A 68-year-old woman is evaluated on postoperative day 5 following an open right hemicolect… — USMLE Step 2 CK

A $68$ -year-old woman is evaluated on postoperative day $5$ following an open right hemicolectomy for a localized cecal adenocarcinoma. Over the last $24$ hours, she has developed crampy, intermittent abdominal pain, significant nausea, and three episodes of bilious vomiting. The patient passed flatus on postoperative day $2$ but has not passed flatus or had a bowel movement since then. Her temperature is $38.3^\circ\text{C}$ ( $100.9^\circ\text{F}$ ), blood pressure is $118/76\text{ mm Hg}$ , and pulse is $98/\text{min}$ . Physical examination reveals a diffusely distended and tympanitic abdomen with mild, diffuse tenderness. There is no rebound tenderness or guarding. The surgical incision is clean, intact, and without erythema or drainage.

Laboratory studies show:

Test	Result
Leukocytes	$10,500/\text{mm}^3$
Serum sodium	$135\text{ mEq/L}$
Serum potassium	$3.2\text{ mEq/L}$
Serum chloride	$96\text{ mEq/L}$
Serum bicarbonate	$30\text{ mEq/L}$

An abdominal computed tomography (CT) scan with oral and intravenous contrast reveals dilated loops of small bowel up to $4.5\text{ cm}$ in diameter, terminating in the right lower quadrant near the ileocolic anastomosis. The distal colon is completely decompressed. There is no evidence of bowel wall thickening, pneumatosis intestinalis, or pelvic fluid collection. Which of the following is the most appropriate next step in the management of this patient?

Nasogastric tube decompression and intravenous fluid resuscitation with normal salineAnswer
B
Immediate exploratory laparotomy
C
Intravenous administration of broad-spectrum antibiotics
D
Lower extremity venous duplex ultrasonography
E
Intravenous administration of $0.45\%$ sodium chloride with sodium bicarbonate

Answer

Nasogastric tube decompression and intravenous fluid resuscitation with normal saline

This patient presents with an early postoperative small bowel obstruction (EPBO), characterized by crampy abdominal pain, bilious vomiting, obstipation, and characteristic CT findings (dilated small bowel with a transition point and decompressed colon) following recent abdominal surgery. Because there are no clinical or radiographic signs of bowel ischemia (e.g., severe localized pain, peritonitis, bowel wall thickening, pneumatosis), the most appropriate next step is conservative management. This involves nasogastric tube decompression to relieve symptoms and prevent aspiration, alongside aggressive intravenous fluid resuscitation with isotonic saline (

0.9\%

) and potassium to correct her hypokalemic, hypochloremic metabolic alkalosis resulting from vomiting.

Step-by-Step Solution

Analyze the clinical presentation and timing.

The patient has crampy abdominal pain, bilious emesis, obstipation, and a transition point on CT on postoperative day 5, establishing a diagnosis of early postoperative small bowel obstruction (EPBO).

Differentiating EPBO from postoperative ileus is critical; return of bowel function (flatus on day 2) followed by obstructive symptoms and a mechanical transition point points to EPBO.

Assess for complications requiring immediate surgery.

CT shows no bowel wall thickening, pneumatosis, or abscess. Clinical exam lacks peritonitis. There is no evidence of bowel ischemia or strangulation.

The presence of ischemia, strangulation, or peritonitis mandates immediate surgical exploration. Their absence allows for a conservative initial approach.

Identify the metabolic derangement.

Labs reveal hypokalemia (

3.2\text{ mEq/L}

), hypochloremia (

96\text{ mEq/L}

), and metabolic alkalosis (bicarbonate

30\text{ mEq/L}

) due to vomiting.

Repeated bilious vomiting depletes fluids, hydrogen ions, chloride, and potassium, requiring targeted intravenous replacement.

Determine the definitive next management step.

Initiate nil per os (NPO) status, place a nasogastric tube for decompression, and administer

0.9\%

normal saline with potassium.

Conservative management is the standard first-line treatment for uncomplicated EPBO, as most cases resolve without surgical reintervention.

Key Concept

Early Postoperative Small Bowel Obstruction (EPBO)

Estimated Time:1m 30s

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