A 42-year-old woman is evaluated in the surgical ward for sudden-onset left-sided shoulder… — USMLE Step 2 CK

A 42-year-old woman is evaluated in the surgical ward for sudden-onset left-sided shoulder pain, nausea, and severe anxiety. She is currently on her third postoperative day following a laparoscopic Roux-en-Y gastric bypass for morbid obesity. She has a history of obstructive sleep apnea, hypertension, and osteoarthritis. Current medications include subcutaneous enoxaparin, intravenous fluids, and a patient-controlled analgesia pump with morphine.

Vital signs reveal a temperature of $38.6^\circ\text{C}$ ( $101.5^\circ\text{F}$ ), blood pressure of $112/68\text{ mmHg}$ , pulse of $132/\text{min}$ , and respiratory rate of $22/\text{min}$ . Pulse oximetry shows $95\%$ on room air.

Physical examination demonstrates a restless, anxious patient. The lungs are clear to auscultation bilaterally. Cardiac auscultation reveals a rapid, regular rhythm with no murmurs. The abdomen is obese, soft, and mildly tender diffusely, with no rebound tenderness or guarding. The laparoscopic port sites show no erythema or discharge. An electrocardiogram shows sinus tachycardia.

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

Computed tomography scan of the abdomen with oral contrastAnswer
B
Computed tomography pulmonary angiography
C
Empiric administration of intravenous piperacillin-tazobactam
D
Intravenous administration of furosemide
E
Nasogastric tube placement and bowel rest

Answer

The most appropriate next step in management is a computed tomography (CT) scan of the abdomen with oral contrast to evaluate for an anastomotic leak.

The correct action is to obtain a computed tomography (CT) scan of the abdomen with oral contrast. The patient is presenting with marked tachycardia, fever, and left shoulder pain on postoperative day 3 following a Roux-en-Y gastric bypass, a presentation highly suspicious for a gastrojejunal anastomotic leak. Unexplained tachycardia (often

>120/\text{min}

) is recognized as the earliest and most sensitive clinical sign of an anastomotic leak in bariatric patients, frequently preceding severe abdominal pain or overt peritonitis. The leakage of gastric and intestinal contents into the peritoneum causes subdiaphragmatic irritation, which refers pain to the left shoulder via the phrenic nerve (C3-C5), a phenomenon known as Kehr sign. An abdominal CT scan with oral contrast or an upper gastrointestinal series using water-soluble contrast is the definitive next step to visually confirm the leak and guide operative source control.

Step-by-Step Solution

Analyze the timing and the specific surgical procedure.

The patient is on postoperative day 3 following a Roux-en-Y gastric bypass.

Different surgeries have specific, highly characteristic postoperative complications based on timing.

Interpret the combination of vital signs and localized pain.

The patient has marked unexplained tachycardia (HR > 120), a low-grade fever, and left shoulder pain with a relatively benign abdominal exam.

Tachycardia is the most sensitive early sign of a gastrointestinal anastomotic leak. Left shoulder pain indicates diaphragmatic irritation (Kehr sign).

Select the safest and most definitive diagnostic study.

An abdominal CT scan with oral contrast (or an upper gastrointestinal series) is selected over blind interventions.

It visualizes the extravasation of contrast from the newly created anastomosis, confirming the diagnosis and guiding subsequent surgical or percutaneous drainage.

Key Concept

Unexplained tachycardia is the earliest and most sensitive clinical indicator of an anastomotic leak following bariatric surgery. Left shoulder pain (Kehr sign) represents referred pain from subdiaphragmatic irritation, necessitating urgent imaging with an oral contrast study.

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