Paramedics bring a distressed gentleman in his late sixties to the emergency department. H… — USMLE Step 2 CK

Paramedics bring a distressed gentleman in his late sixties to the emergency department. He reports severe, unremitting abdominal pain that began $48$ hours ago as intermittent cramps but has now become constant and sharply localized. His last bowel movement was three days ago, and he has vomited dark, foul-smelling fluid multiple times since yesterday. His surgical history is notable for a ruptured appendix requiring an open appendectomy in his twenties.

On evaluation, his temperature is $38.8^\circ\text{C}$ ( $101.8^\circ\text{F}$ ), heart rate is $122/\text{min}$ , blood pressure is $88/54\text{ mmHg}$ , and respiratory rate is $22/\text{min}$ . The abdomen is tense, visibly distended, and exquisitely tender to light palpation across all quadrants, with involuntary guarding. Auscultation reveals a silent abdomen. Laboratory analysis demonstrates a leukocyte count of $19,500/\text{mm}^3$ and a serum lactate of $4.5\text{ mmol/L}$ . Upright abdominal radiography displays multiple dilated loops of small bowel with air-fluid levels and a complete absence of gas in the rectum.

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

A
Nasogastric tube placement and serial abdominal examinations
B
Transfer to radiology for an abdominal computed tomography scan
C
Initiation of intravenous broad-spectrum antibiotics and close observation
Urgent surgical explorationAnswer
E
Administration of intravenous sodium bicarbonate

Answer

Urgent surgical exploration

The clinical presentation is highly indicative of a strangulated small bowel obstruction (SBO). The patient has a history of abdominal surgery (open appendectomy), which strongly predisposes him to adhesive disease. While uncomplicated SBO can initially be managed conservatively with nasogastric decompression and intravenous fluids, the presence of fever, tachycardia, hypotension, severe localized pain, peritoneal signs (guarding), marked leukocytosis, and lactic acidosis signifies intestinal ischemia or infarction. When these warning signs of strangulation are present, conservative management and additional imaging must be abandoned in favor of immediate operative intervention to resect necrotic bowel and prevent further clinical deterioration.

Step-by-Step Solution

Identify the primary clinical syndrome from the presentation and imaging.

The patient's history of prior abdominal surgery, obstipation, bilious/feculent vomiting, and radiographic evidence of dilated small bowel loops with absent rectal gas confirm a mechanical small bowel obstruction (SBO).

Establishing the baseline diagnosis is necessary before evaluating for complications.

Assess the patient for signs of complicated disease, such as ischemia or strangulation.

The patient exhibits fever (

38.8^\circ\text{C}

), tachycardia (

122/\text{min}

), hypotension (

88/54\text{ mmHg}

), peritonitis (involuntary guarding), marked leukocytosis (

19,500/\text{mm}^3

), and lactic acidosis (

4.5\text{ mmol/L}

Differentiating between simple and complicated (strangulated) SBO dictates the entire management pathway.

Select the most appropriate management pathway based on the presence of complications.

Because clear signs of bowel ischemia and hemodynamic instability are present, the patient must bypass conservative measures and proceed directly to the operating room.

Strangulated SBO involves compromised blood flow leading to necrosis and perforation; it requires emergent surgical exploration to resect non-viable bowel and prevent death.

Key Concept

Management of complicated (strangulated) small bowel obstruction

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