A 62-year-old man presents to the emergency department with a 4-hour history of severe, un… — USMLE Step 2 CK

A $62$ -year-old man presents to the emergency department with a $4$ -hour history of severe, unrelenting abdominal pain and nonbilious vomiting. He has a history of an open cholecystectomy $12$ years ago. His temperature is $37.3^\circ\text{C}$ ( $99.1^\circ\text{F}$ ), blood pressure is $135/85\text{ mmHg}$ , pulse is $88/\text{min}$ , and respirations are $16/\text{min}$ . Physical examination reveals a moderately distended abdomen. There is diffuse tenderness to deep palpation, but no involuntary guarding, rigidity, or rebound tenderness is present. Laboratory studies show a leukocyte count of $9,800/\text{mm}^3$ and a serum lactate level of $1.1\text{ mmol/L}$ . Computed tomography of the abdomen and pelvis with intravenous contrast reveals a high-grade mechanical small bowel obstruction. A transition point is identified in the mid-ileum, accompanied by a cluster of dilated, fluid-filled bowel loops arranged in a U-shaped configuration. The mesenteric vessels supplying this segment demonstrate a "whirl" pattern. The bowel wall shows normal contrast enhancement, and there is no pneumatosis intestinalis or free intraperitoneal air.

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

Urgent surgical explorationCevap
B
Nasogastric tube insertion and serial clinical examinations
C
Administration of oral water-soluble contrast
D
Systemic anticoagulation with intravenous heparin
E
Mesenteric angiography with vasodilator infusion

Cevap

Urgent surgical exploration is the most appropriate next step because the CT findings indicate a closed-loop small bowel obstruction, which is a surgical emergency.

The correct answer is urgent surgical exploration. The patient has a closed-loop small bowel obstruction, indicated by the U-shaped configuration of fluid-filled bowel loops and the 'whirl' sign of twisted mesenteric vessels on the CT scan. In a closed-loop obstruction, a segment of bowel is obstructed at two adjacent points (often due to twisting around an adhesive band from prior surgery). This creates a trapped segment of bowel that rapidly develops venous congestion, arterial compromise, ischemia, and eventually necrosis. Because of the high and unpredictable risk of rapid strangulation, a closed-loop obstruction is considered a surgical emergency. Immediate surgical intervention is required to detorse the bowel and relieve the obstruction before irreversible infarction occurs. The absence of fever, tachycardia, leukocytosis, elevated lactate, or peritonitis indicates that the bowel has not yet infarcted, which is the ideal time to intervene, rather than a reason to delay surgery.

Adım Adım Çözüm

Analyze the patient's clinical presentation and imaging findings.

The patient has a mechanical small bowel obstruction with a U-shaped transition point and a mesenteric 'whirl' sign.

These specific CT findings define the anatomical nature of the obstruction.

Identify the specific diagnosis based on the radiological signs.

The findings indicate a closed-loop small bowel obstruction (volvulus).

A closed-loop obstruction occurs when the bowel is obstructed at two adjacent points, often leading to mechanical twisting of the mesentery (whirl sign).

Determine the appropriate management for a closed-loop obstruction.

The correct management is immediate surgical exploration.

Closed-loop obstructions carry a very high risk of rapid progression to bowel strangulation and infarction. Surgery is mandatory even if current vital signs and laboratory markers are completely normal.

Anahtar Kavram

A closed-loop small bowel obstruction (indicated by U-shaped loops and a mesenteric whirl sign on CT) carries a high risk of rapid strangulation and is an absolute indication for urgent surgical exploration, even in the absence of systemic signs of ischemia or peritonitis.

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