The etiology of indirect inguinal hernias: congenital and/or acquired?

The development of indirect inguinal hernias in infants is caused by a patent processus vaginalis (PPV). Consequently, this type of hernia is cured by simple herniotomy. In adults, however, herniotomy alone is accompanied by a high recurrence rate. This indicates that additional factors play a part in the development of indirect inguinal hernias in adults. The aim of this study was to determine the etiology of the development of an indirect hernia in adult life. Also, the prevalence of a PPV without clinical evidence of a hernia was determined and related to age. From November 1998 until February 2002, 599 patients from four different teaching hospitals, who underwent abdominal laparoscopy for various pathologies, were included. During laparoscopy, the deep inguinal ring was bilaterally inspected. Patients undergoing laparoscopy for inguinal hernia repair were excluded. Mean age was 45 years (range 8-89 years). Thirty-two percent (189/599) were male. Twelve percent (71/599) had PPV, all without clinical symptoms. Fifty-five percent (39/71) with PPV were male (P<0.0001). Fifty-nine percent (42/71) with PPV were right-sided, 29% (21/71) with PPV were left sided, and 12% (8/71) were bilateral (P=0.01). The prevalence of PPV in patients under 20 years was 22%. Of those between 20 and 30 years of age, 6% had PPV. Of those between 30 and 50 years, 24 patients (11%) had PPV. Of patients over 50 years, 33 (14%) had PPV. No significant differences between ages were observed. It is concluded that asymptomatic patent processus vaginalis frequently exists in adult life. The prevalence of PPV does not increase significantly with age. Assuming that indirect hernias start with asymptomatic peritoneal protrusion that can be observed laparoscopically, the incidence of PPV, like the incidence of adult indirect hernias, should increase in case of acquired etiology. Such an increase of incidence with age was not confirmed by our results. It is concluded that the etiology of indirect inguinal hernia in adults, as in infants, is congenital.