The dentate line (pectinate line) is the single most important anatomical landmark in anorectal surgery. It is the junction between the embryological endoderm (hindgut) above and ectoderm (proctodeum) below. Nearly every clinical distinction in this lecture hinges on it:

Correct the slide shorthand: tissue above the dentate line is not devoid of nerves. It has predominantly visceral innervation and much lower sensitivity to cutting/thermal pain, while pressure and stretch remain perceptible. Tissue below the line has somatic innervation and is sharply pain-sensitive. This is why a band must be placed proximal to the dentate line and why a thrombosed external haemorrhoid is exquisitely tender. ^[1][11]

Anal cushions are normal vascular structures, conventionally described as left lateral, right anterior and right posterior columns. They aid continence and protect the sphincter during defecation ^[1][2]. Haemorrhoidal disease is symptomatic enlargement and/or distal displacement of these cushions—not simply “varicose veins.”

Anal canal musculature:

• Internal anal sphincter (IAS): smooth muscle, involuntary, continuous with the circular muscle of the rectum. Maintains resting anal tone (~70-80% of resting pressure). This is the target in lateral internal sphincterotomy for fissure.
• External anal sphincter (EAS): skeletal muscle, voluntary, supplied by pudendal nerve. Maintains squeeze pressure.
• Intersphincteric space: the potential space between IAS and EAS — this is where cryptoglandular abscesses originate.

The anal glands sit in the intersphincteric space and drain into the anal crypts at the dentate line. Infection of these glands is the basis for most anorectal abscesses and fistulae. The pus can track in multiple directions depending on which tissue planes it dissects through — hence the classification of abscesses and fistulae.

Common anorectal symptoms: Bleeding (usually fresh blood), Anal pain, Discharge (blood or purulent), Prolapse, Perianal mass, Pruritus ani, Incontinence ^[1]

History must include: ^[1]

• Present illness — anorectal symptoms: pain, bleeding, mass, prolapse
• Past health — medical diseases, previous surgery
• Family history — colorectal cancer, IBD, polyposis syndromes
• Sexual history — critically important for STIs (syphilis, HPV, HIV, gonorrhoea), anal cancer risk

Pain characterization: ^[1]

• Duration, characteristics (sharp/dull/burning), constant vs intermittent
• Association with bowel movements, bleeding, or other factors ^[1]
• Pain on defecation → think fissure
• Constant throbbing pain → think abscess
• Pain with prolapse → think thrombosed or incarcerated haemorrhoid

Bleeding characterization: ^[1]

• Onset and duration
• Bright red vs altered blood ^[1]
• On paper / in bowl / on stool / in stool ^[1] — this is a classic discriminator:
  • On paper after wiping → haemorrhoids, fissure
  • In the bowl (dripping) → haemorrhoids
  • On stool (coating) → low rectal/anal lesion
  • Mixed in stool → higher lesion (proximal rectum/colon)
• Association with bowel movements and pain ^[1]
• Black, tarry stools → upper GI source, requires different workup entirely

Examination sequence: ^[1]

1. General examination — pallor (chronic blood loss), cachexia (malignancy), lymphadenopathy
2. Abdominal examination — masses, organomegaly, signs of IBD
3. Perianal examination — patient in left lateral position (standard UK/HK) or prone jackknife position ^[1]
4. Digital rectal examination (DRE)
5. Proctoscopy

Inspection: ^[1]

• Look for skin tags, external haemorrhoids, fissure, fistula openings, condylomata, ulcers, prolapse, erythema/swelling of abscess

Palpation (DRE): ^[1]

• Pain, masses, induration, sphincter tone (at rest and on squeeze), prostate/rectovaginal septum
• Suspected acute fissure: gentle separation of the buttocks will often establish the diagnosis. Defer a painful DRE/anoscopy when the typical fissure is clearly seen; this is not a permanent contraindication. An atypical, indurated, multiple or nonhealing lesion may require endoscopy, biopsy or examination under anaesthesia to exclude Crohn disease, infection or cancer. ^[12]

Anoscopy/Proctoscopy: ^[1]

• Visualizes the anal canal and lower rectum
• Essential for grading internal haemorrhoids

Investigations serve to: (1) help diagnosis and assess severity, (2) define anatomy of the pathological process (abscess/fistula), (3) exclude diseases in the proximal bowel and associated bowel problems (e.g. IBD) ^[1]

Cushions of vascular tissue at the anal canal. Aid in continence (act as a plug). Protect sphincters/anus from the trauma of defecation. ^[1]

Epidemiology on the deck: the quoted US prevalence and haemorrhoidectomy rates are historical teaching figures, not universal contemporary incidence estimates. They do not determine diagnosis or treatment. ^[1]

Aetiology: ^[1]

• Constipation, straining, pregnancy, low fibre diet, family history ^[1]
• The mechanism: chronic straining → ↑ intra-abdominal pressure → engorgement of vascular cushions → degeneration of supporting fibroelastic tissue → prolapse ^[2]

Classification of Internal Haemorrhoids: ^[1]

Symptoms: ^[1]

Bleeding, Prolapse (mass), Mucus discharge, Pruritus. Pain occurs ONLY when complications are present (thrombosis, prolapse). ^[1]

This is a high-yield exam discriminator: uncomplicated internal haemorrhoids are painless. If a patient presents with bleeding AND significant pain, think fissure, abscess, or thrombosed external haemorrhoid — not simple internal haemorrhoids.

Visual recognition: the grade III photograph shows separate, congested mucosal columns protruding through the anus. Their radial grooves distinguish prolapsed haemorrhoidal cushions from the circumferential/concentric folds of full-thickness rectal prolapse shown later in the deck. Grade describes prolapse behaviour, not colour or size. ^[1]

Assessment: ^[1]

• DRE (to exclude other rectal lesions) ^[1]
• Proctoscopy: for diagnosis and assessment of severity ^[1]
• Endoscopy is selective, guided by colorectal-cancer screening status, persistent bleeding, anaemia, abdominal symptoms, altered bowel habit, weight loss or family history—not automatically required for every young patient with an obvious benign source. Conversely, a visible haemorrhoid must not end the search when red flags are present. ^[11]

Treatment: ^[1]

Grade-by-grade table on slide 29: treat it as a historical teaching scaffold rather than a rigid algorithm. Symptoms, external component, prior therapy, continence and patient preference matter; selected grade III disease may still be treated in the office. ^[1][11]

Surgical Haemorrhoidectomy: ^[1]

Excision of haemorrhoids. Indications: Severe haemorrhoids (3rd or 4th degree), Mixed internal and external haemorrhoids, Failure of other treatments, Patient preference, In conjunction with another procedure. ^[1]

What the operative photographs show: excision leaves discrete wounds while preserving intervening anoderm/skin bridges. Circumferential excision risks the pale, narrowed anal canal pictured on the complications slide—anal stenosis. ^[1]

Complications of haemorrhoidectomy: ^[1]

Bleeding, Urine retention, Pain, Faecal impaction, Infection, Anal tags, Anal stenosis, Incontinence ^[1]

Stapled Haemorrhoidopexy: ^[1]

Uses a stapling device to remove a ring of rectal mucosa and submucosa with creation of a mucosal anastomosis above the dentate line. Haemorrhoids are NOT excised. Haemorrhoidal tissues pulled back into the anal canal from the prolapsed position. Interruption of blood supply to the haemorrhoids. ^[1]

The device photographs show a circular stapler introduced through an anal dilator after a circumferential purse-string. The excised “doughnut” must be complete, and the postoperative image shows reduction of the prolapse. The accurate name is stapled haemorrhoidopexy, not the deck's “stapled haemorrhoidectomy,” because the cushions themselves are not excised. ^[1]

Outcomes of stapled haemorrhoidopexy vs conventional (lecture-era comparison): ^[1]

Transanal Haemorrhoidal Artery Devascularization (THD): ^[1]

Reduces blood flow to haemorrhoids. Involves inserting a small ultrasound probe into the anus to locate the vessels (arteries) supplying the haemorrhoids using a Doppler ultrasound beam. Each blood vessel is stitched closed to block the blood supply to the haemorrhoidal plexus. ^[1]

Key components of the THD device (from lecture diagram): Doppler probe, dearterializer, needle holder, and light source. The drawing shows a Doppler-localised arterial branch ligated above the dentate line, often combined with mucopexy for prolapse. It may reduce pain compared with excision but has greater recurrence, especially in advanced prolapse; the labelled 6 mm is device geometry, not a patient-specific operative rule. ^[1][11]

An anal fissure is a longitudinal tear in the anoderm extending from the anal verge towards (but usually not above) the dentate line. The deck's “at the dentate line” wording is anatomically misleading. Most are posterior midline; anterior midline fissures are relatively more frequent in women. ^[1][12]

Why posterior midline? Chronic fissure is associated with IAS hypertonia and reduced anodermal perfusion; the posterior midline is especially vulnerable to this ischaemia–spasm–nonhealing cycle. Do not reduce the mechanism to stool trauma alone. ^[12]

Aetiology: ^[1]

Hard stool, tight internal anal sphincter, ischaemia of the overlying anoderm at the posterior midline ^[1]

The vicious cycle: hard stool → tears anoderm → pain → sphincter spasm → ↓ blood flow → impaired healing → chronic fissure → more spasm. This is why treatment targets reducing sphincter pressure.

Chronic fissure features (triad): ^[1]

Sentinel pile (external skin tag), Hypertrophic papilla (internal), Internal sphincter muscle visible at base of fissure ^[1]

Read the photographs from outside in: distal sentinel tag → chronic longitudinal ulcer with pale/exposed IAS fibres in its floor → proximal hypertrophied anal papilla. A fresh superficial split with a small streak of bright blood is acute; chronicity is a morphological diagnosis, not merely “pain for a long time.” ^[1][12]

Atypical fissures (red flag): ^[1]

Atypical position and multiple in number → consider: inflammatory bowel disease, tuberculosis, syphilis, HIV infection, CMV ^[1]

This is an important exam discriminator: a lateral fissure, or multiple fissures, should raise suspicion for secondary causes (especially Crohn's disease or STI).

Clinical features: ^[1]

Pain on defecation and a small amount of fresh bleeding are typical. Gentle buttock separation may reveal the fissure. DRE/anoscopy can be deferred when this is acutely painful and the appearance is typical, but persistent, atypical or indurated disease warrants further assessment rather than an indefinite “no examination” rule. ^[1][12]

Treatment: ^[1]

Non-operative: ^[1]

Start with fibre/bulking, adequate fluid, stool-softening where needed and warm baths for acute fissure. For chronic fissure, topical diltiazem/nifedipine has efficacy similar to topical nitrate with fewer adverse effects and is a reasonable first-line chemical sphincterotomy; nitrate commonly causes headache. Botulinum toxin has similar results to topical therapy and is often used after topical failure. ^[12]

Why these work: GTN donates nitric oxide → relaxes smooth muscle of IAS → ↓ resting anal pressure → ↑ blood flow to posterior midline → promotes healing. Calcium channel blockers work similarly. Botulinum toxin paralyzes the sphincter temporarily.

Operative: ^[1]

Lateral internal sphincterotomy (LIS) has the highest healing rate for selected chronic fissure, but the deck's fixed “95% / 0–15%” figures hide patient selection and follow-up. Modern practice tailors division to the fissure length to reduce incontinence. Avoid routine LIS in patients with baseline faecal incontinence, prior anorectal surgery, sphincter injury (including obstetric injury) or Crohn-related fissure; consider a sphincter-preserving flap or other specialist strategy. ^[12]

The surgery divides the lower portion of the IAS laterally (NOT posteriorly, because the posterior midline already has a "keyhole" defect from the fissure — cutting there would worsen it). This permanently reduces resting pressure.

Aetiology: ^[1]

Cryptoglandular infection (most common). Specific infections: IBD, tuberculosis, actinomycosis. Foreign body. Surgery. Malignancies. ^[1]

Clinical features: ^[1]

Pain, Swelling, Drainage, Constipation, Urinary difficulties ^[1]

Classification by anatomical location: ^[1]

Treatment: ^[1]

Prompt incision and drainage is definitive treatment. Add antibiotics for cellulitis, systemic illness/sepsis or immunosuppression; valvular disease or a prosthetic valve alone is not a blanket modern indication for post-drainage antibiotics. Culture is selective (recurrent, nonhealing, immunosuppressed or unusual infection), not routine. ^[13]

Why antibiotics are not routinely needed: source control is the decisive treatment and routine antibiotics after drainage do not improve healing or recurrence in an otherwise healthy patient with an uncomplicated abscess. This is different from withholding antibiotics in a septic or immunocompromised patient. ^[13]

Key principle: a substantial minority later develop a fistula or recurrent abscess. Primary fistulotomy at drainage is reasonable only when a simple, low tract is unmistakable and the continence risk is acceptable; do not probe aggressively or divide sphincter for an uncertain/high tract during acute sepsis. A draining seton may be safer when a fistula involves sphincter. ^[13]

Abnormal tract communicating the rectum or anal canal [to the perianal skin]. Cryptoglandular infection [is the underlying cause]. ^[1]

Parks Classification: ^[1]

How to read the four drawings: follow the black tract against the IAS and outer EAS/levator complex. Intersphincteric stays between the sphincters; transsphincteric pierces EAS; suprasphincteric rises in the intersphincteric plane and loops over puborectalis; extrasphincteric begins above the sphincter complex and descends through levator. The amount of functional EAS crossed—not the distance to the skin opening—drives continence risk. ^[1][13]

Clinical features: ^[1]

Drainage, pain, bleeding, swelling, decrease in pain with drainage, external opening visible, PR: induration with cord-like structure ^[1]

Goodsall's Rule (not explicitly on slides but commonly examined):

• External opening anterior to the transverse anal line → track runs directly (radially) to the nearest crypt
• External opening posterior to the transverse anal line → track curves to the posterior midline internal opening

Goodsall's rule is a prediction, not proof; accuracy is imperfect, especially for posterior and complex tracts. Do not force a probe to make the anatomy obey the rule. ^[13]

Diagnosis: ^[1]

Clinical examination. MRI in cases of: complicated high fistula, recurrent fistula, when anatomy is not obvious ^[1]

Treatment: ^[1]

Other treatment modalities shown on the deck: VAAFT uses a fistuloscope to identify and treat the tract from within; FiLaC withdraws a radial laser fibre through the tract; paste/plug products attempt biological closure. These endoscopic/laser approaches have reasonable short-term results but uncertain long-term healing and recurrence, so the slide is a menu of technologies—not a hierarchy of proven equivalents. Mesenchymal stem-cell therapy is reserved for selected refractory Crohn-related fistulas, not routine cryptoglandular disease. ^[1][13]

Read the seton photographs: the coloured loop passes from the external opening, through the internal opening and out of the anus. A loose draining seton keeps sepsis controlled without dividing sphincter and can bridge to definitive repair. A cutting seton deliberately migrates through muscle and is now used only selectively because continence impairment can be substantial. ^[1][13]

Read the LIFT diagram: enter the intersphincteric plane at A, identify and ligate the tract close to the internal opening at B, then divide/ligate the distal tract at C. The aim is to disconnect the internal source while leaving EAS intact. Advancement flap and LIFT are established sphincter-sparing options; anal fistula plugs and fibrin glue are relatively ineffective. ^[1][13]

IBD connection: Perianal fistulae are an important Crohn phenotype ^[3][4]. Management is multidisciplinary: image/EUA as needed, drain every collection first, use a loose seton for ongoing drainage when appropriate, and coordinate disease-directed biologic therapy. Fistulotomy is reserved for carefully selected superficial/low tracts with acceptable continence risk; active proctitis and complex branching disease make healing less reliable. ^[4][6][13]

Occurs in 1-5% of the population. Common in 5th and 6th decades. Itchiness in the perianal region. Scratching leads to excoriation and secondary infection. ^[1]

Aetiology: ^[1]

Personal hygiene, diet, systemic diseases, dermatological conditions, neoplasm, infection, psychogenic, drugs, diarrhoea, idiopathic ^[1]

Approach: ^[1]

Identify aetiology and treat appropriately. For idiopathic: reassurance, keep perianal skin dry, avoid soap and local applications, avoid prolonged topical steroids, dietary change ^[1]

Potential dietary triggers (coffee, alcohol, spicy food, citrus, tomatoes or chocolate) should be tested by a time-limited individual elimination and rechallenge, not imposed as a universal exclusion list. More important is to stop the itch–scratch cycle: gentle water cleansing, pat dry, avoid wet wipes/soap/fragrance, correct seepage or diarrhoea, use a barrier, and reserve a short low-potency steroid course for marked inflammation. Persistent unilateral, ulcerated, pigmented or indurated skin warrants biopsy/dermatology-colorectal review.

Full thickness protrusion of the rectum through the anal sphincters. Internal prolapse: rectum intussuscepts but does not pass beyond the anus. Occurs at any age but more commonly at extremes of life. ^[1]

Anatomical abnormalities: ^[1]

Rectal intussusception, deep cul-de-sac, loss of rectal fixation, redundant sigmoid, levator ani diastasis, patulous anal sphincter, pudendal neuropathy ^[1]

Aetiology: ^[1]

Neurological disorders, parity, 25-50% associated with constipation. Childhood: cystic fibrosis, whooping cough, developmental abnormalities and malnutrition. ^[1]

Symptoms: ^[1]

Incontinence, constipation, protrusion, bleeding, discharge, sensation of incomplete emptying, rectal pressure/tenesmus ^[1]

Distinguishing prolapse from prolapsed haemorrhoids:

• Full-thickness rectal prolapse: a cylindrical sleeve with concentric circumferential folds, as in slide 65
• Prolapsed haemorrhoids: separate vascular columns with radial grooves, as in slides 10 and 26
• Mucosal prolapse: usually a shorter segment without the full-thickness concentric cylinder

Treatment: ^[1]

Abdominal approach options (from lecture slide): ^[1]

• Fixation method: suture or mesh
• Resection (sigmoid)
• Approach: laparoscopic vs open vs robotic

Operation choice is individualized by physiology, constipation/incontinence pattern, prolapse length, previous operations and surgeon expertise. Abdominal rectopexy is commonly used in fit patients; perineal operations are useful when comorbidity or an incarcerated prolapse favours less abdominal stress, but age alone should not dictate the route. ^[15]

Read the operative photographs: slides 70–71 show an Altemeier perineal rectosigmoidectomy—the prolapsed full-thickness rectum is opened, redundant rectosigmoid is delivered/resected, and a coloanal anastomosis is fashioned. Slide 72 shows mesh fixed to the ventral rectum in laparoscopic ventral mesh rectopexy, with careful patient selection because mesh-related complications, although uncommon, can be serious. ^[1][15]

Laparoscopic ventral mesh rectopexy: the 3.4% recurrence and functional percentages on slide 72 come from a 2010 review of non-randomised series. They are historical cohort results, not guaranteed patient outcomes or proof that mesh is superior to every alternative. ^[1][15]

Squamous Cell Carcinoma of the Anal Canal (the deck's older “epidermoid carcinoma”): ^[1]

Persistent high-risk HPV is the central risk factor; HIV/immunosuppression, smoking, prior HPV-related lower-genital-tract neoplasia and receptive anal intercourse increase risk. Presentation may mimic benign disease with bleeding, pain, nonhealing ulcer or mass—biopsy the suspicious lesion rather than calling it a haemorrhoid. ^[1][16]

Definitive concurrent chemoradiation is standard for most nonmetastatic anal-canal SCC; capecitabine or 5-FU is combined with mitomycin and radiation. Response can continue for months, so an early residual-looking lesion is not automatically surgical failure. APR is the standard salvage operation for biopsy-proven persistent or recurrent local disease. Survival is stage-dependent; the deck's fixed 80–90% is most applicable to early-stage disease. ^[16]

This treatment derives from the Nigro regimen, but use contemporary multidisciplinary terminology rather than assuming one immutable drug/dose protocol. Small, well-differentiated anal-margin cancers may be locally excised when adequate margins preserve sphincter; anal-canal disease is generally treated with chemoradiation. ^[16]

Anorectal Melanoma: ^[1]

A rare mucosal melanoma that may be amelanotic and mistaken for a polyp or haemorrhoid. Confirm with biopsy and stage systemically. Surgery ranges from sphincter-preserving local excision to APR according to resectability and symptoms; more radical surgery has not reliably overcome the high metastatic risk. Checkpoint immunotherapy and molecularly targeted treatment may benefit selected advanced mucosal melanoma, but the slide's blanket “favourable outcome” claim is unsafe—prognosis remains poor and management belongs in a melanoma multidisciplinary team. ^[17]

Anal Margin Cancers: ^[1]

Squamous cell carcinoma, Basal cell carcinoma, Kaposi's sarcoma ^[1]

• Perianal disease occurs in up to 40% of Crohn's disease patients ^[3][4]
• Perianal features include: abscess, fistula, anal fissures (often atypical — lateral, multiple), skin tags ^[4]
• In Montreal classification for CD, "P" modifier indicates perianal disease ^[4]
• Management of Crohn's perianal disease: EUA + abscess drainage, ciprofloxacin/metronidazole, simple fistula → fistulotomy, complex fistula → seton + azathioprine/biologics (infliximab/adalimumab) ^[6]

• IL-10 receptor deficiency presents with early-onset IBD including diarrhoea, perianal sepsis, pyoderma gangrenosum ^[7]
• Neutropenic patients: perianal area must be examined but avoid DRE ^[5]

• Syphilitic chancre can present at the anus ^[8]
• HPV → condylomata acuminata → risk factor for anal SCC ^[1]
• HIV → atypical fissures, Kaposi's sarcoma ^[1]