How gallstones are tested on Step 1

Expect RUQ pain after fatty meals and a question on stone type, location, or lab pattern.

Cholesterol stonesMost common in the USUsually radiolucentEstrogen, obesity, rapid weight lossFibrates, ileal diseaseYellow, facetedPigment stonesBlack: hemolysis, cirrhosis (radiopaque)Brown: biliary infection (radiolucent)Unconjugated bilirubin with calciumBrown stones common in East AsiaBlack stones in sickle cell diseasevs
Stone types. Estrogen increases cholesterol secretion into bile; fibrates inhibit cholesterol 7α-hydroxylase, reducing bile acid synthesis.

The biliary disease spectrum

Where the stone sits determines the disease.

Biliary colicTransient cystic duct block; normal labsCholecystitisPersistent cystic duct block; fever, Murphy signCholedocholithiasisCommon bile duct stone; ↑ bilirubin, ALPCholangitisInfected obstructed duct; Charcot triadPancreatitisStone at the ampulla; ↑ lipaseGallstone ileusFistula; obstruction at the ileocecal valve
Location matters. Cystic duct stones do not cause jaundice; common bile duct stones do.
ConditionDiagnosisTreatment
Biliary colicUltrasound shows stonesElective cholecystectomy
Acute cholecystitisUltrasound: wall thickening, pericholecystic fluid; HIDA scan: no gallbladder fillingAntibiotics and cholecystectomy
Choledocholithiasis↑ Direct bilirubin and ALP; dilated ductERCP stone removal
Ascending cholangitisFever, jaundice, RUQ pain; often E. coli, Klebsiella, EnterococcusAntibiotics and urgent biliary drainage (ERCP)

Acalculous cholecystitis occurs in critically ill patients (gallbladder stasis and ischemia) without stones.

Physiology and anatomy

Bile flow links the liver, gallbladder, and small intestine.

Bile releaseCCKFrom I cells;contractsgallbladderSphincter ofOddiRelaxes with CCKBile acidsEmulsify fat;reabsorbed in ileumEnterohepaticloopIleal disease → bileacid loss
Bile physiology. Fat and protein in the duodenum release CCK, which explains postprandial pain.
  • The cystic artery usually arises from the right hepatic artery, within the hepatocystic (Calot) triangle.
  • Murphy sign: inspiratory arrest during palpation of the RUQ as the inflamed gallbladder meets the examiner's hand.
  • Porcelain gallbladder (calcified wall) is associated with gallbladder carcinoma; gallstones are the main risk factor for gallbladder cancer.
  • Ursodiol (ursodeoxycholic acid) can dissolve small cholesterol stones by reducing cholesterol secretion into bile.

Gallstone ileus

An uncommon complication with a classic picture.

  • Usually an older woman with long-standing gallstones.
  • Chronic inflammation creates a fistula between the gallbladder and the duodenum.
  • A large stone travels down the small intestine and lodges at the narrow ileocecal valve.
  • Imaging may show small bowel obstruction, air in the biliary tree (pneumobilia), and an ectopic stone.

Worked example

Use the lab pattern to locate the stone.

functions Worked example — fever and jaundice

A 70-year-old with known gallstones has fever 39.2°C, jaundice, and RUQ pain. BP 88/54, and he is confused. Bilirubin 5.8 mg/dL, ALP 410 U/L. What is the diagnosis and the key treatment?

  1. Fever, jaundice, and RUQ pain form Charcot triad.
  2. Hypotension and confusion complete Reynolds pentad, signaling sepsis.
  3. High bilirubin and ALP indicate an obstructed common bile duct.
  4. Treat with IV antibiotics and urgent biliary decompression by ERCP.

Answer. Ascending cholangitis with sepsis from choledocholithiasis; antibiotics and urgent ERCP drainage.