A 49-year-old man arrives at the emergency department due to a 24-hour history of unremitt… — USMLE Step 2 CK

A $49$ -year-old man arrives at the emergency department due to a $24$ -hour history of unremitting, severe abdominal pain. He reports multiple episodes of dark green vomiting and an inability to pass flatus since the onset of his symptoms. His surgical history is notable for a ruptured appendix requiring an open midline laparotomy at age $20$ . His temperature is $38.5^\circ\text{C}$ ( $101.3^\circ\text{F}$ ), blood pressure is $96/55\text{ mm Hg}$ , pulse is $124/\text{min}$ , and respirations are $22/\text{min}$ . Physical examination reveals a visibly distended abdomen that is diffusely tender. There is pronounced involuntary guarding and board-like rigidity. Laboratory studies show a leukocyte count of $18,500/\text{mm}^3$ with $15\%$ bandemia and a serum lactate of $4.2\text{ mmol/L}$ . An upright abdominal radiograph demonstrates multiple dilated loops of small bowel with air-fluid levels, and no free air under the diaphragm. Which of the following is the most appropriate next step in the management of this patient?

Urgent exploratory laparotomyAnswer
B
Conservative management with nasogastric decompression
C
Contrast-enhanced cross-sectional imaging
D
Diagnostic laparoscopy
E
Intravenous antimicrobial therapy and serial abdominal examinations

Answer

Urgent exploratory laparotomy is the most appropriate next step for a complicated small bowel obstruction with peritonitis.

The correct answer is urgent exploratory laparotomy. This patient presents with classic signs of a complicated small bowel obstruction (SBO), likely secondary to adhesions from his previous laparotomy. While uncomplicated SBO can often be managed conservatively with bowel rest, intravenous fluids, and nasogastric decompression, this patient's clinical picture has evolved into a surgical emergency. The presence of fever, tachycardia, hypotension, significant leukocytosis with a left shift, elevated serum lactate, and unequivocal peritonitis (involuntary guarding and board-like rigidity) strongly suggests bowel ischemia, necrosis, or impending perforation (strangulation). In the setting of a complicated SBO with hemodynamic compromise and an acute surgical abdomen, immediate operative intervention via exploratory laparotomy is required for source control, resection of non-viable bowel, and relief of the obstruction.

Step-by-Step Solution

Identify the primary clinical syndrome from the patient's history and imaging.

The patient has a small bowel obstruction (SBO), evidenced by colicky pain, bilious emesis, obstipation, prior abdominal surgery, and multiple air-fluid levels on abdominal radiograph.

Establishing the baseline diagnosis is necessary before assessing for life-threatening complications.

Evaluate the physical examination and laboratory findings for signs of complicated SBO.

The presence of fever (

38.5^\circ\text{C}

), tachycardia (

124/\text{min}

), leukocytosis (

18,500/\text{mm}^3

), lactic acidosis (

4.2 \text{ mmol/L}

), and board-like rigidity indicates peritonitis and bowel ischemia.

Differentiating between uncomplicated and complicated (strangulated/ischemic) SBO dictates whether management is medical or surgical.

Determine the most appropriate definitive management based on the patient's clinical stability and findings.

Immediate surgical intervention is required to resect necrotic tissue and relieve the obstruction.

Delaying for advanced imaging or attempting conservative management in a patient with an acute surgical abdomen and hemodynamic compromise leads to significantly increased mortality.

Key Concept

Patients with a small bowel obstruction who develop signs of strangulation, ischemia, or peritonitis (e.g., fever, tachycardia, metabolic acidosis, continuous pain, guarding, rigidity) require immediate exploratory laparotomy.

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