MD Gastrointestinal Tract Disorders 2 — Questions and Answers
Question 1: A 45-year-old man presents with episodic epigastric pain relieved by food and antacids. Upper endoscopy reveals a duodenal ulcer. Which organism is most likely responsible?
- Campylobacter jejuni
- Helicobacter pylori (Correct answer)
- Clostridium difficile
- Escherichia coli
Correct answer: Helicobacter pylori
Helicobacter pylori is responsible for approximately 90% of duodenal ulcers and disrupts the mucosal defense by producing urease and inflammatory mediators.
Question 2: A patient with ulcerative colitis limited to the rectum is best described as having which subtype?
- Pancolitis
- Left-sided colitis
- Proctitis (Correct answer)
- Ileocolitis
Correct answer: Proctitis
Proctitis refers to ulcerative colitis confined to the rectum, the most distal and mildest form of the disease.
Question 3: A 60-year-old woman presents with progressive dysphagia to solids then liquids, weight loss, and regurgitation of undigested food. Barium swallow shows a 'bird's beak' tapering. What is the diagnosis?
- Esophageal carcinoma
- Zenker's diverticulum
- Achalasia (Correct answer)
- Diffuse esophageal spasm
Correct answer: Achalasia
Achalasia is characterized by failure of the lower esophageal sphincter to relax and loss of peristalsis, producing the classic bird's beak appearance on barium swallow.
Question 4: Which complication is most feared in a patient with Barrett's esophagus?
- Squamous cell carcinoma of the esophagus
- Adenocarcinoma of the esophagus (Correct answer)
- Esophageal perforation
- Mallory-Weiss tear
Correct answer: Adenocarcinoma of the esophagus
Barrett's esophagus involves intestinal metaplasia of the lower esophageal epithelium and is a precursor to esophageal adenocarcinoma.
Question 5: A newborn fails to pass meconium within 48 hours of birth. Rectal biopsy shows absence of ganglion cells in the submucosal and myenteric plexuses. What is the diagnosis?
- Meconium ileus
- Intussusception
- Hirschsprung disease (Correct answer)
- Imperforate anus
Correct answer: Hirschsprung disease
Hirschsprung disease is caused by failure of neural crest cell migration, resulting in an aganglionic segment of colon that cannot relax.
Question 6: A 35-year-old woman presents with chronic watery diarrhea, flushing, and wheezing. Urine 5-HIAA is elevated. CT abdomen shows liver metastases. What is the most likely primary tumor site?
- Pancreas
- Stomach
- Small intestine (Correct answer)
- Lung
Correct answer: Small intestine
Carcinoid tumors most commonly arise in the small intestine (ileum) and cause carcinoid syndrome only after metastasizing to the liver, bypassing first-pass metabolism of serotonin.
Question 7: Which finding on colonoscopy is most characteristic of Crohn's disease compared to ulcerative colitis?
- Continuous mucosal involvement from rectum
- Pseudopolyps
- Skip lesions with cobblestoning (Correct answer)
- Crypt abscesses on biopsy
Correct answer: Skip lesions with cobblestoning
Crohn's disease characteristically produces skip lesions with transmural inflammation, cobblestoning of the mucosa, and can affect any segment of the GI tract.
MD Gastrointestinal Tract Disorders 2
A 45-year-old man presents with episodic epigastric pain relieved by food and antacids.
Upper endoscopy reveals a duodenal ulcer.
Which organism is most likely responsible?