A 52-year-old man presents to the emergency department with a 24-hour history of generaliz… — USMLE Step 2 CK

A 52-year-old man presents to the emergency department with a 24-hour history of generalized, colicky abdominal pain, intractable nausea, and multiple episodes of bilious emesis. He states he has not had a bowel movement or passed flatus for the past day. His medical history is significant for an open appendectomy 15 years ago. His temperature is $37.1^{\circ} \text{C}$ ( $98.8^{\circ} \text{F}$ ), blood pressure is $135/82 \text{ mmHg}$ , heart rate is $88/\text{min}$ , and respiratory rate is $16/\text{min}$ . Physical examination reveals a markedly distended abdomen with high-pitched, hyperactive bowel sounds. The abdomen is mildly tender to palpation diffusely, but there is no guarding, rigidity, or rebound tenderness. Laboratory studies show a leukocyte count of $8,500/\text{mm}^3$ . An upright abdominal radiograph demonstrates multiple dilated loops of small bowel with prominent air-fluid levels and a paucity of air in the colon. Which of the following is the most appropriate next step in the management of this patient?

Intravenous fluid resuscitation and placement of a nasogastric tubeAnswer
B
Urgent exploratory laparotomy
C
Administration of intravenous piperacillin-tazobactam
D
Administration of oral metoclopramide
E
Colonoscopy to evaluate for an obstructive lesion

Answer

Intravenous fluid resuscitation and placement of a nasogastric tube

The correct answer is to initiate intravenous fluid resuscitation and place a nasogastric tube. This patient presents with the classic triad of colicky abdominal pain, bilious vomiting, and obstipation, which, combined with a history of prior abdominal surgery and radiographic evidence of dilated loops with air-fluid levels, confirms a diagnosis of small bowel obstruction (SBO). Because the patient's vital signs are stable, his leukocyte count is normal, and his abdominal exam lacks peritoneal signs (guarding, rigidity, rebound tenderness), this is considered an uncomplicated SBO. The standard initial management for uncomplicated SBO is conservative, focusing on bowel rest (NPO status), volume resuscitation with intravenous fluids to correct third-spacing and emesis-related fluid losses, and decompression of the stomach and proximal bowel via a nasogastric tube.

Step-by-Step Solution

Analyze the clinical presentation and history.

The patient has colicky abdominal pain, bilious emesis, obstipation, and a history of abdominal surgery.

These are the classic hallmarks of a mechanical small bowel obstruction (SBO), most commonly caused by postoperative adhesions.

Evaluate the physical examination and laboratory findings for complications.

The patient has normal vital signs, no peritoneal signs (no guarding or rigidity), and a normal leukocyte count.

This confirms the diagnosis is an uncomplicated SBO, without signs of bowel ischemia, necrosis, or perforation (strangulation).

Determine the appropriate initial management for uncomplicated SBO.

The standard of care is conservative management with bowel rest, gastrointestinal decompression, and fluid replacement.

A nasogastric tube relieves distension and prevents aspiration, while intravenous fluids correct volume depletion from third-spacing and emesis.

Key Concept

The initial management of an uncomplicated mechanical small bowel obstruction consists of conservative measures, including intravenous fluid resuscitation, bowel rest (NPO), and nasogastric tube decompression.

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