Independent risk factors for contralateral patent processus vaginalis undetected by pre-operative ultrasonography in boys with unilateral inguinal hernia.

Purpose: Many trials have been done to make sure probability of metachronous contralateral side hernia (MCH) and contralateral patent processus vaginalis (CPPV). But the necessity of contralateral side exploration is still on debate. The aim is to investigate the risk factors for the consideration of contralateral examination on operation.
Materials and Methods: The study was designed as retrospectively. Patients with unilateral inguinal hernia from January 2010 to May 2015 were enrolled. Pre-operative ultrasonography was done in all patients. Patients with obvious contralateral side hernia on pre-operative US were excluded. The presence of CPPV was evaluated by transinguinal laparoscopy during the operation.
Results: In univariate analysis, hernial sac size only shows difference (P value: 0.001). The others, location of the hernia, age at surgery, gestational age (preterm), low birth weight and parent's age, did not show statistically significant differences. Multivariate analysis also demonstrates CPPV is more common in patients with large hernial sac (Odds ratio: 2.727, 95% confidence interval 1.495-4.974, P value: 0.001).
Conclusion: We propose that surgeons should consider contralateral evaluation during operation in case with large ipsilateral hernial sac, although CPPV was not detected by pre-operative US.