Barrett's esophagus is defined as metaplasia of squamous epithelium to columnar epithelium. The chronic exposure to gastric acid causes the normal squamous epithelial cells above the GE junction to be replaced by the columnar epithelial cells from below the GE junction.

This man demonstrates Courvoisier's law, which states that in patients with an enlarged, palpable, but painless gallbladder, jaundice is not likely to be caused by gallstones. Gallstones typically cause chronic inflammation that results in a shrunken, fibrotic, and non-distendable gallbladder. The fact that his gallbladder appears normal suggests an obstruction further down the biliary tree most likely caused by a pancreatic malignancy.

The patient has hepatic encephalopathy likely precipitated by a deterioration in hepatic function following his binge. The appropriate treatment for hepatic encephalopathy is lactulose, which works to decrease ammonia buildup by preventing diffusion of ammonia from the bowel into the blood and by acting as a laxative to eliminate nitrogen-producing bacteria from the colon. Other important treatment points are to keep the patient away from alcohol or any factors that could worsen his liver disease and to decrease his dietary protein (produces nitrogenous compounds in the bowels).

The elevated serum transaminases strongly suggest hepatocellular damage rather than a cholestatic process (which would result in an elevated ALP and GGT). Of the four diagnoses, only acute viral hepatitis represents primarily a disease of hepatocellular damage. Common bile duct stone and primary biliary cirrhosis both are cholestatic processes while cholecystitis also usually presents with elevated ALP/GGT.

'BROW' (barley, rye, oats (though still controversial), and wheat) is a useful acronym that can be used to remember grains that contain gluten. Along with rice, other examples of allowed foods include corn, flax, millet, and soy.

Quinoa is also a fantastic alternative to gluten.

Anti-TTG is a diagnostic test for celiac disease. However, a negative anti-TTG value alone cannot rule out celiac disease. Approximately 10% of the population is IgA deficient and cannot produce anti-TTG, so an IgA level needs to be taken at the same time as the anti-TTG level. Trialing a gluten-free diet would also help with diagnosis, but ultimately, an upper endoscopy with small bowel biopsy is the gold standard for diagnosing celiac disease.

The sonographic Murphy's sign is associated with acute cholecystitis. The ultrasound transducer is used to press down on the gallbladder while the patient inspires and causes inspiratory arrest due to pain. This technique is more sensitive than the physical exam because the ultrasound transducer can confirm that the gallbladder is being pushed on during the test.

This woman likely has ascending cholangitis with overlying sepsis. Charcot's triad of abdominal pain, fever, and jaundice allows for the clinical diagnosis of ascending cholangitis. The cholestatic picture of liver enzymes supports this diagnosis. Once she has been resuscitated, she should be treated with empiric, broad-spectrum antibiotics (Pip/Tazo) while cultures are taken and be booked for urgent ultrasound to visualize her biliary tree and to decide on proper interventions (likely ERCP with insertion of stents or sphincterotomy).

Her renal failure is most likely acute and prerenal.

Temperature <35C is an sign of SIRS. This patient might have been febrile initially but is now showing signs of septic shock.

This man's history includes strong risk factors for C. difficile diarrhea, including advanced age (>60yo), hospitalization, and recent antibiotic use. The appropriate therapy for C. difficile diarrhea is metronidazole (Flagyl). Gastroenteritis is a possible differential diagnosis, but given the history, C. difficile diarrhea is more likely. Furthermore, of the two, C. difficile is more worrisome and must be ruled out. Neither of the inflammatory bowel diseases is likely to present in this acute manner and at this age.

Chest x-ray is the most sensitive of the listed exams for free air. Due to the wider spreading pattern of the x-rays, an erect abdominal x-ray offers a much poorer view of the diaphragm than does the erect chest x-ray and can often miss free air under the diaphragm. A normal erect abdominal x-ray thereby does not necessarily rule out a bowel perforation. The other two views would not show free air well. The other sensitive option to visualize free air is left lateral decubitus abdominal x-ray, in which the free air would collect above the liver and cause the entire liver margins to be seen on x-ray.