'Waterproofing layers' for urethrocutaneous fistula repair after hypospadias surgery: evidence synthesis with systematic review and meta-analysis.

Objective: To summarize the available evidence and to quantitatively evaluate the global results of different waterproofing layers in substantiating the UCF repair.
Material and Methods: After defining the study protocol, the review was conducted according to the PRISMA guidelines by a team comprising experts in hypospadiology, systematic reviews and meta-analysis, epidemiology, biostatistics and data science. Studies published from 2000 onwards, reporting on the results of UCF closure after hypospadias repair were searched for on PUBMED, Embase and Google Scholar. Study quality was assessed using Joanna Briggs Checklist (JBI) critical appraisal tool. The results with different techniques were compared with the two samples independent proportions test with the help of Microsoft Excel, MedCalc software and an online calculator.
Results: Seventy-three studies were shortlisted for the synthesis; the final analysis included 2886 patients (71 studies) with UCF repair failure in 539. A summary of various dimensions involved with the UCF repair has been generated including time gap after last surgery, stent-vs-no stent, supra-pubic catheterization, suture material, suturing technique, associated anomalies, complications, etc. The success rates associated with different techniques were calculated and compared: simple catheterization (100%), simple primary closure (73.2%), dartos (78.8%), double dartos flaps (81%), scrotal flaps (94.6%), tunica vaginalis (94.3%), PATIO repair (93.5%), biomaterials or dermal substitutes (92%), biocompatible adhesives (56.5%) and skin-based flaps (54.5%). Several techniques were identified as solitary publications and discussed.
Conclusions: Tunica vaginalis and scrotal flaps offer the best results after UCF closure in the synthesis. However, it is not possible to label any technique as ideal or perfect. Almost all popular waterproofing layers have depicted absolute (100%) success sometimes. There are a vast number of other factors (patient's local anatomy, surgeon's expertise and technical perspectives) which influence the final outcome.
(© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)