EXPRESS: Evaluation of the incidence of haematuria following the placement of subcutaneous ureteral bypass devices in 18 cats (2016-2022)

OBJECTIVES: To evaluate the incidence of post-operative haematuria in cats treated with a subcutaneous ureteral bypass (SUB) device for the management of benign ureteral obstruction. METHODS: Medical records from a single referral institute were retrospectively searched for cats that underwent placement of a SUB device for the management of benign ureteral obstruction between June 2016 and June 2022. Signalment, history, diagnostic imaging findings, surgery duration, pre- and postprocedural clinicopathological data were recorded. RESULTS: In total, 18 cats presented with placement of de novo SUB devices; 14 unilateral SUBs and 4 bilateral SUBs. All 18 (100%) cats developed microscopic haematuria post-operatively. Median time to detection of microscopic haematuria was one month (range 1 - 11 months), with 16/18 (89%) detected on the first post-operative urinalysis. Fourteen (78%) cats had persistent microscopic haematuria, two cats (11%) had recurrent microscopic haematuria, and a further two cats (11%) had recurrent persistent microscopic haematuria. Severe haematuria (≥ 50 RBC per hpf) was identified in 13 cats (72%), however gross haematuria as a clinical sign was infrequently reported (two out of 18 cats, 11%). The median time to first detection of severe haematuria was one month (range: 1 - 31 months). Persistent severe haematuria was documented in seven cats with a median duration of persistence of 17 months (range: 5 - 31). Haematuria without a positive urine culture at any time point was present in 11 out of 18 (61%) cats. CONCLUSIONS AND RELEVANCE: In this study population, post-operative persistent microscopic haematuria was a frequent finding in cats following subcutaneous ureteral bypass device placement. Further studies are necessary to understand if microscopic haematuria is a clinically relevant finding, and to further understand the aetiology of haematuria in such patients.