Estimation of successful capping with complete aspiration of bladder via nephroureterostomy tube.

Background: Ureteral stent and nephroureterostomy tube (NUT) are treatments of ureteral obstruction. Ureteral stent provides better quality of life. Internalization of NUT is desired whenever possible.

Aim: To assess outcomes of capping trial among cancer patients with complete aspiration of retained contrast from bladder via NUT.

Methods: Our Institutional Review Board approved retrospective review of all NUT placement, NUT exchange and conversion of nephrostomy catheter into NUT performed during June 2013 to June 2015 (n = 578). Cases were excluded due to lack of imaging of bladder (n = 37), incomplete aspiration of bladder (n = 324), no attempt at capping NUT (n = 166), and patients with confounding factors interfering with results of capping trial including non-compliant bladder, bladder outlet obstruction and catheter malposition (n = 14). Study group consisted of 37 procedures in 34 patients (male 19, female 15, age 2-83 years, average 58, median 61) most with cancer (prostate 8, endometrial 5, bladder 4, colorectal 4, breast 2, gastric 2, neuroblastoma 2, cervical 1, ovarian 1, renal 1, sarcoma 1, urothelial 1 and testicular 1) and one with Crohn's disease. Medical records were reviewed to assess outcomes of capping trial. Exact 95% confidence intervals (95%CI) were calculated.

Results: Among patients with complete aspiration of retained contrast, 30 (81%, 95%CI: 0.65-0.92) catheters were successfully capped (range 12-94 d, average 40, median 24.5) until planned conversion to internal stent (23), routine exchange (5), removal (1) or death unrelated to catheter (1). Seven capping trials (19%, 95%CI: 0.08-0.35) were unsuccessful (range 2-22 d, average 12, median 10) due to leakage (3), elevated creatinine (2), fever/hematuria (1) and nausea/vomiting (1).

Conclusion: Capping trial success among patients with complete aspiration of retained contrast/ urine from bladder via NUT appears high.