Survival and complications in cats treated with subcutaneous ureteral bypass

Abstract

To report the complications and factors affecting outcome for cats following placement of a subcutaneous ureteral bypass (SUB™). Materials and MethOds: In this retrospective study, complications, the presence of a urinary tract infection and survival time were recorded following subctutaneous ureteral bypass placement. Factors affecting survival time were assessed using a Kaplan Meier curve and log rank test. results: Ninety-five cats had 130 subcutaneous ureteral bypasses placed. Ten cats did not survive to discharge. Forty cats died or were euthanised after discharge (42%); the median survival time of these cats was 530 days (range 7 to 1915). Minor complications occurred in 18 cats (19%) and major complications occurred in 46 cats (48%), the majority of which were after hospital discharge. Twentyseven cats were diagnosed with a urinary tract infection (UTI) post-operatively. A significant association between long-term survival and creatinine at presentation was identified. The median survival time for cats presenting with creatinine concentration ≥440 μmol/L (International Renal Interest Society stage acute kidney injury (AKI) 4 and 5) was 530 days (95% CI 273-787 days), compared to a median survival time of 949 days (95% CI 655-1243 days; Log Rank P=0.024) for those cats presenting with creatinine <440 μmol/L (International Renal Interest Society stage AKI 1-3). clinical significance: In this population of cats, subcutaneous ureteral bypass placement was associated with an approximately 10% in-hospital mortality and a high complication rate. Most complications were manageable, resulting in an overall median survival time of over 2 years.

Complications and survival after subcutaneous ureteral bypass device placement in 24 cats: a retrospective study (2016–2019)

“…It is recommended to take orthogonal radiographs immediately postoperatively in cats that have a SUB placed blindly or with US guidance to detect kinking of the catheters. The number of cats in the present study that had kinks in their catheters (12.5%) was higher than that described by Kulendra et al (5%), 17 who attributed the kinking to the length of tubing in the subcutaneous space. Prospective studies are needed to investigate the optimal length of tubing to avoid kinking of catheters postoperatively.…”

“…21,27 Plain postoperative radiographs were used in our study and therefore subtle urine leakage could not be excluded, and a correct positioning of the pigtail in the renal pelvis could not be confirmed. 17 This is mainly important for cats that had the SUB placed blindly, as intraoperative US guidance enabled confirmation of the correct intrarenal positioning of the catheter. Fluoroscopic guidance has the advantage over US guidance that it might detect leakage and kinking of the nephrostomy catheter more accurately, allowing immediate intraoperative correction.…”

“…Kinking of the nephrostomy catheter can result in fewer holes (stuck within renal parenchyma or non-functional owing to kinking) available to drain urine, with possible insufficient urine drainage, resulting in persistent hydronephrosis, azotaemia and an increased risk of device obstruction. 17 Therefore, urine stasis can predispose to pyelonephritis. 14,[28][29][30][31][32] The incomplete pigtail formation was also observed by others in a very recent study; despite intraoperative fluoroscopy, penetration of the kidney with subcapsular leakage was noted postoperatively.…”

“…[9][10][11][12][13][14] The main disadvantage of these devices is the introduction of implants, which is associated with complications, including haematuria, sterile cystitis, urinary tract infection (UTI) and device obstruction. 10,[13][14][15][16][17] Reported median survival times (MST) in cats after stent and SUB placement are 420-498 and 820-827 days, respectively. [9][10][11]15,17 Ureteral stenting is considered technically more difficult than SUB placement.…”

“…10,[13][14][15][16][17] Reported median survival times (MST) in cats after stent and SUB placement are 420-498 and 820-827 days, respectively. [9][10][11]15,17 Ureteral stenting is considered technically more difficult than SUB placement. 18,19 This study aimed to document the complications and survival after SUB placement and to identify risk factors for complications and mortality prior to discharge.…”