Emergency medical personnel transport an 83-year-old female resident of a skilled nursing … — USMLE Step 2 CK

Emergency medical personnel transport an 83-year-old female resident of a skilled nursing facility to the acute care unit for intractable bilious vomiting and progressive abdominal distension over the past three days. Her medical history includes severe chronic obstructive pulmonary disease, type 2 diabetes mellitus, and osteoarthritis. She has not passed flatus or stool for 48 hours. Vital signs reveal a temperature of $37.4^\circ\text{C}$ ( $99.3^\circ\text{F}$ ), a pulse of $112/\text{min}$ , a blood pressure of $105/65\text{ mm Hg}$ , and respirations of $22/\text{min}$ . Physical examination shows a markedly distended, tympanitic abdomen with high-pitched, tinkling bowel sounds. There is diffuse tenderness to deep palpation, but no guarding or rigidity. Laboratory studies indicate a leukocyte count of $11,500/\text{mm}^3$ and a serum creatinine of $1.8\text{ mg/dL}$ (baseline $0.9\text{ mg/dL}$ ). A non-contrast computed tomography scan of the abdomen and pelvis reveals significantly dilated loops of small intestine with a transition point in the distal ileum. An ovoid, $3.5\text{-cm}$ calcified structure is impacted at this transition point. Furthermore, linear branching lucencies are noted centrally within the hepatic shadow. Which of the following is the most appropriate next step in the management of this patient?

Surgical enterolithotomy without concurrent biliary tree interventionAnswer
B
Surgical enterolithotomy, cholecystectomy, and closure of the cholecystoenteric fistula
C
Bowel decompression, fluid resuscitation, and serial abdominal examinations
D
Enteral administration of hyperosmolar contrast medium followed by serial radiographs
E
Endoscopic retrograde cholangiopancreatography with mechanical lithotripsy

Answer

Surgical enterolithotomy without concurrent biliary tree intervention

The correct approach is surgical enterolithotomy without concurrent biliary tree intervention. This patient presents with gallstone ileus, a rare complication of chronic cholecystitis where a large gallstone erodes through the gallbladder wall into the adjacent duodenum, creating a cholecystoenteric fistula. The stone travels distally and typically impacts in the terminal ileum (the narrowest segment of the small bowel), causing a mechanical obstruction. The diagnosis is confirmed by computed tomography demonstrating Rigler triad: small bowel obstruction, an ectopic gallstone, and pneumobilia (linear branching lucencies in the liver representing air in the biliary tree). Because gallstone ileus predominantly affects elderly patients with significant medical comorbidities (like this 83-year-old with severe COPD and acute kidney injury), the primary surgical goal is damage control. The standard of care is a simple enterolithotomy (an incision into the bowel proximal to the stone to extract it). Performing a concurrent cholecystectomy and fistula closure (a one-stage procedure) in this fragile demographic is associated with significantly elevated morbidity and mortality and should be avoided.

Step-by-Step Solution

Analyze the clinical and radiologic presentation

The patient has a mechanical small bowel obstruction, an ectopic calcified stone in the ileum, and pneumobilia (air in the biliary tree).

These three findings constitute Rigler triad, which is pathognomonic for gallstone ileus.

Evaluate the patient's physiological status and operative risk

The patient is 83 years old with severe COPD and acute kidney injury, placing her at very high risk for prolonged general anesthesia.

Surgical decision-making must balance the need to treat the acute pathology with the patient's ability to survive the physiologic stress of the procedure.

Determine the optimal surgical approach

Select enterolithotomy alone to extract the stone and resolve the obstruction.

In frail patients, a one-stage procedure (including cholecystectomy and fistula repair) has an unacceptably high mortality rate. Relief of the obstruction is the sole immediate priority.

Key Concept

Gallstone ileus classically presents with Rigler triad (small bowel obstruction, pneumobilia, and an ectopic gallstone) and is managed in frail, elderly patients with enterolithotomy alone to minimize operative mortality.

Estimated Time:1m 30s

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