GI Cheat Sheet 2026

The 30 highest-yield GI facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Protein digestion begins in the stomach with pepsin and is completed in the small intestine; the final products absorbed by enterocytes are primarily: → Di- and tripeptides and free amino acids via specific transporters
2. Anorectal manometry is the first-line diagnostic test for which condition in adults? → Fecal incontinence and Hirschsprung disease evaluation
3. A patient with celiac disease who ingests gluten will show damage primarily to which intestinal structure? → Intestinal villi
4. Mesalamine (5-ASA) is the first-line therapy for mild to moderate disease in which condition? → Ulcerative colitis
5. Endoscopic band ligation is the preferred endoscopic treatment for acute bleeding from which source? → Esophageal variceal bleeding
6. Endoscopic ultrasound (EUS) is the most accurate modality for staging which malignancy? → Esophageal and gastric cancer (T and N staging)
7. A patient presents with watery diarrhea, hypokalemia, and achlorhydria (WDHA syndrome). Which tumor is most likely? → VIPoma
8. The Forrest classification is used to guide endoscopic management of which condition? → Risk stratification of peptic ulcer bleeding lesions
9. Which layer of the GI tract contains blood vessels, lymphatics, and the submucosal (Meissner's) plexus? → Submucosa
10. Toxic megacolon is a life-threatening complication most commonly associated with which condition? → Severe ulcerative colitis or Clostridioides difficile colitis
11. Which enzyme converts trypsinogen to active trypsin in the duodenum? → Enterokinase (enteropeptidase)
12. Peyer's patches, lymphoid aggregates important for gut immunity, are found predominantly in which GI segment? → Ileum
13. Endoscopic retrograde cholangiopancreatography (ERCP) is considered first-line therapy for which condition? → Common bile duct stones (choledocholithiasis)
14. Colonic fermentation of undigested carbohydrates by bacteria produces which gases responsible for flatulence? → Carbon dioxide, hydrogen, and methane
15. Fat-soluble vitamins (A, D, E, K) are primarily absorbed via which mechanism in the small intestine? → Incorporation into micelles and passive diffusion into enterocytes
16. Which type of fiber is most effective at lowering LDL cholesterol by binding bile acids in the intestinal lumen? → Soluble viscous fiber (psyllium, beta-glucan)
17. In hepatic encephalopathy, which neurotoxic substance primarily accumulates due to failed hepatic clearance? → Ammonia
18. Which medication is used to treat hepatic encephalopathy by reducing gut bacteria that produce ammonia, without being significantly absorbed systemically? → Rifaximin
19. Over-the-scope clips (OTSC, 'bear claw clips') are used in endoscopy primarily for which indication? → Full-thickness closure of GI perforations and treatment of refractory hemorrhage
20. Brunner's glands, which secrete alkaline mucus to protect the duodenal mucosa, are located in which layer? → Submucosa
21. Primary sclerosing cholangitis (PSC) is most strongly associated with which inflammatory bowel disease? → Ulcerative colitis
22. Which GI hormone inhibits gastric acid secretion and is released by D cells in the gastric antrum? → Somatostatin
23. Iron absorption is primarily regulated at which level and is enhanced by which concurrent intake? → Intestinal enterocyte uptake; vitamin C (ascorbic acid)
24. Self-expanding metal stents (SEMS) placed endoscopically in the colon are used as a bridge to surgery for which condition? → Malignant colonic obstruction
25. A Hartmann's procedure involves which surgical steps? → Sigmoid resection with end colostomy and closure of the rectal stump
26. Which antibody is most characteristic of primary biliary cholangitis (PBC)? → Anti-mitochondrial antibody (AMA)
27. Vitamin B12 absorption requires intrinsic factor and is completed in which GI segment? → Terminal ileum
28. Charcot's triad — fever, right upper quadrant pain, and jaundice — is the classic presentation of which condition? → Ascending cholangitis
29. Which modality is the preferred first-line imaging for suspected acute appendicitis in adult patients in the US? → CT scan of the abdomen/pelvis with IV contrast
30. Which sphincter, located at the gastroesophageal junction, is primarily responsible for preventing gastroesophageal reflux? → Lower esophageal sphincter