MCQs on Acute Abdomen

Written by Dr. Andrew McAllister
(MBBS, FRACS) – Surgeon

Question 1

A 22-year-old man presents to the Emergency Department with a 12-hour history of abdominal pain. He initially experienced vague discomfort around the umbilicus, which later migrated to the right lower quadrant. He also reports nausea and a reduced appetite. On examination, he has localized tenderness and guarding at McBurney’s point. Rovsing’s sign is positive. His temperature is 37.9°C, and his white blood cell count is elevated.

Which of the following is the most likely diagnosis?

A) Acute diverticulitis
B) Acute appendicitis
C) Ureteric colic
D) Crohn’s disease
E) Mesenteric adenitis

Correct Answer: B) Acute appendicitis

Explanation:

Acute appendicitis typically presents with periumbilical pain that migrates to the right lower quadrant (RLQ) as the inflammation progresses and irritates the parietal peritoneum. Associated features include anorexia, nausea, low-grade fever, and tenderness at McBurney’s point. A positive Rovsing’s sign (pain in RLQ when LLQ is palpated) also supports the diagnosis.

Diverticulitis usually causes left lower quadrant pain and occurs more commonly in older adults. Ureteric colic causes sudden flank pain radiating to the groin and is often associated with hematuria. Crohn’s disease can cause RLQ pain but is typically chronic with systemic symptoms like weight loss and diarrhea. Mesenteric adenitis may mimic appendicitis but is more common in children and follows a viral illness.

The classic sequence of migratory pain, anorexia, and localized RLQ tenderness strongly supports acute appendicitis.

Question 2

James, a 55-year-old man, presents to the Emergency Department with sudden onset severe upper abdominal pain that started 3 hours ago. He describes the pain as sharp and constant. He has a history of long-term NSAID use for chronic back pain. On examination, he appears anxious, is tachycardic, and lies still in bed. His abdomen is rigid with generalized tenderness and rebound tenderness. An erect chest X-ray is performed and shows free air under the diaphragm.

What is the most likely diagnosis?

A) Acute pancreatitis
B) Acute cholecystitis
C) Perforated peptic ulcer
D) Bowel obstruction
E) Gastritis

Correct Answer: C) Perforated peptic ulcer

Explanation:

A perforated peptic ulcer presents with sudden, severe abdominal pain, typically in the epigastrium, and rapidly progresses to generalized peritonitis. The rigid abdomen, rebound tenderness, and guarding are classic signs of peritoneal irritation. Long-term NSAID use is a known risk factor due to inhibition of prostaglandin synthesis, which weakens the gastric mucosal barrier.

The presence of free air under the diaphragm on an erect chest X-ray is a hallmark of hollow viscus perforation, most often from a gastric or duodenal ulcer.

Acute pancreatitis usually presents with pain radiating to the back and elevated serum amylase or lipase. Cholecystitis causes right upper quadrant pain and Murphy’s sign. Bowel obstruction presents with colicky pain and vomiting. Gastritis causes epigastric discomfort but not peritonitis or pneumoperitoneum.

Question 3

Sarah, a 22-year-old university student, presents with abdominal pain that started around the umbilicus 18 hours ago and has since shifted to the right lower quadrant. She reports nausea and anorexia. On examination, her temperature is 37.9°C, and there is localized tenderness with guarding in the right iliac fossa. Rovsing’s sign is positive. A pregnancy test is negative.

What is the most likely diagnosis?

A) Acute appendicitis
B) Pelvic inflammatory disease
C) Ectopic pregnancy
D) Crohn’s disease
E) Ovarian torsion

Correct Answer: A) Acute appendicitis

Explanation:

Acute appendicitis typically begins with periumbilical pain due to visceral peritoneal irritation and then localizes to the right lower quadrant as the parietal peritoneum becomes inflamed. Associated features include nausea, anorexia, low-grade fever, and localized tenderness in the right iliac fossa. A positive Rovsing’s sign (pain in the right lower quadrant on palpation of the left side) supports the diagnosis.

A negative pregnancy test helps rule out ectopic pregnancy, an important differential in women of reproductive age. Pelvic inflammatory disease and ovarian torsion can present similarly but often have additional gynecological symptoms like vaginal discharge or adnexal mass/tenderness. Crohn’s disease may cause chronic right lower quadrant pain but is less likely to present acutely with localized tenderness and signs of peritonitis.

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8. General Surgery Module

8.1 Acute Abdomen

8.2 Upper GI Tract

8.3 Hepatobiliary System

8.4 Lower GI Tract

8.5 Lumps

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