Natural history and consequence of patent processus vaginalis: An interim analysis from a multi-institutional prospective observational study

Background: The prevalence and natural history of patent processus vaginalis (PPV) are unknown. An interim analysis was performed of a multi-institutional, prospective, observational study in neonates undergoing laparoscopic pyloromyotomy during which bilateral inguinal canals were evaluated. Methods: Infants under 4 months undergoing laparoscopic pyloromyotomy were enrolled at 8 children's hospitals. The presence of a PPV was evaluated and measurements recorded. Patients with a PPV are undergoing annual phone follow-up to 18 years of age. Interim analysis was performed. Results: In a cohort of 610 patient, 80 did not have a PPV examined, 4 had consent issues and were excluded, leaving 526 patients. Of these, 433 (82%) were male, median age 1.2 months (IQR 0.9, 1.6), median weight 3.89 kg (IQR 3.4, 4.46), and EGA 39 weeks (IQR 37, 40). There were 283 PPVs, 132 bilateral (47%), 116 right (41%), and 35 left (12%). Patients with a PPV were significantly younger (1.1 months (IQR 0.9, 1.5) vs 1.3 months (IQR 0.9, 1.7), p=0.02), weighed less (3.76kg (IQR 3.35, 4.26) vs 3.9kg (IQR 3.4, 4.5) p=0.03) and had a significantly lower EGA at birth (38 weeks (IQR 37, 40) vs 39 weeks (IQR 38, 40) p=0.003). Of 246 eligible infants, 208 (85%) responded to at least one annual follow-up. Two patients had an inguinal hernia repair for a symptomatic hernia, 49- and 51-days post pyloromyotomy. One had an orchiopexy and incidental inguinal hernia repair 120 days post pyloromyotomy; for a total of 3 (1.2%) hernia repairs. No additional hernias were identified in 116 patients with the PPV patients who have been followed for > 1 year. Conclusions: The presence of a PPV at the time of pyloromyotomy is common but the need for hernia repair is rare within the first year of life. Continued long-term longitudinal follow-up of this cohort is needed.