Source / episode info
- **Episode:**107
- **Title:**Divine Intervention Episode 107 – USMLE Step 1 Rapid Review Series 8 (GI)
- **Published:**2019-05-29
- Source:Episode page
One-liner
Episode 107 is a comprehensive review of GI topics, covering the differential diagnosis of chronic cholestatic liver diseases (PBC/PSC), differentiating gastric vs duodenal ulcer symptoms, recognizing anatomical pitfalls like Zenker's and Meckel's diverticula, and mastering key diagnostic workups such as the Schilling test for B12 deficiency.
High-yield summary
- Primary Biliary Cholangitis (PBC): Characterized by chronic cholestasis, pruritus, jaundice, elevated ALP, and positive anti-mitochondrial antibodies (AMA). It involves damage to small intrahepatic bile ducts.
- Primary Sclerosing Cholangitis (PSC): Associated with IBD (especially UC), characterized by strictures and fibrosis of both intra- and extrahepatic bile ducts; high suspicion if associated with positive p-ANCA. Imaging shows a "beads on a string" pattern.
- Peptic Ulcer Management: For patients taking NSAIDs, use a prostaglandin analogue like Misoprostol to replace the protective effects lost due to COX inhibition.
- Diverticula Pitfalls: Meckel's diverticulum is classically found in the right lower quadrant and can cause painless bloody diarrhea; Zenker's diverticulum requires diagnosis via barium swallow, as EGD carries a high risk of perforation.
- Electrolyte Management Pre-Surgery: For any patient with significant electrolyte abnormalities (e.g., hypokalemia from vomiting/diarrhea, severe uremia), always correct the metabolic derangements and hydrate before proceeding to surgery or invasive procedures.
Learning objectives
- Differentiate between Primary Biliary Cholangitis (PBC) and Primary Sclerosing Cholangitis (PSC), including their associated antibodies and imaging findings.
- Recognize the clinical presentation of various GI ulcers based on meal timing (gastric vs duodenal).
- Identify the anatomical location, symptoms, and diagnostic pitfalls of common diverticula (Meckel's, Zenker's).
- Understand the pathophysiology and workup of Vitamin B12 deficiency using the Schilling test.
- Apply knowledge of metabolic acid-base disturbances related to GI losses (e.g., vomiting, diarrhea).
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