Objective This study was done (I)to determine whether congenital indirect inguinal hernias in male pigs could be repaired by placing a polypropylene mesh prosthesis over the defect intra-abdominally, (2) to measure the incidence of adhesions between intra-abdominal viscera and the prosthesis with and without the adhesion barrier oxidized regenerated cellulose, (3) to determine the incidence of other complications, and (4) to assess the effect on fertility. Summary Background Data Several techniques for laparoscopic inguinal herniorrhaphy are currently being evaluated to determine whether there are advantages over conventional inguinal herniorrhaphy. Perhaps the most controversial is the intraperitoneal onlay mesh procedure (IPOM). Its advantage is its simplicity (in that the repair is accomplished by placing a prosthesis over the hernia defect intraabdominally, avoiding a groin dissection). Its disadvantage is the potential for complications because the prosthesis is in contact with the intra-abdominal viscera. Methods In male pigs, polypropylene mesh alone or polypropylene mesh plus the adhesion barrier oxidized regenerated cellulose (composite prosthesis) was fixed to the peritoneum surrounding the hernia defect. In phase 1 (6-week follow-up), two groups of 13 pigs each underwent herniorrhaphy at laparotomy or laparoscopy. In phase 2 (7.1-month fellow-up), 21 pigs underwent laparoscopic herniorrhaphy. Results All IPOM herniorrhaphies were successful. The prostheses adhered most frequently to the bladder, followed by small bowel, peritoneum, and cord structures. Prosthetic erosion into these organs was not observed. Laparoscopically placed prostheses in phases 1 and 2 had significantly less surface covered by adhesions (13% +/- 13% and 19% +/- 27%, respectively) and a lower adhesion tenacity grade (1.5 +/- 0.9 and 1.3 +/- 1.1, respectively) than those placed at laparotomy (44% +/- 27% and 2.5 +/- 0.7, respectively; p < 0.01). In phase 1, a histologic evaluation of laparoscopically placed specimens demonstrated significantly thinner above-mesh fibrotic ic tissue compared with the prostheses implanted at laparotomy (p < 0.04). In either phase, the use of the adhesion barrier did not produce any histologic difference between the polypropylene alone and the composite prosthesis. Fertility studies were performed in phase 2 and showed no adverse effects caused by either prosthesis. Conclusions This study demonstrated that the intraperitoneal placement of a polypropylene prosthesis was an effective technique for indirect inguinal herniorrhaphy in a pig. Furthermore, with laparotomy, the addition of oxidized regenerated cellulose significantly decreased the rate of adhesion formation to the prosthesis. However, oxidized regenerated cellulose would appear to have no value when used with a prosthesis placed laparoscopically.
