A 76-year-old man presents to the emergency department with sudden-onset severe abdominal pain that began 4 hours ago. His medical history is significant for atrial fibrillation, hypertension, and hyperlipidemia. Medications include metoprolol and atorvastatin. He stopped taking anticoagulation several months ago because of recurrent nosebleeds. Temperature is 37.2°C (99.0°F), blood pressure is 138/82 mm Hg, pulse is 118/min and irregularly irregular, and respiratory rate is 22/min. The patient appears uncomfortable and repeatedly shifts position on the stretcher. Abdominal examination reveals minimal diffuse tenderness without guarding or rebound. Laboratory studies show a leukocyte count of 17,000/mm³ and serum lactate level of 5.1 mmol/L.
Which of the following is the most likely diagnosis?
The correct answer is:
A: Acute mesenteric ischemia.
This patient has the classic presentation of acute mesenteric ischemia: severe abdominal pain that is out of proportion to physical examination findings. His history of untreated atrial fibrillation significantly increases the risk of arterial embolization to the mesenteric circulation. Elevated lactate and leukocytosis further support bowel ischemia and tissue hypoperfusion. Prompt diagnosis and treatment are essential because delayed intervention can lead to bowel necrosis and death.
Answer choice B: Acute pancreatitis, is incorrect.
Acute pancreatitis can cause severe abdominal pain and leukocytosis. However, pancreatitis typically presents with epigastric pain radiating to the back and significant abdominal tenderness. The history of atrial fibrillation and pain out of proportion to examination findings strongly favors mesenteric ischemia.
Answer choice C: Cholecystitis, is incorrect.
Cholecystitis generally presents with right upper quadrant pain, fever, and a positive Murphy sign. This patient’s vascular risk factors and elevated lactate make ischemia much more likely.
Answer choice D: Diverticulitis, is incorrect.
Diverticulitis usually causes localized left lower quadrant pain and tenderness. Patients generally have examination findings that correspond to the severity of symptoms, unlike the disproportionate pain seen in mesenteric ischemia.
Answer choice E: Small bowel obstruction, is incorrect.
Small bowel obstruction often presents with abdominal distention, vomiting, and high-pitched bowel sounds. Although abdominal pain occurs, the patient’s embolic risk factor and elevated lactate point toward mesenteric ischemia.
Key Learning Point
Acute mesenteric ischemia should be suspected in patients with severe abdominal pain out of proportion to examination findings, particularly in the setting of atrial fibrillation or other embolic risk factors.
