A 42-year-old man is evaluated in the surgical step-down unit due to a sudden deterioratio… — USMLE Step 2 CK

A $42$ -year-old man is evaluated in the surgical step-down unit due to a sudden deterioration in his clinical status. He was admitted $48$ hours ago for management of an adhesive small bowel obstruction. Initial treatment with intravenous fluids, bowel rest, and nasogastric tube decompression led to mild improvement during the first day. However, over the past $3$ hours, his previously intermittent, crampy periumbilical pain has transitioned to severe, constant, and diffuse abdominal pain. Temperature is $39.2^\circ\text{C}$ ( $102.6^\circ\text{F}$ ), pulse is $128/\text{min}$ , respirations are $24/\text{min}$ , and blood pressure is $86/50\text{ mm Hg}$ . Physical examination reveals a rigid, distended abdomen with marked rebound tenderness and involuntary guarding in all quadrants. Bowel sounds are absent. Laboratory evaluation demonstrates a leukocyte count of $18,500/\text{mm}^3$ with $15\%$ band forms, and a serum lactate of $4.8\text{ mmol/L}$ . Which of the following is the most appropriate next step in management?

Exploratory laparotomyAnswer
B
Continuation of nasogastric decompression and intravenous fluids
C
Computed tomography of the abdomen and pelvis with contrast
D
Upper gastrointestinal series with water-soluble contrast
E
Initiation of broad-spectrum antibiotics and close observation

Answer

Exploratory laparotomy

The correct answer is exploratory laparotomy. This patient initially presented with an uncomplicated small bowel obstruction (SBO), which is typically managed with bowel rest, intravenous fluids, and nasogastric decompression. However, his clinical picture has drastically changed, indicating progression to a strangulated SBO (ischemia and necrosis of the bowel wall). Classic signs of strangulation include a transition from colicky to severe, constant abdominal pain, fever, tachycardia, and signs of peritonitis (rigidity, rebound tenderness, guarding). The markedly elevated leukocyte count and lactic acidosis further confirm bowel ischemia. In any patient with an acute surgical abdomen, hemodynamic instability, and suspected necrotic bowel, emergent exploratory laparotomy is required to perform a bowel resection and achieve source control.

Step-by-Step Solution

Identify the patient's initial diagnosis and current clinical trajectory.

The patient was initially diagnosed with a partial small bowel obstruction but has now acutely deteriorated, developing severe, constant pain.

Tracking symptom progression distinguishes an resolving uncomplicated obstruction from life-threatening complications like bowel ischemia.

Analyze vital signs and physical examination findings.

The patient exhibits high fever, tachycardia, hypotension, and a rigid abdomen with severe rebound tenderness.

These findings indicate the development of peritonitis and septic shock.

Interpret laboratory results in the context of the clinical picture.

Leukocytosis with a left shift and an elevated serum lactate of

4.8\text{ mmol/L}

confirm the presence of bowel ischemia and necrosis.

Lactic acidosis and marked leukocytosis are classic markers for bowel strangulation in the setting of an obstruction.

Determine the most appropriate management based on the overall assessment.

Immediate surgical intervention via exploratory laparotomy is required.

Patients with a strangulated small bowel obstruction and peritonitis require emergent resection of the necrotic bowel segment to achieve source control.

Key Concept

Patients with a small bowel obstruction who develop clinical signs of strangulation (fever, tachycardia, severe constant pain, peritonitis, lactic acidosis) require emergent exploratory laparotomy.

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