HY lecture notes:
Choledocholithiasis
High direct bilirubin + high ALP + high amylase (or lipase) = gallstone pancreatitis = choledocholithiasis (stone in biliary tree)
Diagnose and Tx with ERCP.
High direct bilirubin + high ALP + NORMAL amylase (or lipase) in patient with history of intermittent epigastric pain (cholelithiasis; stone in gallbladder) = choledocholithiasis, just simply the stone hasn’t descended distal to where the pancreatic duct enters the common bile duct, so there’s no gallstone pancreatitis in this case; do ERCP to diagnose and Tx gallstone pancreatitis; MRCP is a non-invasive and equally effective option, but the USMLE wants ERCP. In fact I don’t think I’ve ever seen an NBME or clinical mastery series question where MRCP was ever the answer.
USMLE really wants you to know that a patient who has a cholecystectomy and then a week later has either of the above presentations –> choledocholithiasis –> sometimes a patient has a retained stone in the cystic duct that will descend after the procedure.
If the USMLE tells you a patient had a cholecystectomy a week ago and intraoperative cholangiography was not performed, that’s an obvious giveaway for choledocholithiasis –> same situation –> likely cystic duct stone that descended into common bile duct. If USMLE mentions the bold detail, it quite frankly makes the question too easy. You should be aware mere recent cholecystectomy should be sufficient info to get the answer.
Sphincter of Oddi dysfunction
Will sound just like gallstone pancreatitis, except they’ll tell you there’s a remote history of cholecystectomy, so you know there’s no way it’s a stone lodged there.
Cholelithiasis
Hx of colicky epigastric pain in woman in: Fat, forties, female, fertile + NO increase in bilirubin or ALP + epigastric pain + NO fever = cholelithiasis; do abdominal ultrasound to diagnose; treat with cholecystectomy; in patients who don’t want surgery or who are pregnant, can give ursodiol (ursodeoxycholic acid).
Fat, forties, female, fertile + NO increase in bilirubin or ALP + epigastric pain + YES fever = cholecystitis; do abdominal ultrasound; if equivocal or negative, do HIDA scan –> involves injecting radiologically visible substance that is taken up by the liver and secreted into bile. Cholecystitis is almost always due to gall bladder outlet obstruction, so if the gallbladder does not light up on HIDA scan, that means an obstruction is indeed present and is confirmatory for cholecystitis.
Cholecystitis has positive Murphy sign –> epigastric pain + sudden voluntary guarding when epigastric pressure is applied during inspiration.
Pregnancy increases risk for cholesterol stones because estrogen increases HMG-CoA reductase activity + progesterone slows biliary peristalsis (sludging).
USMLE likes hemolytic disorders or conditions associated with increased RBC turnover (i.e., sickle cell) as causes of pigment stone cholelithiasis. Black stones are calcium bilirubinate. Brown stones are often infective origin. Bacteria will de-conjugate the bilirubin and make it less water soluble –> precipitation.
Chronic cholecystitis (caused by recurrent bouts of acute) can lead to porcelain gallbladder –> circumferential calcification of gallbladder walls –> 1/3 go on to get gallbladder cancer (90% are adenocarcinoma). Prognosis is obnoxiously poor.
Pancreatic cancer presents in a few different ways on the USMLE:
History of smoking always helps but isn’t specific for pancreatic cancer.
1) Middle-age patient with high direct bilirubin + high ALP + NORMAL pancreatic enzymes + history of cholecystectomy performed 25 years ago (i.e., they give you an absurdly remote history, meaning there’s zero chance there’s a stone) –> answer = head of pancreas cancer obstructing common bile duct.
2) Standard Courvoisier sign –> painless, palpable gallbladder in a jaundiced, afebrile patient = head of pancreas cancer till proven otherwise.
3) Image of a jaundiced abdomen (USMLE will increase yellow saturation of image to make it clear the patient is jaundiced) + visible epigastric bulge; they’ll tell you the patient is afebrile and not in pain –> head of pancreas cancer till proven otherwise.
4) They might say patient had abdominal x-ray (AXR) in the setting of high direct bilirubin + high ALP + NORMAL pancreatic enzymes and that the pancreas is poorly visualized due to overlying gas –> answer is do CT next to look for head of pancreas cancer.
If you get one of the three vignettes above, the answer is abdo CT with contrast, NOT ultrasound, because you’re trying to visualize the pancreas.
Cholangiocarcinoma
You’ll get a vignette that sounds like pancreatic cancer (often in a smoker), then they’ll go ahead and tell you that the CT was done and was negative. So you’re like, “Wait, this vignette sounds just like pancreatic cancer, so I don’t understand why the CT is negative.” Answer = bile duct cancer (cholangiocarcinoma). CT might not pick it up. Must do ERCP or MRCP to diagnose. But as I’ve said, the USMLE wants ERCP, and this is Q I believe on one of the newer surgery forms.
If the CT does pick it up and shows non-cystic mass of common bile duct, cholangiocarcinoma is the answer.
If an ultrasound is performed in select patients, there’s dilatation of the intrahepatic and/or extrahepatic ducts due to the cancer, but the USS itself isn’t diagnostic of cholangiocarcinoma.
Choledochal cyst
They’ll give you standard presentation that sounds similar to pancreatic cancer, but when the CT is performed, shows a cystic mass of the common bile duct –> answer = simple excision of cyst.
Primary biliary cirrhosis
If you get a vignette of a woman 20s-50s who has high direct bilirubin, high ALP, high cholesterol, and generalized pruritis, this is really HY for primary biliary cirrhosis –> do anti-mitochondrial antibody screen. After that, confirmatory is with liver biopsy.
They might tell you there’s a stone visualized in the gallbladder. This confuses so many students unnecessarily. If a patient has high cholesterol, isn’t it possible he or she also has a cholesterol stone or two? But the rest of the vignette will still scream PBC.
If they say there’s history of autoimmune disease, e.g., thyroiditis, SLE, etc., in the patient or in a family member, that’s a giveaway that the USMLE is saying “autoimmune diseases go together.”
Post-operative bile leak
This is now showing up in UWorld apparently. I’ve seen it as a distractor on one of the surgery forms, but not as a correct answer yet. But basically if a patient has a cholecystectomy and then goes on to get abdominal pain and fever, think post-op bile leak.
Patient will have just had a laparoscopic cholecystectomy for cholelithiasis/cholecystitis –> during procedure, there’s oblivious damage to bile ducts, failure to adequately ligate the cystic duct stump, or leakage from the liver bed/drainage site. –> causes biliary peritonitis.
On the USMLE, the answer is treat with ERCP to stent / make repairs as necessary.
Cholecystoduodenal fistula
In patients with chronic gall bladder obstruction, you can get a fistula/connection to the duodenum, leading to small bowel obstruction (high-pitched bowel sounds). They’ll say there’s air visualized in the bile ducts + liver in someone who has had variable history of biliary pathology, i.e., high direct bilirubin, high ALP, etc. These patients often have small bowel obstruction from the stone. Essentially just memorize “air visualized in the bile ducts + liver.” Patient will need endoscopic removal of stone.
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