Groin or femoral hernias may be concealed behind intact peritonea when the laparoscopic transabdominal preperitoneal (TAPP) mesh technique is used. The aim of this study was to determine the causes, frequency, and surgical procedures in cases of clinically diagnosed hernias without peritoneal defects.

A prospective controlled study comprising 1795 consecutive patients undergoing 2190 laparoscopic TAPP herniorraphies was conducted. All hernias were first subjected to clinical investigations by the surgeons. Intraoperatively, all suspicious hernias were examined with regard to the presence of peritoneal hernial sacs.

Of 2190 hernias, no hernia was seen transperitoneally in the laparoscopic procedures in 136 cases (6.2%). Forty-one femoral hernias (30.1%) were concealed behind intact peritonea. Forty-six lateral (33.8%) and 31 medial (22.8%) defects were sacless sliding fatty inguinal hernias.

When using the TAPP technique, in addition to femoral hernias, especially sacless sliding fatty inguinal hernias may be overlooked because of intact peritonea. Therefore, in cases of clinically diagnosed inguinal hernias, the preperitoneal space should be inspected intraoperatively to avoid unsatisfactory results.