The preperitoneal loop in inguinal hernia repair following the totally extraperitoneal technique

With increasing experience in totally extraperitoneal (TEP) hernia repair, we observed an anatomical structure not described in the literature. It is a loop-like structure under the ductus deferens or ligamentum teres uteri anchored laterally and medially to the peritoneum. Relatively constant in distance to the inner inguinal ring and individual in the grade of prominence, it inhibits correct patch placement medially. To identify and describe this so-called preperitoneal loop (pl), we performed this study.

Between February 2nd and July 15th 2006, all patients undergoing a TEP procedure at our institution in primary inguinal hernia without previous operations in the lower abdomen were included. The main topic was the prominence and distance to the inner inguinal ring of the pl and histological examinations were made.

A total of 219 patients (194 male, 25 female) were included, with 97 right-side, 64 left-side and 58 bilateral hernias. The pl could be shown in 206 cases (94%), the distance to the inner ring was up to 1.5 cm in 60, between 1.5 and 3.0 cm in 112, and over 3 cm in 34 cases. Anatomical examinations showed smaller blood vessels embedded in fatty tissue and surrounded by collagen fibres (standard haematoxylin eosin [HE]) and collagen connective tissue strongly filled with elastic fibres and, occasionally, nerve fibres and lymphatic capillaries (van Gieson).

The pl is a very constant structure that is independent of gender and hernia type and size. In most cases, it is found close to the inner inguinal ring and, therefore, has to be cut for adequate parietalisation of cord structures/ligamentum teres uteri and correct mesh placement medially. As no mesothel was found, the origin of pl might be the deeper sheet of transversalis fascia.