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USMLE Step 2 CK High-Yield Gastrointestinal Topics
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Gastrointestinal
High Yield USMLE Step 2 CK Notes
Welcome to the Gastrointestinal High-Yield Notes for Step 2 CK.
These are the most commonly tested topics on the exam—ideal for quick review in your last 2 weeks before the exam, when you’re short on time, or when you’re just starting out and want to focus on what is high yield. Created and peer-reviewed by physicians who scored 260+ on Step 2 CK in a Q&A style to reinforce active learning.
How to use this file
- Read the question ➔ cover the answer ➔ self-quiz before revealing.
- Review the NOTES ➔ they include high-yield details you don’t want to miss.
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Table of Contents
Upper GIT Disorders
1. An elderly patient presents with dysphagia, halitosis, and regurgitation of undigested food. What’s the next step in diagnosis?
➔ Barium swallow (Symptoms suggestive of Zenker’s diverticulum)
- Note: Regurgitation of undigested food and gurgling nick mass are key factors for diagnosis.
- Note: Caused by outpouching above the Cricopharyngeus muscle.
- Note: Treatment is surgical diverticulectomy / myotomy.
- Note: VS GERD presents with heartburn and acid regurgitation, not halitosis or regurgitation of undigested food.
- Note: VS Achalasia causes esophageal dysphagia to both solids and liquids, not oropharyngeal dysphagia and regurgitation soon after swallowing.
2. A patient presents with substernal chest pain, regurgitation, occasional worsening of asthma and absence of red flags. What’s the next step in treatment?
➔ PPI (Symptoms suggestive of GERD; PPIs reduce acid reflux and improve symptoms)
- Note: Pain is substernal chest pain vs if epigastric pain think pancreatitis or gallstones.
- Note: Treatment includes lifestyle changes, antacids and PPIs if no alarming features or risk factors for Barrett’s esophagus.
- Note: If alarming features or risk factors for Barrett’s esophagus proceed with upper gastrointestinal endoscopy.
- Note: Alarming features include weight loss, GI bleeding, anemia, persistent vomiting, age >60 or a family history of upper GI malignancy.
- Note: Risk factors for Barrett’s esophagus: chronic GERD, male gender, age >50, white race, obesity, smoking and family history of Barrett’s esophagus or esophageal carcinoma.
3. A 67-year-old man with GERD refractory to PPIs is found to have grade III esophagitis and Barrett esophagus with mild dysplasia. He undergoes Nissen fundoplication. What is the next step in management?
➔ Repeat esophagogastroduodenoscopy (EGD) in 6 months
- Note: Barrett esophagus with dysplasia requires close surveillance due to risk of progression to esophageal adenocarcinoma.
- Note: Barrett esophagus with low-grade dysplasia may regress, especially after effective acid suppression or surgical intervention (e.g., Nissen fundoplication).
4. A patient with a history of stroke presents with coughing or choking during swallowing, and nasal regurgitation. What’s the next step in diagnosis?
➔ Video fluoroscopic swallowing study (Neurological disorder (ALS , parkinson’s, stroke) + difficulty initiating swallowing → indicates oropharyngeal dysphagia → confirm with video fluoroscopic swallowing.)
- Note: Same clinical picture can be a presentation for aspiration pneumonia.
5. A 55-year-old patient presents with progressive dysphagia, to both solids and liquids, along with regurgitation of undigested food. No history of choking or coughing. What’s the next step in diagnosis?
➔ Barium swallow → Followed by manometry with endoscopy(Symptoms suggestive of achalasia)
- Note: In achalasia: dysphagia starts with solids and liquids in the same time VS Mechanical obstruction (e.g., cancer): dysphagia starts with solids and progresses to liquids
- Note: Bird’s beak sign on barium swallow is classic for achalasia
- Note: Achalasia is treated with myotomy or pneumatic dilation, ± botulinum toxin, CCBs, nitrates
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6. A patient with HIV presents with dysphagia, odynophagia, and substernal pain. What’s the next step in diagnosis?
➔ Esophagogastroduodenoscopy with biopsy (HIV or IV drug use + dysphagia → suspect infectious esophagitis; confirmed with EGD and biopsy.)
- Note:
- White plaques on EGD → Candida → treat with Fluconazole
– Microscopy: Yeast with pseudohyphae invading squamous epithelium. - Small, punched-out ulcers on EGD → HSV → treat with Acyclovir
– Microscopy: Multinucleated giant cells, eosinophilic intranuclear inclusions. - Large, linear ulcers on EGD → CMV → treat with Ganciclovir
– Microscopy: Enlarged cells with intranuclear and cytoplasmic inclusions
7. A patient with osteoarthritis presents with dysphagia and odynophagia. The patient is on alendronate, and esophagogastroduodenoscopy (EGD) reveals shallow ulcers surrounded by normal mucosa in the esophagus. What’s the next step in treatment?
➔ Stop alendronate (Bisphosphonates like alendronate can cause pill-induced esophagitis → stop the offending agent.)
- Note: Other common causes include NSAIDs, antibiotics, potassium chloride and iron supplements
8. A 45-year-old man with a history of heavy alcohol use, ascites and splenomegaly presents with hematemesis. What is the initial treatment?
➔ IV Abs, octreotide, and PPIs (Portal hypertension signs + hematemesis → think bleeding varices → start resuscitation with IV antibiotics, octreotide, and PPIs.)
- Note: Octreotide causes splanchnic vasoconstriction
- Note: Prophylactic IV antibiotics as there’s a high risk of bacterial infections.
- Note: PPIs stabilize clots and reduce acid.
- Note: After stabilization, proceed with upper endoscopy (diagnostic and therapeutic).
- Note: Primary prophylaxis against variceal bleeding can be achieved either with endoscopic variceal ligation (EVL) or administration of a nonselective beta blocker.
- Note: All patients with newly diagnosed cirrhosis should undergo screening endoscopy for esophageal varices.
9. A 17-year-old boy is brought to the ED after ingesting liquid drain cleaner in a suicide attempt. He has gray exudate on the lips/oral mucosa, and epigastric tenderness. What is the next step?
➔ Supportive care, decontamination, emergent esophagogastroduodenoscopy (Symptoms suggestive of caustic ingestion)
- Note: Emergent esophagogastroduodenoscopy used to assess severity and guide management.
- Note: Complications
– Esophageal strictures/fibrosis due to scarring—typically symmetrical.
– Esophageal squamous cell carcinoma—usually asymmetrical.
10. A 45-year-old patient presents with chronic epigastric discomfort but has no alarming symptoms. What is the next step in management?
➔ Test for H. Pylori (Symptoms suggestive of peptic ulcer)
- Note: Low risk of malignancy: (<60 years, no alarming symptoms) → Test for H. pylori.
- Note: High risk of malignancy: (>60 years, with alarming symptoms) → Upper endoscopy.
- Note: Alarming symptoms include: weight loss, GI bleeding, anemia, early satiety, persistent vomiting, dysphagia, or a family history of upper GI cancer.
- Note: Duodenal ulcers (DU): present with epigastric pain that improves with food and recurs 2-5 hours after eating.
- Note: Gastric ulcers: present with epigastric pain that worsens with food and is often associated with weight loss.
11. A 47-year-old man presents with sudden, severe epigastric pain, tachycardia, hypotension, and board-like abdominal rigidity. History of intermittent epigastric pain relieved by food over the past few months. What is the diagnosis?
➔ Perforated duodenal ulcer (History suggests duodenal ulcer + symptoms suggestive of peritonitis)
- Note: Complications include perforation, gastric outlet obstruction, bleeding.
- Note: Treatment with IV PPIs, resuscitation with saline and RBCs if shock is present (regardless of Hgb Concentration) → then surgery.
12. A 25-year-old woman develops fever and malaise 7 days after splenectomy for trauma; chest x-ray shows a left pleural effusion. What is the next step in diagnosis?
➔ Abdominal CT scan with contrast (to evaluate for possible intra abdominal abscess)
- Note: VS Diverticulitis (presents with left lower quadrant pain, fever, and sometimes changes in bowel habits; associated with a history of Constipation).
- Note: VS Appendicitis (presents with right lower quadrant pain, nausea, vomiting, and fever).
- Note: VS Cholecystitis (presents with right upper quadrant pain, fever, and +ve Murphy’s sign).
13. A 30-year-old woman presents with chronic diarrhea, weight loss, and abdominal bloating after consuming gluten-containing foods (e.g., wheat, barley, or rye), What is the next step?
➔ Serum anti-transglutaminase antibodies, (Symptoms suggestive of Celiac disease → treat with a gluten-free diet.)
- Note: Dermatitis herpetiformis and Iron def anemia are associated with Celiac disease.
- Note: Duodenal biopsy typically shows villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes.
14. A 45-year-old man presents with chronic diarrhea, weight loss, and fatigue, along with knee pain and recurrent hand numbness. What is the most appropriate treatment?
➔ IV ceftriaxone for 2 weeks, followed by daily TMP-SMX for 1 year. (Chronic diarrhea + joint pain + neurologic symptoms → Think Whipple disease)
15. A 9-month-old girl presents with watery stools, gas, and mild abdominal distention after resuming cow milk-based formula. What is the most likely cause?
➔ Transient lactase deficiency (treat with lactose-free diet or lactase enzyme supplementation.)
16. A newborn with bilious vomiting, sudden abdominal pain, bloody diarrhea, Fever and leukocytosis. X-ray is normal. What’s the next best step in diagnosis?
➔ Upper GI barium series (Symptoms suggestive of midgut volvulus)
- Note: Malrotation is the predisposing factor.
- Note: Treatment is an emergency Ladd procedure after resuscitation.
17. An elderly patient with abdominal distention,Vomiting , and LLQ pain. X ray shows coffee bean sign. What’s the most likely diagnosis?
➔ Sigmoid volvulus
- Note: Treated with Endoscopic detorsion ± surgery if perforated (perforation presents with fever, leukocytosis, peritonitis, and free air on imaging).
- Note: In patients with abdominal distention, the first step is to order an abdominal X-ray, which may show air-fluid levels (suggesting obstruction) → Additional findings like the coffee bean sign suggest a specific cause—sigmoid volvulus in this case.
sigmoid volvulus (image on Wikimedia Commons https://commons.wikimedia.org/wiki/File:Sigmoidvolvulus.jpg)
18. A 42-year-old woman with a history of appendectomy presents with nausea, vomiting, abdominal distention and failure to pass gas or stool. What is the imaging finding on x-ray?
➔ Multiple air-fluid levels (Prior surgery + signs of bowel obstruction → think small bowel obstruction from adhesions → Multiple air-fluid levels is typical)
- Note: Treat SBO with bowel rest, nasogastric tube suction, and intravenous fluids.
- Note: Treat with surgical exploration if complicated (complications can be hernia, ischemia or perforation).
19. A 42-year-old man presents with epigastric pain, vomiting, and loss of appetite. He has high-pitched bowel sounds and a tender mass in the right groin. What is the next step in management?
➔ Surgical exploration of the right inguinal canal. (Tender groin mass + signs of bowel obstruction → think incarcerated or strangulated inguinal hernia → treated with emergency surgical exploration)
- Note: VS testicular torsion (young male with acute groin or lower abdominal pain along with sudden-onset scrotal pain, absent cremasteric reflex, and scrotal swelling, but no signs of bowel obstruction.)
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Lower GIT Disorders
20. A 32-year-old woman with severe abdominal pain, bloody diarrhea, fever, and tenesmus. She has not improved despite medications. Colonoscopy shows friable mucosa and continuous ulceration. What is the next step in management?
➔ IV corticosteroids (Symptoms suggestive of ulcerative colitis flare)
- Note: VS chronic ulcerative colitis treatments which includes 5-aminosalicylates, immune modulators (e.g., azathioprine, 6-MP, methotrexate) or surgery
- Note: Colorectal cancer is a serious long-term complication → so screening includes routine surveillance colonoscopy every 1-3 years starting 8 years after diagnosis.
21. A 25-year-old man reports intermittent crampy abdominal pain, weight loss, and diarrhea for 3 months. Colonoscopy shows cobblestone appearance and skip lesions. What is the next step in management?
➔ Aminosalicylates (e.g., mesalamine) (Symptoms suggestive of mild Crohn disease)
- Note: IBD (UC, Crohn) treatment
○ Mild IBD: 5-aminosalicylates (e.g., sulfasalazine, mesalamine)
○ Moderate IBD: Immune modulators (e.g., azathioprine, 6-MP, methotrexate)
○ Severe IBD: TNF-α inhibitors (e.g., Infliximab for Crohn’s) vs Surgery (for UC)
○ Steroids are used for treatment of flare-ups - Note: Mesalamine is well-tolerated by patients with sulfa allergies (unlike sulfasalazine)
22. A 53-year-old woman with ulcerative pancolitis presents with worsening abdominal pain, hematochezia, tachycardia, mild fever, and abdominal distension. X-rays >6 cm colonic dilation. What is the next step in management?
➔ IV corticosteroids and supportive care (Ulcerative colitis flare + >6 cm colon dilation → think Toxic megacolon → treat with supportive care and IV corticosteroids)
- Note: Surgery in severe cases
- Note: VS treatment of C. difficile–associated toxic megacolon:
– Stop inciting antibiotics immediately
– Start oral vancomycin (or rectal if ileus) ± IV metronidazole
– Corticosteroids are not used unless there’s underlying IBD
– Surgery if there is no response, perforation, or worsening sepsis
23. A 42-year-old woman with 4 months of abdominal pain relieved by defecation and constipation. Prior colonoscopy was normal. No red flag signs. What is next in management?
➔ Stress management and dietary modification (Chronic abdominal pain + change in stool frequency/form + relief with defecation >3 months → arediagnostic for IBS)
- Note: Loperamide for diarrhea, Dicyclomine for pain, Diphenoxylate for motility.
- Note: Red flag signs include; weight loss, anemia, rectal bleeding or melena, nocturnal symptoms, onset after 50 years and family history or colon cancer or IBD
24. A 72-year-old man develops crampy abdominal pain and bright red rectal bleeding after recent AAA repair. Exam shows left lower quadrant tenderness. What is the most likely diagnosis?
➔ Ischemic colitis (signs of GI ischemia after hypotension/surgery → think ischemic colitis)
- Note: Affects watershed areas: splenic flexure and rectosigmoid junction
- Note: CT → shows edematous intestinal wall
- Note: Endoscopy → shows friable mucosa ± infarction
- Note: Treatment; supportive care, antibiotics, surgery if severe
- Note: Ischemic colitis pain is at the LLQ VS The pain of acute mesenteric ischemia is periumbilical or epigastric.
Created with BioRender.com
25. A 75-year-old man with atrial fibrillation, and hypertension presents with sudden, severe periumbilical abdominal pain out of proportion to exam, along with vomiting and occult blood in stool. He has lactic acidosis. What is the next step in management?
➔ CT angiography of the abdomen (AF or irregular rhythm + Periumbilical or epigastric pain out of proportion to exam + blood in stool → think acute mesenteric ischemia, get CT angiography)
- Note: Treatment is emergent surgical embolectomy if acute mesenteric ischemia due to embolism.
26. A 22-year-old pregnant woman at 22 weeks gestation presents with fever, nausea, vomiting, and right-sided abdominal pain. Exam shows guarding and peritoneal signs. What is the next best step?
➔ Exploratory laparotomy. (Acute appendicitis + prescience of peritoneal signs → indicates exploratory laparotomy)
- Note: Pregnancy and neonates: ultrasound 1st step
- Note: In non-pregnant adults: CT abdomen 1st step
- Note: Treatment: appendectomy; If perforation:
○ Abscess → IV antibiotics + drainage → then Delayed (interval) appendectomy after inflammation resolves (usually 6–8 weeks later)
○ Diffuse contamination → exploratory laparotomy - Note: Abscess clinical picture:
– Appendicitis symptoms >5 days and CT shows appendiceal abscess.
27. A 62-year-old man presents with fatigue, unintentional weight loss, and intermittent blood in his stool, and history of prolonged constipation. What is the next step?
➔ Colonoscopy (Age >50 + anemia or bowel habit changes → suspect colorectal cancer → do colonoscopy)
- Note: Occult blood testing is sensitive but not specific
- Note: If colonoscopy positive → Do CT scan for staging and evaluation of metastasis
- Note: Another clinical picture would be a patient presenting with liver metastasis → consider colorectal cancer as a possible source→ Perform colonoscopy
28. A 47-year-old man with a mother diagnosed with colon cancer at age 47 comes for a health maintenance exam. What is the recommendation regarding colon cancer screening?
➔ Colonoscopy now, and repeat every 5 years
- Note: Patients with a first-degree relative diagnosed with colon cancer before age 60 → Begin screening at age 40 or 10 years earlier than the relative’s age at diagnosis (whichever comes first) → repeat every 5 years.
- Note: Patients at average risk → Begin routine colorectal cancer screening from age 45 to 75 years, typically every 10 years.
- Note: Screening in cases of Familial Adenomatous Polyposis (FAP) → Begin screening at age 10–12 years with flexible sigmoidoscopy or colonoscopy annually.
29. A 62-year-old woman presents with LLQ pain, fever, nausea, and leukocytosis. What’s the next step in treatment?
➔ Oral antibiotics and bowel rest. (Symptoms suggestive of uncomplicated diverticulitis)
- Note: Complicated diverticulitis (abscess, fistula, peritonitis) → requires IV antibiotics, possible drainage, or surgery.
- Note: VS Splenic abscess (presents in younger patient with IV drug use, fever, LUQ pain)
- Note: VS Appendicitis (presents in younger patient with fever, RLQ pain and vomiting)
- Note: VS Cholecystitis (presents with RUQ pain, nausea, vomiting and +ve Murphy’s sign)
30. A 77-year-old man with a history of constipation presents with passing air and fecal material during urination, and recurrent UTIs. What’s the cause?
➔ Colovesical fistula (Symptoms suggestive of diverticulosis → complicated to colovesical fistula → leading to fecaluria + pneumaturia)
- Note: Diverticulosis (not cancer!) is the most common cause of colovesical fistula in elderly patients with chronic constipation.
- Note: Crohn disease is also a common cause of fistula
- Note: Diagnosis involves contrast CT imaging or direct visualization.
31. A 37-year-old woman presents with new-onset constipation, anxiety, and recent diphenhydramine use for sleep. What’s the next step in management?
➔ Discontinue diphenhydramine
- Note: Common drugs causing constipation include anticholinergics (e.g., diphenhydramine, TCAs), opioids, iron supplements and calcium channel blockers
- Note: These drugs can also cause Urine retention
32. A 77-year-old woman presents with decreased appetite, nausea, vomiting, and loose stool after 5 days of no bowel movements. Rectal exam shows a firm stool in the rectal vault. She is on oxybutynin. What is the most likely cause of her symptoms?
➔ Fecal impaction (The loose stools is due to severe constipation leading to overflow diarrhea.)
- Note: First-line treatment is enema administration to relieve the impaction → then treat the underlying cause of constipation.
33. A 50-year-old man with chronic constipation has 2 weeks of anal pain and bright red blood on toilet tissue after bowel movements. Pain improves with sitz baths. What is the most likely diagnosis?
➔ Anal fissure (tear below the dentate line causing painful defecation and bleeding)
- Note: Mostly occurs at the posterior midline.
- Note: Initial treatment includes stool softeners, sitz baths, topical analgesics, and vasodilators.
- Note: Chronic fissures, or those that are unresponsive to conservative management, require surgical repair.
- Note: VS Internal hemorrhoids: Painless bleeding, typically seen with straining; swelling or bulging in the anal region; no significant pain on defecation.
- Note: VS External hemorrhoids: Located below the dentate line; can be painful, especially if thrombosed; may cause swelling and visible bluish perianal lump.
- Note: VS Abscess: Fluctuant mass, tender with erythema and warmth, associated with fever or systemic signs of infection, requires incision and drainage (I&D).
- Note: VS HPV Infection (Anal warts): Painless growths in the anal region, may cause bleeding if traumatized, often with itching, treatable with topical treatments or surgical removal.
Armin Kübelbeck (https://commons.wikimedia.org/wiki/File:Analfissur.svg), „Analfissur“, https://creativecommons.org/licenses/by/3.0/legalcode
34. A 47-year-old man with a 3-week history of painless, bright red rectal bleeding that has progressed to occur between bowel movements has a normal rectal exam and positive fecal occult blood test. What is the most likely diagnosis?
➔ Internal hemorrhoids (Painless bleeding due to dilated submucosal veins above the pectinate line vs external hemorrhoids which are painful)
35. A 37-year-old woman with a 6-month history of rectal pain, bleeding, and itching is found to have tender, inflamed rectal tissue on exam. What is the next step in diagnosis?
➔ Anoscopy (To confirm diagnosis of hemorrhoids)
- Note: Hemorrhoids are diagnosed clinically with rectal exam and confirmed by anoscopy.
- Note: Hemorrhoids treatment is mainly supportive (high-fiber diet, sitz baths, NSAIDs); severe cases may require band ligation, sclerotherapy, or surgical excision.
- Note: Indications for surgery include (severe or recurrent hemorrhoidal bleeding, prolapsed or thrombosed hemorrhoids and failure of non-surgical treatments).
Pancreatic and Hepatobiliary Disorders
36. A 45-year-old man with chronic hepatitis C presents for follow-up. His liver function tests are mildly elevated, and he is a heavy drinker. What is the most important recommendation to minimize the progression of liver disease?
➔ Abstain from alcohol consumption
37. A 52-year-old man with a history of alcoholism and recent pancreatitis presents with fever, diffuse abdominal pain, tenderness, and ascites. What is the next step?
➔ Paracentesis. (Symptoms suggestive of spontaneous bacterial peritonitis)
- Note: Paracentesis: leukocyte count >1000/mm³ or neutrophils >250/mm
- Note: Treated with antibiotics with gram-negative rod coverage (e.g., Cefotaxime)
- Note: Ascites causes: cirrhosis, heart failure, malignancy (liver, ovarian, pancreatic), pancreatitis, tuberculosis, nephrotic syndrome and infection (e.g., spontaneous bacterial peritonitis).
38. A 42-year-old obese woman presents with a 2-hour episode of colicky RUQ pain without fever, leukocytosis, or abnormal liver function tests. Ultrasound shows gallstones. What is the most likely cause of the abdominal pain?
➔ Biliary colic (Suggested by postprandial pain <6 hours without fever or leukocytosis)
- Note: Initial treatment includes pain control, dietary modifications → definitive treatment includes cholecystectomy (either laparoscopic or open), usually indicated if symptoms persist or if complications arise.
39 A 55-year-old man with a history of gallstones presents with persistent right upper quadrant pain for 12 hours, fever, and leukocytosis. On ultrasound, there is gallbladder wall thickening and pericholecystic fluid. What is the next step?
➔ Urgent cholecystectomy (Cholecystitis Suggested by persistent pain >6 hours, fever and leukocytosis)
- Note: Treatment: NPO, IV fluids, antibiotics, cholecystectomy (within 24-48 hours).
- Note: HIDA scan confirms cholecystitis if ultrasound findings are equivocal.
- Note: If emphysematous cholecystitis treatment includes IV antibiotics, urgent cholecystectomy.
- Note: VS cholangitis treatment includes antibiotics, supportive care, and urgent biliary decompression via ERCP.
40. A 27-year-old man with recurrent pancreatitis since childhood, no alcohol use, normal biliary imaging, and no trauma. What is the test to confirm the diagnosis?
➔ Measurement of serum triglycerides (Recurrent pancreatitis with –ve alcohol use or biliary abnormalities → the most likely cause is hypertriglyceridemia)
- Note: 2 of the following: epigastric pain radiating to the back, serum amylase/lipase >3x ULN, characteristic imaging findings is diagnostic of pancreatitis
- Note: If pancreatitis is suggested → to know the cause take history for alcohol or drug induced pancreatitis → then US is performed to diagnose gallstones.
- Note: Supportive care, opioid analgesics for pain
- Note: If gallstone-related:treat with ERCP + cholecystectomy after stabilization
41. An 82-year-old woman presents with painless jaundice, weight loss, and a palpable liver edge. Labs show cholestatic liver injury. What is the next step for diagnosis?
➔ Abdominal ultrasound, Symptoms suggestive of pancreatic cancer (particularly in the head of the pancreas)
- Note: Symptoms suggestive of cancer in pancreatic head are obstruction of the common bile duct causing painless jaundice and palpable liver edge
- Note: Abdominal ultrasound shows dilation of the common bile duct and pancreatic duct
- Note: Treated with palliative care
42. A 35-year-old woman presents with fatigue, generalized itching, dry eyes, and dry mouth. Liver biopsy shows lymphocytic infiltrates in portal tracts with loss of bile ducts. What’s the next step in treatment?
➔ Ursodeoxycholic acid (Middle aged woman + signs of biliary obstruction(itching, jaundice) → Thinkprimary biliary cholangitis)
- Note: Associated with +ve serum antimitochondrial antibody, biopsy is needed for definitive diagnosis.
- Note: Complications include cirrhosis, fat-soluble vitamin deficiency, osteoporosis, hyperlipidemia and hepatocellular carcinoma.
43. A 17-year-old boy presents with a 4-day history of RUQ pain, nausea, fever, and jaundice after returning from Mexico. Eating worsens his pain. What serologic finding will confirm the diagnosis?
➔ Positive anti-HAV IgM (present in acute hepatitis A infection)
- Note: IgM = Acute infection (early phase)
- Note: IgG = Past infection or vaccinated (long-term immunity)
- Note: In acute hepatitis A, LFTs typically show ALT and AST >1000 IU/L
44. A 72-year-old man with a history of heavy alcohol use presents with 4 months of right upper quadrant pain, weight loss, elevated direct bilirubin, and alkaline phosphatase. Ultrasound shows dilated intrahepatic ducts. What is the next best step in diagnosis?
➔ ERCP (Symptoms suggestive of cholangiocarcinoma, it is suspected when imaging shows biliary dilation without a mass, this is presented in the question as dilated intrahepatic ducts.)
- Note: ERCP allows for direct visualization, biopsy, and possible stent placement if obstruction is present.
- Note: If the US is present in choices it would be the best next step.
High-Yield GI Pathogens
45. A 32-year-old man presents with bloody diarrhea, fever, and crampy abdominal pain after traveling to a rural area and consuming undercooked chicken. What is the diagnosis?
➔ Campylobacter jejuni
- Note: May be complicated by Guillain-Barré syndrome
- Note: Treated with supportive care
- Note: Can mimic appendicitis (pseudoappendicitis), differentiate by the presence of bloody diarrhea.
46. A 28-year-old woman presents with foul-smelling, fatty diarrhea, bloating, cramping, and weight loss after drinking contaminated water while traveling abroad. What is the diagnosis?
➔ Giardia lamblia
- Note: Treated with Metronidazole
- Note: If the presentation includes bloody diarrhea, consider Entamoeba histolytica (also treated with Metronidazole, but may require paromomycin to eliminate cysts in the lumen).
47. A 60-year-old man with liver disease presents with severe pain and hemorrhagic bullae at a wound site after exposure to seawater. He is febrile and in septic shock.What is the most likely diagnosis?
➔ Vibrio vulnificus
- Note: Treated with IV antibiotics + urgent surgical debridement.
- Note: Seawater-related pathogens: Vibrio vulnificus (wound infections/sepsis), Vibrio parahaemolyticus (gastroenteritis), Vibrio cholerae (watery diarrhea), Hepatitis A virus (via contaminated shellfish).
48. A 25-year-old woman presents with bloody diarrhea, which worsens over several days. She later develops decreased urine output, dark-colored urine, fatigue, pallor, and petechiae. What is the diagnosis?
➔ Shiga toxin-producing E. coli (STEC)
- Note: Decreased urine output, dark-colored urine, fatigue, pallor, and petechiae indicate Hemolytic uremic syndrome, a common complication of STEC.
- Note: Treatment with supportive care; antibiotics are contraindicated due to risk of worsening toxin release.
49. A 35-year-old man presents with watery, non-bloody diarrhea, abdominal cramps, and nausea after traveling to Mexico. What is the most likely diagnosis?
➔ Enterotoxigenic E. coli (ETEC) (Traveler’s diarrhea)
- Note: Treated with oral rehydration; fluoroquinolones or azithromycin may be used in moderate to severe cases or in high-risk patients.
50. A 58-year-old woman presents with watery diarrhea and abdominal pain after a recent course of antibiotics for a urinary tract infection. What is the most likely diagnosis?
➔ Clostridium difficile
- Note: Treated with oral vancomycin or fidaxomicin, depending on severity
- Note: Risk for toxic megacolon if loperamide is used.
- Note: Prevention: proper hand hygiene with soap and water (not alcohol-based sanitizers, which do not kill spores)
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High-Yield Causes of Diarrhea
Bloody diarrhea causes
| Pathogen/Condition | Key Features |
|---|---|
| Campylobacter jejuni | Undercooked poultry; fever, crampy pain; may → Guillain-Barré syndrome |
| Shiga toxin-producing E. coli (STEC) | Undercooked beef; bloody diarrhea; risk of HUS (anemia, thrombocytopenia, AKI) |
| Shigella | High fever, seizures (esp. children); fecal-oral transmission |
| Entamoeba histolytica | Gradual onset; travel history; flask-shaped ulcers; risk of liver abscess |
| Inflammatory bowel disease (UC/Crohn) | Chronic course; bloody diarrhea, abdominal pain; extraintestinal signs; ↑ fecal calprotectin |
Watery diarrhea causes
| Pathogen/Condition | Key Features |
|---|---|
| Enterotoxigenic E. coli (ETEC) | Traveler’s diarrhea; watery, non-bloody |
| Vibrio cholerae | Profuse “rice-water” diarrhea → rapid dehydration |
| Clostridium difficile | Recent antibiotics; watery diarrhea; toxic megacolon risk |
| Cryptosporidium | Immunocompromised (HIV/AIDS); watery diarrhea |
| Norovirus | Outbreaks (cruise ships); vomiting + watery diarrhea |
| Rotavirus | Infants/children; vomiting + watery diarrhea |
| Irritable bowel syndrome (IBS) | Functional; no red flags; pain ↓ with defecation |
| Lactose intolerance | Bloating, flatulence, watery diarrhea after dairy; improves with lactose-free diet |
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Fatty/ Watery diarrhea causes
| Pathogen/Condition | Key Features |
|---|---|
| Celiac disease | Chronic diarrhea; steatorrhea; wt loss; Fe-def anemia; +tTG-IgA |
| Pancreatic insufficiency | Post-meal pain; fatty stools; wt loss; ADEK deficiency; chronic pancreatitis / CF |
| Small intestinal bacterial overgrowth (SIBO) | Bloating, flatulence, diarrhea; post-surgery/motility issues; ↓B12; ↑Folate |
| Giardiasis | Foul-smelling fatty diarrhea; bloating; wt loss; contaminated water |
🏁 Final Thoughts
You made it to the end—well done! These high-yield notes are designed to save you time and keep you focused on what actually matters for Step 2 CK. Review these vignettes regularly—steady practice beats cramming.
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Good luck and we’re rooting for you all the way to Match Day! 🎯
Disclaimer
Version 1.0 August 2025. No part of this document may be reproduced or distributed without written permission. For personal study only. Medical information herein is for educational purposes and does not constitute clinical advice. Always confirm with current guidelines and your institution’s policies.
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