Emergency medical services bring a 72-year-old female to the acute care facility following… — USMLE Step 2 CK

Emergency medical services bring a $72$ -year-old female to the acute care facility following the acute onset of severe, unrelenting diffuse abdominal pain. The patient reports that the pain started roughly $6$ hours ago and has been associated with recurrent bilious emesis and absolute constipation. Her surgical history includes a laparotomy for a perforated appendix during childhood. Current vital signs include a temperature of $38.6^\circ\text{C}$ ( $101.5^\circ\text{F}$ ), a heart rate of $118\text{/min}$ , a blood pressure of $95/58\text{ mmHg}$ , and a respiratory rate of $22\text{/min}$ . On abdominal evaluation, the abdomen is tensely distended with high-pitched 'tinkling' sounds initially, which have now progressed to absent bowel sounds. Palpation elicits diffuse rigidity, marked rebound tenderness, and involuntary guarding. Laboratory results reveal a white blood cell count of $18,500/\text{mm}^3$ and a serum lactate concentration of $4.8\text{ mmol/L}$ . Initial plain films of the abdomen display prominently dilated small bowel loops with differential air-fluid levels and an absence of gas in the distal colon. Which of the following represents the most appropriate definitive management for this patient?

A
Initiation of nonoperative management with bowel rest
B
Cross-sectional abdominal imaging to identify the transition point
Urgent surgical exploration of the abdomenAnswer
D
Administration of broad-spectrum antimicrobials and observation
E
Fluoroscopic contrast study of the small intestine

Answer

Urgent surgical exploration of the abdomen

The correct answer is urgent surgical exploration of the abdomen. This patient presents with the classic triad of a small bowel obstruction (SBO): colicky abdominal pain, bilious vomiting, and obstipation. Her history of an appendectomy predisposes her to adhesive disease, the most common cause of SBO. Critically, she demonstrates clinical and laboratory signs of a strangulated obstruction and bowel ischemia, including fever, marked tachycardia, diffuse abdominal rigidity with rebound tenderness (peritonitis), significant leukocytosis, and lactic acidosis. When an SBO is complicated by peritonitis or signs of strangulation, it represents a surgical emergency. Immediate operative intervention (exploratory laparotomy) is required to resect necrotic bowel and relieve the obstruction. Delaying surgery for imaging or attempting conservative management in this scenario drastically increases mortality.

Step-by-Step Solution

Identify the primary clinical syndrome based on the presentation and imaging.

The patient has a complete small bowel obstruction (SBO), evidenced by prior abdominal surgery, bilious emesis, obstipation, dilated small bowel loops, and air-fluid levels.

Recognizing the core pathology is the first step in directing management.

Assess for complications such as bowel ischemia, strangulation, or perforation.

The patient exhibits fever (

38.6^\circ\text{C}

), tachycardia, peritonitis (rigidity, rebound tenderness), leukocytosis (

18,500/\text{mm}^3

), and elevated lactate (

4.8\text{ mmol/L}

), all indicating strangulation and severe ischemia.

Complicated SBOs require drastically different management than uncomplicated ones.

Determine the definitive management based on the presence of complications.

Due to the frank peritonitis and signs of necrosis indicating a strangulated SBO, immediate operative intervention is mandated.

Surgical source control is necessary to prevent complete bowel infarction and mortality.

Key Concept

Surgical management is immediately indicated for a small bowel obstruction when signs of strangulation, peritonitis, or bowel ischemia are present.

Estimated Time:1m 15s

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