A 71-year-old male is transported to the emergency room by emergency medical services afte… — USMLE Step 2 CK

A $71$ -year-old male is transported to the emergency room by emergency medical services after his family found him writhing in severe abdominal pain. He reports a $3$ -day history of colicky abdominal pain, intractable nausea, and bilious vomiting. He has not passed stool or flatus for the past $48$ hours. His medical history includes hypertension, hyperlipidemia, and an open partial colectomy performed $8$ years ago. On arrival, his temperature is $39.4^\circ\text{C}$ ( $102.9^\circ\text{F}$ ), blood pressure is $88/50\text{ mmHg}$ , pulse is $128/\text{min}$ , and respiratory rate is $26/\text{min}$ . Physical examination reveals a tensely distended abdomen. There is diffuse, severe tenderness to palpation with involuntary guarding and positive rebound tenderness. Auscultation reveals a complete absence of bowel sounds.

Laboratory studies show:

Laboratory Test	Result
Leukocyte count	$22,500/\text{mm}^3$ ( $18\%$ bands)
Hemoglobin	$13.8\text{ g/dL}$
Platelet count	$245,000/\text{mm}^3$
Serum lactate	$6.2\text{ mmol/L}$

An upright abdominal radiograph displays multiple dilated loops of small bowel with prominent air-fluid levels and a complete absence of gas in the colon and rectum.

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

Urgent exploratory laparotomyAnswer
B
Placement of a nasogastric tube and serial abdominal examinations
C
Computed tomography of the abdomen and pelvis with oral contrast
D
Intravenous administration of broad-spectrum antibiotics and observation
E
Review of the patient's medication list for pharmacological causes of paralytic ileus

Answer

The most appropriate next step in management is urgent exploratory laparotomy.

The correct answer is urgent exploratory laparotomy. This patient presents with cardinal signs of a mechanical small bowel obstruction (colicky pain, bilious vomiting, obstipation) and a history of prior abdominal surgery, which is a major risk factor for adhesive disease. Crucially, he also demonstrates 'red flag' signs of a complicated obstruction. These include hemodynamic instability (hypotension, tachycardia), high fever, generalized peritonitis (guarding, rebound tenderness), marked leukocytosis with a left shift, and elevated serum lactate. These findings strongly suggest that the bowel has progressed to ischemia, strangulation, or frank necrosis. Complicated small bowel obstruction is an absolute surgical emergency that requires immediate exploratory laparotomy for definitive source control and resection of any necrotic bowel segments.

Step-by-Step Solution

Analyze the patient's symptoms, surgical history, and initial imaging.

The clinical triad of colicky pain, vomiting, and obstipation, combined with prior abdominal surgery and radiographic evidence of dilated loops with air-fluid levels, establishes the diagnosis of a mechanical small bowel obstruction (SBO).

Identifying the primary underlying structural pathology is the first step in abdominal emergencies.

Evaluate vital signs, physical examination findings, and laboratory data for complications.

The patient is hemodynamically unstable (hypotension, tachycardia) with high fever, generalized peritonitis (rebound tenderness, guarding), marked leukocytosis with a left shift, and severe lactic acidosis.

These 'red flag' findings indicate that the obstruction is complicated by bowel ischemia, strangulation, or perforation.

Determine the appropriate management pathway based on the presence of these complications.

Because there are clear signs of a complicated obstruction, conservative management is bypassed in favor of immediate surgical exploration.

Ischemic or perforated bowel is a surgical emergency requiring immediate operative source control to prevent sepsis and death.

Key Concept

Management of Complicated Small Bowel Obstruction (SBO)

Estimated Time:1m 30s

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