41. Cholecystitis: definition, types, causes, diagnosis, complications and treatment; cholelithiasis

Cholecystitis and cholelithiasis

DEFINITIONS & AETIOLOGY

• Cholelithiasis is the presence of gallstones in the gallbladder. Stones may be cholesterol, black pigment or brown pigment stones.
• Acute calculous cholecystitis usually results from persistent cystic duct obstruction by a stone, causing gallbladder distension, chemical inflammation and sometimes secondary bacterial infection.
• Acalculous cholecystitis occurs without stones, particularly in critically ill, fasting, septic or post-trauma patients, and may progress rapidly to gangrene or perforation.

RISK FACTORS & PATHOPHYSIOLOGY

• Cholesterol stones form when bile is supersaturated with cholesterol, nucleation occurs and gallbladder emptying is impaired. Risk factors include age, female sex, pregnancy/oestrogen, obesity, rapid weight loss, metabolic disease and family history.
• Pigment stones are associated with haemolysis, cirrhosis or biliary infection depending on type.
• Obstruction raises intraluminal pressure, impairs perfusion and causes wall oedema and inflammation. Secondary infection may involve enteric organisms.

CLINICAL FEATURES

• Biliary colic is episodic right upper quadrant or epigastric pain, often after meals, lasting typically minutes to hours and resolving when obstruction clears; fever and persistent inflammatory signs are absent.
• Acute cholecystitis causes persistent RUQ pain, fever, nausea/vomiting and local tenderness. Murphy sign is inspiratory arrest due to pain on palpation beneath the right costal margin.
• Complications include empyema, gangrene, perforation, pericholecystic abscess, biliary peritonitis, fistula and gallstone ileus.

INVESTIGATIONS

• Ultrasound is first-line: gallstones, gallbladder wall thickening, distension, pericholecystic fluid and sonographic Murphy sign support acute cholecystitis.
• Blood tests include full blood count, CRP, liver function tests, bilirubin, renal function and lipase to assess inflammation, obstruction and pancreatitis.
• If common bile duct stones are suspected, use MRCP or endoscopic ultrasound; ERCP is primarily therapeutic when duct clearance is needed.
• HIDA scan may help when ultrasound is equivocal. CT is useful for suspected complications or alternative diagnoses.
• Differential diagnosis includes peptic ulcer, pancreatitis, hepatitis, liver abscess, pneumonia, renal colic and acute coronary syndrome.

TREATMENT

• Uncomplicated biliary colic: analgesia, antiemetic if needed and planned laparoscopic cholecystectomy for symptomatic gallstones.
• Acute cholecystitis: analgesia, IV fluids, antibiotics according to severity/local microbiology, and early laparoscopic cholecystectomy during the index admission when feasible.
• Patients unfit for surgery may require percutaneous cholecystostomy as a bridge or alternative, with reassessment for definitive management.
• Common bile duct stones require duct clearance, commonly by ERCP, followed by cholecystectomy when appropriate to prevent recurrence.
• Complications of surgery include bile leak, bile duct injury, bleeding, infection and retained stones. Recognise and refer suspected bile duct injury early.