Strategies for the Treatment of Indirect Hernia Strategien für die Therapie der indirekten Hernie

Summary: Background: It is generally assumed that groin hernia is caused by ‘intra-abdominal pressure’ that is contained by transversalis fascia. The intra-abdominal compartment consists of two components: the intraperitoneal and the extraperitoneal compartment. The respective contribution of each of these two components to groin hernia aetiology has never been differentiated. Methods: Morphological and physiological correlates were sought to explain striking inconsistencies in the above-mentioned theory: The processus vaginalis obliterates only after birth, when crying and straining first raises intraperitoneal pressure. Epidemiologically, groin hernia incidence is lowest in the 15 –  45-years age group, in which pressure strains from physical work, sports, pregnancy and delivery are highest. Maximal intra-abdominal pressure increase in pregnancy and labour never causes a groin hernia in women. In patients treated with chronic pneumoperitoneum at a pressure of 10 mm Hg, stretching of the abdominal wall and a large increase of the intraperitoneal space occurs without concomitant hernia development. Intraperitoneal pressure of 20 mm Hg causes a lethal compartment syndrome. Results: The internal inguinal ring is formed by the separation of two portions of transversalis fascia: Laterally, transversalis fascia is attached to the posterior edge of the inguinal ligament. Medial to the inferior epigastric vessels, transversalis fascia inserts into the Cooper ligament, at some distance from the inguinal ligament, and extends over the pubis into the cavity of the pelvis. The course of an indirect hernia corresponds to a tangentially acting aetiology. Intraperitoneal pressure acts at a right angle upon the oblique course of the processus vaginalis, causing compression and obliteration of the processus. Radially acting intraperitoneal pressure would have to be deviated at a right angle to cause de novo formation of an indirect hernia. Conclusions: The word and the historical notion of traumatic ‘rupture’ are misleading conceptions for groin hernia aetiology. In childhood, indirect hernia is a process of foetal development; at old age, a process of involution of the extraperitoneal fatty-fascial compartment. This involution is characterized by the formation of lipomas and, histologically, by fatty degeneration of connective tissue components. The extraperitoneal fatty-fascial compartment is contained by external oblique aponeurosis, not by transversalis fascia. This is the reason why a small prosthesis sublayed to external oblique aponeurosis is more effective than a much larger prosthesis sublayed to transversalis fascia. This concept is helpful in the strategy of using as little prosthetic material as possible.