Hannah Oelschlager MD, Aarish Shahab MD, Rachna Subramony MD, Bryan Merte MD
A 63-year-old man with bladder cancer and type 2 diabetes mellitus presented on postoperative day 8 after robotic-assisted laparoscopic radical cystoprostatectomy with orthotopic neobladder creation. He had been discharged three days earlier with a transurethral Foley catheter in the neobladder and externalized ureteral stents draining into an abdominal collection appliance. His postoperative course had otherwise been uncomplicated, with adequate urinary drainage before discharge.
During the two days preceding presentation, he developed progressively worsening diffuse abdominal pain and markedly decreased urine output from both the Foley catheter and the externalized ureteral stents. The stents drained only intermittently and produced substantially less urine than previously. The pain was sharp, constant, and more severe on the right. He also reported chills and an inability to tolerate oral intake but denied fever.
Vital signs: BP 131/81 | HR 79 | RR 14 | SpO2 97% on room air | T 36.9°C.
On physical exam the patient appeared uncomfortable. His abdomen was diffusely tender, more prominently on the right, without rebound or guarding. He reported bilateral flank pain but had no costovertebral-angle tenderness. The abdominal stent exit sites and surrounding skin showed no erythema, bleeding, or discharge. His mucous membranes were dry, and capillary refill was delayed.
| Lab Test | Value |
| WBC | 12.3 x 109/L |
| Hemoglobin | 13.1 g/dL |
| BUN | 16 mg/dL |
| Creatinine | 2.61 mg/dL |
| Sodium | 136 mmol/L |
| Potassium | 4.4 mmol/L |
| Urinalysis | 3+ blood 3+ protein + leukocyte esterase 21–50 WBCs >50 RBCs. |
A renal POCUS examination and FAST-style intraperitoneal free-fluid assessment were performed to evaluate the patient’s abdominal pain, decreased urinary output, and elevated serum creatinine.


Contrast-enhanced CT of the abdomen and pelvis demonstrated moderate intraperitoneal free fluid, a decompressed neobladder with the Foley catheter in place, and no hydronephrosis. The distal ends of the ureteral stents had retracted from the neobladder lumen and were positioned within the peritoneal cavity. Delayed excretory-phase imaging demonstrated contrast-opacified urine extravasating into the peritoneal cavity, confirming uroperitoneum.

Clinical Course:
Given concern for a potentially infected urinary leak, the patient received intravenous fluids, analgesia, and empiric broad-spectrum antibiotics. Urology attempted bedside retrieval of the retracted ureteral stents in the emergency department but was unsuccessful. The left ureteral stent was subsequently removed by interventional radiology, but the right stent could not be retrieved. Bilateral percutaneous nephrostomy tubes were therefore placed for urinary diversion. Urine cultures showed no growth, and antibiotics were discontinued. The patient’s serum creatinine returned to 0.73 mg/dL, and he was discharged on postoperative day 13 with the nephrostomy tubes in place.
Discussion:
Radical cystectomy may be required for the management of bladder cancer. Orthotopic neobladder reconstruction is one urinary-diversion option and may offer continence and body-image advantages in appropriately selected patients.1 However, the procedure is technically complex and is associated with both early and late complications. Early complications, occurring within the first three months postoperatively, are often related to the intestinal and urinary tract and include urine leakage, bowel obstruction, and fluid collections.2 Late complications include hydronephrosis, urinary tract infection, urinary calculi, bowel obstruction, vesicoureteral reflux, and neobladder rupture.
A bedside renal POCUS examination and modified FAST examination were performed during the initial evaluation of the patient’s abdominal pain, elevated serum creatinine, and decreased urine output. The FAST exam is most widely used in the trauma setting to detect free abdominal fluid with a pooled sensitivity and specificity of 74% and 98%, respectively.3 However, a recent study utilizing a modified FAST exam to evaluate for intra-abdominal bleeding in postoperative cesarean section patients suggests it may be useful in selected postoperative patients. In a cohort of 61 patients, the modified FAST exam demonstrated a sensitivity of 80% and specificity of 100% for detecting intra-abdominal fluid.4 Notably, all 10 false-negative examinations corresponded to “scant” or “trace” free fluid on formal imaging, and none of these patients required relaparotomy.
In the present case, POCUS demonstrated free intraperitoneal fluid in both upper quadrants without hydronephrosis. Ultrasound cannot reliably determine the composition of intraperitoneal fluid; therefore, the differential diagnosis included urine, blood, simple ascites, and an infected or sterile postoperative collection. The patient’s hemodynamic stability and hemoglobin concentration made major ongoing hemorrhage less likely. In the setting of recent urinary reconstruction, markedly decreased urinary drainage, and diffuse intraperitoneal free fluid, a postoperative urinary leak became a leading consideration.
Contrast-enhanced CT with delayed excretory-phase imaging confirmed urinary contrast extravasation into the peritoneal cavity. Delayed-phase CT is particularly useful for identifying urinary leakage and distinguishing urine from other postoperative fluid collections.5 In this patient, the distal ends of the ureteral stents had retracted from the neobladder lumen into the peritoneal cavity. This malposition likely allowed urine to drain into the peritoneal cavity rather than into the neobladder, producing uroperitoneum, also termed urinary ascites.
The patient’s serum creatinine increased from a baseline of 0.68 mg/dL to 2.61 mg/dL over three days. Renal POCUS demonstrated no hydronephrosis, making substantial upper urinary tract obstruction less likely. A component of true acute kidney injury remained possible given his poor oral intake and clinical evidence of volume depletion. However, in the presence of uroperitoneum, reverse peritoneal dialysis likely contributed substantially to the creatinine elevation. Urinary creatinine and other solutes can diffuse across the semipermeable peritoneal membrane into the systemic circulation, producing laboratory findings that mimic acute kidney injury despite relatively preserved glomerular filtration. This phenomenon is termed pseudo-azotemia or pseudo–acute kidney injury.6 Hyperkalemia, hyponatremia, and metabolic acidosis have also been described. The return of the patient’s creatinine to 0.73 mg/dL after urinary diversion supported a substantial component of pseudo-azotemia.
Empiric antibiotics were administered because of concern for a potentially infected postoperative urinary leak. However, hematuria, pyuria, and positive leukocyte esterase should be interpreted cautiously in patients with ileal neobladders because abnormal urinalysis findings are common after urinary diversion. In a study of 185 patients with orthotopic ileal neobladders who underwent urinalysis 18 days after surgery, 80% had positive leukocytes, 83.8% had positive erythrocytes, and 41% had more than 20 leukocytes per high-power field.7 The patient’s urine culture ultimately showed no growth, and antibiotics were discontinued.
In this patient, abdominal pain, decreased urinary output, elevated serum creatinine, and free intraperitoneal fluid on POCUS raised early concern for a postoperative urinary leak. POCUS could not determine the composition of the fluid but identified clinically significant intraperitoneal free fluid and facilitated early urologic consultation and delayed excretory-phase CT imaging. This case highlights uroperitoneum as an important cause of abdominal pain, oliguria, and apparent acute kidney injury after urinary reconstruction. The absence of hydronephrosis does not exclude urinary diversion failure, and an elevated serum creatinine may partly reflect reverse peritoneal dialysis rather than impaired renal filtration alone.
References:
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2. Mirto BF, Barone B, Balsamo R, et al. Early and late post-procedural complications in different orthotopic neobladder surgical approaches: A systematic review. Surgical Oncology. 2024;55:102090. doi:10.1016/j.suronc.2024.102090
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Simler MAZ, Desouky E, Zakharious F, Mandal AKJ, Missouris CG. A Syndrome of Apparent Renal Failure. Ann Emerg Med. 2020;76(2):191-193. doi:10.1016/j.annemergmed.2020.02.018
7. Magistro G, Zimmermann L, Bischoff R, et al. The natural course of urinalysis after urinary diversion. World J Urol. 2021;39(5):1559-1567. doi:10.1007/s00345-020-03355-0

















