Contralateral Metachronous Hernia Following Negative Laparoscopic Evaluation for Contralateral Patent Processus Vaginalis: A Meta-analysis

Objective: To conduct a meta-analysis of contralateral metachronous inguinal hernia (CMIH) that originated from negative laparoscopic evaluation for contralateral patent processus vaginalis (CPPV) in children who presented with a unilateral inguinal hernia and to determine the incidence of and factors associated with such a CMIH. Materials and Methods: A PubMed search was performed for all studies concerning laparoscopic repair or evaluation of inguinal hernia in children. The search strategy was as follows: (laparoscop* OR coelioscop* OR peritoneoscop* OR laparoendoscop* OR minilaparoscop*) AND (inguinal hernia OR metachronous hernia) AND child*. Inclusion criteria included unilateral inguinal hernia in children, negative laparoscopic evaluation of CPPV, without history of contralateral inguinal surgery previously, and clearly reporting CMIH development or not. Editorials, letters, review articles, case reports, animal studies, and duplicate patient series were excluded. Results: Twenty-three studies comprising 6091 children with negative CPPV fulfilled the inclusion criteria and were included in the final analysis, of whom 80 (1.31%) subsequently presented with a CMIH. Subgroup analysis showed that CMIH incidence was lower through an umbilical approach than via an inguinal one (0.85% versus 1.78%, P=.009). As for the transinguinal approach, there was a CMIH incidence of 0.78% and 2.05%, respectively, for laparoscopy with a small angle (30 degrees and 70 degrees), whereas there was no CMIH development for that with a large angle (110 degrees, 120 degrees, and flexible). A high pneumoperitoneum pressure (>10mm Hg, >12mm Hg, and >14mm Hg) was usually associated with a slightly higher CMIH incidence than a low one (10mm Hg, 12mm Hg, and 14mm Hg), all without significant difference. CMIH incidence was slightly lower for using a broad CPPV definition than for using a narrow one (0.64% versus 1.35%, P=.183). Conclusions: CMIH following negative laparoscopic evaluation for CPPV was a rare but possible phenomenon. Choosing the transumbilical approach, transinguinal laparoscopy with a large angle, low-pressure pneumoperitoneum, and broad CPPV definition would probably reduce the occurrence of such CMIHs.