Right upper quadrant pain is abdominal pain localized beneath the right costal margin, most commonly associated with gallbladder, liver, or biliary tract pathology.

Right Upper Quadrant (RUQ) Pain

Right upper quadrant (RUQ) pain refers to pain or discomfort localised to the area beneath the right costal margin, roughly bounded by the midline (linea alba) medially, the right mid-axillary line laterally, the right costal margin superiorly, and the umbilical plane inferiorly. It is one of the most common acute abdominal presentations and serves as a clinical syndrome — not a diagnosis in itself — that demands systematic evaluation.

The term essentially describes "where" the pain is. Your job is to work out "why" it's there.

2. Epidemiology and Risk Factors

The most common cause of RUQ pain is biliary disease (biliary colic and cholecystitis), accounting for roughly 30–50% of presentations. ^[1]^[2]
Gallstones affect ~10–15% of the adult population in Western countries; in Hong Kong the prevalence is slightly lower (~5–10%) but rising with westernisation of diet and increasing obesity. ^[1]
Cholecystitis accounts for 3–10% of all patients presenting with abdominal pain to the emergency department. ^[1]
Acute cholangitis and gallstone pancreatitis are less frequent but carry significant morbidity and mortality if untreated.
Liver abscess (particularly Klebsiella pneumoniae primary liver abscess) is a diagnosis with particular significance in East and Southeast Asia, including Hong Kong, where diabetes mellitus prevalence is high. ^[3]

The classic mnemonic for cholesterol gallstone risk factors is the "5 Fs": Fat, Female, Fertile, Forty, Fair/Family. Let's break this down pathophysiologically:

Risk Factor	Mechanism
Fat (Obesity)	Increased hepatic cholesterol synthesis → supersaturation of bile with cholesterol → cholesterol crystal nucleation
Female	Oestrogen increases hepatic HMG-CoA reductase activity (↑ cholesterol synthesis) and stimulates hepatic lipoprotein receptors (↑ cholesterol uptake). Progesterone impairs gallbladder contractility → stasis
Fertile (Multiparity / OCP / HRT)	Same oestrogen/progesterone mechanisms amplified during pregnancy
Forty (Age > 40)	Cumulative bile stasis, ↑ biliary cholesterol saturation with age, ↓ gallbladder motility
Fair / Family	Genetic polymorphisms in cholesterol transporters (e.g. ABCG5/ABCG8) and bile salt metabolism; higher prevalence in certain ethnic groups (e.g. Pima Indians, Scandinavians)

Additional risk factors:

Rapid weight loss / Total parenteral nutrition (TPN) → gallbladder stasis (lack of CCK stimulation)
Haemolytic anaemias (e.g. sickle cell disease, hereditary spherocytosis) → excess unconjugated bilirubin → black pigment stones
Cirrhosis → impaired bile salt synthesis and gallbladder hypomotility
Ileal disease or resection (e.g. Crohn's disease) → bile salt malabsorption → ↓ bile salt pool → cholesterol supersaturation
Diabetes mellitus → gallbladder hypomotility (autonomic neuropathy) and increased risk of complicated biliary disease and Klebsiella liver abscess ^[1]^[3]
Drugs: octreotide, fibrates (clofibrate), ceftriaxone (forms biliary sludge)

High Yield — 5Fs + Extra Risk Factors

Remember the 5Fs for cholesterol stones. But in Hong Kong, also think about:

Recurrent pyogenic cholangitis (RPC) — endemic in Southeast Asia, associated with Clonorchis sinensis and pigment stones formed de novo in intrahepatic ducts ^[4]
Klebsiella pneumoniae liver abscess — strongly associated with diabetes mellitus, particularly in East Asian populations ^[3]

3. Anatomy and Function

Understanding the anatomy of the biliary tree is absolutely critical for approaching RUQ pain. Let's build it from first principles.

The gallbladder consists of fundus, body, infundibulum (Hartmann's pouch), and neck ^[4]
- Fundus: the blind end that projects beyond the inferior liver edge at the tip of the right 9th costal cartilage (landmark for Murphy's sign)
- Body: the main storage portion, lies in the gallbladder fossa on the visceral surface of the right liver lobe (segments IVb and V)
- Infundibulum (Hartmann's pouch): a saccular outpouching between the body and neck — this is where stones most commonly become impacted → can compress the common hepatic duct in Mirizzi syndrome ^[4]
- Neck: the narrow portion that tapers into the cystic duct; contains the spiral valves of Heister which help regulate bile flow

Right and left hepatic ducts converge to form the common hepatic duct (CHD)
The cystic duct joins the CHD to form the common bile duct (CBD) — the CBD runs in the free edge of the lesser omentum (hepatoduodenal ligament), anterior to the portal vein and to the right of the hepatic artery proper
The CBD passes behind the first part of the duodenum and through the head of the pancreas before opening at the ampulla of Vater in the second part of the duodenum (D2)
The sphincter of Oddi controls bile (and pancreatic juice) flow into the duodenum

Cystic artery (usually a branch of the right hepatic artery) — runs through the Triangle of Calot (bounded by the cystic duct, common hepatic duct, and inferior border of the liver)
- Identifying the Triangle of Calot and achieving the "critical view of safety" is the key step in laparoscopic cholecystectomy to avoid bile duct injury ^[1]
The gallbladder is drained by the cystic vein into the portal vein

Visceral afferents: travel via the coeliac plexus and greater splanchnic nerves (T5–T9) → this is why biliary pain is felt as a vague epigastric or RUQ ache (visceral peritoneum → poorly localised)
Phrenic nerve (C3–C5): the diaphragmatic peritoneum overlying the gallbladder fossa is innervated by the phrenic nerve → inflammation here causes referred pain to the right shoulder tip (Kehr's sign equivalent for the biliary system) ^[2]
Somatic afferents (intercostal nerves T7–T11): when inflammation extends to involve the parietal peritoneum, pain becomes sharp, well-localised, and worsened by movement or breathing — this is the transition from biliary colic to acute cholecystitis

Why does gallbladder pain radiate to the right shoulder/scapula?

The gallbladder sits on the undersurface of the liver, directly beneath the right hemidiaphragm. Inflammation of the gallbladder can irritate the diaphragmatic peritoneum, whose sensory fibres travel in the phrenic nerve (C3–C5). The brain misinterprets this as pain from the dermatome of C3–C5, which overlies the shoulder tip. This is referred pain via shared spinal cord segments.

Bile is produced continuously by hepatocytes (~500–1000 mL/day)
Between meals, the sphincter of Oddi is closed → bile diverts into the gallbladder for storage and concentration (5–10× via Na⁺/H₂O absorption)
After a meal (especially fatty), CCK is released from I-cells in the duodenum → stimulates gallbladder contraction and relaxation of the sphincter of Oddi → bile enters the duodenum
Bile composition: bile salts (conjugated bile acids), phospholipids (lecithin), cholesterol, bilirubin (conjugated), water, electrolytes
When the cholesterol-to-bile-salt-to-lecithin ratio exceeds the critical micellar solubility, cholesterol crystallises → cholesterol gallstones

Remember, not everything in the RUQ is biliary. Other structures:

Liver (hepatitis, abscess, tumour → capsular distension → RUQ pain)
Right kidney and adrenal (pyelonephritis, renal colic, adrenal haemorrhage)
Hepatic flexure of the colon (colitis, obstruction, tumour)
Duodenum (duodenal ulcer — especially posterior wall)
Right lower lobe of the lung/pleura (right basal pneumonia, pulmonary embolism)
Appendix (high/subhepatic appendix can mimic biliary disease)

4. Etiology (Focus on Hong Kong)

Here we systematically list the causes of RUQ pain, grouped by organ system, with pathophysiological explanation.

4.1 Biliary Causes (Most Common)

Pathophysiology: A gallstone transiently impacts in the cystic duct or Hartmann's pouch → gallbladder contracts against a fixed obstruction → visceral pain ^[1]^[2]
The pain is called "colic" but is actually steady/constant (not truly colicky like intestinal colic) because the gallbladder is a smooth-muscle sac without peristalsis; it generates a sustained contraction. "False colic" is a better descriptor. ^[2]
The stone either dislodges (pain resolves in < 6 hours) or remains impacted (→ cholecystitis)

Pathophysiology: Prolonged gallstone impaction at Hartmann's pouch or cystic duct → stagnant bile becomes concentrated (mucocele/hydrops) → chemical inflammation (mediated by lysolecithin, prostaglandins, and phospholipase A) in the first 48 hours → secondary bacterial infection (15–30% of cases) by enteric organisms: E. coli, Klebsiella, Enterococcus, Enterobacter ^[1]^[2]^[4]
Prolonged obstruction → gallbladder distension → compromised blood supply → gangrenous cholecystitis (20%) → perforation → biliary peritonitis ^[2]

Occurs in critically ill patients: ICU, TPN, sepsis, major burns, multi-organ dysfunction ^[4]
Mechanism: gallbladder stasis + ischaemia (due to hypoperfusion in critical illness) → bile stasis → mucosal injury → inflammation without stones
Requires urgent percutaneous cholecystostomy (drainage) + antibiotics as these patients are usually too sick for surgery ^[4]

Most common manifestation is jaundice (obstructive/post-hepatic); pain is often more prolonged (> 6 hours) than simple biliary colic ^[4]
Transient impaction at the ampulla → transient jaundice; persistent impaction → progressive jaundice
Complications: acute cholangitis, gallstone pancreatitis

Definition: Infection of the biliary tree secondary to obstruction and bacterial contamination ^[1]^[4]
Requires BOTH obstruction + bacteria — obstruction alone = obstructive jaundice; bacteria alone without obstruction rarely causes clinical cholangitis ^[4]
Most common cause: choledocholithiasis ^[4]
Other causes: benign/malignant strictures, stent occlusion, parasitic infection, post-ERCP
Bacteriology: E. coli, Klebsiella pneumoniae, Enterococcus, Enterobacter, Bacteroides fragilis ^[4]
Pathogenesis: biliary obstruction → stasis → loss of normal barrier mechanisms (continuous bile flushing, bacteriostatic bile salts, secretory IgA, sphincter of Oddi barrier) → ascending bacterial infection from duodenum or haematogenous spread via portal vein → cholangiovenous reflux (bacteria/endotoxins enter the bloodstream through disrupted bile duct epithelium at high biliary pressures → sepsis) ^[4]

Also called "Hong Kong disease" / "Oriental cholangiohepatitis" ^[4]
Characterised by recurrent bouts of cholangitis from de novo formation of brown pigment/calcium bilirubinate stones within intrahepatic bile ducts (contrast with gallbladder origin of Western gallstones) ^[4]
Pathogenesis: Stasis + Stricturing + Recurrent infection — bacterial β-glucuronidase deconjugates bilirubin glucuronide → unconjugated bilirubin complexes with calcium → calcium bilirubinate stones; repeated cycles of stone formation → obstruction → infection → inflammation → stricturing → more stone formation ^[4]
Associated with Clonorchis sinensis, Opisthorchis viverrini, Ascaris lumbricoides ^[4]
Peak prevalence in 30–40s; equal sex distribution; found predominantly in Southeast Asia ^[4]

Extrinsic compression of the common hepatic duct by a stone impacted in the cystic duct or Hartmann's pouch ^[4]
Presents with fever, jaundice, and RUQ pain — can mimic choledocholithiasis
Classification (Csendes-McSherry, based on cholecystobiliary fistula): ^[4]
- Type I: External compression only, no fistula
- Type II: Fistula involving < 1/3 of CBD circumference
- Type III: Fistula involving 1/3–2/3 of CBD circumference
- Type IV: Fistula involving > 2/3 of CBD circumference (destruction of entire CBD wall)

4.2 Hepatic Causes

Pyogenic liver abscess — most commonly involves the right lobe (larger, greater portal blood flow) ^[3]
- Routes of spread: ^[3]
  - Intra-abdominal (via portal vein): appendicitis, diverticulitis, peritonitis
  - Direct (from biliary infection): gallstones, malignant obstruction
  - Haematogenous (arterial): infective endocarditis
  - External inoculation: surgical/traumatic
- Microbiology: Klebsiella pneumoniae (dominant in Hong Kong/East Asia, especially in diabetics), E. coli, Streptococcus milleri group, Staphylococcus aureus, anaerobes; polymicrobial in many cases ^[3]
- Risk factors: diabetes mellitus, hepatobiliary disease, liver transplantation ^[3]
Amoebic liver abscess — caused by Entamoeba histolytica; most common extra-intestinal manifestation of amoebiasis; consider in travellers from endemic areas ^[3]

Viral (HAV, HBV, HCV, HEV), drug-induced (paracetamol, isoniazid), alcoholic hepatitis
Mechanism: hepatocyte inflammation and swelling → distension of the Glisson's capsule (the liver capsule) → dull RUQ ache
Capsular distension is a key concept: the liver parenchyma itself has no pain fibres; it is the capsule that is innervated

In Hong Kong, HCC is strongly associated with chronic hepatitis B (and increasing HCV/NAFLD)
Large tumour → capsular stretching → RUQ pain; tumour rupture → acute haemoperitoneum

Hepatic venous outflow obstruction → hepatomegaly, RUQ pain, ascites
Causes: myeloproliferative disorders, OCP, hypercoagulable states

Acute pancreatitis (gallstone pancreatitis is the most common cause in Hong Kong) — epigastric pain radiating to the back, but can present as or include RUQ pain ^[4]
- Pathophysiology: unregulated premature activation of trypsin within pancreatic acinar cells → autodigestion → peripancreatic necrosis → NF-κB–dependent inflammatory cascade → SIRS ^[4]

Duodenal ulcer (especially posterior D1): epigastric pain, may localise to RUQ; aggravated by hunger, relieved by food (in classic DU)
Hepatic flexure pathology: colorectal carcinoma, colitis, diverticulitis (rare at hepatic flexure)
High / subhepatic appendicitis: can mimic biliary disease — always consider in young patients with RUQ tenderness and fever

Right renal colic (ureteric stone): severe, colicky loin-to-groin pain, but can be felt in RUQ
Right pyelonephritis: flank pain + fever + pyuria; can overlap with RUQ tenderness

Right basal pneumonia / pleuritis: lower lobe pneumonia can cause referred RUQ pain via irritation of the diaphragm
Pulmonary embolism: pleuritic chest pain in right lower zone can mimic RUQ pathology
Inferior MI: can present with epigastric/RUQ discomfort (especially in elderly, diabetics) — always do an ECG!

Fitz-Hugh-Curtis syndrome: perihepatitis secondary to PID (Chlamydia trachomatis or Neisseria gonorrhoeae) — young sexually active woman with RUQ pain + "violin string" adhesions on the liver surface ^[5]
Right adrenal haemorrhage (in anticoagulated patients, sepsis, Waterhouse-Friderichsen syndrome)
Gallbladder cancer: usually presents late; associated with gallstones (95%), porcelain gallbladder, gallbladder polyps > 1 cm, PSC ^[4]
Cholangiocarcinoma: perihilar (Klatskin tumour, most common), distal, or intrahepatic; risk factors include PSC, RPC, choledochal cysts, Caroli's disease, Clonorchis sinensis, Lynch syndrome ^[4]
Choledochal cysts: congenital dilatation of intra/extrahepatic biliary system; RUQ mass + pain + jaundice; risk of cholangiocarcinoma ^[2]

5. Classification

Organ System	Conditions
Biliary	Biliary colic, acute cholecystitis (calculous/acalculous), choledocholithiasis, acute cholangitis, RPC, Mirizzi syndrome, gallbladder cancer, cholangiocarcinoma, choledochal cyst
Hepatic	Hepatitis (viral, alcoholic, drug-induced), liver abscess (pyogenic, amoebic), HCC/metastases, Budd-Chiari syndrome, hepatic congestion (right heart failure)
Pancreatic	Acute pancreatitis (gallstone, alcoholic), pancreatic head tumour
GI	Duodenal ulcer, hepatic flexure pathology, subhepatic appendicitis
Renal	Renal colic, pyelonephritis
Thoracic	Right basal pneumonia, pulmonary embolism, inferior MI
Gynaecological	Fitz-Hugh-Curtis syndrome
Vascular	Budd-Chiari, portal vein thrombosis

Acute (hours)	Subacute (days–weeks)	Chronic (weeks–months)
Biliary colic, acute cholecystitis, cholangitis, pancreatitis, perforated DU, ruptured liver abscess, hepatic artery aneurysm rupture	Liver abscess, subacute hepatitis, RPC	Chronic cholecystitis, HCC, cholangiocarcinoma, chronic hepatitis, Budd-Chiari

Type	Cholesterol Stones (80% in West)	Black Pigment Stones (10–15%)	Brown Pigment Stones (5–10%)
Composition	> 50% cholesterol monohydrate crystals + mucin glycoprotein + calcium bilirubinate	Calcium bilirubinate polymer + calcium carbonate/phosphate	Calcium bilirubinate + calcium palmitate + cholesterol
Pathogenesis	Supersaturation of bile with cholesterol (↑ cholesterol, ↓ bile salts, ↓ lecithin) + nucleation + gallbladder hypomotility	Excess unconjugated bilirubin in bile (haemolysis, cirrhosis)	Bacterial infection (E. coli, Klebsiella) → β-glucuronidase deconjugates bilirubin → unconjugated bilirubin + calcium; associated with RPC, Clonorchis sinensis
Location	Gallbladder	Gallbladder	Intrahepatic and extrahepatic bile ducts (de novo)
Radiopacity	15% radio-opaque	Radio-opaque	Radio-lucent
Associations	5Fs, obesity, TPN, rapid weight loss, fibrates	Haemolytic anaemias (SCD, spherocytosis), cirrhosis	RPC, parasitic infections

6. Clinical Features

6.1 Symptoms

The clinical features of RUQ pain depend on the underlying pathology. Here we present them condition-by-condition with pathophysiological rationale.

Feature	Description	Pathophysiological Basis
Site	RUQ or epigastrium (sometimes substernal)	Visceral afferents from gallbladder travel via coeliac plexus to T5–T9 → referred to epigastrium/RUQ
Onset	Abrupt	Sudden impaction of stone in cystic duct
Character	Intense, dull, constant ("steady") — despite the name "colic"	Gallbladder is a muscular sac, not a tube; it contracts as a whole unit against obstruction → sustained pressure, not peristaltic waves
Radiation	Right shoulder tip or interscapular region	Phrenic nerve irritation (C3–C5) from diaphragmatic peritoneal inflammation
Associated	Nausea, vomiting, diaphoresis	Vagal stimulation from visceral pain
Timing	Lasts ≥ 30 min, plateaus within 1 hour, resolves within 6 hours	Stone dislodges from cystic duct → pressure normalises
Exacerbating	After a fatty meal	Fat in duodenum → CCK release → gallbladder contraction against impacted stone
Relieving	NOT relieved by position change, bowel movements, or antacids	Not GI motility-related or acid-related
NOT present	No fever, no peritoneal signs	No infection, no parietal peritoneal involvement — purely visceral pain

Key Distinction

Students often mistake biliary colic for a "colicky" pain with pain-free intervals. Biliary "colic" is actually a constant, steady pain (false colic). It is the duration (< 6 hours) and absence of fever that distinguishes it from cholecystitis, not the character of the pain.

Feature	Description	Pathophysiological Basis
Pain	Starts as biliary colic but becomes more constant, prolonged (> 4–6 hours), and severe	Stone remains impacted → chemical inflammation → parietal peritoneal irritation
Site	RUQ	Gallbladder fossa is in the RUQ (segments IVb/V)
Radiation	Right shoulder (Boas sign) or back / interscapular	Phrenic nerve (C3–C5) from diaphragmatic irritation
Fever	Present (low-grade initially, high-grade if empyema/gangrene)	Chemical then bacterial inflammation → cytokine release → hypothalamic set-point elevation
Exacerbated by	Movement and deep inspiration	Inflamed gallbladder adherent to parietal peritoneum → movement stretches inflamed peritoneum
Nausea/vomiting	Common	Vagal stimulation
Anorexia	Common	Systemic inflammatory response

Complications of acute cholecystitis (clinical features) ^[2]:

Gallbladder empyema: tender RUQ mass + septic-looking patient — pus fills the gallbladder
Gangrenous cholecystitis (20%): disproportionately severe pain, high fever, toxaemia — ischaemic necrosis of gallbladder wall
Perforation: biliary peritonitis — generalised guarding (though usually contained by omentum)
Emphysematous cholecystitis: gas-forming organisms (e.g. Clostridium welchii) → gas in gallbladder wall; insidious onset, abdominal crepitus — more common in diabetics
Cholecystoenteric fistula → gallstone ileus: large stone erodes through gallbladder into duodenum → impacts at ileocaecal valve → small bowel obstruction

Feature	Description	Pathophysiological Basis
Charcot's triad (present in ~2/3)	Fever (with rigors), RUQ pain, jaundice	Biliary obstruction + infection → intermittent bacteraemia (rigors), biliary distension (pain), impaired bilirubin excretion (jaundice)
Reynolds' pentad	Charcot's triad + hypotension + altered mental status	Indicates overwhelming sepsis → cholangiovenous reflux (bacteria/endotoxin enter bloodstream from bile ducts under pressure) → septic shock

Fever is often intermittent with chills/rigors — classic "spiking" fever pattern of cholangitis due to intermittent bacteraemia as bile duct pressure fluctuates ^[4]
Scleral icterus, pale stools, dark urine = obstructive jaundice pattern (conjugated hyperbilirubinaemia → absent urobilinogen in stool, increased renal conjugated bilirubin excretion) ^[1]

High Yield — Charcot vs Reynolds

Charcot's triad = Fever + RUQ pain + Jaundice → suggests cholangitis
Reynolds' pentad = Charcot's triad + Hypotension + Altered mental status → suggests suppurative/toxic cholangitis with septic shock — emergency biliary decompression needed

Charcot's triad (fever ± chills, RUQ/epigastric pain, jaundice) — recurrent episodes
History of prior biliary interventions, known intrahepatic stones
May have hepatomegaly (from intrahepatic stone-related hepatic parenchymal damage)

Feature	Description	Pathophysiological Basis
Fever (90%)	High spiking fever with rigors	Abscess = contained infection → intermittent bacteraemia
RUQ pain	Dull, constant, may be pleuritic	Hepatic capsular distension (Glisson's capsule)
Right shoulder pain	Referred pain	Diaphragmatic irritation → phrenic nerve (C3–C5)
Hepatomegaly	Tender, smooth enlargement	Abscess expanding within liver parenchyma
Weight loss, malaise	Subacute/chronic presentations	Chronic infection and catabolic state
Cough / right pleural effusion	In right lobe abscess abutting diaphragm	Diaphragmatic irritation → reactive pleural effusion

Feature	Description	Pathophysiological Basis
Pain	Epigastric (can be RUQ), severe, radiates to back	Pancreas is retroperitoneal → pain felt in epigastrium and referred posteriorly
Relieved by	Sitting up or leaning forward	Shifts the inflamed pancreas away from the retroperitoneal structures
Nausea/vomiting	Prominent	Gastric and duodenal ileus from adjacent inflammation
Onset	Rapid (gallstone); less abrupt (alcohol)	Gallstone impacts at ampulla suddenly vs. chronic alcohol-induced ductal changes

Epigastric pain that can localise to RUQ
DU: pain ~2 hours after meals, relieved by eating (food buffers acid, then acid rebounds)
GU: pain immediately after meals (food stimulates acid production on an already ulcerated mucosa)
Perforation: sudden, severe, constant epigastric pain → generalised peritonitis

Condition	Key Features
Right pyelonephritis	Fever, costovertebral angle tenderness, dysuria, pyuria
Right basal pneumonia	Cough, fever, pleuritic pain, crackles on auscultation, CXR infiltrate
Fitz-Hugh-Curtis	Young woman, sexually active, RUQ pain, concurrent vaginal discharge/PID features
Subhepatic appendicitis	Mimics cholecystitis — fever, RUQ tenderness, but more progressive course typical of appendicitis

6.2 Signs

How to elicit: With the examiner's fingers hooked under the right costal margin (at the gallbladder point — intersection of the lateral border of rectus abdominis with the costal margin), ask the patient to inspire deeply. A positive Murphy's sign = inspiratory arrest (the patient catches their breath and stops inhaling) due to the inflamed gallbladder descending onto the examiner's fingers during inspiration
Pathophysiological basis: In acute cholecystitis, the gallbladder wall is inflamed and adherent to parietal peritoneum. During inspiration, the diaphragm pushes the liver (and gallbladder) down → the inflamed gallbladder contacts the examining fingers → sharp peritoneal pain → reflex cessation of inspiration
Positive in acute cholecystitis; NEGATIVE in chronic cholecystitis (fibrotic gallbladder does not distend or move as much)
Sonographic Murphy sign: Murphy's sign elicited under ultrasound guidance — one of the cardinal ultrasound signs of acute cholecystitis ^[2]

Tenderness: localised pain on palpation → peritoneal inflammation (from biliary, hepatic, or other cause)
Guarding: voluntary (patient tenses abdominal muscles) or involuntary (reflex spasm due to peritonitis) → indicates parietal peritoneal involvement
Rigidity (board-like): indicates diffuse peritonitis (e.g. perforated cholecystitis or duodenal ulcer)

Courvoisier's law: In the presence of painless obstructive jaundice, a palpable (non-tender, distended) gallbladder is unlikely to be due to gallstones ^[2]
- Why? A gallbladder chronically exposed to gallstones becomes fibrotic and shrunken from repeated cholecystitis → it cannot distend. A palpable gallbladder in painless jaundice implies a previously normal gallbladder now distended by a distal obstruction (e.g. periampullary tumour — pancreatic head cancer, ampullary cancer, cholangiocarcinoma) ^[2]
- Exceptions: double impaction (stone in cystic duct + CBD simultaneously), Mirizzi syndrome, RPC ^[2]

Scleral icterus: visible when bilirubin > 35–50 µmol/L (look at the sclerae in natural light)
Indicates biliary obstruction (choledocholithiasis, cholangitis, Mirizzi) or hepatocellular dysfunction (hepatitis)

Present in cholecystitis, cholangitis, liver abscess, pancreatitis (late), and extra-biliary infections
Rigors (true shaking chills) are particularly suggestive of bacteraemia — classic for cholangitis and liver abscess

Sign	Condition	Mechanism
Tender RUQ mass	Gallbladder empyema, mucocele, large liver abscess	Pus-filled gallbladder or expanding hepatic abscess → palpable
Abdominal crepitus	Emphysematous cholecystitis	Gas-forming organisms (Clostridium) in gallbladder wall
Board-like rigidity	Perforation (gallbladder, duodenal ulcer)	Generalised peritonitis → involuntary abdominal wall spasm
Hepatomegaly	Liver abscess, HCC, hepatitis, Budd-Chiari	Parenchymal expansion or venous congestion
Cullen's sign / Grey Turner's sign	Severe acute pancreatitis	Retroperitoneal haemorrhage tracking to periumbilical area (Cullen) or flanks (Grey Turner)

High Yield Summary

RUQ pain differential — always think biliary first, but don't forget liver, pancreas, duodenum, kidney, lung, and gynaecological causes.
Biliary colic = constant (not truly colicky) pain, < 6 hours, no fever, no peritoneal signs. Pain is due to gallbladder contracting against an impacted stone.
Acute cholecystitis = biliary colic that persists > 4–6 hours + fever + Murphy's sign + peritoneal signs. Pathogenesis: impaction → chemical inflammation (lysolecithin) → secondary bacterial infection.
Acute cholangitis = Charcot's triad (fever + RUQ pain + jaundice). Reynolds' pentad adds hypotension + confusion → suppurative cholangitis/septic shock. Requires BOTH obstruction + bacteria.
RPC ("Hong Kong disease") = recurrent cholangitis from de novo intrahepatic brown pigment stones. Think Clonorchis sinensis, stasis + stricturing + recurrent infection.
Courvoisier's law = painless jaundice + palpable gallbladder → NOT gallstones → think periampullary tumour.
Murphy's sign = inspiratory arrest on deep RUQ palpation during inspiration. Positive in acute cholecystitis. Sonographic Murphy sign is one of the 5 cardinal USG features.
5 cardinal USG signs of acute cholecystitis: gallstones + distended GB (> 4 × 10 cm) + wall thickening (> 3 mm) + pericholecystic fluid + sonographic Murphy sign.
Liver abscess in Hong Kong → think Klebsiella pneumoniae in a diabetic patient.
Gallstone pancreatitis is the most common cause of acute pancreatitis in Hong Kong. Pain is epigastric, radiates to back, relieved by leaning forward.

Active Recall - RUQ Pain: Definition to Clinical Features

^[1] Lecture slides: GC 200. RUQ pain, jaundice and fever Cholecytitis and cholangitis Imaging of GI system.pdf ^[2] Senior notes: maxim.md (Section: Biliary colic, Acute cholecystitis, Gallstone classification) ^[3] Senior notes: felixlai.md (Section: Liver abscess) ^[4] Senior notes: felixlai.md (Sections: Cholecystitis, Acute cholangitis, Recurrent pyogenic cholangitis, Mirizzi syndrome, Gallbladder cancer, Acute pancreatitis) ^[5] Lecture slides: GC 195. Lower and diffuse abdominal pain RLQ problems; pelvic inflammatory disease; peritonitis and abdominal emergencies.pdf

Differential Diagnosis of RUQ Pain

The differential diagnosis of RUQ pain is one of the most commonly tested clinical reasoning exercises. The key to nailing it is to think anatomically — what organs live in the RUQ? — and then pathophysiologically — what can go wrong with each of them? Let's build this systematically.

When a patient presents with RUQ pain, you should mentally "scan" the structures in and near the RUQ:

Biliary system (gallbladder, cystic duct, CBD, intrahepatic ducts)
Liver (parenchyma, capsule, vasculature)
Pancreas (head — anatomically close to RUQ)
Duodenum (especially D1 and D2)
Hepatic flexure of colon
Right kidney and adrenal
Right lung base / pleura / diaphragm (referred pain)
Gynaecological (in females)
Vascular (aorta, hepatic/portal vasculature)
Abdominal wall

Think of the differential as a series of concentric circles radiating outward from the gallbladder. Biliary is most common, but don't stop there.

Systematic Differential Diagnosis — Condition by Condition

These are the bread-and-butter of RUQ pain. In the exam and on the ward, biliary disease should be at the top of your list.

Condition	Key Distinguishing Features	Why It Causes RUQ Pain
Biliary colic	Intense, dull, constant ("false colic"); lasts ≥ 30 min, plateaus within 1 h, resolves < 6 h; NO fever; NO peritoneal signs; often after fatty meal ^[1]^[2]	Gallstone transiently impacts cystic duct/Hartmann's pouch → gallbladder contracts against fixed obstruction → visceral pain via coeliac plexus (T5–T9)
Acute cholecystitis	Pain > 4–6 h, fever, Murphy's sign positive; exacerbated by movement/breathing ^[1]^[2]^[4]	Prolonged impaction → chemical inflammation (lysolecithin) → parietal peritoneal irritation → well-localised somatic pain
Choledocholithiasis	More prolonged pain (> 6 h), ± jaundice (conjugated hyperbilirubinaemia), dark urine, pale stools ^[4]	Stone in CBD → biliary obstruction → duct distension → visceral pain; impaired bilirubin excretion → jaundice
Acute cholangitis	Charcot's triad: fever with rigors + RUQ pain + jaundice; Reynolds' pentad adds hypotension + altered mental status ^[1]^[4]	Obstruction + bacterial contamination → ascending infection → cholangiovenous reflux (bacteria enter bloodstream under high biliary pressure) → sepsis
Recurrent pyogenic cholangitis (RPC)	Recurrent Charcot's triad episodes; Southeast Asian/Hong Kong patient; intrahepatic stones on imaging ^[4]	De novo intrahepatic brown pigment stones → cycles of obstruction → stasis → infection → stricturing → more stones
Mirizzi syndrome	Fever + jaundice + RUQ pain mimicking choledocholithiasis; imaging shows stone in cystic duct/Hartmann's pouch compressing CHD ^[4]	Impacted cystic duct stone → extrinsic compression of common hepatic duct → obstructive jaundice; chronic inflammation → cholecystobiliary fistula
Sphincter of Oddi dysfunction	Biliary-type pain < 6 h, intermittent; normal labs and imaging; diagnosis of exclusion ^[4]	Functional spasm or stenosis of sphincter of Oddi → transient biliary/pancreatic duct hypertension → visceral pain
Gallbladder cancer	Late presentation; associated with gallstones (95%), porcelain gallbladder, polyps > 1 cm; weight loss ^[4]	Tumour invades gallbladder wall → capsular/peritoneal irritation; may obstruct cystic duct or invade liver
Cholangiocarcinoma	Painless jaundice (extrahepatic type); weight loss; pruritus; risk factors: PSC, RPC, choledochal cysts, Clonorchis sinensis ^[4]	Extrahepatic tumour obstructs bile duct → progressive jaundice; perineural invasion → pain; intrahepatic type may cause capsular distension
Choledochal cyst	RUQ mass + pain + jaundice; often diagnosed in childhood; risk of cholangiocarcinoma ^[2]	Congenital cystic dilatation of biliary system → may become infected or obstruct bile flow

Differentiating Biliary Colic from Acute Cholecystitis

The single most important distinction to make in RUQ pain:

Biliary colic: pain resolves within < 6 hours, no fever, no peritoneal signs — the stone dislodges and the gallbladder relaxes.
Acute cholecystitis: pain persists > 4–6 hours, fever present, Murphy's sign positive — the stone stays impacted, chemical and then bacterial inflammation ensues.

If you remember one thing: the 6-hour rule separates colic from cholecystitis. ^[1]^[4]

The liver itself has no pain fibres. All hepatic pain is due to distension of Glisson's capsule (the fibrous liver capsule that IS innervated by somatic sensory nerves). Anything that swells the liver — inflammation, congestion, abscess, tumour — stretches the capsule and causes a dull, constant RUQ ache.

Condition	Key Distinguishing Features	Why It Causes RUQ Pain
Acute hepatitis	Tender hepatomegaly; jaundice; markedly elevated AST/ALT (typically > 10× ULN); viral prodrome or drug history ^[1]	Hepatocyte inflammation and swelling → liver enlargement → Glisson's capsule distension
Liver abscess (pyogenic)	High spiking fever (90%) with rigors; tender hepatomegaly; ± right pleural effusion; diabetic patient in Hong Kong → think Klebsiella pneumoniae ^[3]	Expanding abscess within parenchyma → capsular stretch; diaphragmatic irritation → referred right shoulder pain
Liver abscess (amoebic)	Similar to pyogenic but travel to endemic area; single right lobe abscess; anchovy sauce pus; serology for E. histolytica ^[3]	Same capsular distension mechanism; amoebae reach liver via portal vein from intestinal infection
HCC / liver metastases	Background chronic liver disease (HBV in HK), ↑AFP; constitutional symptoms; hepatomegaly with irregular edge ^[6]	Large tumour → capsular stretching; tumour rupture → acute haemoperitoneum
Budd-Chiari syndrome	RUQ pain + massive ascites + hepatomegaly + LL oedema; thrombotic risk factors (myeloproliferative, OCP, APS) ^[1]	Hepatic venous outflow obstruction → hepatic congestion → capsular distension
Portal vein thrombosis	Background cirrhosis; acute RUQ pain + fever + dyspepsia ^[1]	Acute portal congestion → hepatomegaly → capsular distension
Hepatic congestion (Right heart failure)	Raised JVP, peripheral oedema, hepatojugular reflux; tender hepatomegaly	Elevated right atrial pressure → back-pressure transmitted to hepatic veins → sinusoidal congestion → liver swelling → capsular stretch

Condition	Key Distinguishing Features	Why It Causes RUQ Pain
Acute pancreatitis	Epigastric pain (can be RUQ) radiating to back; relieved by sitting up/leaning forward; prominent N/V; ↑ amylase/lipase > 3× ULN; history of gallstones or alcohol ^[4]	Pancreas is retroperitoneal → inflammation radiates anteriorly to epigastrium/RUQ and posteriorly to back; leaning forward moves inflamed pancreas away from retroperitoneal structures
Pancreatic head tumour	Painless progressive jaundice; palpable gallbladder (Courvoisier's law); weight loss; new-onset diabetes	Tumour at pancreatic head compresses CBD → obstructive jaundice; perineural invasion → deep boring pain

Condition	Key Distinguishing Features	Why It Causes RUQ Pain
Peptic ulcer disease (duodenal ulcer)	Upper abdominal burning pain related to eating; DU pain ↓ after eating, recurs ~2 h later; NSAID/H. pylori history; may present with UGIB ^[1]^[6]	Acid erosion of duodenal mucosa (D1 is in the RUQ) → visceral nociceptor stimulation; posterior DU can erode into the pancreas → back pain
Perforated duodenal ulcer	Sudden severe epigastric pain rapidly generalising; board-like rigidity; ↓ liver dullness (pneumoperitoneum); history of NSAIDs	Full-thickness erosion → peritoneal contamination with acid and then bacteria → chemical then bacterial peritonitis
Hepatic flexure pathology	Colorectal carcinoma, diverticulitis, colitis at hepatic flexure; altered bowel habit, PR bleeding ^[1]	Distension or inflammation of colon at hepatic flexure → visceral pain referred to RUQ
Subhepatic/high appendicitis	Fever, RUQ tenderness (mimics cholecystitis); younger patient; progressive course typical of appendicitis	Appendix in retrocaecal or subhepatic position → inflamed appendix sits high in RUQ
Gastric outlet obstruction	Epigastric pain; non-bilious projectile vomiting of undigested food; succussion splash; malignant until proven otherwise ^[2]	Mechanical obstruction at pylorus/duodenum → gastric distension → visceral pain

Condition	Key Distinguishing Features	Why It Causes RUQ Pain
Right renal colic	Severe, colicky flank-to-groin pain; haematuria; restlessness (patient cannot lie still — unlike peritonitis) ^[7]	Ureteric stone → ureteric spasm and distension → true colic (peristaltic smooth muscle); upper ureteric stones may refer pain to RUQ
Right pyelonephritis	Classical triad: loin pain + tenderness + fever; dysuria, frequency; pyuria; costovertebral angle tenderness (Murphy's kidney punch) ^[7]	Renal parenchymal infection → capsular distension + pelvicalyceal inflammation
Renal cell carcinoma	Traditional triad: flank pain + painless haematuria + palpable flank mass (rare); constitutional symptoms; paraneoplastic features	Tumour expanding within kidney → capsular distension

These are the classic "catches" in exams — extra-abdominal pathology causing RUQ pain via diaphragmatic irritation or referred pain.

Condition	Key Distinguishing Features	Why It Causes RUQ Pain
Right basal pneumonia	Cough, fever, pleuritic pain, crackles on auscultation, CXR infiltrate in right lower zone ^[1]^[6]	Infection of right lower lobe → inflammation of visceral and parietal pleura overlying diaphragm → phrenic nerve (C3–C5) irritation → referred to RUQ/right shoulder
Pleural effusion	Dyspnoea, dullness to percussion, ↓ breath sounds at right base	Pleural fluid irritates diaphragmatic pleura → same phrenic nerve mechanism
Pulmonary embolism	Sudden pleuritic chest pain + dyspnoea ± haemoptysis; DVT risk factors; tachycardia	Right-sided pulmonary infarction → pleuritic inflammation → referred diaphragmatic pain
Basal myocardial infarction (inferior MI)	Epigastric/RUQ discomfort (especially elderly, diabetics); diaphoresis; ECG changes (ST elevation in leads II, III, aVF) ^[6]^[8]	Inferior wall of the heart shares vagal afferent pathways with the upper abdomen → pain misinterpreted as GI; also diaphragmatic irritation

Never Forget the ECG

An inferior MI can masquerade as RUQ pain, especially in elderly and diabetic patients. Always do a 12-lead ECG in any patient presenting with acute upper abdominal pain, particularly if the abdominal examination is surprisingly benign. Missing an MI is catastrophic. ^[6]^[8]

Condition	Key Distinguishing Features	Why It Causes RUQ Pain
Fitz-Hugh-Curtis syndrome	Young, sexually active woman; pleuritic RUQ pain ± radiation to right shoulder; vaginal discharge; concurrent PID features; "violin string" adhesions on liver surface ^[5]	Chlamydia trachomatis or Neisseria gonorrhoeae ascends from pelvis → perihepatitis (inflammation of liver capsule/peritoneum) → RUQ pain

Condition	Key Distinguishing Features	Why It Causes RUQ Pain
Herpes zoster	Unilateral dermatomal burning pain ± vesicular rash in T7–T11 distribution ^[6]	Reactivation of VZV in dorsal root ganglia → neuropathic pain along the intercostal/subcostal nerve dermatomes overlying the RUQ
Abdominal wall pain	Localised, superficial tenderness that worsens with tensing abdominal muscles (Carnett's sign positive)	Myofascial pain, nerve entrapment, or rectus sheath haematoma → somatic pain in the RUQ
Right adrenal haemorrhage	Anticoagulated patient or sepsis (Waterhouse-Friderichsen syndrome); acute flank/RUQ pain; adrenal insufficiency	Haemorrhage into adrenal gland → capsular distension and retroperitoneal irritation
Subphrenic abscess	Post-surgical or post-perforation; fever, RUQ pain, referred shoulder pain; ↓ breath sounds at right base	Collection of pus between liver dome and diaphragm → diaphragmatic irritation → phrenic nerve referral

Here is a practical approach to narrowing the differential when a patient presents with RUQ pain:

How to read this diagram: Start with the two most discriminating questions — is there fever? Is there jaundice? These two features alone stratify most biliary-hepatic RUQ pathology. Then refine with pain duration, lab results, and imaging.

This table is designed for rapid revision. Each row highlights the single most distinguishing feature of each condition.

Condition	"If you see this, think this"
Biliary colic	Constant pain < 6 h + no fever + no peritoneal signs
Acute cholecystitis	Pain > 6 h + fever + Murphy's sign
Choledocholithiasis	Jaundice + prolonged pain + cholestatic LFTs
Acute cholangitis	Charcot's triad (fever + pain + jaundice)
Suppurative cholangitis	Reynolds' pentad (add shock + confusion)
RPC	Recurrent cholangitis in SE Asian patient + intrahepatic stones
Mirizzi syndrome	Jaundice + stone in cystic duct/Hartmann's compressing CHD on imaging
Liver abscess	Spiking fever + tender hepatomegaly + diabetic (Klebsiella in HK)
Acute hepatitis	Tender hepatomegaly + massively ↑ AST/ALT + jaundice
HCC	Chronic liver disease background + irregular hepatomegaly + ↑ AFP
Budd-Chiari	RUQ pain + massive ascites + thrombotic risk factors
Acute pancreatitis	Epigastric/RUQ pain to back + ↑ amylase/lipase > 3×
Duodenal ulcer	Epigastric pain ↓ by eating + NSAID/H. pylori history
Perforated DU	Sudden severe pain + board-like rigidity + ↓ liver dullness
Right renal colic	Colicky loin-to-groin + haematuria + restless patient
Right pyelonephritis	Loin pain + fever + pyuria + CVA tenderness
Right basal pneumonia	Cough + fever + pleuritic pain + CXR infiltrate
Inferior MI	Elderly/diabetic + RUQ pain + ECG changes (II, III, aVF)
Fitz-Hugh-Curtis	Young sexually active woman + RUQ + PID features
Herpes zoster	Dermatomal burning pain ± vesicular rash

1. The "6-hour rule" for biliary pain ^[4]

Pain < 6 hours, no fever → biliary colic
Pain > 6 hours, fever → cholecystitis
This is because the stone either dislodges (colic resolves) or stays impacted long enough for chemical inflammation to set in (cholecystitis begins)

2. Courvoisier's law — when the gallbladder is palpable ^[4]

"In painless jaundice, if the gallbladder is palpable, the cause is unlikely to be gallstones"
Why? Chronic gallstones → repeated cholecystitis → fibrosed, shrunken gallbladder that cannot distend. A palpable gallbladder therefore implies a previously normal gallbladder distended by distal obstruction (periampullary tumour)
Exceptions: double impaction (stone in cystic duct + CBD), Mirizzi syndrome, RPC ^[4]

3. Always consider extra-abdominal causes ^[6]^[8]

Right basal pneumonia and inferior MI are the two most dangerous "mimics" of RUQ pain
A CXR and ECG should be part of the initial workup for any acute RUQ pain presentation

4. Age and context matter

Young woman with RUQ pain → consider Fitz-Hugh-Curtis, ectopic pregnancy, ovarian pathology ^[5]
Elderly diabetic with RUQ pain and fever → Klebsiella liver abscess in Hong Kong context ^[3]
Patient with known chronic liver disease and new RUQ pain → HCC rupture until proven otherwise

5. Referred pain patterns ^[1]

Right shoulder/scapula → diaphragmatic irritation (phrenic nerve C3–C5): cholecystitis, liver abscess, subphrenic abscess, basal pneumonia
Back → retroperitoneal structure (pancreas, posterior DU, kidney, AAA)
Loin to groin → ureteric colic

High Yield Summary — Differential Diagnosis of RUQ Pain

Biliary disease is the most common cause — always consider biliary colic, cholecystitis, choledocholithiasis, and cholangitis first.
The 6-hour rule: pain < 6 h without fever = biliary colic; pain > 6 h with fever = cholecystitis.
Charcot's triad (fever + pain + jaundice) = cholangitis. Reynolds' pentad adds shock + confusion = suppurative cholangitis needing emergency drainage.
Courvoisier's law: painless jaundice + palpable gallbladder = periampullary tumour (NOT gallstones). Exceptions: double impaction, Mirizzi, RPC.
Hepatic pain = Glisson's capsule distension (liver itself has no nociceptors). Think hepatitis, abscess, HCC, Budd-Chiari, congestion.
In Hong Kong: Klebsiella liver abscess in diabetics, RPC with intrahepatic pigment stones, HBV-related HCC.
Don't forget extra-abdominal causes: right basal pneumonia, PE, inferior MI (especially in elderly/diabetics — always do ECG and CXR).
Fitz-Hugh-Curtis syndrome: young sexually active woman with pleuritic RUQ pain + PID features.

Active Recall - Differential Diagnosis of RUQ Pain

References

^[1] Lecture slides: GC 200. RUQ pain, jaundice and fever Cholecytitis and cholangitis Imaging of GI system.pdf ^[2] Senior notes: maxim.md (Sections: Biliary colic, Acute cholecystitis, Choledochal cyst, Gastric outlet obstruction) ^[3] Senior notes: felixlai.md (Section: Liver abscess) ^[4] Senior notes: felixlai.md (Sections: Cholecystitis, Acute cholangitis, Choledocholithiasis, Recurrent pyogenic cholangitis, Mirizzi syndrome, Cholangiocarcinoma, Gallbladder cancer, Acute pancreatitis) ^[5] Lecture slides: GC 195. Lower and diffuse abdominal pain RLQ problems; pelvic inflammatory disease; peritonitis and abdominal emergencies.pdf ^[6] Senior notes: Ryan Ho GI.pdf (Section: RUQ Pain differential table, p209–210) ^[7] Senior notes: Ryan Ho Urogenital.pdf (Sections: Acute pyelonephritis, Haematuria and Urolithiasis) ^[8] Senior notes: Ryan Ho Cardiology.pdf (Section: Approach to acute chest pain, biliary as chest pain mimic)

Diagnostic Criteria, Diagnostic Algorithm, and Investigation Modalities for RUQ Pain

RUQ pain is a clinical syndrome, not a single diagnosis. The investigation strategy is therefore a staged approach — you start with bedside and blood tests to narrow the differential, then use targeted imaging to confirm (or exclude) specific diagnoses. Let's build this from first principles.

1. Formal Diagnostic Criteria for Major Causes of RUQ Pain

While "RUQ pain" itself has no single diagnostic criterion, the major conditions that present with RUQ pain each have well-defined criteria. Knowing these is essential for exams.

The TG criteria are the internationally accepted standard. They combine local signs, systemic signs, and imaging into a structured diagnostic framework.

Component	Criteria
A: Local signs of inflammation	Murphy's sign (Sens 50–65%, Spec 79–96%), RUQ mass/pain/tenderness
B: Systemic signs of inflammation	Fever, ↑ WBC, ↑ CRP (> 3 mg/dL)
C: Imaging findings	Findings characteristic of acute cholecystitis (see USG section below)

Interpretation ^[4]^[6]:

Suspected diagnosis = one item from A + one item from B
Definite diagnosis = one item from A + one item from B + C (imaging confirmation)

Why three components? Because clinical signs alone can be non-specific (Murphy's sign has only ~50–65% sensitivity), and imaging alone may show incidental findings. The combination increases both sensitivity (~91%) and specificity (~97%). ^[6]

TG18 Severity Grading — Don't Just Diagnose, Grade It

Once you diagnose acute cholecystitis, the TG18 system also grades severity — this directly determines management:

Grade I (Mild): Acute cholecystitis in a healthy patient with no organ dysfunction → early laparoscopic cholecystectomy
Grade II (Moderate): Any of: WBC > 18,000, palpable RUQ mass, duration > 72 h, marked local inflammation (gangrenous, emphysematous, pericholecystic abscess) → early LC if suitable, otherwise percutaneous cholecystostomy
Grade III (Severe): With organ dysfunction (cardiovascular, neurological, respiratory, renal, hepatic, haematological) → urgent drainage + ICU care

Component	Criteria
A: Systemic inflammation	Fever/chills OR laboratory evidence of inflammatory response (↑ WBC, ↑ CRP)
B: Cholestasis	Jaundice OR abnormal liver chemistries (↑ AST/ALT/ALP/GGT)
C: Imaging	Biliary dilatation on imaging OR evidence of aetiology (stone, stricture, stent)

Interpretation ^[4]:

Suspected diagnosis = one item from A + one item from B
Definite diagnosis = suspected criteria met + BOTH items from C (biliary dilatation + identified cause)

Severity grading ^[4]:

Grade I (Mild): responds to initial medical treatment (antibiotics)
Grade II (Moderate): does not respond to initial treatment; any 2 of: WBC > 12,000 or < 4,000, fever ≥ 39°C, age ≥ 75, bilirubin ≥ 85 µmol/L, albumin < 0.7 × LLN
Grade III (Severe / Reynolds' pentad territory): organ dysfunction — cardiovascular (hypotension requiring vasopressors), neurological (altered consciousness), respiratory, renal, hepatic, haematological (DIC)

Diagnosis requires ≥ 2 out of 3 ^[4]^[9]:

Clinical: Acute onset of persistent, severe, epigastric pain often radiating to the back
Biochemical: Serum amylase or lipase ≥ 3× upper limit of normal (ULN)
Imaging: Characteristic findings of acute pancreatitis on USG, contrast-enhanced CT, or MRI

Why 2 of 3? Because in most cases, the clinical picture + elevated enzymes are sufficient. Imaging is reserved for diagnostic uncertainty or to assess complications (CT ideally done ≥ 72 hours after onset to detect necrosis). ^[9]

Amylase vs Lipase

Students often confuse these:

Serum amylase: rises within 6–12 h, normalises in 3–5 days. Less specific — can be elevated in PPU, ruptured AAA, DKA, macroamylasaemia, salivary disease. Cut-off for pancreatitis = ≥ 3× ULN (NOT just any elevation). ^[9]
Serum lipase: rises within 4–8 h, normalises in 8–14 days (longer half-life). More specific for pancreatic origin. Preferred test for delayed presentations (> 24 h) because amylase may have already normalised by then. ^[9]
Neither enzyme level correlates with severity — a patient with amylase of 5000 is not necessarily sicker than one with 1000. ^[9]

"In painless obstructive jaundice, if the gallbladder is palpable, the cause is unlikely to be gallstones" ^[4]

Why? Chronic exposure to gallstones → repeated episodes of cholecystitis → gallbladder becomes fibrosed and contracted → cannot distend even when the CBD is obstructed. A palpable gallbladder therefore implies the gallbladder was previously normal and is now distended by a new, distal obstruction (i.e., periampullary tumour — pancreatic head cancer, ampullary cancer, distal cholangiocarcinoma). ^[4]
Exceptions: double impaction (stone in cystic duct + CBD simultaneously), Mirizzi syndrome, RPC ^[4]

The approach to investigating RUQ pain is systematic: bedside → bloods → first-line imaging (USG) → second-line imaging/intervention as needed. ^[1]^[6]

The RUQ Pain Investigation Hierarchy

Think of investigations as a pyramid:

Base (always do): CBC/D, L/RFT, amylase/lipase — these are your screening bloods ^[1]^[6]
First-line imaging: USG HBS — this is THE first investigation for RUQ pain. It is quick, readily available, non-invasive, and highly sensitive for gallstones (95%) ^[1]^[6]^[9]
Second-line: MRCP (non-invasive ductal imaging, more sensitive than CT) or CT abdomen (for complications, alternative diagnoses, staging) ^[1]^[6]
Therapeutic/diagnostic: ERCP (when you need to intervene — stone extraction, stent, sphincterotomy) ^[1]^[6]
Rarely needed: HIDA scan (cholescintigraphy) — for equivocal USG in suspected cholecystitis ^[6]

3. Investigation Modalities — Detailed Breakdown

Test	What You're Looking For	Why
Vital signs	Fever (cholecystitis, cholangitis, abscess), tachycardia (sepsis, dehydration), hypotension (Reynolds' pentad)	Fever + hypotension = think septic cholangitis → emergency
Urinalysis	Pyuria/bacteriuria (pyelonephritis), haematuria (renal colic), bilirubinuria (obstructive jaundice)	Bilirubinuria = conjugated bilirubin in urine, confirms obstructive jaundice (only conjugated bilirubin is water-soluble enough to be filtered) ^[4]
Urine pregnancy test	Rule out ectopic pregnancy in women of childbearing age	Ruptured ectopic can cause acute abdominal pain; essential before CT (radiation) ^[5]^[9]
12-lead ECG	ST elevation in leads II, III, aVF (inferior MI)	Inferior MI can masquerade as RUQ/epigastric pain, especially in elderly and diabetics ^[8]^[9]

Test	Key Findings	Interpretation and Pathophysiology
CBC with differential	Leukocytosis with left shift (↑ neutrophils/bands)	Bacterial infection — cholecystitis, cholangitis, abscess, appendicitis. Markedly ↑ WBC (> 18,000) suggests gangrenous/complicated cholecystitis or abscess. Normal WBC does NOT rule out surgical pathology. ^[4]^[6]
Liver function tests (LFT)	Hepatocellular pattern: ↑↑ AST/ALT (> 10× ULN)	Hepatitis (viral, drug-induced, ischaemic). Transaminases leak from damaged hepatocytes into the blood.
	Cholestatic pattern: ↑ ALP, ↑ GGT, ↑ conjugated bilirubin	Biliary obstruction (choledocholithiasis, cholangitis, Mirizzi, tumour). ALP is concentrated in the canalicular membrane of hepatocytes — obstruction causes back-pressure and ↑ ALP synthesis. GGT confirms hepatic origin of ↑ ALP (vs. bone). ^[4]
	Mixed pattern: ↑ AST/ALT early, then ALP/GGT predominate	Early biliary obstruction — transient hepatocyte injury from acute bile duct pressure, then cholestatic pattern emerges as obstruction persists ^[4]
	↑ Bilirubin (conjugated)	Post-hepatic obstruction → conjugated bilirubin cannot be excreted into bile → regurgitates into blood → dark urine (conjugated bilirubin is water-soluble) + pale stools (no urobilinogen in gut)
Amylase / Lipase	≥ 3× ULN diagnostic of pancreatitis (in context of clinical features) ^[9]	See box above for amylase vs. lipase differences. Mild elevations (< 3× ULN) can occur in cholecystitis, cholangitis, intestinal obstruction, and PPU — these are not diagnostic of pancreatitis ^[9]
CRP	↑ in infection/inflammation	Non-specific but used in TG18 criteria (CRP > 3 mg/dL) for diagnosing cholecystitis. Also useful for monitoring treatment response.
Clotting profile (PT/INR)	Prolonged PT/INR in obstructive jaundice	Vitamin K is a fat-soluble vitamin that requires bile salts for intestinal absorption. Biliary obstruction → no bile in gut → Vitamin K malabsorption → ↓ synthesis of clotting factors II, VII, IX, X → coagulopathy. Must correct before any invasive procedure (ERCP, surgery, drainage). ^[4]
RFT (Cr, urea, electrolytes)	↑ Cr (dehydration from vomiting; contrast suitability); electrolyte derangement	Hypokalemia and hypochloraemia from prolonged vomiting; Cr needed to assess safety of contrast CT ^[9]
Blood cultures	Positive in cholangitis, liver abscess	Should be taken before starting antibiotics. Identifies causative organism and guides targeted therapy. Cholangitis classically grows E. coli, Klebsiella, Enterococcus. ^[4]
Tumour markers	CEA, CA 19-9	Often elevated in cholangiocarcinoma and pancreatic cancer but lack sensitivity and specificity — NOT diagnostically useful on their own ^[4]. Useful for serial monitoring after resection.

The LFT Pattern Tells You WHERE the Problem Is

↑↑ AST/ALT (hepatocellular) → the problem is in the liver (hepatitis, ischaemia, drug toxicity)
↑↑ ALP/GGT/bilirubin (cholestatic) → the problem is downstream of the liver (bile duct obstruction)
Mixed → early biliary obstruction or infiltrative liver disease

This simple pattern recognition is one of the highest-yield concepts for interpreting LFTs in RUQ pain. ^[4]

USG of the hepatobiliary system is THE first-line investigation for RUQ pain. There is no debate about this.

Why USG first?

Readily available, quick (can be done at bedside)
No radiation, no contrast
Highly sensitive for gallstones (~95%) ^[9]
Can assess gallbladder wall, bile duct diameter, liver parenchyma, kidneys
Can perform sonographic Murphy's sign in real time

Limitations:

Operator-dependent ^[2]
Limited by body habitus (obesity) and bowel gas (especially the distal CBD and pancreas) ^[1]^[6]
Cannot reliably detect CBD stones (sensitivity ~50–75% for choledocholithiasis vs. ~95% for gallbladder stones) — distal bile duct is obscured by duodenal gas ^[1]^[6]

Key USG Findings by Condition:

1. Gallstones (Cholelithiasis)

Hyperechoic focus with posterior acoustic shadowing ^[2]
Gravity-dependent: moves when patient turns → "rolling stone sign" (helps differentiate from polyps, which are fixed) ^[2]

2. Five Cardinal USG Signs of Acute Cholecystitis ^[2]^[6]

This is extremely high yield. Memorise these:

Sign	Finding	Pathophysiological Basis
1. Gallstones	Hyperechoic with posterior shadowing	Causative agent of calculous cholecystitis
2. Distended gallbladder	> 4 × 10 cm	Obstructed cystic duct → bile cannot exit → gallbladder distends
3. Gallbladder wall thickening	> 3 mm	Inflammatory oedema of the gallbladder wall
4. Pericholecystic fluid	Anechoic rim around gallbladder	Inflammatory exudate/oedema seeping through inflamed wall
5. Sonographic Murphy's sign	Maximal tenderness when USG probe presses directly over the visualised gallbladder	Confirms that the tenderness is specifically arising from the gallbladder (not adjacent structures)

USG performance for acute cholecystitis: Sens ~88%, Spec ~80% ^[6]

Sonographic Murphy's sign is simply Murphy's sign performed under ultrasound guidance — the examiner presses the ultrasound probe over the gallbladder and watches for inspiratory arrest. This is more specific than clinical Murphy's sign because you know you are pressing directly on the gallbladder. ^[6]^[9]

3. Choledocholithiasis / Biliary Obstruction

Dilated CBD (> 6–7 mm): measured at the porta hepatis. In post-cholecystectomy patients, up to 10 mm may be normal.
Dilated intrahepatic ducts (> 2 mm or "parallel channel sign" — dilated duct running alongside portal vein branch, creating a "double barrel shotgun" appearance)
Stone may be visible in CBD but often not seen due to distal bowel gas — this is why MRCP or ERCP is needed as second-line when CBD stone is suspected ^[1]^[6]

4. Liver Abscess

Hypoechoic or heterogeneous lesion within liver parenchyma, often with internal echoes/debris (pus)
Usually in right lobe (greater portal blood flow)
May show gas within abscess (hyperechoic foci with "dirty shadowing")

5. Mirizzi Syndrome ^[4]

Gallstone impacted in gallbladder neck
Dilatation of biliary system above the level of gallbladder neck
Abrupt change to normal-width CBD below the level of the stone ^[4]

6. Other Findings

Hepatomegaly / liver masses (HCC, metastases — require CT/MRI for characterisation)
Ascites (anechoic free fluid)
Renal pathology (hydronephrosis, renal stones)

D. Second-Line Imaging

MRCP = "MR" (magnetic resonance) + "C" (cholangio- = bile ducts) + "P" (pancreatography = pancreatic duct). It is a non-invasive way to visualise the biliary and pancreatic ductal systems using heavily T2-weighted MRI sequences (fluid-filled structures appear bright).

When to use:

Second-line investigation when USG is inconclusive — more sensitive than CT for biliary pathology ^[1]^[6]
Suspected choledocholithiasis when USG shows dilated CBD but no visible stone
Mirizzi syndrome — high sensitivity for demonstrating stone position and fistula; T2-weighted images can differentiate neoplastic from inflammatory mass ^[4]
Suspected cholangiocarcinoma — maps ductal anatomy before intervention
When intervention is NOT immediately needed (if you need intervention, go straight to ERCP)

Advantages:

No radiation, no contrast, non-invasive
Excellent for ductal anatomy
Can detect small CBD stones missed by USG

Limitations:

Less available, takes longer
Cannot provide therapy (unlike ERCP)
Claustrophobia, metal implants (MRI contraindications)

When to use:

Rule out complications of cholecystitis (gangrenous cholecystitis, perforation, emphysematous cholecystitis, pericholecystic abscess) ^[6]
Rule out alternative diagnoses (pancreatitis, appendicitis, perforated ulcer, renal pathology, aortic pathology)
Suspected liver abscess (CT better characterises than USG)
Staging of malignancy (gallbladder cancer, cholangiocarcinoma, pancreatic cancer)
Pancreatic protocol CT for suspected pancreatic head tumour: oral water contrast, early arterial phase (25 s), pancreatic phase (40 s), delayed phase (70 s) ^[6]

Key CT Findings:

Condition	CT Findings
Acute cholecystitis	GB wall thickening, pericholecystic fat stranding (not seen on USG), gallstones (less readily seen than on USG), pericholecystic fluid; Sens 94%, Spec 59% ^[6]
Emphysematous cholecystitis	Gas within GB wall — pathognomonic; gas-forming organisms (Clostridium welchii)
Gallbladder perforation	Discontinuity of GB wall, pericholecystic collection/abscess
Liver abscess	Hypoattenuating lesion with rim enhancement (enhancing wall), ± gas
Acute pancreatitis	Diffuse pancreatic enlargement, peripancreatic fat stranding, ± necrosis (hypoenhancement on contrast), ± peripancreatic fluid collections ^[9]
Pancreatic head tumour	Hypoenhancing mass in pancreatic head + double duct sign (dilated CBD + dilated pancreatic duct) ^[6]
Perforated DU	Free gas under diaphragm (also seen on erect CXR), peri-duodenal fluid
Renal stone	Non-contrast CT (NCCT) is gold standard for urolithiasis — hyperdense focus in ureter
Appendicitis	Distended appendix (> 6 mm), wall thickening (> 2 mm) + hyperenhancement, periappendiceal fat stranding, ± appendicolith ^[6]

Often overlooked but still important as part of the initial workup:

Modality	Key Findings	Interpretation
Erect CXR	Free gas under diaphragm	Perforated viscus (PPU, perforated GB) — however, absence of free gas does NOT rule out perforation (~20% of PPU have no visible free gas)
	Right basal consolidation / pleural effusion	Right basal pneumonia or reactive effusion from subdiaphragmatic pathology
Supine AXR	Radio-opaque stones	Only 15% of gallstones are radio-opaque (pigment stones contain calcium); 90% of urinary stones are radio-opaque — this helps differentiate gallstones from renal stones ^[9]
	Mercedes-Benz sign	Triradiate lucency within a gallstone — gas fissures in a gallstone (rare but pathognomonic) ^[2]
	Sentinel loop sign	Single dilated loop of bowel (usually jejunum) adjacent to inflamed organ — indicates localised ileus from nearby inflammation (e.g. pancreatitis) ^[9]
	Colonic cut-off sign	Distended colon from ascending to mid-transverse colon with spasm/paucity of gas distal to splenic flexure — suggests pancreatitis ^[9]
	Rigler's triad (gallstone ileus)	Pneumobilia + small bowel obstruction + ectopic gallstone — pathognomonic for cholecystoenteric fistula with gallstone ileus
	Pancreatic calcification	Chronic pancreatitis

E. Therapeutic / Diagnostic Interventional Procedures

ERCP = "E" (endoscopic) + "R" (retrograde — contrast injected backwards up the ducts) + "C" (cholangio) + "P" (pancreatography)

When to use ^[6]:

High probability of CBD stone AND need for therapeutic intervention
Acute cholangitis requiring biliary decompression (stone extraction, stent placement)
Suspected biliary pancreatitis with concurrent cholangitis
Suspected periductal malignancy (cholangiocarcinoma, ampullary cancer)
Sphincter of Oddi dysfunction
Biliary strictures and RPC ^[6]

Therapeutic capabilities ^[6]:

Endoscopic sphincterotomy (cutting the sphincter of Oddi to widen the bile duct opening)
Stone retrieval (using balloon or basket)
Stent insertion (for malignant or benign strictures — allows bile drainage)
Balloon dilatation of strictures
Brush biopsy (sensitivity ~60% only) ^[6]

Complications of ERCP (important for exams):

Post-ERCP pancreatitis (most common, 3–10%) — due to trauma to ampulla/pancreatic duct orifice
Bleeding (post-sphincterotomy)
Perforation (duodenal)
Cholangitis (introducing bacteria during the procedure)
Basket impaction (stone too large to extract)

When NOT to use ERCP: if you only need diagnostic imaging and no intervention is planned → use MRCP instead. ERCP carries procedural risks and should be reserved for when therapeutic intervention is intended. ^[6]

HIDA = "Hepatobiliary Iminodiacetic Acid" — a nuclear medicine scan.

Mechanism: IV 99mTc-labelled HIDA is taken up selectively by hepatocytes → excreted into bile → normally fills the gallbladder within 1 hour. Non-visualisation of the gallbladder indicates cystic duct obstruction (i.e., acute cholecystitis). ^[6]

When to use:

When USG is equivocal/inconclusive for acute cholecystitis ^[6]
Acalculous cholecystitis (no stones on USG but clinical picture fits)

Performance: Sens 90–97%, Spec 71–90% ^[6] — highest sensitivity of any single test for acute cholecystitis, but rarely available and takes time.

Morphine augmentation: Morphine can be administered during HIDA scan to contract the sphincter of Oddi, increasing biliary pressure → if gallbladder still doesn't fill, it strongly confirms cystic duct obstruction. ^[2]

When to use:

When ERCP fails or is not possible (e.g., altered anatomy from previous Billroth II / Roux-en-Y surgery, tumour blocking endoscopic access)
Proximal biliary obstruction (e.g., hilar cholangiocarcinoma) where ERCP cannot reach
Percutaneous cholecystostomy in acalculous cholecystitis (critically ill patient unfit for surgery) ^[4]

Complications: sepsis (spillage of infected bile), haemorrhage (puncturing hepatic vessels), bile leak ^[10]

High sensitivity for small CBD stones (< 5 mm) that may be missed on USG and even MRCP
Can perform fine-needle aspiration (FNA) of pancreatic masses, lymph nodes
Increasingly used in biliary/pancreatic workup

Condition	First-Line	Second-Line	Gold Standard / Definitive
Biliary colic	USG HBS (gallstones + normal GB wall) + bloods (normal WBC, LFT)	Rarely needed	USG confirming gallstones + consistent clinical picture
Acute cholecystitis	USG HBS (5 cardinal signs) + TG18 criteria	CT (complications), HIDA (equivocal USG)	TG18 criteria (local + systemic + imaging)
Choledocholithiasis	USG (dilated CBD ± stone) + cholestatic LFTs	MRCP (non-invasive ductal imaging)	ERCP (diagnostic + therapeutic)
Acute cholangitis	USG (dilated CBD) + TG18 criteria + blood cultures	MRCP/CT	ERCP with bile culture
Acute pancreatitis	Amylase/lipase ≥ 3× ULN + clinical features	Contrast-enhanced CT (≥ 72 h for necrosis)	Revised Atlanta criteria (2/3)
Liver abscess	USG (hypoechoic lesion) + blood cultures	Contrast CT (characterisation)	USG/CT-guided aspiration (diagnostic + therapeutic)
Perforated DU	Erect CXR (free gas under diaphragm)	CT abdomen	Surgical exploration
Cholangiocarcinoma	USG + cholestatic LFTs + CA 19-9	MRCP + CT with pancreatic protocol	ERCP with brush biopsy / surgical histology
Right renal colic	Urinalysis (haematuria)	NCCT KUB (gold standard)	NCCT KUB
Right basal pneumonia	CXR	CT thorax if needed	CXR + clinical response to antibiotics

High Yield Summary — Diagnosis of RUQ Pain

USG HBS is the first-line investigation for all RUQ pain — quick, non-invasive, 95% sensitive for gallstones.
5 cardinal USG signs of acute cholecystitis: gallstones, distended GB (> 4 × 10 cm), wall thickening (> 3 mm), pericholecystic fluid, sonographic Murphy's sign.
TG18 criteria for acute cholecystitis: Suspected = 1 local sign + 1 systemic sign; Definite = + imaging.
TG18 criteria for acute cholangitis: Suspected = systemic inflammation + cholestasis; Definite = + biliary dilatation + identified cause.
Revised Atlanta criteria for acute pancreatitis: ≥ 2 of 3 (clinical + amylase/lipase ≥ 3× ULN + imaging).
Lipase is preferred over amylase for delayed presentations (> 24 h) due to longer half-life and greater specificity.
MRCP is second-line for ductal imaging (non-invasive); ERCP is for when you need to intervene (therapeutic).
HIDA scan is the most sensitive test for acute cholecystitis (Sens 90–97%) but is reserved for equivocal USG cases.
Always do ECG + CXR in acute RUQ pain to rule out inferior MI and right basal pneumonia.
Cholestatic LFT pattern (↑ ALP, GGT, conjugated bilirubin) points to biliary obstruction; hepatocellular pattern (↑↑ AST/ALT) points to liver parenchymal disease.
Courvoisier's law: painless jaundice + palpable GB → periampullary tumour, NOT gallstones.
Coagulopathy in obstructive jaundice is due to Vitamin K malabsorption (fat-soluble vitamin requiring bile salts) — must correct before invasive procedures.

Active Recall - Diagnostic Criteria and Investigations for RUQ Pain

References

^[1] Lecture slides: GC 200. RUQ pain, jaundice and fever Cholecytitis and cholangitis Imaging of GI system.pdf ^[2] Senior notes: maxim.md (Sections: Biliary colic USG findings, Acute cholecystitis USG signs, Mercedes Benz sign) ^[4] Senior notes: felixlai.md (Sections: Cholecystitis diagnostic criteria Tokyo 2013, Acute cholangitis diagnosis, Mirizzi syndrome diagnosis, Choledocholithiasis diagnosis, Courvoisier's law) ^[5] Lecture slides: GC 195. Lower and diffuse abdominal pain RLQ problems; pelvic inflammatory disease; peritonitis and abdominal emergencies.pdf ^[6] Senior notes: Ryan Ho GI.pdf (Sections: Acute cholecystitis TG13 criteria and imaging p247-248, RUQ pain approach p209-210, ERCP indications p299, Acute pancreatitis diagnostic criteria p340-341, Appendicitis workup p150) ^[8] Senior notes: Ryan Ho Cardiology.pdf (Section: Approach to acute chest pain p56-58) ^[9] Senior notes: Ryan Ho Fundamentals.pdf (Sections: Investigations for abdominal pain p279, RUQ pain approach p308, Dyspepsia approach p263) ^[10] Senior notes: Ryan Ho Diagnostic Radiology.pdf (Section: Percutaneous drainage p81)

Management Algorithm and Treatment Modalities for RUQ Pain

The management of RUQ pain is not a single treatment pathway — it is a condition-specific approach guided by the diagnosis you've established. However, there are universal principles that apply to almost every acute RUQ presentation. Let's build from first principles: stabilise the patient first, then treat the cause.

Before you even know the exact diagnosis, every patient with acute RUQ pain needs:

Step	Action	Rationale
A — Assess and resuscitate	NPO (nil per os), IV fluids, monitor vitals and I/O ^[2]^[4]	NPO rests the biliary/GI system (food triggers CCK → gallbladder contraction → worsens biliary pain); IV fluids replace insensible losses from vomiting, fever, and third-spacing
B — Bloods	CBC/D, L/RFT, amylase/lipase, CRP, clotting, blood cultures (if febrile), cross-match	Establish baseline, identify organ-specific pattern, prepare for surgery
C — Analgesia	NSAIDs preferred for biliary pain (e.g. diclofenac IM/IV); paracetamol; opioids if needed ^[2]	NSAIDs are first-line for biliary colic because they reduce prostaglandin-mediated gallbladder wall inflammation AND relax gallbladder smooth muscle. Opioids (especially morphine) were historically feared to cause sphincter of Oddi spasm, though this is now considered clinically insignificant at standard doses. Pethidine was preferred but is now falling out of favour due to seizure risk.
D — Imaging	USG HBS as first-line	Confirm/exclude biliary pathology
E — ECG + CXR	Rule out inferior MI and right basal pneumonia	These are the dangerous mimics you must not miss ^[6]^[8]

3. Condition-Specific Management

Biliary colic is uncomplicated — there is no infection, no inflammation of the gallbladder wall. The stone transiently impacts and dislodges. Management is therefore relatively straightforward.

Acute management:

NPO, analgesics (NSAIDs preferred) ^[2]
Anti-emetics (e.g. ondansetron) if vomiting
Pain typically resolves within 6 hours

Definitive management:

Elective laparoscopic cholecystectomy (LC) ^[2]
- Why? A patient who has had one episode of biliary colic has a 1–4% per year risk of future complications (cholecystitis, cholangitis, pancreatitis) ^[2]. Elective LC removes the stone-bearing gallbladder and eliminates this risk.
- Performed as a planned, elective procedure after the acute episode resolves

Alternative for non-surgical candidates:

Ursodeoxycholic acid (UDCA) — an oral bile acid that works by reducing biliary cholesterol secretion and promoting cholesterol desaturation, thereby slowly dissolving cholesterol stones. Only useful for cholesterol stones (not pigment stones), small stones (< 10 mm), and functioning gallbladder. Very slow (6–24 months) and high recurrence rate (~50% within 5 years). ^[2]

B. Acute Cholecystitis — Management by TG18 Severity [1][2][4]

The key principle: treat the infection, then remove the gallbladder. The timing of cholecystectomy depends on severity.

NPO and IV fluids until inflammation subsides (bowel rest) ^[2]
IV antibiotics: empirical coverage for gram-negative aerobes and anaerobes ^[4]:
- Augmentin (amoxicillin-clavulanate) — first-line for mild/moderate ^[2]
- Tazocin (piperacillin-tazobactam) — for severe or if Augmentin inadequate ^[2]
- Alternatives: Metronidazole + 3rd-generation cephalosporin (e.g. ceftriaxone) OR Metronidazole + fluoroquinolone (e.g. ciprofloxacin/levofloxacin) ^[4]
Monitor vitals, I/O, analgesia

Why these antibiotic choices? The organisms causing secondary biliary infection are enteric bacteria — E. coli, Klebsiella, Enterobacter, Enterococcus — that ascend from the duodenum. They are gram-negative rods and facultative anaerobes. You need a beta-lactam/beta-lactamase inhibitor combination (like Augmentin or Tazocin) to cover beta-lactamase-producing gram-negatives, plus anaerobic coverage (the beta-lactamase inhibitor component provides this, or add metronidazole separately). ^[4]

TG18 Grade	Definition	Management
Grade I (Mild)	Healthy patient, no organ dysfunction, mild inflammatory changes	Early laparoscopic cholecystectomy (within 72 hours of symptom onset ideally) ^[4]^[2]
Grade II (Moderate)	↑ WBC > 18,000, palpable RUQ mass, duration > 72 h, marked local inflammation (gangrenous, emphysematous, pericholecystic abscess) but no organ dysfunction	Early LC if feasible and patient fit; otherwise IV antibiotics → interval (delayed) LC after 6–8 weeks ^[2]^[4]
Grade III (Severe)	Organ dysfunction (cardiovascular, neurological, respiratory, renal, hepatic, haematological)	IV antibiotics + organ support (ICU) + gallbladder drainage → interval LC when patient stabilises ^[4]

	Early LC (within 72 h / 3–5 days)	Interval LC (after 6–8 weeks)
Timing	During the index admission	Separate admission, after inflammation resolves
Advantage	Shorter hospital stay, single admission; initial inflammation creates pericholecystic oedema that can serve as a dissection plane ^[2]	Lower risk of conversion to open; fibrosis creates clearer planes (in theory)
Disadvantage	Higher risk of bleeding and post-op infection; higher conversion rate to open	Separate admission; fibrosis at Calot's triangle can make dissection difficult; risk of recurrent symptoms while waiting ^[2]
Current evidence	Early LC is now preferred — multiple RCTs and meta-analyses show equivalent safety with shorter total hospital stay and lower costs	Reserved for patients presenting late (> 72 h) or those unfit for early surgery

Critical View of Safety — The Key to Safe Cholecystectomy

During laparoscopic cholecystectomy, the surgeon must achieve the "critical view of safety" before clipping and dividing any structure. This means clearly identifying:

The cystic duct joining the gallbladder to the CBD
The cystic artery entering the gallbladder
The hepatocystic triangle (Triangle of Calot) cleared of all fat and fibrous tissue

This prevents the most feared complication: bile duct injury (incidence ~0.3–0.6% for LC). If the critical view cannot be achieved, the surgeon should convert to open or perform a "bail-out" procedure (subtotal cholecystectomy or cholecystostomy). ^[1]

Percutaneous transhepatic cholecystostomy (PTC / PC) ^[2]^[4]
- Indication: Grade III (severe) cholecystitis in patients too sick for surgery, OR patients not responding to antibiotics ^[2]
- Technique: USG/CT-guided percutaneous catheter placed into the gallbladder lumen → drains infected bile → decompresses the gallbladder
- Advantages: Can be both diagnostic (culture the bile) and therapeutic (decompress)
- Complications: catheter migration, bile leakage, bowel injury ^[2]
- Definitive treatment remains interval cholecystectomy once the patient recovers ^[4]
Endoscopic drainage ^[2]
- Transpapillary (via ERCP — placement of a pigtail stent from the CBD into the gallbladder through the cystic duct)
- EUS-guided transmural drainage (EUS-guided gallbladder drainage with lumen-apposing metal stent — LAMS)
- Reserved for when percutaneous approach is not feasible

Gangrenous cholecystitis: progressive symptoms despite antibiotics, disproportionate toxaemia → emergency LC
Gallbladder perforation: generalised peritonitis → emergency LC + peritoneal lavage
Emphysematous cholecystitis: gas-forming organisms in GB wall (Clostridium welchii); more common in diabetics → emergency LC ^[2]
Gallbladder empyema: pus-filled gallbladder → urgent LC or percutaneous drainage

Occurs in critically ill/hospitalised patients (ICU, TPN, sepsis, burns) ^[4]
Higher mortality than calculous cholecystitis
Management: IV antibiotics + laparoscopic cholecystectomy (if fit) or gallbladder drainage (percutaneous cholecystostomy) if unfit ^[2]^[4]

The principle is: clear the duct, then remove the gallbladder.

Management approach ^[2]:

Supportive care (NPO, IVF, analgesia)
Biliary decompression — remove the CBD stone
Prevent recurrence — cholecystectomy

Methods of stone clearance:

Method	Details
ERCP with sphincterotomy + stone extraction	First-line approach ^[1]^[2]. Endoscopic sphincterotomy cuts the sphincter of Oddi to widen the bile duct opening → stones are extracted using a balloon or Dormia basket. For large stones (> 15 mm), mechanical lithotripsy may be needed.
Laparoscopic CBD exploration	Alternative at the time of LC — common duct is explored intraoperatively. Requires expertise.
Open CBD exploration (ECBD) with T-tube	Reserved for failed ERCP and failed PTBD ^[4]. T-tube is placed in the CBD to decompress the biliary tree and allows post-operative cholangiography. Higher morbidity.

Followed by:

Laparoscopic cholecystectomy — ideally during the same admission (early rather than interval) to reduce risk of recurrent biliary events ^[2]
- Ascending cholangitis is still possible after LC due to ERCP-induced CBD dilatation or age-related CBD dilatation causing stasis ^[2]

D. Acute Cholangitis — Management: "RAD" (Resuscitation, Antibiotics, Drainage) [2][4]

This is one of the most important management algorithms in surgery. Acute cholangitis can kill rapidly if biliary decompression is delayed.

Must Know — RAD for Cholangitis

The mnemonic RAD captures the management of acute cholangitis ^[2]:

R = Resuscitation (NPO, IV fluids, monitor vitals and I/O hourly)
A = Antibiotics (broad-spectrum IV)
D = Drainage (biliary decompression — the definitive treatment)

NPO, IV fluids, monitor vitals and I/O Q1h ^[2]
Recognise signs of shock: hypotension, oliguria, confusion, cold/clammy skin, metabolic acidosis ^[4]
Fluid resuscitation to prevent multi-organ failure
15% of patients will NOT respond to antibiotics alone and require emergency biliary decompression ^[4]

IV Augmentin (mild) or IV Tazocin (severe) × 7 days ^[2]
- Same rationale as cholecystitis — cover enteric gram-negatives and anaerobes
Blood cultures BEFORE starting antibiotics
Adjust based on culture and sensitivity results

Indications for urgent drainage ^[2]:

Reynolds' pentad (hypotension + altered mental status)
Not responding to antibiotics within 24 hours — because obstruction impairs secretion of antibiotics into bile, meaning antibiotics alone cannot treat an obstructed infected system ^[2]
Worsening clinical status despite medical therapy

The QMH hierarchy for biliary decompression ^[4]:

1. ERCP (First-Line) ^[1]^[2]^[4]

ERCP is ALWAYS first-line for biliary drainage in acute cholangitis ^[1]
Procedure in acute cholangitis ^[2]:
- First aspirate bile duct to remove bile and pus → decompresses the biliary tree and reduces risk of inducing bacteraemia during contrast injection ^[2]
- Then inject contrast and identify the obstruction
- Place a plastic stent (temporary) for biliary drainage ^[2]
- Stone removal can be done now or at interval ERCP after sepsis resolves ^[2] — in an acutely septic patient, the priority is drainage, NOT definitive stone clearance
Potential complications: perforation, bleeding from papillotomy (sphincterotomy), post-ERCP pancreatitis ^[1]
Relative contraindications for ERCP: altered GI anatomy (e.g. Billroth II gastrectomy, Roux-en-Y reconstruction) ^[1]
- Why? The duodenoscope needs to reach the ampulla of Vater in D2. Surgically altered anatomy makes access technically very difficult or impossible.

2. Percutaneous Transhepatic Biliary Drainage (PTBD) (Second-Line) ^[4]^[10]

Indicated when ERCP is unsuccessful or contraindicated ^[2]^[10]
Technique: Under fluoroscopic and USG guidance, a needle is passed percutaneously through the liver parenchyma into a dilated intrahepatic bile duct → guidewire advanced → drainage catheter placed ^[10]
Requires antibiotic coverage (risk of seeding infection during manipulation) ^[10]
Types ^[4]:
- Simple external PTBD: short-term drainage to bridge to surgery; prone to fluid and electrolyte loss (bile drains externally → loss of bile salts, bicarbonate)
- External-internal PTBD: catheter crosses the stricture/obstruction and re-enters the duodenum → bile drains both externally and internally → can be capped for internal drainage only
Complications: bleeding into biliary system (most common), septic shock, pancreatitis, puncture of adjacent organs, catheter migration, bile leak, metastatic seeding ^[10]

3. Surgical ECBD (Exploration of Common Bile Duct) (Third-Line) ^[1]^[4]

Indication: failure of both endoscopic and percutaneous drainage, or clinical deterioration despite drainage ^[1]
Procedure: Open (or rarely laparoscopic) exploration of the CBD → stone removal → T-tube placement for ongoing decompression and post-operative cholangiography
High mortality (~30%) in emergency setting ^[2] — this is why it is the last resort

Gallstone-related cholangitis: ERCP for stone clearance + laparoscopic cholecystectomy (early rather than interval) ^[2]
Stricture-related cholangitis (benign or malignant): endoscopic stent placement or definitive surgical correction
RPC: regular stone clearance + surgical resection of affected hepatic segments (see below)

E. Gallstone Pancreatitis [4][9]

The pancreas is treated supportively — you cannot "fix" the inflamed pancreas directly. The key is to support the patient through the acute episode and then address the underlying biliary cause.

Measure	Details	Rationale
IV fluid resuscitation	Lactated Ringer's preferred over NS (may reduce SIRS); aim urine output ≥ 0.5 mL/kg/h (minimum) to 1.0 mL/kg/h (optimal) ^[4]	Pancreatitis causes massive third-spacing and intravascular volume depletion → aggressive fluid resuscitation prevents end-organ ischaemia
O₂ supplementation	Pulse oximetry + ABG monitoring ^[4]	Pancreatitis can cause ARDS and pleural effusions → hypoxaemia
NPO only if necessary	Only if significant nausea/vomiting; otherwise early enteral nutrition is preferred ^[4]	It is NO longer acceptable to "rest the pancreas" by prolonged NPO. Early enteral feeding (NG or NJ tube) reduces infection rates, surgical intervention rates, and length of stay. The gut barrier function is maintained by enteral nutrition, preventing bacterial translocation. ^[4]
Analgesia	Paracetamol, NSAIDs, opioids as needed	Pain control is critical; there is no evidence that opioids worsen pancreatitis at standard doses
Electrolyte correction	Correct hypocalcaemia (saponification of peripancreatic fat binds Ca²⁺), hyperglycaemia	Complications of pancreatitis
NG tube	Only if ileus or protracted vomiting	Nasogastric decompression decreases neurohormonal stimulation of pancreatic secretion ^[4]
Nutritional support	Enteral route preferred (NG or NJ) ^[4]; parenteral only if enteral not tolerated	Recommended: Energy 25–35 kcal/kg/day, Protein 1.2–1.5 g/kg/day ^[4]

Scenario	Management
Gallstone pancreatitis WITH concurrent cholangitis	Urgent ERCP within 24 hours of admission ^[4] — the cholangitis requires emergency biliary decompression
Gallstone pancreatitis with CBD obstruction (visible stone on imaging, dilated CBD, or rising LFTs) but NO cholangitis	Early ERCP (within 24–72 h) for stone extraction ^[4]
Gallstone pancreatitis without evidence of CBD obstruction	ERCP is NOT indicated ^[4] — the stone has likely already passed. Proceed to cholecystectomy.

Should be performed after recovery in ALL patients with gallstone pancreatitis to prevent recurrence ^[4]
Mild pancreatitis: cholecystectomy can be performed safely within the same index hospitalisation (within 1 week of recovery) ^[4]
Severe necrotising pancreatitis: delay cholecystectomy until active inflammation subsides and fluid collections resolve or stabilise (interval cholecystectomy) ^[4]
Intraoperative cholangiography (IOC) is performed to rule out persistent choledocholithiasis ^[4]

Risk stratification for CBD stone before cholecystectomy ^[4]:

High suspicion of CBD stone → ERCP (before cholecystectomy)
Moderate suspicion → MRCP or EUS to confirm before proceeding
Low suspicion → Cholecystectomy with intraoperative cholangiogram

The management of RPC is challenging because of the recurrent nature and intrahepatic stone burden.

Step	Details
Acute management	Same as acute cholangitis: RAD (Resuscitation, Antibiotics, Drainage)
ERCP	Initial biliary decompression with sphincterotomy, stricture dilatation, and biliary stent placement. Challenging due to multiple intrahepatic/extrahepatic stones and stricturing ^[4]
Percutaneous/surgical drainage	For patients in whom ERCP cannot achieve adequate drainage ^[4]
Hepatobiliary resection	Resection of hepatobiliary segments with the aim to remove areas of recurrent infection, biliary stasis, and hepatic atrophy ^[4]. Hepaticojejunostomy (Roux-en-Y) is frequently required. Standard biliary drainage (choledochoduodenostomy/choledochojejunostomy) is contraindicated since residual strictured biliary segments may not be drained adequately ^[4].
Choledochoscopy	Endoscopic or percutaneous choledochoscopy for intrahepatic stone clearance — allows direct visualisation and lithotripsy of intrahepatic stones

Step	Details
IV antibiotics	Empirical broad-spectrum antibiotics covering gram-negatives and anaerobes (e.g. ceftriaxone + metronidazole, or Tazocin). Adjust based on blood/aspirate cultures. For Klebsiella pneumoniae abscess (Hong Kong context): 3rd-gen cephalosporin is usually adequate.
Percutaneous drainage	USG/CT-guided aspiration or catheter drainage — indicated for abscesses > 5 cm, those not responding to antibiotics alone (within 48–72 h), or for diagnostic purposes (culture, rule out amoebic vs pyogenic) ^[3]^[10]
Amoebic abscess	Metronidazole is the primary treatment (amoebiasis). Drainage is reserved for large abscesses (> 5–10 cm), failure to respond to medical therapy, or risk of rupture. Follow with luminal agent (e.g. diloxanide furoate or paromomycin) to eradicate intestinal cysts.
Surgical drainage	Rarely needed — for ruptured abscess, multiloculated abscess not amenable to percutaneous drainage, or failed percutaneous approach

The principles here are different — the goal is to determine resectability first, then decide between curative and palliative intent. ^[6]^[11]

Management principles ^[6]^[11]:

Establish diagnosis
Delineate level and cause of obstruction
Treat suppurative cholangitis (if present — this takes priority)
Assess resectability
Definitive or palliative treatment

Key Principle — Drainage is NOT Always Urgent in MBO

Unlike gallstone disease, drainage of malignant biliary obstruction is NOT always urgent ^[6]. The effect on liver function is slow in onset. Premature drainage (especially stenting) before CT can obscure tumour assessment. Drainage should be done after CT if no indications for early decompression.

Indications for early drainage in MBO ^[6]:

Biliary sepsis or stones (contaminated biliary system)
Poor liver function due to prolonged cholestasis (needs pre-operative optimisation)
Klatskin tumour (drainage allows normalisation of liver function → important for pre-op ICG testing and post-op monitoring, as hepatectomy is part of management)

Palliative Biliary Drainage Options ^[4]:

Method	Details
ERCP with endoprosthesis (stenting)	ALWAYS first-line regardless of level of obstruction, especially for periampullary carcinoma ^[4]. Metallic stent preferred if confirmed inoperable (more durable). Plastic stent for short-term drainage or uncertain diagnosis.
PTBD	Second-line when ERCP fails or is contraindicated (e.g. altered anatomy) ^[4]. Complications: bleeding (hepatic artery/portal vein puncture), bile leak, catheter migration.
Palliative bypass surgery	Hepaticojejunostomy or choledochojejunostomy (Roux-en-Y) for patients with good performance status and failed endoscopic/percutaneous drainage. ± Gastrojejunostomy if concurrent duodenal obstruction.

ERCP vs PTBD ^[4]:

ERCP is preferred over PTBD because PTBD is technically more difficult, has higher bleeding risk (needle must traverse the portal triad — hepatic artery and portal vein lie adjacent to the bile ducts), and carries risk of catheter-related complications ^[4]

Condition	Management Summary
Asymptomatic gallstones	Watchful waiting (1–4%/year risk of complications). Prophylactic cholecystectomy only in high-risk groups: porcelain gallbladder, gallstones > 3 cm, polyps > 1 cm, anomalous pancreaticobiliary junction ^[2]
Gallbladder polyps	< 1 cm: surveillance USG (Q6 months if 6–9 mm, Q12 months if ≤ 5 mm). ≥ 1 cm: laparoscopic cholecystectomy (risk of malignancy). Rapidly growing polyps or sessile polyps: cholecystectomy ^[2]
Porcelain gallbladder	ALL porcelain gallbladders should be removed (absolute indication for cholecystectomy) — risk of gallbladder cancer ^[4]
Choledochal cyst	Radical excision of cyst + biliary tract reconstruction (Roux-en-Y hepaticojejunostomy or choledochojejunostomy) — to prevent cholangiocarcinoma, reduce stricture risk, and reduce recurrent cholangitis ^[2]
Sphincter of Oddi dysfunction	Endoscopic sphincterotomy (if manometry confirms elevated sphincter pressure)
Mirizzi syndrome	Depends on Csendes type: Type I → cholecystectomy (may need subtotal/open); Types II–IV → cholecystectomy + repair of CBD defect (± Roux-en-Y hepaticojejunostomy for large fistulae) ^[4]

Procedure	Contraindications
ERCP	Altered GI anatomy (Billroth II, Roux-en-Y) — relative C/I (can use device-assisted enteroscopy ERCP in some centres) ^[1]; suspected perforation; severe coagulopathy (must correct PT/INR before sphincterotomy)
PTBD	Massive ascites (no safe window), severe coagulopathy, lack of intrahepatic duct dilatation (difficult to access non-dilated ducts)
Laparoscopic cholecystectomy	No absolute contraindications to LC itself, but inability to tolerate general anaesthesia or inability to tolerate pneumoperitoneum (e.g. severe cardiopulmonary disease) may favour open approach or percutaneous drainage. Gallbladder cancer with suspected invasion may favour open approach to avoid port-site recurrence and bile spillage ^[4].
TACE	Portal vein thrombosis (liver depends on hepatic artery → total ischaemia), Child C cirrhosis, distant metastasis, AV shunting ^[2]

High Yield Summary — Management of RUQ Pain

Universal initial management: NPO, IVF, analgesia (NSAIDs first-line for biliary pain), monitoring, bloods (CBC, LFT, amylase/lipase), ECG, CXR, USG HBS.
Biliary colic: analgesics → elective LC to prevent future complications.
Acute cholecystitis (TG18): IV antibiotics + LC. Grade I → early LC; Grade II → early or delayed LC; Grade III → drainage (percutaneous cholecystostomy) → interval LC.
Early LC is preferred over interval LC — shorter hospital stay, single admission, equivalent safety.
Cholangitis = RAD: Resuscitation, Antibiotics (Augmentin mild / Tazocin severe), Drainage (ERCP 1st → PTBD 2nd → ECBD 3rd).
Urgent drainage indications in cholangitis: Reynolds' pentad, failure to respond to antibiotics within 24 h.
ERCP is first-line for biliary drainage — role in cholangitis is decompression first, NOT definitive stone clearance in the acute septic setting.
Gallstone pancreatitis: supportive care + early enteral nutrition (NO prolonged NPO). Urgent ERCP only if concurrent cholangitis. LC during same admission for mild; interval for severe.
Malignant biliary obstruction: drainage is not always urgent — CT before drainage to avoid obscuring tumour assessment. ERCP with stent is first-line for palliation.
Porcelain gallbladder = absolute indication for cholecystectomy (cancer risk).
ERCP preferred over PTBD (less technically difficult, lower bleeding risk). ECBD is last resort (30% mortality).

Active Recall - Management of RUQ Pain

References

^[1] Lecture slides: GC 200. RUQ pain, jaundice and fever Cholecytitis and cholangitis Imaging of GI system.pdf ^[2] Senior notes: maxim.md (Sections: Biliary colic management, Acute cholecystitis management, Early vs interval LC, Cholangitis RAD, GB drainage, Asymptomatic gallstones, GB polyps, Choledochal cyst, TACE contraindications) ^[3] Senior notes: felixlai.md (Section: Liver abscess) ^[4] Senior notes: felixlai.md (Sections: Cholecystitis treatment, Cholangitis treatment, RPC treatment, Gallstone pancreatitis management, Mirizzi syndrome, Periampullary carcinoma palliative management, Gallbladder cancer surgery, ERCP/PTBD) ^[6] Senior notes: Ryan Ho GI.pdf (Sections: Acute cholecystitis management p247-248, RUQ pain approach p209-210, ERCP indications p299, Pancreatitis management p340-341, HCC management p266) ^[8] Senior notes: Ryan Ho Cardiology.pdf (Section: Approach to acute chest pain) ^[9] Senior notes: Ryan Ho Fundamentals.pdf (Sections: Approach to MBO p298-299, ERCP preparation p299) ^[10] Senior notes: Ryan Ho Diagnostic Radiology.pdf (Sections: PTBD p82, Cholangiogram p22) ^[11] Lecture slides: Malignant biliary obstruction.pdf

Complications of RUQ Pain Conditions

Complications are where the clinical stakes are highest. Every condition that causes RUQ pain can progress, and understanding why each complication develops — the pathophysiological chain from the primary insult to the downstream disaster — is what separates safe clinical practice from pattern-matching. Let's work through each major condition systematically.

Gallstones are the most common cause of RUQ pain, and their complications form a branching tree depending on where the stone sits and how long it has been there.

Complications of gallstone disease ^[1]:

Mucocele of gallbladder
Empyema of gallbladder
Rupture of gallbladder
Acute cholangitis
Acute pancreatitis
Cholecystoduodenal fistula
Liver abscess

These can be organised by the structure involved ^[2]:

Structure Involved	Complications
Gallbladder	Acute cholecystitis, chronic cholecystitis, mucocele/hydrops, empyema, gangrenous cholecystitis, perforation, emphysematous cholecystitis, gallbladder cancer, Mirizzi syndrome
Biliary tree	Choledocholithiasis, acute cholangitis, biliary stricture
Pancreas	Acute biliary pancreatitis
Bowel	Cholecystoenteric fistula (Bouveret's syndrome, gallstone ileus) ^[2]

2. Complications of Acute Cholecystitis

Once a gallstone impacts in the cystic duct and cholecystitis develops, the disease follows a predictable escalation pathway if untreated. Understanding this sequence is essential.

What happens: Prolonged impaction of a stone in the cystic duct → bile cannot enter or exit the gallbladder → existing bile is absorbed → gallbladder fills with clear mucoid secretion ("white bile")
Why it matters: The gallbladder becomes massively distended, tense, and palpable. It can compress adjacent structures (e.g. common hepatic duct → Mirizzi syndrome) or predispose to perforation.
Clinical features: Palpable, non-tender (or mildly tender) RUQ mass; may be asymptomatic or present with chronic discomfort

What happens: The obstructed, inflamed gallbladder becomes infected → pus fills the gallbladder lumen
Why it happens: Stagnant bile + compromised mucosal barrier → secondary bacterial infection → purulent collection that cannot drain (cystic duct is blocked)
Clinical features: Tender RUQ mass + septic-looking patient (high fever, rigors, tachycardia, raised WCC) ^[2]
Management: Urgent intervention — emergency cholecystectomy or percutaneous cholecystostomy if patient too sick for surgery
Risk: If untreated → perforation → biliary peritonitis or septic shock

What happens: Ischaemic necrosis of the gallbladder wall
Why it happens: Gallbladder distension → wall tension exceeds perfusion pressure → compromised arterial inflow (cystic artery is an end-artery with limited collaterals) → transmural necrosis
Clinical features: Disproportionately severe pain relative to examination findings; high fever; toxaemia. The patient looks sicker than you'd expect. Paradoxically, Murphy's sign may be absent because the gallbladder wall is necrotic and denervated.
Risk: Precursor to perforation

Gangrenous Cholecystitis — The Silent Escalation

Gangrenous cholecystitis can present deceptively. The patient may have less localised tenderness (because the necrotic wall has lost its nerve supply) but is systemically much sicker. If a patient with cholecystitis has worsening sepsis but seemingly "improving" abdominal signs, suspect gangrene. This is an indication for emergency cholecystectomy. ^[2]

What happens: Necrotic gallbladder wall breaks down → contents leak
Three types of perforation:
1. Free perforation into peritoneal cavity → generalised biliary peritonitis (rare, because the omentum usually wraps around the inflamed gallbladder)
2. Localised perforation → pericholecystic abscess (walled off by omentum and adjacent viscera)
3. Perforation into adjacent viscus → cholecystoenteric fistula (usually into duodenum)
Clinical features: Sudden worsening of pain → generalised abdominal tenderness → peritoneal signs (guarding, rigidity, rebound tenderness)
Management: Emergency surgery (cholecystectomy + peritoneal lavage)

What happens: Secondary bacterial infection of the gallbladder wall with gas-forming organisms (classically Clostridium welchii/perfringens, but also E. coli, Klebsiella)
Why certain patients: More common in diabetics (microangiopathy → gallbladder ischaemia predisposes to anaerobic infection) and elderly males
Clinical features: Insidious onset, abdominal crepitus (gas in the gallbladder wall palpable as crepitation) ^[2]
Imaging: CT shows gas within the gallbladder wall (intramural gas) — pathognomonic
Management: Emergency cholecystectomy — this is a surgical emergency with high mortality (~15–25%)

What happens: Chronic inflammation erodes through the gallbladder wall into an adjacent hollow viscus (usually the duodenum → cholecystoduodenal fistula). A large gallstone (> 2.5 cm) passes through the fistula into the bowel lumen → impacts at the narrowest point of the small bowel (usually the ileocaecal valve) → mechanical small bowel obstruction
Why the ileocaecal valve? It is the narrowest fixed point in the small bowel. Stones large enough to cause ileus are typically > 2.5 cm.
Bouveret's syndrome: Variant where the gallstone impacts in the duodenum (causing gastric outlet obstruction) rather than distally — rare but important to recognise
Clinical features: Symptoms of small bowel obstruction — colicky abdominal pain, vomiting, abdominal distension, absolute constipation
Rigler's triad on AXR/CT ^[6]:
1. Pneumobilia (air in the biliary tree — entered through the fistula)
2. Small bowel obstruction (dilated loops with air-fluid levels)
3. Ectopic gallstone (visible in the bowel, usually at the ileocaecal valve)
Management: Surgery — enterotomy and stone extraction (enterolithotomy); cholecystectomy and fistula repair may be done at the same time or as a staged procedure depending on the patient's fitness

CBD stones can cause downstream complications affecting the biliary tree and pancreas:

Complication	Mechanism	Clinical Features
Acute cholangitis	Obstruction + bacterial contamination → ascending infection → cholangiovenous reflux → bacteraemia/sepsis	Charcot's triad → Reynolds' pentad if severe ^[4]
Gallstone pancreatitis	Stone impacts at the ampulla of Vater → obstructs the pancreatic duct → premature trypsin activation within acinar cells → autodigestion ^[4]	Severe epigastric pain radiating to back, ↑ amylase/lipase ≥ 3× ULN
Obstructive jaundice	Stone blocks the CBD → conjugated bilirubin cannot be excreted → regurgitates into blood	Progressive jaundice, dark urine, pale stools, pruritus
Secondary biliary cirrhosis	Chronic/recurrent biliary obstruction → chronic cholestasis → periductal fibrosis → biliary cirrhosis	Develops over months–years of untreated obstruction; ultimately leads to portal hypertension and liver failure

Cholangitis itself is a complication of biliary obstruction, but it can further escalate:

Complication	Mechanism
Septic shock (suppurative cholangitis)	Cholangiovenous reflux — at high biliary pressures, bacteria and endotoxins are forced through the bile duct epithelium into the hepatic venous sinusoids → bloodstream → systemic sepsis → multi-organ failure. This is what Reynolds' pentad represents. ^[4]
Liver abscess	Ascending infection from the bile ducts into the liver parenchyma → focal collection of pus. Direct spread from the biliary tree is one of the major routes of pyogenic liver abscess formation. ^[3]
Multi-organ failure	Sepsis → SIRS → cardiovascular collapse, ARDS, AKI, DIC
Biliary stricture	Recurrent cholangitis → chronic inflammation → cicatricial stricturing of the bile duct → further predisposes to obstruction and recurrent cholangitis (vicious cycle)

RPC has a unique set of complications because of its chronic, recurrent nature and intrahepatic involvement:

Complication	Mechanism
Biliary sepsis	Recurrent bacterial infection of obstructed bile ducts — the defining feature of RPC
Pancreatitis	Passage of biliary stones through the ampulla — same mechanism as gallstone pancreatitis ^[4]
Rupture	Obstructed, pus-filled bile ducts rupture into the peritoneum → biliary peritonitis ^[4]
Liver abscess	Ascending intrahepatic infection → focal abscess formation; can also occur at distant sites (lungs, brain via haematogenous spread) ^[4]
Fistula formation	Choledocho-duodenal fistula — chronic inflammation erodes into the GI tract or abdominal wall ^[4]
Secondary biliary cirrhosis	Chronic biliary obstruction and recurrent inflammation → progressive fibrosis → portal hypertension → liver failure ^[4]
Cholangiocarcinoma	Chronic inflammation of the biliary epithelium → dysplasia → malignant transformation. This is one of the most feared long-term complications and is the reason patients with RPC require surveillance and consideration for hepatobiliary resection. ^[4]
Portal vein thrombosis	Chronic peribiliary inflammation extends to involve adjacent portal vein branches ^[4]

6. Complications of Acute Pancreatitis

Pancreatitis complications are divided into local and systemic, and further by timing (early vs. late).

Complication	Mechanism
Organ failure (most common cause of early death)	NF-κB–dependent inflammatory cascade → massive cytokine release (TNF-α, IL-1, IL-6) → SIRS → multi-organ dysfunction: ARDS (pulmonary capillary leak), AKI (hypovolaemia + cytokine-mediated tubular injury), cardiovascular collapse (vasodilatory shock)
Peripancreatic fluid collections	Inflammatory exudate from the inflamed pancreas → fluid accumulates in the lesser sac and retroperitoneum
Sterile pancreatic necrosis	Autodigestion of pancreatic and peripancreatic tissue by prematurely activated enzymes → areas of non-enhancing (dead) tissue on contrast CT

Complication	Mechanism	Clinical Features
Infected pancreatic necrosis	Bacterial translocation from the gut (due to ileus and mucosal barrier breakdown) colonises necrotic tissue → infected necrosis	Persistent or new-onset fever after initial improvement; CT shows gas bubbles within necrotic tissue; confirmed by FNA. This is one of the main indications for intervention (necrosectomy).
Pancreatic pseudocyst	Encapsulated collection of pancreatic juice (amylase-rich fluid) that lacks an epithelial lining (hence "pseudo"); develops when a disrupted pancreatic duct leaks into an inflammatory capsule	Palpable epigastric mass, persistent pain, prolonged elevation of amylase; can compress stomach (early satiety), CBD (jaundice), or vessels
Walled-off necrosis (WON)	Mature, encapsulated collection containing necrotic pancreatic/peripancreatic tissue; develops ≥ 4 weeks after onset	Distinguished from pseudocyst by containing solid necrotic debris (not just fluid)
Pancreatic duct disruption	Necrosis disrupts the main pancreatic duct → pancreatic juice leaks freely	Pancreatic ascites (if leaks into peritoneal cavity) or pleural effusion (if tracks superiorly)
Pseudoaneurysm	Pancreatic enzymes erode into peripancreatic arteries (splenic, gastroduodenal, pancreaticoduodenal) → weakened arterial wall → pseudoaneurysm formation	Risk of catastrophic haemorrhage — can bleed into the pancreatic duct (haemosuccus pancreaticus), peritoneum, or GI tract. Severe and fatal haemorrhage can occur following endoscopic drainage in patients with an unsuspected pseudoaneurysm ^[4]
Splenic complications	Splenic vein thrombosis (due to adjacent inflammation) → left-sided portal hypertension → gastric varices	GI bleeding from gastric varices

Complication	Mechanism
Exocrine insufficiency	Loss of functional pancreatic acinar tissue → malabsorption and steatorrhoea (fatty, foul-smelling stools) ^[4]
Endocrine insufficiency	Loss of islet cells → diabetes mellitus (pancreatogenic / Type 3c DM) ^[4]
Gastric stasis	Especially in patients undergoing pylorus-preserving pancreaticoduodenectomy (Whipple's) ^[4]

Complication	Mechanism
Abscess rupture (3.8%)	Large abscess (> 6 cm) or in cirrhotic liver → wall breaks down → rupture into peritoneal cavity (subphrenic abscess, peritonitis), viscera, IVC, or kidney ^[6]
Pleuropulmonary complications (15–20%)	Right lobe abscess abutting the diaphragm → diaphragmatic irritation/erosion → pleurisy, pleural effusion, empyema, or even bronchohepatic fistula (abscess erodes through diaphragm into the lung → patient coughs up pus/bile) ^[6]
Local compression	Large abscess compresses adjacent structures → Budd-Chiari syndrome (IVC/hepatic vein compression), bile duct compression (jaundice) ^[6]
Metastatic abscess	Haematogenous seeding → distant abscesses (brain, lung) — especially in Klebsiella pneumoniae liver abscess, which has a well-described propensity for metastatic infection (endophthalmitis, meningitis) in diabetic patients
Sepsis and multi-organ failure	If abscess is not drained → progressive sepsis

8. Complications of Cholecystectomy (Surgical Complications) [2]

Since laparoscopic cholecystectomy is the definitive treatment for most gallstone disease, its complications are frequently tested.

Complication	Details
Conversion to open surgery	5% in elective, 25% in emergency ^[2] — this is NOT a failure; it is a safety decision when the critical view cannot be achieved
GA risks	Aspiration, cardiovascular complications
Bleeding	From liver bed (middle hepatic vein is close to GB fossa), cystic artery, trocar sites
Damage to neighbouring structures	Bile leakage (biliary tree injury), bleeding (cystic artery), pneumoperitoneum from injury to duodenum, transverse colon, or hepatic flexure ^[2]

Complication	Details
Biliary leakage (0.5%)	From cystic duct stump or duct of Luschka (small accessory bile ducts draining directly from the liver bed into the gallbladder fossa). Usually presents post-op day 2–10 with fever, RUQ pain, deranged LFTs. Investigated with USG/CT → HIDA scan/MRCP. Managed by ERCP with stenting (minor) or laparotomy + Roux-en-Y hepaticojejunostomy (major) ^[2]
Post-op jaundice	Due to dropped or missed CBD stones — presents with cholestatic LFTs and jaundice. Investigate with MRCP/ERCP.
Post-op cholangitis	Infected retained stone
Post-op diarrhoea	Initial uncoordinated excessive bile salt excretion (without gallbladder storage, bile flows continuously into the duodenum) + fat malabsorption ^[2]. Usually self-limiting.
Wound infection	Trocar site infection

Complication	Details
Bile duct stricture	Ischaemic or mechanical injury to the bile duct during surgery → cicatricial stricture → recurrent jaundice/cholangitis. Managed by reconstruction ± hepaticojejunostomy ^[2]
Subphrenic abscess	Infected collection in the subphrenic space — managed by drainage + antibiotics
Post-cholecystectomy syndrome	Persistent symptoms (biliary-type pain, dyspepsia, diarrhoea) after cholecystectomy ^[2]. Causes include retained CBD stone, bile duct injury, sphincter of Oddi dysfunction, or non-biliary causes that were misattributed to gallstones.
Post-cholecystectomy choledocholithiasis	Bile stasis due to increased CBD calibre (loss of gallbladder storage function → CBD dilates to compensate → stasis → stone formation) ^[2]

Bile Duct Injury — The Most Feared Complication of LC

Bile duct injury during laparoscopic cholecystectomy (incidence ~0.3–0.6%) is the most feared complication. It typically occurs when the CBD is mistaken for the cystic duct (especially when Calot's triangle is obscured by inflammation or aberrant anatomy). The consequences can be devastating — biliary stricture, recurrent cholangitis, secondary biliary cirrhosis, and need for complex reconstructive surgery. This is why achieving the critical view of safety is paramount. ^[2]

ERCP is both a diagnostic and therapeutic tool, but it carries significant procedural risks:

Complication	Incidence	Mechanism
Post-ERCP pancreatitis	2–10% (MOST frequent) ^[4]	Manipulation of the pancreatic orifice/duct → traumatic oedema of the papilla → transient obstruction of pancreatic duct outflow → premature enzyme activation. Minimised by pancreatic duct stenting and rectal NSAIDs (indomethacin). ^[4]
Cholangitis	~0.6%	Manipulation of an obstructed biliary system introduces bacteria or fails to achieve complete drainage ^[4]
Bleeding	1–2%	Occurs after sphincterotomy — the cut traverses the sphincter muscle and surrounding vessels. Increased risk in coagulopathy and thrombocytopenia. ^[4]
Perforation	< 1%	Perforation of oesophagus, stomach, duodenum, or at the sphincterotomy site (retroperitoneal perforation). Increased risk with stenotic segments and previous gastric resection. ^[4]
Papillary stenosis	Late	Long-term fibrotic scarring of the ampulla of Vater following sphincterotomy → recurrent biliary obstruction ^[4]
Stent occlusion/migration	Late	Biofilm formation and sludge → blocked stent; mechanical dislodgement → migrated stent ^[4]

Timing	Complication	Mechanism
Acute (5–10%)	Bleeding into biliary system (most common)	Needle traverses liver parenchyma → puncture of hepatic artery or portal vein branches
	Septic shock	Infected bile spills during manipulation
	Pancreatitis (rare)	CBD damage during catheter manipulation
	Puncture of other organs	Lung (pneumothorax), kidney, colon
Delayed (45–50%)	Biliary sepsis (cholangitis)	Catheter serves as foreign body → nidus for infection
	Catheter migration	Mechanical dislodgement
	Bile leak	Around catheter entry site → peritoneal irritation
	Metastatic seeding	Tumour cells track along the catheter tract (in malignant obstruction)
	Skin infection	At catheter entry site

For patients undergoing liver resection (e.g. for RPC, HCC, cholangiocarcinoma):

Complication	Definition / Details
Bile leakage	Drain bilirubin concentration ≥ 3× serum bilirubin on or after post-op day 3 ^[2] — leaking from the transected liver surface or biliary anastomosis
Post-hepatectomy liver failure	Day 5 bilirubin > 50 µmol/L AND INR > 1.7 ("50-50 rule") → high risk of mortality ^[2]. Occurs because the remaining liver is insufficient to support metabolic demands.
Ischaemic damage to liver remnant	Prolonged liver rotation during surgery → twisting of inflow and outflow pedicles → hepatic ischaemia ^[2]
Haemorrhage	From raw liver transection surface, hepatic vein injury
Subphrenic abscess/collection	Infected fluid collection below the diaphragm

Timing	Complication	Mechanism
Early	Delayed gastric emptying (common)	Disruption of vagal innervation and gastric/duodenal motility after reconstruction
	Pancreatic fistula (common)	Leak from the pancreaticojejunostomy anastomosis — surgeons traditionally place drains around this anastomosis for this reason ^[4]
	Pancreatic anastomotic leak	Technical failure of the pancreatic-enteric anastomosis
	Biliary anastomotic breakdown	Leak from the hepaticojejunostomy
	Intra-abdominal bleeding / abscess	From the extensive dissection and multiple anastomoses
Late	Exocrine insufficiency → malabsorption, steatorrhoea	Loss of pancreatic parenchyma → ↓ lipase, amylase, protease secretion
	Endocrine insufficiency → diabetes mellitus	Loss of islet cells → ↓ insulin production
	Gastric stasis	Especially in pylorus-preserving Whipple's ^[4]

High Yield Summary — Complications of RUQ Pain Conditions

Acute cholecystitis complications follow a predictable escalation: mucocele → empyema → gangrene (20%) → perforation → biliary peritonitis.
Emphysematous cholecystitis: gas-forming organisms in GB wall; more common in diabetics; insidious onset + abdominal crepitus; surgical emergency.
Cholecystoenteric fistula → gallstone ileus: large stone erodes into duodenum → impacts at ileocaecal valve → SBO. Rigler's triad: pneumobilia + SBO + ectopic stone.
Cholangitis → suppurative cholangitis: cholangiovenous reflux at high biliary pressures → bacteria enter bloodstream → septic shock (Reynolds' pentad).
RPC long-term complications: secondary biliary cirrhosis, cholangiocarcinoma (most feared), liver abscess, portal vein thrombosis.
Acute pancreatitis: Early death from organ failure (SIRS/MODS); Late complications: infected necrosis, pseudocyst, pseudoaneurysm (risk of fatal haemorrhage), exocrine/endocrine insufficiency.
Post-cholecystectomy: Bile duct injury is the most feared complication (~0.3-0.6%); biliary leakage from cystic duct stump or duct of Luschka (0.5%); post-cholecystectomy syndrome (persistent symptoms).
Post-ERCP pancreatitis is the most common ERCP complication (2-10%); minimised by pancreatic duct stent + rectal indomethacin.
PTBD: bleeding is the most common acute complication; delayed biliary sepsis and catheter migration are the most common late complications.
Post-hepatectomy liver failure: 50-50 rule (Day 5 bilirubin > 50 AND INR > 1.7) predicts high mortality.

Active Recall - Complications of RUQ Pain Conditions

References

^[1] Lecture slides: GC 200. RUQ pain, jaundice and fever Cholecytitis and cholangitis Imaging of GI system.pdf ^[2] Senior notes: maxim.md (Sections: Gallstone complications, Acute cholecystitis complications, Cholecystectomy specific complications, Choledocholithiasis, RPC complications, Post-hepatectomy care) ^[3] Senior notes: felixlai.md (Section: Liver abscess) ^[4] Senior notes: felixlai.md (Sections: Cholecystitis pathogenesis, Acute cholangitis, RPC complications, Acute pancreatitis complications, Whipple's complications, ERCP complications, Pseudoaneurysm haemorrhage, Gallstone pancreatitis prevention) ^[6] Senior notes: Ryan Ho GI.pdf (Sections: Liver abscess complications p237, Gallstone ileus Rigler's triad p136) ^[10] Senior notes: Ryan Ho Diagnostic Radiology.pdf (Section: PTBD complications p82)

Ruq Pain

Right Upper Quadrant (RUQ) Pain

2. Epidemiology and Risk Factors

3. Anatomy and Function

4. Etiology (Focus on Hong Kong)

4.1 Biliary Causes (Most Common)

4.2 Hepatic Causes

5. Classification

6. Clinical Features

6.1 Symptoms

6.2 Signs

Active Recall - RUQ Pain: Definition to Clinical Features

Differential Diagnosis of RUQ Pain

Systematic Differential Diagnosis — Condition by Condition

Active Recall - Differential Diagnosis of RUQ Pain

References

Diagnostic Criteria, Diagnostic Algorithm, and Investigation Modalities for RUQ Pain

1. Formal Diagnostic Criteria for Major Causes of RUQ Pain

3. Investigation Modalities — Detailed Breakdown

Key USG Findings by Condition:

D. Second-Line Imaging

E. Therapeutic / Diagnostic Interventional Procedures

Active Recall - Diagnostic Criteria and Investigations for RUQ Pain

References

Management Algorithm and Treatment Modalities for RUQ Pain

3. Condition-Specific Management

B. Acute Cholecystitis — Management by TG18 Severity [1][2][4]

D. Acute Cholangitis — Management: "RAD" (Resuscitation, Antibiotics, Drainage) [2][4]

E. Gallstone Pancreatitis [4][9]

Active Recall - Management of RUQ Pain

References

Complications of RUQ Pain Conditions

2. Complications of Acute Cholecystitis

6. Complications of Acute Pancreatitis

8. Complications of Cholecystectomy (Surgical Complications) [2]

Active Recall - Complications of RUQ Pain Conditions

References

On this page

Ruq Pain

1. Definition

2. Epidemiology and Risk Factors

2.1 Epidemiology

2.2 Risk Factors — Focused on Biliary Disease

3. Anatomy and Function

3.1 Gallbladder Anatomy

3.2 Biliary Ductal Anatomy

3.3 Blood Supply

3.4 Nerve Supply and Referred Pain Patterns

3.5 Physiology of Bile

3.6 Other RUQ Structures

4. Etiology (Focus on Hong Kong)

4.1 Biliary Causes (Most Common)

A. Biliary Colic

B. Acute Cholecystitis (Calculous, 90–95%)

C. Acalculous Cholecystitis (5–10%)

D. Choledocholithiasis (CBD Stones)

E. Acute Cholangitis

F. Recurrent Pyogenic Cholangitis (RPC)

G. Mirizzi Syndrome

4.2 Hepatic Causes

A. Liver Abscess

B. Acute Hepatitis

C. Hepatocellular Carcinoma (HCC) / Liver Metastases

D. Budd-Chiari Syndrome

4.3 Pancreatic Causes

4.4 Gastrointestinal Causes

4.5 Renal Causes

4.6 Thoracic Causes (Don't Forget!)

4.7 Other / Rare Causes

5. Classification

5.1 By Organ System (Anatomical Classification)

5.2 By Acuity

5.3 Gallstone Classification by Composition [1][2]

6. Clinical Features

6.1 Symptoms

A. Biliary Colic [1][2]

B. Acute Cholecystitis [1][2]

C. Acute Cholangitis [1][4]

D. Recurrent Pyogenic Cholangitis (RPC) [4]

E. Liver Abscess [3]

F. Acute Pancreatitis [4]

G. Peptic Ulcer Disease (Duodenal Ulcer)

H. Other Causes (Characteristic Features)

6.2 Signs

A. Murphy's Sign [1][2]

B. RUQ Tenderness and Guarding

C. Palpable Gallbladder [2]

D. Jaundice [1]

E. Fever and Rigors

F. Signs of Complications

7. High Yield Summary

Active Recall - RUQ Pain: Definition to Clinical Features

References

Organising Framework: Think Anatomically, Then Pathologically

Systematic Differential Diagnosis — Condition by Condition

1. Biliary Causes (Most Common) [1][2][4]

2. Hepatic Causes [1][3][6]

3. Pancreatic Causes [4]

4. Gastrointestinal Causes [1][6]

5. Renal / Urological Causes [1][7]

6. Thoracic Causes (Don't Forget!) [1][6][8]

7. Gynaecological Causes [5]

8. Other / Rare Causes [1][6]

Clinical Decision-Making Diagram

Key Differentiating Features — Summary Table

Important Principles for the Differential

Active Recall - Differential Diagnosis of RUQ Pain

1. Formal Diagnostic Criteria for Major Causes of RUQ Pain

A. Tokyo Guidelines 2018/2013 (TG18/TG13) — Acute Cholecystitis [4][6]

B. Tokyo Guidelines 2018/2013 — Acute Cholangitis [4]

C. Revised Atlanta Classification 2012 — Acute Pancreatitis [4][9]

D. Courvoisier's Law — A "Diagnostic Principle" Rather Than Formal Criteria [4]

2. Diagnostic Algorithm — Stepwise Approach

3. Investigation Modalities — Detailed Breakdown

A. Bedside Investigations

B. Blood Tests

C. First-Line Imaging: Transabdominal Ultrasound (USG HBS) [1][2][6][9]

D. Second-Line Imaging