MCCQE - Medical Council of Canada Qualifying Examination Acute Surgical Presentations Questions and Answers 1 — Questions and Answers
Question 1: A 78-year-old female with a history of atrial fibrillation presents with the sudden onset of severe, diffuse abdominal pain. On examination, her abdomen is soft and non-tender with normal bowel sounds. Laboratory tests reveal a significant metabolic acidosis and a markedly elevated lactate level. Which of the following is the most likely diagnosis?
- Acute pancreatitis
- Ruptured abdominal aortic aneurysm
- Acute mesenteric ischemia (Correct answer)
- Perforated diverticulitis
Correct answer: Acute mesenteric ischemia
The classic presentation of acute mesenteric ischemia is 'pain out of proportion to physical exam findings'. The severe pain with a benign abdominal exam, combined with risk factors (atrial fibrillation, a source of emboli) and evidence of tissue hypoperfusion (metabolic acidosis, high lactate), is highly suggestive of this diagnosis. The other options would typically present with more pronounced physical findings like tenderness, guarding, or a pulsatile mass.
Question 2: A 55-year-old male with a history of NSAID use for arthritis presents to the emergency department with a sudden onset of severe, diffuse abdominal pain. On examination, he is tachycardic, hypotensive, and has a rigid, board-like abdomen with guarding and rebound tenderness. Which of the following is the most appropriate initial imaging modality to confirm the suspected diagnosis?
- Abdominal ultrasound
- CT scan with oral contrast
- HIDA scan
- Upright chest X-ray (Correct answer)
Correct answer: Upright chest X-ray
The clinical presentation is highly suggestive of peritonitis from a perforated viscus (e.g., peptic ulcer). An upright chest X-ray is the fastest and most appropriate initial imaging test to look for free air under the diaphragm (pneumoperitoneum), which would confirm the diagnosis. While a CT scan is more sensitive, the chest X-ray is a crucial and rapid first step, especially in a potentially unstable patient.
Question 3: Which of the following clinical features is most characteristic of a small bowel obstruction (SBO) rather than a large bowel obstruction (LBO)?
- Profuse, early-onset bilious vomiting (Correct answer)
- Marked abdominal distension appearing early in the course
- Obstipation as a primary presenting feature
- A plain abdominal radiograph showing significant colonic gas with haustra
Correct answer: Profuse, early-onset bilious vomiting
Early and frequent vomiting, often bilious, is a hallmark of a proximal SBO due to the rapid accumulation of fluid and gas proximal to the obstruction. In LBO, vomiting is typically a late feature, and prominent distension is more characteristic. Obstipation is common to both. Haustra are specific to the large bowel.
Question 4: A 24-year-old male presents with 12 hours of right flank pain and dysuria. He has a low-grade fever and mild tenderness in the right lower quadrant, but also significant right costovertebral angle (CVA) tenderness. A urinalysis shows 5-10 WBCs and 5-10 RBCs. What is the most likely diagnosis?
- Acute Pyelonephritis
- Retrocecal Appendicitis (Correct answer)
- Ureteral Colic
- Testicular Torsion
Correct answer: Retrocecal Appendicitis
A retrocecal appendix can irritate the adjacent psoas muscle, ureter, and bladder, leading to atypical symptoms that mimic a urinary tract or renal pathology, such as flank pain, CVA tenderness, and sterile pyuria. The presence of right lower quadrant tenderness should maintain a high index of suspicion for appendicitis despite the urinary symptoms.
Question 5: A 45-year-old female presents with a 12-hour history of constant right upper quadrant (RUQ) pain, fever, and nausea after a fatty meal. Examination reveals a temperature of 38.5°C, localized RUQ tenderness, and a positive Murphy's sign. Ultrasound confirms gallstones, a thickened gallbladder wall, and pericholecystic fluid. In addition to intravenous fluids and analgesia, what is the most appropriate next step in management?
- Arrange for an outpatient cholecystectomy in 6-8 weeks
- Schedule an urgent ERCP
- Administer broad-spectrum intravenous antibiotics (Correct answer)
- Discharge with oral antibiotics and follow-up
Correct answer: Administer broad-spectrum intravenous antibiotics
The patient has a clear diagnosis of acute cholecystitis. Initial management involves supportive care (NPO, IV fluids, analgesia) and the administration of broad-spectrum intravenous antibiotics to cover common biliary pathogens. This stabilizes the patient and treats the infectious component in preparation for an early cholecystectomy, which is the definitive treatment.
Question 6: Which of the following findings most strongly suggests that an incarcerated inguinal hernia has progressed to strangulation?
- The hernia can no longer be manually reduced.
- The patient develops fever, tachycardia, and erythema over the hernia. (Correct answer)
- The patient reports a recent increase in the size of the bulge.
- The patient experiences nausea and constipation.
Correct answer: The patient develops fever, tachycardia, and erythema over the hernia.
Incarceration means the hernia is non-reducible. Strangulation implies compromised blood flow to the herniated contents, leading to ischemia. Systemic signs of infection/inflammation (fever, tachycardia) and localized skin changes (erythema, extreme tenderness) are red flags for strangulation, which is a surgical emergency. Nausea and constipation can occur with simple incarceration due to obstruction, but the systemic signs point specifically to strangulation.
MCCQE - Medical Council of Canada Qualifying Examination Acute Surgical Presentations Questions and Answers 1
A 78-year-old female with a history of atrial fibrillation presents with the sudden onset of severe, diffuse abdominal pain.
On examination, her abdomen is soft and non-tender with normal bowel sounds.
Laboratory tests reveal a significant metabolic acidosis and a markedly elevated lactate level.
Which of the following is the most likely diagnosis?