Six days following a complex total laparoscopic hysterectomy for deeply infiltrating endom… — USMLE Step 2 CK

Six days following a complex total laparoscopic hysterectomy for deeply infiltrating endometriosis, a patient presents to her physician's office reporting progressive right-sided back pain. She notes that the pain occasionally radiates to her right groin and is associated with nausea and feeling feverish. The operative report indicates that extensive adhesiolysis was required due to significant anatomical distortion in the posterior cul-de-sac and broad ligament. She is currently voiding normally without dysuria. Vital signs show a temperature of $38.2^{\circ}\text{C}$ ( $100.8^{\circ}\text{F}$ ), blood pressure of $118/76\text{ mm Hg}$ , and a pulse of $88\text{/min}$ . Abdominal examination is notable for a soft, non-distended abdomen with normal bowel sounds. Severe tenderness is present upon percussion of the right costovertebral angle. Laboratory testing demonstrates a leukocyte count of $11,500/\mu\text{L}$ and a serum creatinine level of $0.8\text{ mg/dL}$ , which is unchanged from her preoperative baseline. Urinalysis reveals $15$ - $20$ red blood cells per high-power field and is negative for leukocyte esterase and nitrites. Which of the following is the most appropriate next step in management?

A
Initiation of empiric intravenous broad-spectrum antimicrobial therapy
B
Reassurance and instruction to increase incentive spirometry use
Computed tomography of the abdomen and pelvis with intravenous contrastAnswer
D
Placement of a nasogastric tube and restriction of oral intake
E
Urgent scheduling for exploratory laparotomy

Answer

Computed tomography of the abdomen and pelvis with intravenous contrast

The clinical presentation of unilateral flank pain, costovertebral angle tenderness, low-grade fever, and microscopic hematuria following a complex gynecologic surgery strongly suggests a unilateral ureteral injury. The ureter is particularly vulnerable during ligation of the uterine vessels (where it passes "under the bridge" of the uterine artery) or during dissection of the infundibulopelvic ligament, especially when normal anatomy is distorted by deep endometriosis. Unilateral ureteral obstruction typically does not cause an elevation in serum creatinine because the intact, contralateral kidney undergoes compensatory hyperfiltration to maintain normal overall renal function. The most appropriate next step to evaluate a suspected ureteral injury (whether transection, ligation, or thermal injury) is computed tomography (CT) urography or a CT scan of the abdomen and pelvis with intravenous contrast. This imaging modality reliably identifies hydroureter, hydronephrosis, or contrast extravasation, guiding subsequent management.

Step-by-Step Solution

Evaluate the patient's clinical presentation and surgical history.

The patient has unilateral flank pain, costovertebral angle tenderness, low-grade fever, and microscopic hematuria six days after a complex hysterectomy for severe endometriosis.

Identifying the timing of symptoms and specific signs (flank pain, hematuria) helps narrow the differential diagnosis from general postoperative complications to a urologic source.

Synthesize the findings to determine the most likely underlying postoperative complication.

The symptoms strongly point to a unilateral ureteral injury. Normal serum creatinine indicates the contralateral kidney is functioning normally, which is classic for a unilateral injury.

The ureter is highly vulnerable during ligation of the uterine vessels or dissection of the infundibulopelvic ligament, especially in cases where normal anatomy is distorted by conditions like endometriosis.

Select the most appropriate diagnostic modality to confirm the clinical suspicion.

Computed tomography with intravenous contrast (CT urography) is the diagnostic study of choice.

This imaging study provides definitive visualization of contrast extravasation, hydroureter, or hydronephrosis, which dictates the subsequent surgical or endoscopic management plan.

Key Concept

Evaluation and management of suspected ureteral injury following gynecologic surgery.

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