6 months → common, genetically determined [4]
Management is stepwise:
Step 1: Behavioural changes (first-line, although evidence is limited) [4]:
- Avoid use of spermicides and diaphragms → use alternative contraceptive methods
- Observe personal hygiene → wipe from front to back after voiding
- Post-coital voiding
- Hydration to maintain adequate urine output → aim 2–3 L/day fluid intake
- Liberal fluid intake to increase micturition [3]
Step 2: Topical oestrogen for postmenopausal women [4]:
- ↓75% incidence of cystitis in RCTs
- Mechanism: restores Lactobacillus-dominant vaginal flora → ↓vaginal pH → ↓uropathogen colonisation
Step 3: Antimicrobial prophylaxis in selected cases [3][4]:
- Indication: recurrent symptoms specific for UTI that persist despite non-Rx measures
- Continuous prophylaxis: if no temporal relation to sexual activity
- Post-coital prophylaxis: if temporally related to sexual activity — single post-coital dose may be a more efficient and acceptable method of prevention than continuous prophylaxis [3]
- Regimen: usually co-trimoxazole or nitrofurantoin [4]; can give trial for a few months to assess response first
- Intermittent self-treatment: indicated in women who prefer to minimise antimicrobial intake — patients self-diagnose and self-treat with a pre-prescribed short course [3]
Paediatric prophylaxis [3]:
- Antibiotic prophylaxis should NOT be routinely prescribed to young children with first episode of UTI
- Prophylactic antibiotics with cotrimoxazole indicated if VUR Grade ≥ 3
| Condition | Treatment | Rationale |
|---|---|---|
| Gonococcal urethritis | IM ceftriaxone 500 mg single dose + azithromycin 1 g PO single dose | Dual therapy to cover potential co-infection with Chlamydia and to combat rising gonococcal resistance (especially to fluoroquinolones, which are no longer recommended for GC in HK) |
| Non-gonococcal urethritis (Chlamydia) | Doxycycline 100 mg BD × 7 days (preferred) OR Azithromycin 1 g PO single dose | Doxycycline preferred per 2021 updated guidelines as it has slightly higher cure rates for Chlamydia; azithromycin useful if compliance is a concern |
| Mycoplasma genitalium | Azithromycin 1 g stat → if resistance → moxifloxacin | Macrolide resistance in M. genitalium is rising; resistance-guided therapy preferred |
| Trichomonas | Metronidazole 2 g PO single dose or 400 mg BD × 7 days | Metronidazole is the only effective drug against Trichomonas |
Key principles:
- Always treat sexual partners (contact tracing)
- Screen for other STDs (HIV, syphilis, hepatitis B)
- Abstinence from sexual intercourse until treatment of both partners is complete
C. Management of Prostatitis
- Empirical antibiotics: prefer quinolone (excellent prostatic penetration) for 2–6 weeks [4]
- Why quinolone? The prostate has a blood-prostate barrier (similar concept to BBB) — only lipophilic drugs with good tissue penetration can achieve therapeutic concentrations in prostatic tissue. Fluoroquinolones (ciprofloxacin, levofloxacin) are lipophilic, have excellent prostatic penetration, and achieve prostatic tissue concentrations exceeding serum levels.
- Alternative: co-trimoxazole (also penetrates prostate well)
- Duration: prolonged (minimum 2 weeks, often 4–6 weeks) to prevent relapse and development of chronic prostatitis
- Supportive: analgesics, stool softeners (straining worsens perineal pain), adequate hydration
- Do NOT perform vigorous prostatic massage — risk of bacteraemia
- Prolonged antibiotics (fluoroquinolone 4–6 weeks)
- Alpha-blocker (tamsulosin) for obstructive symptoms — relaxes prostatic smooth muscle
- Chronic pain management
D. Management of BPH
Medical Therapy
Indications for treatment: IPSS moderate or above (≥ 8) [5]
Mechanism: Block α₁-adrenergic receptors on prostatic smooth muscle → ↓dynamic component of obstruction → relaxation of bladder neck and prostatic urethra → improved urine flow. Rapid onset (days to weeks).
| Subtype | Drugs | Side Effects |
|---|---|---|
| Non-selective α₁ blockers | Prazosin (Minipress), Terazosin (Hytrin), Doxazosin (Cardura), Alfuzosin (Xatral) | More orthostatic hypotension, nasal congestion, dizziness, tiredness [5] — because α₁ receptors are also found on vascular smooth muscle |
| Selective α₁A blockers | Tamsulosin (Harnal), Silodosin (Rapaflo) | More retrograde ejaculation [5] — because α₁A receptors are concentrated in the vas deferens and seminal vesicles; blocking them impairs seminal emission |
To reduce side effects: slow titration, subtype-selective (α₁A), slow-release formulations [5]
Why α₁A Selectivity Matters
The prostate predominantly expresses α₁A receptor subtypes, while blood vessels predominantly express α₁B. Selective α₁A blockers (tamsulosin, silodosin) target the prostate with less vascular effect → less orthostatic hypotension. However, α₁A receptors are also present in the vas deferens → selective blockers cause more retrograde ejaculation. It's a trade-off.
Mechanism: Block the enzyme 5α-reductase that converts testosterone → dihydrotestosterone (DHT). DHT is the primary androgen driving prostatic stromal proliferation. Blocking this → ↓prostate size over time → ↓static component of obstruction. Also ↓vascularity → less bleeding from BPH.
- Drugs: Finasteride (type 2 selective), Dutasteride (dual type 1 + 2)
- 2nd line / in combination with α₁-blockers: slow onset (3–6 months for maximum effect) [5]
- Preferred for larger glands ≥ 30–40 mL (TRUS) / IPSS ≥ 12 [5]
- Side effects: erectile dysfunction (10%), gynaecomastia [5]
- 50% decrease in PSA: multiply PSA by 2 when screening for CA prostate [5] — because 5ARIs reduce PSA levels by ~50%, if you need to interpret a PSA while the patient is on 5ARI, you must double the measured value
Combination Therapy: MTOPS and CombAT Trials
The landmark MTOPS and CombAT trials showed that combination therapy (α₁-blocker + 5ARI) is superior to either monotherapy for preventing BPH progression (AROU, need for surgery) in men with large prostates and high symptom scores. Combination therapy is now standard for men with moderate-severe LUTS and enlarged prostates.
- Drug: Tadalafil (Cialis) — the only PDE5i approved for LUTS/BPH
- Mechanism: PDE5-mediated reduction in smooth muscle and endothelial cell proliferation; increases smooth muscle relaxation and perfusion to prostate and bladder [3]. Also increases NO/cGMP signalling → relaxation of bladder neck and prostatic smooth muscle.
- Indicated in patients who also have erectile dysfunction [3]
- Side effects: Hypotension, blue/blurred vision (cross-reaction with PDE6 in retina), hearing loss, flushing, headache, dyspepsia [3]
- Avoid if using nitrate [5] — concomitant PDE5i + nitrate → severe hypotension (both increase cGMP-mediated vasodilation)
When BPH causes secondary detrusor overactivity (irritative LUTS):
-
Anticholinergics: oxybutynin, solifenacin
- Mechanism: block muscarinic M₃ receptors on detrusor → ↓uninhibited detrusor contractions → ↓urgency and frequency
- Side effects: dry mouth, dry eye, constipation, cognitive impairment [5]
- C/I if post-void residual > 150 mL due to risk of AROU [5] — because anticholinergics reduce detrusor contractility; if there is already significant residual urine, further weakening the detrusor → retention
-
Beta-3 agonist: Mirabegron [3][5]
- Mechanism: activates β₃-adrenergic receptors → relaxation of detrusor smooth muscle during urine storage phase [3]
- Effective as other anticholinergics in reducing frequency, urgency and incontinence [3]
- Does not have the same concern for urinary retention as anticholinergic medications [3] — because it relaxes the detrusor during filling but does not impair detrusor contractility during voiding
- Side effects: elevated BP ( > 10%) [5]
Surgical Management of BPH [4][5]
Absolute indications (complications of BPH):
- Recurrent acute retention of urine (AROU) — failed a trial without catheter (TWOC)
- Recurrent urinary tract infection
- Recurrent haematuria
- Renal insufficiency secondary to BPH (obstructive uropathy)
- Bladder stones
Relative indication:
Technique: Resectoscope loaded with monopolar diathermy loop introduced into bladder → strips of prostate tissue resected under direct vision → prostate chips evacuated and bleeding controlled with electrocautery [3]
Monopolar vs Bipolar TURP [3][5]:
| Feature | Monopolar TURP | Bipolar TURP |
|---|---|---|
| Irrigant | Non-conductive glycine solution (glycine better than distilled water — less TUR syndrome; saline CANNOT be used because it conducts electricity, diffuses power) [3] | Saline can be used → eliminates risk of hyponatraemia / TUR syndrome [5] |
| Speed | Faster | Slower due to smaller probe [4] |
| TUR syndrome risk | Present | Eliminated [5] |
| Cost | Cheaper | More expensive [5] |
| Haemostasis | Generally good | Poorer haemostasis [4] |
| Best for | Smaller to moderate prostates | Larger prostates [4] |
Post-operative care: 3-way Foley catheter post-op for bladder irrigation with NS to prevent clot retention [5]
| Complication | Mechanism | Incidence |
|---|---|---|
| Bleeding (haematuria) | Trauma to prostatic vasculature; secondary to trauma or infection (prostatitis); bleeding requiring transfusion ~1% [3] | Common |
| TUR syndrome (post-prostatectomy syndrome) | Hyponatraemia due to systemic absorption of hypotonic irrigating fluid (glycine) in monopolar TURP → dilutional hyponatraemia + fluid overload + glycine toxicity [3][5] | Risk factors: long OT time, massive prostate [5] |
| S/S: nausea (1st symptom), confusion, cerebral oedema, visual disturbance [5] | ||
| Mx: manage as hyponatraemia (check electrolytes, serum osmolality, volume status), hypertonic saline if severe [5] | ||
| Prevention: use bipolar (NS irrigant), limit volume < 1 L and irrigation pressure < 60 mmHg [5] | ||
| Retrograde ejaculation | 70–80% due to resection of bladder neck [5] — the bladder neck normally closes during ejaculation to direct semen anterogradely; resection destroys this mechanism | Very common |
| Urethral stricture | Urethral instrumentation [5] — trauma from passage of resectoscope | |
| Incontinence | 1%: urge (early) / stress (late) [5] | Rare |
| Perforation | Can form fistula [5] | Rare |
| Technique | Description | Advantage |
|---|---|---|
| TUIP (transurethral incision of prostate) | Longitudinal incision in prostate gland → widen bladder neck and prostatic urethra without tissue removal; only for small prostates ≤ 30 g [4] | ↓Morbidity and complication rates [4] |
| Laser enucleation (HoLEP, ThuLEP) | Laser to enucleate BPH adenoma → morcellated for removal [4] | Useful for large prostates; saline can be used; ↓bleeding [4] |
| Ablative techniques (PVP/Green Laser, RFA, microwave, steam/Rezum) | Various energy sources to destroy prostatic tissue | Less bleeding, ↓post-op irritative symptoms; BUT no histological specimen and ↓durability compared to TURP [4] |
| UroLift | Implants to hold different parts of prostate away from prostatic urethra [5] | Preserves ejaculatory function |
| Prostatic artery embolisation (PAE) | Reduce part of blood supply to prostate [5] | Minimally invasive; for high-risk surgical patients |
| Long-term catheterisation (Foley/SPC/CISC) | Ongoing drainage | For very unfit patients not suitable for any intervention [5] |
| Metallic stent | Temporary stent in prostatic urethra | Temporary for very unfit patients [5] |
E. Management of AROU (Acute Retention of Urine) [3][4]
Immediate bladder decompression by urethral catheterisation (first-line) [4]:
Procedure [4]:
- Aseptic technique: clean genital area with hibitane, drape
- Intraurethral LA: apply xylocaine jelly → milk down urethra → wait 5 minutes
- Insert 14–18 Fr Foley's catheter using no-touch technique
- Inflate balloon with 10 mL water → withdraw until resistance
- Males: 14–18 Fr
- Females: 12–16 Fr
- If enlarged prostate → use thicker (20–22 Fr) catheters [4] (the catheter needs to be stiffer to bypass the obstruction)
- If urethral stricture → use thinner (10–12 Fr) catheters [4]
Contraindications to urethral catheterisation [3][4]:
- Urethral trauma (blood at urethral meatus, high-riding prostate) [5]
- Acute prostatitis, radical prostatectomy, urethral reconstruction [3]
If unable to catheterise → Suprapubic catheterisation (SPC) [4]:
- Assess first catheterisation volume [3]:
- Volume > 500 mL = genuine AROU
- Volume > 1000 mL = possible chronic retention
- Monitor hourly urine output
- Look for post-obstructive diuresis [3]:
- Defined as diuresis > 200 mL/hr for 2 hours (or diuresis persisting after decompression) [3]
- Body attempts to excrete excess fluid retained during obstruction
- Primarily a problem of chronic but not acute retention [3]
- Do NOT remove Foley catheter during diuresis — may lead to hydronephrosis [3]
- Patients normally manage by increasing oral fluid intake; IV isotonic saline replacement if unable [3]
- Investigations: CBC, RFT, catheterised urine C/ST, KUB for stones/faecal loading
- Do NOT take PSA during AROU → causes false elevation (check 4–6 weeks later) [4]
- Trial without catheter (TWOC): catheter placed for 2 days → removed → assess if patient can void [3]
- If successful → outpatient workup for underlying cause
- If fails → re-catheterise → plan for definitive surgery (TURP)
- Start alpha-blocker (tamsulosin) before TWOC — improves success rate by relaxing prostatic smooth muscle
Approach [5]:
- Establish frequency (daytime symptoms positive) but not pure nocturia
- Perform voiding diary / frequency-volume chart
- High urine output → look for cause of polyuria
- Low urine output → true frequency: detrusor hypersensitivity or capacity problem
- Exclude infection / stone / tumour [5]
OAB if no other causes identified [5] — Clinical diagnosis by bladder diary:
- Frequent voiding of small volumes
- Normal prostate on DRE
- Good flow rate on uroflowmetry
| Step | Treatment | Mechanism |
|---|---|---|
| 1st line | Bladder training | Timed voiding with progressive increase in intervals; trains cortical inhibition of premature detrusor contractions |
| 2nd line | Anticholinergics: oxybutynin / solifenacin [5] | Block M₃ receptors on detrusor → ↓involuntary contractions |
| S/E: dry mouth, dry eye, constipation, cognitive impairment [5] | ||
| Alternative | Beta-3 agonist: mirabegron [5] | Activate β₃ receptors → detrusor relaxation during storage |
| S/E: elevated BP ( > 10%) [5] | ||
| 3rd line | Botox injection into detrusor | Botulinum toxin blocks ACh release at neuromuscular junction → reduces detrusor contractility for 6–9 months |
- Topical vaginal oestrogen (estriol cream, estradiol vaginal ring) — restores urogenital mucosa, restores Lactobacilli, ↓pH, ↓uropathogen colonisation
- RCTs show ↓75% incidence of cystitis [4]
- Systemic HRT is NOT necessary; topical application is sufficient and has minimal systemic absorption
| Type | Use | Key Points |
|---|---|---|
| Indwelling catheter | Short-term bladder drainage < 3 weeks [3] | Standard 2-way; Latex (yellow) for short-term (max 2 weeks), Silicone (transparent) for longer (max 4 weeks) [3] |
| Intermittent catheter (CISC) | Removal after each decompression; recatheterise on schedule | Reduced complication rate [3]; preferred for neurogenic bladder |
| Suprapubic catheter | Long-term bladder drainage [3] | Prevents urethral trauma/stricture, ↓sphincter dysfunction, ↓CAUTI, allows voiding assessment before removal [3] |
| Triple-lumen (3-way) | Hematuria with clot retention; bladder irrigation [3] | Additional irrigation channel; used post-TURP [5] |
High Yield Summary
UTI Management:
- Uncomplicated cystitis: nitrofurantoin 5d or amoxicillin-clavulanate 5–7d (first-line in current HK guidance). Fosfomycin single dose is an alternative in suitable premenopausal, non-pregnant women. Avoid empirical FQ and co-trimoxazole because of local resistance/adverse-effect concerns.
- Male cystitis: 7 days. Complicated UTI: 10–14 days + address complicating factor.
- Pyelonephritis: culture first; avoid empirical FQ if possible; IV co-amoxiclav if admitted/severe, escalating to piperacillin-tazobactam or carbapenem when indicated; urgent drainage if obstructed + infected.
- Asymptomatic bacteriuria: ONLY treat in pregnancy and pre-urological procedures.
- Recurrent UTI: behavioural changes → topical oestrogen (postmenopausal) → antimicrobial prophylaxis.
BPH Management:
- Conservative: watchful waiting if mild IPSS and not bothered.
- Medical: α₁-blockers (1st line, rapid onset) ± 5ARI (slow onset 3–6 months, for large glands ≥ 30–40 mL). PDE5i if concurrent ED. Anticholinergics/mirabegron for OAB component.
- Surgical indications: refractory AROU, recurrent UTI, bladder stones, obstructive uropathy, refractory haematuria, failed medical therapy.
- TURP gold standard; complications include TUR syndrome (monopolar), retrograde ejaculation (70–80%), urethral stricture.
AROU: Immediate catheterisation → TWOC after 2 days ± alpha-blocker → surgery if TWOC fails.
OAB: Exclude infection/stone/tumour → bladder training → anticholinergics (C/I if PVR > 150 mL) or mirabegron.
Active Recall - Management of Dysuria and Frequency
[1] Lecture slides: murtagh merge.pdf (p40–42, Dysuria) [2] Senior notes: Ryan Ho Fundamentals.pdf (p352, AROU diagnosis and acute management; p354–355, LUTS) [3] Senior notes: felixlai.md (UTI treatment, recurrent UTI prophylaxis, BPH treatment, TURP, catheterisation, AROU management) [4] Senior notes: Ryan Ho Urogenital.pdf (p125–128, UTI management, asymptomatic bacteriuria, recurrent cystitis, prostatitis; p167, AROU management; p176, BPH surgical management) [5] Senior notes: maxim.md (BPH management, alpha-blockers, 5ARI, PDE5i, TURP, OAB management, AROU) [6] Centre for Health Protection / HKMJ: Antibiotic Guidance Notes in Community Setting - Acute uncomplicated cystitis in women (Dec 2025 version; local resistance rates and recommended antibiotic table) [7] IMPACT 6th edition (2025): empirical therapy for UTI and fosfomycin trometamol guidance
Complications of Conditions Presenting with Dysuria and Urinary Frequency
The complications discussed here are organised by the underlying condition. Each complication is explained from first principles — why it occurs, based on the pathophysiology already covered.
A. Complications of UTI
UTI, if left untreated or inadequately treated, can progress along a spectrum of increasing severity. Think of it as bacteria ascending through the urinary tract and eventually entering the bloodstream.
Progression pathway: Bacteria that initially colonise the bladder (cystitis) can ascend via the ureters to the renal pelvis and parenchyma → acute pyelonephritis. If the infected kidney is simultaneously obstructed (e.g. by a stone at the PUJ or ureter), pus accumulates under pressure in the collecting system → pyonephrosis (literally "pus in the kidney" — from Greek "pyo" = pus, "nephros" = kidney).
- Why this matters: Pyonephrosis is a urological emergency. Pus under pressure in a closed obstructed system → rapid parenchymal destruction + bacteraemia → urosepsis. Requires urgent drainage (percutaneous nephrostomy or JJ stent) plus IV antibiotics [3][4].
- Clinical clue: A patient with UTI symptoms who develops high spiking fevers, rigors, loin pain, and renal angle tenderness despite appropriate oral antibiotics → suspect ascending infection or obstruction.
Urosepsis = sepsis arising from a urinary tract source. It is the most feared complication of UTI and carries significant mortality (25–60% in septic shock).
- Mechanism: Bacterial invasion of the bloodstream from the infected urinary tract (bacteraemia) → systemic inflammatory response (SIRS) → if uncontrolled → sepsis → severe sepsis → septic shock. Gram-negative organisms (especially E. coli) release endotoxin (lipopolysaccharide, LPS) → activates TLR4 on macrophages → massive cytokine storm (TNF-α, IL-1, IL-6) → vasodilation, capillary leak, DIC, multi-organ failure.
- Risk factors: obstructed infected urinary tract (pyonephrosis), immunosuppression, diabetes, indwelling catheter, urological instrumentation
- Red flags: fever > 39°C, rigors, tachycardia, hypotension, altered mental status, oliguria
- Mechanism: Severe pyelonephritis → focal areas of suppuration coalesce → renal abscess. If the abscess ruptures through the renal capsule → perinephric abscess (contained by Gerota's fascia).
- Clinical features: failure to defervesce despite appropriate antibiotics for pyelonephritis, persistent loin pain, palpable mass
- Diagnosis: CT with contrast (rim-enhancing fluid collection)
- Management: drainage (percutaneous or surgical) + prolonged antibiotics
- Mechanism: recurrent or prolonged UTI (especially with VUR in children) → chronic tubulointerstitial inflammation → fibrosis and cortical scarring → ↓nephron number → compensatory hyperfiltration in remaining nephrons → secondary FSGS → proteinuria, hypertension, progressive CKD [4]
- Clinical relevance: This is why VUR with recurrent UTI in children must be identified and managed early — to prevent irreversible renal damage.
- Mechanism: Urease-producing organisms (classically Proteus mirabilis, also Klebsiella, S. aureus) split urea → ammonia + CO₂ → ↑urine pH (alkalinisation) → supersaturation with magnesium ammonium phosphate (struvite) → stone formation [5]
- Clinical significance: struvite stones can grow rapidly to fill the entire renal collecting system → staghorn calculus → chronic infection, obstruction, renal parenchymal destruction
- Tip: repeated isolation of Proteus species in urine cultures should prompt investigation for renal stones
B. Complications of BPH
The complications of BPH arise from chronic bladder outlet obstruction. Think of the pathology in a proximal-to-distal sequence — prostate level → bladder level → upper tract [5]:
- Bleeding (ruptured dilated bladder neck veins) [5]: chronic obstruction → venous congestion of the prostatic urethra and bladder neck → dilated submucosal veins → rupture → haematuria. Note: the presence of BPH should not dissuade from further evaluation of haematuria since older men are also at risk of other genitourinary disorders (especially bladder cancer and prostate cancer) [3]
- Acute retention of urine (AROU): progressive obstruction eventually overwhelms the detrusor's ability to compensate → sudden inability to void. Often precipitated by constipation, UTI, anaesthesia, alcohol, or drugs (anticholinergics, sympathomimetics) [5]
- Recurrent UTI: urinary stasis from incomplete emptying → bacterial colonisation and multiplication → recurrent infections [5]
- Bladder stones: stagnant residual urine → supersaturation and crystallisation → stone formation in the bladder [5]
- Bladder diverticulum: chronic high-pressure voiding against the obstruction → ↑intravesical pressure → herniation of bladder mucosa through weak points in the detrusor muscle → diverticula (sac-like outpouchings that don't empty well → further stasis, infection, stone formation)
- Chronic retention of urine ± overflow incontinence: progressive detrusor decompensation → large post-void residual → continuous low-grade overflow [5]
- Detrusor changes: initially, the detrusor hypertrophies (thickened wall on USG) to generate higher pressures to overcome obstruction. Over time, if obstruction persists, detrusor fibres are replaced by collagen → detrusor decompensation (thin, atonic wall) → inability to contract effectively
- Recurrent hydronephrosis: back-pressure from chronically elevated intravesical pressure transmits retrograde through the ureters → bilateral hydroureter and hydronephrosis [5]
- Obstructive uropathy / Obstructive nephropathy: prolonged back-pressure → progressive renal parenchymal damage → ↓GFR → renal impairment [5]
- Renal failure: end-stage consequence of bilateral obstructive uropathy; may present insidiously with uraemic symptoms (vomiting, lethargy, drowsiness) — usually rare in AROU, more likely in CROU [2]
Why Chronic Retention Is More Dangerous Than Acute
In AROU, the patient presents early (pain forces them to seek help) and the obstruction is quickly relieved by catheterisation. In chronic retention, the onset is insidious and painless (because nerve adaptation occurs with gradual distension). By the time the patient presents, there may already be significant bilateral hydronephrosis and renal impairment. Always check RFT in any patient with urinary retention.
C. Complications of AROU and Its Decompression
- UTI: stagnant urine in a distended bladder is an excellent culture medium
- Stone disease: stasis → crystallisation
- Renal failure: back-pressure if bilateral obstruction (more likely in CROU)
After catheterisation for retention, several complications can occur:
| Complication | Mechanism | Management |
|---|---|---|
| Haematuria | Rapid decompression → ↓intravesical pressure → sudden expansion of previously compressed bladder veins → bleeding (ex vacuo haemorrhage) | Usually self-limiting; if significant, bladder irrigation via 3-way catheter |
| Urethral stricture | Mechanical trauma from catheter passage → urethral mucosal injury → fibrosis → stricture (especially with repeated catheterisation) | Prevention: proper technique, appropriate catheter size, adequate lubrication |
| Urinary tract infections | Catheter introduces bacteria directly into the bladder; biofilm formation on catheter surface → CAUTI | Minimise catheter dwell time; aseptic technique |
| Transient hypotension | Rapid drainage of large volume → sudden ↓intra-abdominal pressure → ↓venous return → vasovagal response + redistribution of blood volume | Gradual drainage (although evidence for clamping is debated); monitor vitals |
| Post-obstructive diuresis | Diuresis that persists after decompression of the bladder. Represents an appropriate attempt to excrete excess fluid and solutes retained during obstruction [3] | |
| Primarily a problem of chronic but not acute retention [3] — in CROU, days-to-weeks of obstruction leads to accumulation of urea, sodium, and water; once relieved, the kidneys "dump" the excess | Do NOT remove Foley catheter during diuresis [3] | |
| Defined as diuresis > 200 mL/hr for 2 hours [3] | Patients normally manage by ↑oral fluid intake; isotonic saline replacement if unable to keep up orally [3] | |
| Can also involve a concentrating defect (medullary washout from chronic high-pressure back-flow) → dilute polyuria | Monitor serum electrolytes (risk of hypokalaemia, hyponatraemia) |
Urinary catheterisation itself — as part of managing these conditions — carries its own set of complications:
| Complication | Mechanism |
|---|---|
| Catheter-associated UTI (CAUTI) | Biofilm formation on catheter surface provides a niche for bacterial colonisation; risk ↑3–7% per day of catheterisation; commonest healthcare-associated infection |
| Epididymo-orchitis | Bacteria ascend from catheterised bladder via vas deferens → epididymal infection → orchitis |
| Bladder perforation | Traumatic insertion; over-inflation of balloon before it is fully within the bladder |
| Bladder fistula | Chronic catheter erosion through bladder wall (rare, usually with long-term indwelling catheter) |
| Bladder stone formation | Foreign body (catheter) acts as nidus for crystallisation; also catheter-related stasis |
| Urethral stricture | Repeated catheterisation → mucosal trauma → fibrosis → stricture |
| Periurethral abscess | Infection tracking along catheter → periurethral soft tissue infection |
| Incontinence | Chronic catheterisation → sphincter weakening; mucosal erosion |
E. Complications of TURP [4][5]
These are high-yield for exams — you must be able to discuss them during consent-taking.
| Complication | Mechanism | Details |
|---|---|---|
| Bleeding | Trauma to prostatic vasculature during resection | 3–7% require transfusion [4]; post-op haematuria is expected but usually settles with bladder irrigation |
| Infection and urosepsis | Breach of infected prostatic tissue; bacteraemia during instrumentation | Antibiotic prophylaxis essential |
| TUR syndrome (post-prostatectomy syndrome) | Irrigation fluid (1.5% glycine) low in sodium enters venous channels → dilutional hyponatraemia + ↓osmolarity [4]; aggravated by post-op stress-related ADH release | S/S: N/V, confusion, hypertension, visual disturbance (flashing lights), giddiness, seizures [4] |
| Lowest Na at 1–2h post-op, slowly ↑ afterwards due to glycine uptake into cells [4] | Prevention: bipolar technique (use ionic saline), limit OT < 1h, irrigation pressure < 60 mmHg, monitor glycine deficit [4][5] | |
| Mx: stop OT immediately + Na replacement + furosemide [4] | ||
| Retrograde ejaculation | Incompetent bladder neck after resection → retrograde flow of semen into bladder during ejaculation [4] | 40–60% [4] (some sources quote 70–80% [5]); penile erection and sexual function rarely affected [4]; must counsel regarding fertility impact |
| Incontinence | Damage to external sphincter during resection | 1% [4]; urge incontinence early (temporary detrusor irritability from healing), stress incontinence late (permanent sphincter damage) |
| Strictures / bladder neck stenosis | Urethral instrumentation (resectoscope) → mucosal trauma → fibrosis | |
| Perforation | Resection too deep → perforation of prostatic capsule or bladder dome → can form fistula [5] |
| Complication | Incidence |
|---|---|
| Bladder neck stenosis and urethral strictures | 7–8% [4] |
| Urinary incontinence | 2% [4] |
| Regrowth of prostate | 5% need re-operation in 5 years [4] — because TURP only resects the adenoma, not the entire prostate; remaining tissue can regrow |
| Ejaculatory dysfunction (retrograde ejaculation) | 40–60% [4] |
| Erectile dysfunction | 5% — uncommon [4] |
| Male | Female | Children |
|---|---|---|
| Periurethral abscess | Pelvic inflammatory disease (PID) | Vulvovaginitis |
| Urethral stricture, infertility | Fitz-Hugh-Curtis syndrome (perihepatitis) | Ophthalmia neonatorum |
| Prostatitis, seminal vesiculitis | Peritonitis | Dissemination |
| Epididymo-orchitis | Bartholinitis | |
| Cystitis | Infertility | |
| Inflammation/abscess of bulbourethral, parafrenal, paraurethral glands | Obstetric Cx: ectopic pregnancy, prematurity, PROM, chorioamnionitis, post-abortal PID |
Disseminated gonococcal infection (0.5–3%): classic triad of tenosynovitis, dermatitis, polyarthralgia or purulent monoarthritis [4].
Why Gonorrhoea Causes Urethral Stricture
N. gonorrhoeae triggers intense neutrophilic inflammation in the urethral mucosa. If untreated or recurrent, this inflammation leads to submucosal fibrosis and scar formation → progressive narrowing of the urethral lumen → urethral stricture. This is why early and complete treatment of gonococcal urethritis is essential, and why a history of STDs (especially GC) must be asked in any patient presenting with obstructive LUTS or urethral stricture.
Stones at the VUJ or in the bladder cause dysuria and frequency by irritating the trigone. Their complications include:
| Complication | Mechanism |
|---|---|
| Urosepsis | Obstruction + infection = emergency; pus under pressure |
| Pyelonephritis and pyonephrosis | Ascending infection above an obstructing stone |
| Hydroureter and hydronephrosis | Back-pressure from obstruction; also from scarring around stone / post-obstructive effect [5] |
| Obstructive nephropathy | Prolonged obstruction → renal parenchymal damage |
| Acute kidney injury | Bilateral obstruction or obstruction of a solitary kidney → post-renal AKI |
Bladder cancer, especially carcinoma in situ (CIS), can present with irritative LUTS (frequency, urgency, dysuria) rather than painless haematuria:
| Complication | Mechanism |
|---|---|
| Hydronephrosis and hydroureter | Invasive bladder tumours can cause distal ureteral obstruction → secondary hydronephrosis [3] |
| Vesicocolic fistula → pneumaturia | Tumour extends into adjacent colon [4] |
| Vesicovaginal fistula → incontinence | Tumour extends into vagina [4] |
| Systemic metastasis (liver, bone, brain) | Haematogenous and lymphatic spread of muscle-invasive disease [4] |
GU TB causes dysuria and frequency from bladder involvement (TB cystitis). Complications are primarily cicatricial (scarring-related):
| Complication | Mechanism |
|---|---|
| Ureteric strictures (60–84%) | Chronic granulomatous inflammation → fibrosis and scarring of ureteric wall → segmental strictures and dilatation ("corkscrew ureter"), shortened rigid ureter ("pipe-stem ureter") [4] |
| Contracted "thimble" bladder | Chronic TB cystitis → fibrosis and contracture → markedly reduced bladder capacity (may be < 50 mL) → extreme frequency [4] |
| "Golf-hole" ureteral orifice | Patulous (gaping) ureteral orifice from peri-orifice fibrosis → VUR → ascending infection and upper tract damage [4] |
| Autonephrectomy | Caseous necrosis + calcification → non-functioning calcified kidney [4] |
| Infertility | Male: obstructive azoospermia from epididymal/vas deferens involvement. Female: fallopian tube involvement (90–100%) |
| Underlying Cause | Key Complications |
|---|---|
| UTI (cystitis) | Ascending infection (pyelonephritis, pyonephrosis), urosepsis, renal abscess, chronic pyelonephritis/scarring, recurrent UTI, struvite stones |
| BPH | Prostate: haematuria. Bladder: AROU, recurrent UTI, bladder stones, diverticulum, overflow incontinence. Upper tract: hydronephrosis, obstructive uropathy, renal failure |
| AROU / Decompression | Haematuria, urethral stricture, CAUTI, transient hypotension, post-obstructive diuresis |
| Catheterisation | CAUTI, epididymo-orchitis, bladder perforation/fistula, bladder stone, urethral stricture, periurethral abscess |
| TURP | Bleeding, TUR syndrome, retrograde ejaculation (40–80%), urethral stricture, incontinence (1–2%), perforation, regrowth |
| Gonorrhoea | Male: stricture, prostatitis, epididymo-orchitis. Female: PID, Fitz-Hugh-Curtis. Disseminated: arthritis triad |
| Urinary stones | Urosepsis, pyelonephritis/pyonephrosis, hydronephrosis, obstructive nephropathy, AKI |
| Bladder cancer | Hydronephrosis, fistula (vesicocolic, vesicovaginal), metastasis |
| GU TB | Ureteric strictures, contracted bladder, autonephrectomy, infertility |
High Yield Summary
UTI complications spectrum: cystitis → pyelonephritis → pyonephrosis → urosepsis. Obstructed + infected kidney = urological emergency requiring urgent drainage.
BPH complications by level: Prostate (haematuria) → Bladder (AROU, recurrent UTI, bladder stones, diverticulum, overflow incontinence) → Upper tract (hydronephrosis, obstructive uropathy, renal failure).
Post-decompression complications: Post-obstructive diuresis (primarily in CROU, defined as > 200 mL/hr for 2h; do NOT remove catheter; replace fluids if oral intake insufficient).
TURP complications: TUR syndrome (dilutional hypoNa + glycine toxicity, prevented by bipolar technique/saline irrigant), retrograde ejaculation (40–80%), bleeding, stricture, incontinence (1%). Must discuss during consent.
GC complications: urethral stricture (from fibrosis), PID in women, disseminated gonococcal infection (tenosynovitis, dermatitis, polyarthralgia).
GU TB complications: cicatricial — ureteric strictures, contracted thimble bladder, autonephrectomy, infertility.
Struvite stones: form in alkaline urine from urease-producing organisms (Proteus); can become staghorn calculi.
Active Recall - Complications of Dysuria and Frequency
References
[1] Lecture slides: murtagh merge.pdf (p40–42, Dysuria) [2] Senior notes: Ryan Ho Fundamentals.pdf (p351, AROU complications; p354, LUTS) [3] Senior notes: felixlai.md (UTI complications, decompression complications, TURP complications, catheterisation, urolithiasis complications, bladder cancer complications) [4] Senior notes: Ryan Ho Urogenital.pdf (p128, prostatitis complications; p129, GU TB; p138, stone complications; p153, bladder cancer complications; p159, incontinence; p166, AROU complications; p177, TURP complications; p249, gonorrhoea complications) [5] Senior notes: maxim.md (BPH complications, urolithiasis complications, TURP complications)
High Yield Summary
-
Dysuria = painful urination (burning/scalding/stinging); frequency = voiding too often. Together they strongly suggest lower urinary tract inflammation, most commonly UTI (esp. cystitis).
-
Dysuria is NOT grouped under LUTS headings — it indicates infection/inflammation specifically, while frequency is a storage (irritative) LUTS.
-
UTI is the result of host-pathogen interaction: ascending route is commonest; E. coli causes 75% of uncomplicated UTI; virulence factors (Type 1 pili for cystitis, P pili for pyelonephritis) determine clinical syndrome.
-
Probability diagnoses: UTI, urethritis, urethral syndrome (abacterial cystitis), vaginitis.
-
Serious disorders not to be missed: bladder/prostate/urethral cancer, gonorrhoea, chlamydia, genital herpes, prostatitis, reactive arthritis, calculi.
-
Pitfalls: menopause syndrome, adenovirus urethritis, chronic prostatitis, foreign bodies, acidic urine, interstitial cystitis.
-
Female vs Male differential: Female → UTI, vaginitis, PID, interstitial cystitis, stones. Male → UTI, STD urethritis, prostatitis (acute/chronic), stones, epididymitis.
-
DRE is essential in males: smooth enlarged prostate = BPH; hard irregular nodule = cancer; tender boggy = acute prostatitis.
-
BPH pathophysiology: static (DHT-mediated stromal hyperplasia → 5ARI) + dynamic (α₁-receptor smooth muscle → α₁-blockers) + irritative (secondary detrusor overactivity).
-
Timing of dysuria: onset = urethritis; terminal = cystitis. Unexplained dysuria → think Chlamydia.
-
Cystitis should NOT cause fever — fever with dysuria = think upper tract (pyelonephritis) or prostatitis.
High Yield Summary
Probability diagnoses for dysuria: UTI (cystitis), urethritis, urethral syndrome, vaginitis.
Serious disorders not to miss: CA bladder/prostate/urethra, gonorrhoea, chlamydia, genital herpes, prostatitis, reactive arthritis, calculi.
Pitfalls: menopause syndrome, adenovirus urethritis, chronic prostatitis, foreign bodies, acidic urine, acute fever, interstitial cystitis, urethral caruncle, vaginal prolapse.
Sex-specific DDx: Female → UTI, vaginitis, PID, interstitial cystitis, stones. Male → UTI, STD urethritis, prostatitis, stones, epididymitis.
Key clinical discriminators: Discharge = STD; Fever = upper tract/prostatitis; Suprapubic pain without fever = cystitis; Obstructive LUTS = BPH/prostate cancer/stricture; Chronic refractory + sterile cultures = interstitial cystitis/TB/ketamine cystitis; Painless haematuria + age > 35 = malignancy until proven otherwise.
Timing of dysuria: Onset = urethritis; Terminal = cystitis.
Gonococcal vs NGC: Profuse purulent rapid = GC; Mucoid scanty slow = NGC (Chlamydia).
Hong Kong specifics: Ketamine cystitis in young recreational drug users; genitourinary TB with sterile pyuria; aristolochic acid urothelial CA from TCM; high fluoroquinolone resistance in community E. coli.
High Yield Summary
UTI Diagnosis = Clinical symptoms + Urinalysis (dipstick/microscopy) + Urine C/ST
Dipstick: LE (best single parameter), nitrite (specific but insensitive — negative does NOT exclude UTI), blood, pH
Microscopy: pyuria ( > 5 WBC/HPF), bacteriuria, RBC morphology (dysmorphic = glomerular), casts (WBC cast = pyelonephritis), crystals
Culture thresholds: MSU female ≥ 10⁵ (but ≥ 10³ acceptable in symptomatic cystitis); MSU male ≥ 10³; catheter ≥ 10²; SPA = any growth
IPSS: quantifies LUTS severity (mild 1–7, moderate 8–19, severe 20–35) — NOT a diagnostic tool
Uroflowmetry: Qmax < 15 = obstruction, < 10 = surgical benefit; must void > 150 mL; does not r/o detrusor underactivity
Urodynamics: gold-standard for BOO (high Pdet + low flow)
Sterile pyuria: TB (send 3 EMU for AFB), stones, cancer, Chlamydia, interstitial nephritis
Urine cytology: sensitivity 50%, best for high-grade bladder cancer/CIS; send 2nd morning void on 3 consecutive days
PSA: prostate-specific not cancer-specific; ≥ 4 = biopsy cutoff; affected by UTI, BPH, recent ejaculation, cycling
Paediatric: bag urine for screening ONLY (never culture); SPA is most accurate method; any growth on SPA = significant
High Yield Summary
UTI Management:
- Uncomplicated cystitis: nitrofurantoin 5d or amoxicillin-clavulanate 5–7d (current HK first-line). Fosfomycin single dose is an alternative in selected premenopausal, non-pregnant women. Avoid empirical FQ/co-trimoxazole.
- Male cystitis: 7 days. Complicated UTI: 10–14 days + address complicating factor.
- Pyelonephritis: culture first; IV amoxicillin-clavulanate per IMPACT if admitted/severe, escalate to piperacillin-tazobactam if Pseudomonas risk or carbapenem if severe/ESBL risk; urgent drainage if obstructed + infected.
- Asymptomatic bacteriuria: ONLY treat in pregnancy and pre-urological procedures.
- Recurrent UTI: behavioural changes → topical oestrogen (postmenopausal) → antimicrobial prophylaxis.
BPH Management:
- Conservative: watchful waiting if mild IPSS and not bothered.
- Medical: α₁-blockers (1st line, rapid onset) ± 5ARI (slow onset 3–6 months, for large glands ≥ 30–40 mL). PDE5i if concurrent ED. Anticholinergics/mirabegron for OAB component.
- Surgical indications: refractory AROU, recurrent UTI, bladder stones, obstructive uropathy, refractory haematuria, failed medical therapy.
- TURP gold standard; complications include TUR syndrome (monopolar), retrograde ejaculation (70–80%), urethral stricture.
AROU: Immediate catheterisation → TWOC after 2 days ± alpha-blocker → surgery if TWOC fails.
OAB: Exclude infection/stone/tumour → bladder training → anticholinergics (C/I if PVR > 150 mL) or mirabegron.
High Yield Summary
UTI complications spectrum: cystitis → pyelonephritis → pyonephrosis → urosepsis. Obstructed + infected kidney = urological emergency requiring urgent drainage.
BPH complications by level: Prostate (haematuria) → Bladder (AROU, recurrent UTI, bladder stones, diverticulum, overflow incontinence) → Upper tract (hydronephrosis, obstructive uropathy, renal failure).
Post-decompression complications: Post-obstructive diuresis (primarily in CROU, defined as > 200 mL/hr for 2h; do NOT remove catheter; replace fluids if oral intake insufficient).
TURP complications: TUR syndrome (dilutional hypoNa + glycine toxicity, prevented by bipolar technique/saline irrigant), retrograde ejaculation (40–80%), bleeding, stricture, incontinence (1%). Must discuss during consent.
GC complications: urethral stricture (from fibrosis), PID in women, disseminated gonococcal infection (tenosynovitis, dermatitis, polyarthralgia).
GU TB complications: cicatricial — ureteric strictures, contracted thimble bladder, autonephrectomy, infertility.
Struvite stones: form in alkaline urine from urease-producing organisms (Proteus); can become staghorn calculi.
Dyspepsia
Dyspepsia is a symptom complex of recurrent epigastric pain or discomfort, often accompanied by bloating, nausea, early satiety, or postprandial fullness, originating from the gastroduodenal region.
Ear Pain/hearing
Ear pain (otalgia) and hearing impairment are symptoms arising from conditions affecting the external, middle, or inner ear—such as infections, cerumen impaction, or eustachian tube dysfunction—that disrupt normal sound conduction or auditory perception.