Development of a safety zone for rectus abdominis fascia graft harvest based on dissections of the ilioinguinal and iliohypogastric nerves

Abstract

As a result of the vaginal mesh controversy, surgeons are performing more nonmesh, autologous fascia pubovaginal slings to treat stress urinary incontinence in women. The rectus abdominis fascia is the most commonly harvested site for autologous pubovaginal slings, so it is crucial that surgeons are familiar with the relationship between this graft harvest site and the ilioinguinal and iliohypogastric nerves, which can be injured during this procedure. The aims of this study were as follows: (1) to estimate the safest area between the bilateral courses of the ilioinguinal and iliohypogastric nerves in which a rectus abdominis fascia graft could be harvested with minimal risk of injury to these nerves and (2) to determine the location and dimensions of a graft harvest site that maximized graft length while remaining close to the pubic symphysis. The ilioinguinal and iliohypogastric nerves were dissected bilaterally in 12 unembalmed female anatomical donors. The distances of these nerves to a 10× 2 cm rectus abdominis fascia graft site located 4 cm above the pubic symphysis were measured. Nerve courses inferior to the graft site were determined for each donor by linearly extrapolating measurement points; analysis was performed with and without extrapolation. Average nerve trajectories were estimated assuming a linear regression function to predict the horizontal measurement as a quadratic function of the vertical distance; 95% confidence bands were also estimated. An estimated safety zone was determined to be the region between all credible nerve bounds. The largest safety zone that was closest to the pubic symphysis was located at 5.4 cm superior to the pubic symphysis. At this location, the inferior border of the graft could measure 9.4 cm in length (4.7 cm bilaterally from the midline). Extrapolated nerve courses below the study graft site yielded a smaller safety zone located 2.7 cm superior to the pubic symphysis, allowing for the inferior border of the graft to be 4.8 cm (2.4 cm bilaterally from the midline). A rectus abdominis fascia graft harvested 5.4 cm superior to the pubic symphysis with the inferior border of the graft measuring 9.4 cm in length should minimize injury to the ilioinguinal and iliohypogastric nerves. These dimensions allow for the longest graft while remaining relatively close to the pubic symphysis. The closer a graft is harvested to the pubic symphysis, the smaller in length the graft must be to avoid injury to the ilioinguinal and iliohypogastric nerves.