An otherwise healthy 55-year-old man arrives at the emergency department complaining of ex… — USMLE Step 2 CK

An otherwise healthy 55-year-old man arrives at the emergency department complaining of excruciating, generalized abdominal pain that began $24$ hours ago. The pain is accompanied by intractable nausea and multiple episodes of bilious vomiting. He reports no passage of stool or flatus since the symptoms started. His past surgical history is notable for an uncomplicated open appendectomy over a decade ago. Vital signs show a temperature of $38.6^\circ\text{C}$ ( $101.5^\circ\text{F}$ ), a blood pressure of $98/60$ mm Hg, and a heart rate of $118$ /min. Physical examination reveals a markedly distended and tympanic abdomen. There is diffuse, severe tenderness to palpation, accompanied by involuntary guarding and marked rebound tenderness. Bowel sounds are absent. Initial laboratory testing is significant for a leukocyte count of $18,500/\text{mm}^3$ and a serum lactate concentration of $4.8$ mmol/L. Upright abdominal radiography demonstrates multiple dilated loops of small intestine with prominent air-fluid levels and an absence of distal colonic gas. Which of the following is the most appropriate next step in the management of this patient?

Immediate exploratory laparotomyAnswer
B
Nasogastric tube decompression and continued observation
C
Administration of intravenous broad-spectrum antibiotics and close clinical monitoring
D
Computed tomography of the abdomen and pelvis with oral contrast
E
Administration of intravenous metoclopramide

Answer

Immediate exploratory laparotomy

This patient presents with a mechanical small bowel obstruction (SBO) that is complicated by clear signs of bowel strangulation and ischemia. While his history of a prior appendectomy makes adhesive disease the most likely etiology, the critical aspect of this case is recognizing the severity of his condition. An uncomplicated SBO can often be managed conservatively with bowel rest and nasogastric decompression. However, this patient exhibits classic 'alarm' features of a complicated, strangulated obstruction: fever, tachycardia, hypotension, severe continuous pain, peritonitis (involuntary guarding and rebound tenderness), marked leukocytosis, and lactic acidosis. These findings indicate that the affected segment of the bowel has compromised blood flow and is becoming necrotic. The definitive and life-saving intervention for a strangulated SBO is an immediate exploratory laparotomy to resect any nonviable bowel and relieve the mechanical obstruction.

Step-by-Step Solution

Analyze the patient's presentation and imaging to establish the primary diagnosis.

The patient's obstipation, bilious vomiting, distension, prior abdominal surgery, and radiographic air-fluid levels confirm the diagnosis of an adhesive small bowel obstruction (SBO).

Identifying the mechanical obstruction is the prerequisite for determining the severity and necessary interventions.

Evaluate vital signs, physical examination findings, and laboratory values for severity criteria.

The presence of fever, tachycardia, involuntary guarding, rebound tenderness, leukocytosis, and elevated lactate indicate that the bowel is ischemic or strangulated.

Differentiating between uncomplicated and complicated SBO is critical, as it completely changes the management pathway.

Select the appropriate therapeutic intervention based on the complication status.

Immediate exploratory laparotomy is chosen.

A strangulated SBO is a surgical emergency. Delaying operative management leads to bowel necrosis, perforation, sepsis, and death.

Key Concept

Management of complicated (strangulated) small bowel obstruction

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