Incidence of contralateral metachronous inguinal hernia on long term follow-up after unilateral inguinal hernia repair: a systematic review and meta-analysis.

Background: The repair of inguinal hernias is a common surgical procedure. Some patients will need a second operation after developing a metachronous contralateral inguinal hernia (MCIH). The suggestion has been made to strengthen the contralateral side at the same time as primary unilateral surgery. In this systematic review we aim to determine how many adult patients with a unilateral inguinal hernia will develop a MCIH. Methods: This review was reported in line with PRISMA guidelines. We performed a literature review in PubMed Publisher, Embase, Google Scholar and Cochrane Library until May 2021, including articles reporting MCIH after unilateral inguinal hernia repair in adults. As outcome measure, the number of patients diagnosed with a MCIH was registered. Results: A total of 19 articles with a total of 277,288 patients were included. The combined estimate for MCIH after meta-analysis equaled 8.3% (95% CI 7.1%–9.5%), with a high index of heterogeneity (I2 = 97.9%). A random-effects meta-regression was performed to obtain the percentage of MCIH as a function of median follow-up time. The percentage of MCIH at 3, 5 and 10 years was estimated at 5.2%, 8.0% and 17.1%, respectively. Conclusion: We suggest that there is insufficient clinical evidence to support prophylactic contralateral repair in all patients. We propose a patient-specific approach in the decision to perform prophylactic repair, taking into account potential risk factors for hernia development, type of surgical approach, and general risk factors for chronic postoperative inguinal pain. More long-term prospective data are needed to guide the decision for prophylactic contralateral mesh placement. [ABSTRACT FROM AUTHOR]