A 53-year-old woman is brought to the acute care clinic by her spouse due to severe abdomi… — USMLE Step 2 CK

A 53-year-old woman is brought to the acute care clinic by her spouse due to severe abdominal discomfort. She underwent an uncomplicated laparoscopic cholecystectomy 6 weeks ago. Over the past 48 hours, she developed abdominal swelling, obstipation, and bilious emesis. During the last 2 hours, her pain transitioned from an intermittent crampy sensation to a constant, excruciating ache.

Vital signs reveal a temperature of $39.1^\circ\text{C}$ ( $102.4^\circ\text{F}$ ), heart rate of $132\text{ /min}$ , respiratory rate of $26\text{ /min}$ , and blood pressure of $82/50\text{ mmHg}$ .

Physical examination demonstrates a markedly distended, rigid abdomen with diffuse rebound tenderness and involuntary guarding. Bowel sounds are absent.

Laboratory analysis reveals:

Test	Value
Leukocyte count	$21,500/\text{mm}^3$
Lactic acid	$5.8\text{ mmol/L}$
Arterial pH	$7.26$
Arterial $\text{pCO}_2$	$28\text{ mmHg}$
Arterial $\text{HCO}_3^-$	$12\text{ mEq/L}$

Which of the following is the most appropriate next step in management?

Immediate exploratory laparotomyAnswer
B
Nasogastric tube decompression, intravenous fluids, and serial clinical evaluations
C
Computed tomography of the abdomen and pelvis with intravenous contrast
D
Calculation of expected carbon dioxide level to evaluate for a mixed acid-base disorder
E
Urinalysis and urine culture to investigate a potential infectious source for the fever

Answer

The correct management is immediate exploratory laparotomy.

The patient's clinical presentation is highly concerning for a small bowel obstruction (SBO) that has progressed to strangulation and ischemia. Classic indicators of strangulated SBO include a shift from colicky, intermittent pain to severe, constant pain, accompanied by systemic toxicity (fever, tachycardia, hypotension), peritonitis (rigidity, rebound tenderness), and profound lactic acidosis. In the setting of a surgical acute abdomen with hemodynamic instability, the definitive and sole appropriate next step is immediate exploratory laparotomy for source control and resection of the necrotic bowel.

Step-by-Step Solution

Analyze the clinical history and physical examination findings.

The patient has a history of recent abdominal surgery followed by progressive obstipation and emesis, suggesting a small bowel obstruction. The transition to constant pain, alongside a rigid abdomen and rebound tenderness, indicates peritonitis.

Identifying the transition from a simple obstruction to an acute surgical abdomen is critical for management.

Evaluate the vital signs and laboratory data to assess physiological stability.

The patient is in septic shock (hypotension, tachycardia, fever) and exhibits severe lactic acidosis, pointing toward bowel ischemia and impending or actual perforation.

Hemodynamic instability dictates whether a patient can safely undergo further diagnostic testing or requires emergent intervention.

Select the appropriate intervention based on the diagnosis and stability.

Because the patient has a strangulated small bowel obstruction with hemodynamic collapse, emergent surgical exploration is required to perform source control and resect ischemic bowel.

Delaying surgery for imaging or persisting with conservative measures in this setting rapidly leads to mortality.

Key Concept

Surgical management of strangulated small bowel obstruction

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