Surgery MCQs Q38

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SURGERY • VASCULAR EMERGENCIES

A 60-year-old man with a history of ischemic heart disease (IHD) and generalized atherosclerosis presents with sudden abdominal pain and passage of maroon-colored stools.

What is the most likely diagnosis?

A Acute mesenteric ischemia

B Acute intestinal obstruction

C Peritonitis

D Appendicitis

E Intussusception

The correct answer is Acute mesenteric ischemia.

Decoding the Stem

1

CLUE "Elderly + atherosclerosis + sudden pain + maroon stools"

TRANSLATION Acute vascular occlusion leading to bowel ischemia and eventual necrosis.

Detailed Explanation

✅ Correct Option (Acute Mesenteric Ischemia): This condition is a surgical emergency characterized by a sudden reduction in blood flow to the small intestine. It most frequently involves the Superior Mesenteric Artery (SMA).

Why it fits this case:

→ High-Risk Profile: Generalized atherosclerosis and IHD are primary risk factors for mesenteric arterial thrombosis (clot forming over a plaque).

→ Sudden Abdominal Pain: The pain is typically severe, mid-abdominal, and "out of proportion" to physical exam findings (i.e., the belly is soft but the patient is in agony).

→ Maroon Stools: Also known as "currant jelly" stools in this context, they indicate mucosal sloughing and hemorrhage due to full-thickness bowel wall infarction (necrosis).

→ Physiology: Without blood, the bowel loses its integrity within hours, leading to sepsis, peritonitis, and multi-organ failure if not revascularized immediately.

❌ Why other options are incorrect:

→ Acute intestinal obstruction: Presents with "tinkling" bowel sounds, absolute constipation, and vomiting; maroon stools are highly unusual unless complicated by strangulation.

→ Peritonitis: This is a physical exam finding (rigidity, guarding) rather than a primary diagnosis; it occurs as a late consequence of ischemia once the bowel perforates.

→ Appendicitis: Typically has a migratory pain pattern (umbilicus to RLQ) and is less likely to cause sudden maroon stools in an elderly vascular patient.

→ Intussusception: While it causes bloody stools, it is primarily a pediatric diagnosis. In adults, it usually requires a "lead point" like a tumor and is less common than vascular causes in this age group.

🧠 High-Yield Pearls

✔ Key Risk: Atrial fibrillation (embolism) or Atherosclerosis (thrombosis).

✔ Gold Standard: CT Angiography is the diagnostic test of choice.

✔ Metabolic Marker: Elevated Serum Lactate often indicates advanced ischemia/necrosis.

Integrated Clinical Questions

1. Most common cause in elderly?

→ Thrombosis over an atherosclerotic vessel.

2. Most common artery involved?

→ Superior mesenteric artery (SMA).

3. Key diagnostic test of choice?

→ CT angiography of the abdomen.

4. Why is the pain severe early in the course?

→ Ischemia causes intense visceral pain before peritoneal signs develop.

5. Definitive management strategy?

→ Rapid revascularization and resection of necrotic bowel segments.

⚡ Exam Pearls

• • “Pain out of proportion” is the hallmark of early mesenteric ischemia.
• • Always suspect in an elderly patient with vascular disease or arrhythmia.
• • Time-critical diagnosis: delays significantly increase mortality.

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