Define Gallstones & Cholecystitis. Describe its pathogenesis and complications.

The Concept

Gallstones (cholelithiasis) form when the normal constituents of bile fall out of balance and precipitate. They are extremely common and most are asymptomatic; the many clinical presentations all depend on where a stone lodges. This single idea — that the disease is defined by the site of obstruction — organises the whole topic, from silent stones to life-threatening cholangitis.

Types of Stones & Risk Factors

There are three types: cholesterol stones (from cholesterol supersaturation of bile — the commonest in Western populations), pigment stones (black stones from haemolysis with excess bilirubin, and brown stones from biliary infection/stasis), and mixed stones (commonest overall). The classic risk factors are the 'five Fs' — Female, Forty, Fat, Fertile and Fair — with haemolytic disorders predisposing to pigment stones, and ileal disease (Crohn's) or rapid weight loss also contributing.

Pathogenesis

Stone formation needs three elements: supersaturation of bile with cholesterol, nucleation (crystal formation), and gallbladder stasis that allows crystals to aggregate. Understanding this explains why factors that concentrate bile or slow gallbladder emptying promote stones.

The Clinical Spectrum

• Asymptomatic — the majority, needing no treatment.
• Biliary colic — a stone transiently obstructs the cystic duct/Hartmann's pouch, causing severe colicky right-upper-quadrant/epigastric pain radiating to the back or right shoulder tip, often after a fatty meal; it is self-limiting and there is no fever or inflammation.
• Acute cholecystitis — persistent cystic-duct obstruction leads to inflammation: constant RUQ pain, fever, a positive Murphy's sign, and leucocytosis.
• Complications — empyema, mucocele, gangrene and perforation; migration into the common bile duct (choledocholithiasis) causing obstructive jaundice, cholangitis or pancreatitis; gallstone ileus; and, in the long term, gallbladder carcinoma.

Investigation & Management

• Ultrasound is the first-line investigation, showing stones, gallbladder wall thickening and any bile-duct dilatation
• LFTs and MRCP assess for common-bile-duct stones. Management follows the presentation: asymptomatic stones are left alone
• symptomatic stones (biliary colic or cholecystitis) are treated by laparoscopic cholecystectomy
• common-bile-duct stones are removed by ERCP with sphincterotomy.

Complications in Detail

The complications deserve elaboration because each is a favourite exam topic. A mucocele forms when a stone obstructs the cystic duct and the gallbladder fills with sterile mucus; an empyema is a gallbladder full of pus. Mirizzi syndrome occurs when a stone in Hartmann's pouch compresses the adjacent common hepatic duct, causing obstructive jaundice. Gallstone ileus is small-bowel obstruction from a large stone that has eroded through a cholecysto-duodenal fistula (with air in the biliary tree — pneumobilia — on X-ray). Recognising these explains why symptomatic stones are removed.

Chronic Cholecystitis

Repeated attacks of inflammation produce chronic cholecystitis — a fibrotic, thick-walled, poorly functioning gallbladder — which presents with recurrent biliary pain and fat intolerance. Long-standing inflammation is also the setting for a 'porcelain' (calcified) gallbladder, which carries a raised risk of gallbladder carcinoma. This chronic pathway is part of why elective cholecystectomy is offered for recurrent symptoms rather than waiting for an emergency.

The Complications of Surgery

Laparoscopic cholecystectomy is very safe but the student must know its serious complication — bile duct injury — which can cause bile leak, biliary peritonitis or a stricture, and is minimised by achieving the 'critical view of safety' before dividing structures. Other complications include bleeding, retained CBD stones, and conversion to open surgery. Awareness of these underlies proper consent and the careful identification of anatomy at operation.

Biliary Anatomy & Calot's Triangle

A working knowledge of biliary anatomy underpins safe surgery. The cystic duct, common hepatic duct and inferior border of the liver bound Calot's triangle, within which the cystic artery runs — the structures the surgeon must positively identify before clipping. Anatomical variations (an aberrant right hepatic artery, a low-inserting cystic duct, or accessory ducts) are common and are the reason the 'critical view of safety' is obtained. This anatomy also explains Mirizzi syndrome, where a stone in the cystic duct/Hartmann's pouch compresses the neighbouring common hepatic duct.

• Risk = the five Fs (Female, Forty, Fat, Fertile, Fair); ultrasound is first-line.
• Biliary colic (no fever, self-limiting) vs cholecystitis (fever, Murphy's positive, leucocytosis).
• Symptomatic stones → laparoscopic cholecystectomy; CBD stones → ERCP + sphincterotomy.

Fat, female, forty, fertile — the classical risk profile.

• Gallstones = cholesterol, pigment or mixed; risk = five Fs; most are asymptomatic and the presentation depends on where a stone lodges.
• Biliary colic: transient cystic-duct obstruction → colicky RUQ pain to back/shoulder after fatty meals, no fever, self-limiting.
• Acute cholecystitis: persistent obstruction → constant pain, fever, positive Murphy's sign, leucocytosis.
• Complications: empyema/mucocele/gangrene/perforation, CBD stones (jaundice, cholangitis, pancreatitis), gallstone ileus, gallbladder cancer.
• Ultrasound first-line (+ MRCP for CBD stones); laparoscopic cholecystectomy for symptomatic stones; ERCP for CBD stones.