Percentage of Inguinal Hernia in Undescended Testis
Approximately 70-75% of patients with undescended testis have an associated inguinal hernia, making this one of the most common concurrent findings in cryptorchidism.
Incidence Data from Clinical Studies
The association between undescended testis and inguinal hernia is remarkably high:
- Laparoscopic series demonstrate a 69.9% incidence of inguinal hernia found during orchidopexy for palpable and nonpalpable undescended testes 1
- Retrospective surgical series report 75% of undescended testis cases have an associated inguinal hernia at the time of surgical correction 2
- The hernia typically presents as the chief complaint in 17.5% of cryptorchidism cases, while the remaining patients present primarily for the undescended testis itself 2
Embryological Basis for This Association
The high co-occurrence rate is explained by shared developmental pathology:
- Both conditions result from incomplete involution of the processus vaginalis during testicular descent between 25-35 weeks of gestation 3
- The testis descends through the inguinal canal drawing with it an extension of peritoneal lining (the processus vaginalis), which normally obliterates after descent 3
- When the processus vaginalis remains patent (PPV), it creates both the pathway for inguinal hernia formation and is associated with arrested testicular descent 3, 4
- More than 90% of pediatric inguinal hernias occur in boys, directly reflecting this relationship with testicular descent abnormalities 3
Clinical Implications for Management
This high association rate has important surgical considerations:
- During laparoscopic orchidopexy, surgeons routinely identify and address the associated hernia by removing the membranes of the processus vaginalis 1
- The hernia defect may not require formal closure during orchidopexy, as scar tissue and peritoneal growth can seal the defect, with no recurrences reported in series with 21.5-month follow-up 1, 5
- All inguinal hernias in infants require surgical repair to prevent bowel incarceration and gonadal infarction, making concurrent repair during orchidopexy the standard approach 3, 4
Important Clinical Pitfalls
- An inguinal undescended testis is sometimes mistaken for an isolated inguinal hernia, emphasizing the need for careful testicular examination in all boys presenting with inguinal masses 6
- Failure to properly position the testis in the scrotum during hernia repair can lead to iatrogenic ascending testis, occurring in 0.43% of cases, particularly in boys with scrotal hypoplasia or retractile testes 7
- Patients with retractile testes or scrotal hypoplasia in addition to inguinal hernia need orchiopexy together with herniorrhaphy to prevent postoperative testicular ascent 7