10 USMLE Gastroenterology Questions with Answers and Explanations (Set 1)

These 10 USMLE gastroenterology practice questions cover GI cases that repeat on Step 1 and Step 2 CK: Meckel diverticulum, GERD and its complications, H. pylori testing, small bowel obstruction, hepatitis A, celiac disease, pediatric pancreatitis and Wilson disease. Each question includes the correct answer and an explanation.

Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.

Prefer video? Watch daily USMLE case questions on MedFocus by Dr. Ray on YouTube.

How to use this page: read the question, pick your answer, then tap Show Answer and Explanation.

Questions

Question 1. A 2-year-old girl is brought to the clinic by her mother because of rectal bleeding. Her mother noticed blood in her stool yesterday. There is mild pain, not related to meals. No nausea or vomiting. The girl is healthy and her routine physical examination 2 months ago was normal. You perform a biopsy and the histopathology of the affected part shows mixed gastric and intestinal tissues. Which of the following is the most likely diagnosis?

A- Intussusception
B- Meckel’s diverticulum
C- Volvulus
D- Appendicitis
E- Diverticulitis

This is most likely a Meckel’s diverticulum characterized by mixed tissues. In 90% of cases, Meckel’s diverticulum is made of intestinal tissue only and in this case, there is usually no symptoms. Symptoms and signs start if there is extra tissue present in the diverticulum. Clinical picture varies from mild such as pain, nausea to severe as intestinal obstruction, bleeding and inflammation of the intestines.
The correct answer is B

 

Question 2. A 27-year-old man presents with a 3-month history of heartburn and epigastric discomfort. His symptoms are exaggerated after meals, especially if he eats spicy food. He takes no medications, doesn’t smoke or drink alcohol. He exercises regularly and has an active lifestyle. On physical examination, he has slight epigastric tenderness. His routine lab tests are normal What is the most appropriate intervention at this time?

A- Barium swallow
B- Esophageal manometry
C- 24-hour pH monitoring
D- Upper endoscopy
E- Trial of a proton-pump inhibitor

The most appropriate intervention is a trial of a proton pump inhibitor. If improvement occurs then, no need to other costly and time consuming investigations.
The correct answer is E

 

Question 3. A 50-year-old man presents to the clinic with a long history of heartburn after eating, exaggerated when he is lying down and lessened when he takes antacids. Endoscopy reveals a large irregular, erythematous area in the lower esophagus. Esophageal motility studies reveal dysfunction of the lower esophageal sphincter (LES). Which of the following most likely leads to an increase in the resting pressure of LES?

A- Alcohol
B- Caffeine
C- Chocolate
D- Fat
E- Protein

All of the choices except protein lead to relaxation of the lower esophageal sphincter. Dietary protein, histamine and antacids cause increased resting pressure of the lower esophageal sphincter and eventually improve the symptoms of GERD. On the other hand, dietary fat, alcohol, chocolate, caffeine and smoking lead to relaxation of the LES causing exaggeration of these symptoms.
The correct answer is E

 

Question 4. A 36-year-old man visits his physician complaining of chronic gastric pain for several years. Physical examination is unremarkable. Serology studies are positive for Helicobacter Pylori. Endoscopy reveals gastritis with no ulcers or tumors. Treatment starts with omeprazole, clarithromycin and metronidazole. What is the most appropriate noninvasive test to check for H. pylori eradication?

A- Rapid urease test
B- Stool analysis and culture
C- Examination and culture of gastric contents
D- Urea breath test
E- Serum test for IgG antibodies against H. Pylori

Urea breath test is the most appropriate noninvasive test to check for H. Pylori eradication. It is recommended after one month of treatment.
The correct answer is D

 

Question 5. A 43 year-old man presents to his physician with a complaint of progressive difficulty in swallowing solid food. He has a 10-year history of heartburn which increases with spicy food and relieves by antacids. He does not smoke or drink alcohol. His weight is the same since last visit six months ago. He is scheduled for endoscopy next week. What is the most likely initial diagnosis for this patient?

A- Cancer esophagus
B- Peptic esophageal stricture
C- Diffuse esophageal spasm
D- Achalasia
E- Lower esophageal ring

This patient has progressive dysphagia to solids. He also has a history of heartburn for 10 years. Heartburn that increases with spicy food and relieves by antacids is suggestive of GERD. The first complication of GERD is peptic esophageal stricture which is caused by acid reflux from the stomach into the lower part of esophagus. Cancer esophagus is excluded as the patient didn’t lose any weight and he doesn’t have the precipitating factors such as smoking and alcohol intake. Achalasia is characterized by dysphagia to both liquids and solids.
The correct answer is B

 

Question 6. A 70-year-old woman, having had an appendectomy 25 years ago, is brought to the emergency room with severe abdominal pain. The patient describes the pain as being crampy and colicky. She also says that the pain seems to increase and then improve on its own. She has already vomited 10 times since the pain started in the morning. She has also not had a bowel movement since last 2 days or passed flatus in last couple of days. Physical examination shows that the abdomen is distended slightly. Auscultation of the abdomen shows peristaltic rushes and high-pitched bowel sounds. Tympanic abdomen is revealed during percussion. The patient is also diffusely tender on palpation but there is no rebound tenderness. Rectal examination also shows an absence of stool. What would be the likely diagnosis?

A- Intestinal obstruction
B- Gastroenteritis
C- Diverticulitis
D- Pancreatitis

The patient is suffering from intestinal obstruction, which is a condition in which a blockage occurs that prevents food and beverages from passing through either the small intestine or the large intestine. One of the common causes of intestinal obstruction is the formation of fibrous bands of tissues or adhesions in the abdomen after a surgery. As the patient earlier had an appendectomy this could be the most likely cause of intestinal obstruction.
The correct answer is A

 

Question 7. A 20-year old female student presents with a 1-week history of nausea, vomiting and anorexia. She returned 2-weeks ago from a trip to Guatemala. On physical examination, her temperature was 100.3 F, clear chest and she has mild jaundice and a palpable tender liver. Her CBC was normal and her liver function tests are as follows: Serum total bilirubin 3.1 mg/dL. Serum aspartate aminotransferase 1100. Serum alanine aminotransferase 1900. Serum alkaline phosphatase 112. What is the most likely lab test to confirm your diagnosis?

A- IgM antibody to hepatitis A virus
B- Antibody to hepatitis B surface antigen
C- Antibody to hepatitis C virus
D- DNA for Epstein-Barr virus
E- Serum anti-mitochondrial antibodies

This patient has typical presentation of hepatitis A virus infection. Her recent travel, short incubation period and mode of infection in addition to lab results confirm this diagnosis. The only option that is almost always positive in hepatitis A virus recent infection is IgM antibody to hepatitis A virus.
The correct answer is A

 

Question 8. A 30-year-old man presents to the clinic complaining of recurrent bouts of diarrhea accompanied by bloating over the past few years. He also reports having itchy vesicles around the extensor surfaces of his upper and lower extremities. The rest of the clinical examination is normal. What is the skin condition most likely present in this patient?

A- Dermatitis herpetiformis
B- Psoriasis
C- Rosacea
D- Seborrheic keratosis
E- Shingles (herpes zoster)

Recurrent diarrhea and bloating suggest celiac disease. Intensely pruritic (itchy) vesicles on extensor surfaces (elbows, knees, buttocks) are characteristic of dermatitis herpetiformis, the primary skin manifestation of celiac disease. It is caused by IgA deposition in the dermal papillae.
Psoriasis presents with well-demarcated plaques with silvery scale, not vesicles. Rosacea affects the face with flushing and papules. Seborrheic keratosis is a benign “stuck-on” lesions in older adults. Shingles is characterized by painful, dermatomal vesicles, usually unilateral.
The correct answer is A
Key takeaway:👉 Celiac disease + pruritic vesicles on extensor surfaces = dermatitis herpetiformis.

 

Question 9. A 2-year-old boy is brought to the emergency room by his mother. She tells you that her boy has been crying since she picked him up yesterday from the daycare. She thinks that he has abdominal pain. He vomited twice, and he didn’t want to eat breakfast. There is no history of fever, rashes, or any prior illnesses. On examination, there is diffuse abdominal tenderness. Laboratory tests are significant for amylase of 1500 and lipase of 2500. What is the most likely etiology of this boy’s condition?

A- Trauma
B- Viral infection
C- Cystic fibrosis
D- Gallstones
E- Congenital annular pancreas

Abdominal trauma is the most common cause of acute pancreatitis in children. Daycare is a common place for blunt trauma to kids while playing and fighting with each other. Toddlers often cannot verbalize pain, so they present with crying, vomiting, and refusal to eat.
Viral infection can cause pancreatitis, but is more common in older children and usually follows a viral illness. Cystic fibrosis causes chronic pancreatic insufficiency, not acute pancreatitis with very high enzymes. Gallstones are common cause in adults, rare in a 2-year-old. Annular pancreas typically presents with duodenal obstruction and vomiting in infancy, not acute pancreatitis.
The correct answer is A
Key takeaway:👉 In toddlers with acute pancreatitis, trauma is the most common etiology and should always be considered.

 

Question 10. A 19-year-old man presents to the clinic with a complaint of tremors and incoordination. Serum transaminases are slightly elevated. Slit lamp examination shows brownish corneal deposits. What is the element directly involved in this condition?

A- Arsenic
B- Lead
C- Copper
D- Iron
E- Zinc

This is a presentation of Wilson’s disease in which cellular copper transport is disturbed resulting in copper deposition on tissues. Deposition of copper on the cornea leads to Kayser-Fleischer ring which is found in this patient.
The correct answer is C

 

High-yield points from this set

  • Painless rectal bleeding in a toddler with ectopic gastric tissue = Meckel diverticulum.
  • Typical GERD without alarm symptoms: start with an empirical PPI trial.
  • Dietary protein raises LES pressure; fat, chocolate, caffeine, alcohol and smoking lower it.
  • Urea breath test (or stool antigen) confirms H. pylori eradication at least 4 weeks after therapy.
  • Long-standing GERD with progressive dysphagia to solids and no weight loss = peptic stricture.
  • Colicky pain, vomiting, distension and high-pitched bowel sounds after old abdominal surgery = small bowel obstruction from adhesions.
  • Acute hepatitis after travel with very high ALT: confirm hepatitis A with IgM anti-HAV.
  • Itchy vesicles on extensor surfaces = dermatitis herpetiformis, linked to celiac disease.
  • Blunt abdominal trauma is a leading cause of acute pancreatitis in young children.
  • Tremor, liver disease and Kayser-Fleischer rings = Wilson disease (copper).

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