GI Diagnostics & Treatment 2 — Questions and Answers
Question 1: Which test is considered the gold standard for diagnosing Helicobacter pylori infection in a patient who recently stopped taking proton pump inhibitors?
- Rapid urease test
- Urea breath test
- H. pylori serology
- Stool antigen test (Correct answer)
Correct answer: Stool antigen test
Stool antigen test is preferred when PPI use within 2 weeks may confound the urea breath test, though both are accurate non-invasive options.
Question 2: A patient with suspected celiac disease has negative serology but continues to have symptoms. What is the next best diagnostic step?
- Start a gluten-free diet empirically
- Small bowel capsule endoscopy
- Upper endoscopy with duodenal biopsies (Correct answer)
- HLA-DQ2/DQ8 genetic testing
Correct answer: Upper endoscopy with duodenal biopsies
Upper endoscopy with multiple duodenal biopsies remains the gold standard for celiac diagnosis, even when serology is negative, particularly in IgA-deficient patients.
Question 3: Which of the following is the first-line treatment for acute severe ulcerative colitis in a hospitalized patient?
- Oral mesalamine
- IV cyclosporine
- IV corticosteroids (Correct answer)
- Infliximab infusion
Correct answer: IV corticosteroids
IV corticosteroids (methylprednisolone or hydrocortisone) are the initial treatment of choice for acute severe ulcerative colitis.
Question 4: A 55-year-old male presents with dysphagia to solids progressing to liquids over 6 months and unintentional weight loss. What is the most appropriate next step?
- Barium swallow study
- Upper endoscopy with biopsy (Correct answer)
- CT chest/abdomen
- Esophageal manometry
Correct answer: Upper endoscopy with biopsy
Progressive dysphagia with weight loss is an alarm symptom requiring urgent upper endoscopy with biopsy to rule out esophageal malignancy.
Question 5: What is the mechanism of action of lactulose when used to treat hepatic encephalopathy?
- Inhibits ammonia production in the colon
- Acidifies colonic contents, trapping NH4+ and accelerating transit (Correct answer)
- Directly crosses the blood-brain barrier to reverse encephalopathy
- Stimulates hepatic urea cycle enzymes
Correct answer: Acidifies colonic contents, trapping NH4+ and accelerating transit
Lactulose is metabolized by colonic bacteria to organic acids, lowering pH and trapping ammonia as ammonium (NH4+), which is then expelled with accelerated bowel transit.
Question 6: Which imaging modality is most appropriate for initial evaluation of a patient presenting with right lower quadrant pain and clinical suspicion for appendicitis who is pregnant?
- CT abdomen/pelvis with contrast
- MRI abdomen without contrast
- Ultrasound of the abdomen (Correct answer)
- Plain abdominal X-ray
Correct answer: Ultrasound of the abdomen
Ultrasound is the preferred initial imaging in pregnant patients due to absence of ionizing radiation, though MRI is used if ultrasound is inconclusive.
Question 7: A patient with Crohn's disease develops an enterocutaneous fistula. Which biologic agent is FDA-approved specifically for fistulizing Crohn's disease?
- Vedolizumab
- Ustekinumab
- Natalizumab
- Infliximab (Correct answer)
Correct answer: Infliximab
Infliximab was the first biologic agent approved for fistulizing Crohn's disease and has robust evidence for fistula closure and maintenance.
GI Diagnostics & Treatment 2
Which test is considered the gold standard for diagnosing Helicobacter pylori infection in a patient who recently stopped taking proton pump inhibitors?