The high prevalence of pelvic organ prolapse (POP) in women requires attention and constant review of treatment options. Sacrospinous ligament fixation (SSLF) for apical prolapse has benefits, high efficacy and low cost. SSLF can be performed using the anterior or posterior vaginal approach. There is still no consensus on which of the two approaches is safer. Our objective is to compare anterior and posterior vaginal approach in SSLF in relation with anatomical structures (pudendal artery, gluteal artery, and pudendal nerve) and to correlate them with body mass index (BMI).

This prospective and comparative study with consecutive fresh cadavers. SSLF was performed in fresh female cadavers by posterior  (suture I) and anterior (suture II) vaginal approach, using the CAPIO®SLIM device (Boston Scientific, Natick, MA). The choice of the device to conduct this study, from the range of devices available on the market, was based on the criterion of least tissue damage during ligament fixation. 
The inclusion criteria were defined as female cadavers and age over 18 years. The presence of abdominal or pelvic tumors was the only criterion for non-inclusion in this study. The distances from the point of fixation to the pudendal artery, pudendal nerve, and inferior gluteal artery were measured. The comparison of the distance between the sites of device insertion and the anatomical structures was performed using the paired Student’s t-test.

We evaluated 11 cadavers with a mean age of 70.1 ± 9.9 years and mean BMI 22.4 ± 4.6 kg/m2. The mean distance from the posterior SSLF to the ischial spine, pudendal artery, pudendal nerve and inferior gluteal artery were 21.18 ± 2.22 mm, 17.9 ± 7.3 mm, 19.2 ± 6.8 mm and 18.9 ± 6.9 mm respectively. The same measurements relative to anterior SSLF were 19.7 ± 2.7 mm, 18.6 ± 6.7 mm, 19.2 ± 6.9 mm, and 18.3 ± 6.7 mm. Statistical analysis showed no difference between the distances in the two approaches. 
There was a significant direct correlation in both the anterior and posterior vaginal approaches between the distances from the insertion point to the pudendal artery (p 0001 and  p 0,033 respectively) and to the pudendal nerve (p 0,001 and p 0,043 respectively) and cadaver BMI.

The knowledge of the anatomy of the region surrounding the sacrospinous ligament is imperative, which can be exposed through posterior pararectal dissection or anterior paravaginal dissection. The latest improvements have been implemented to reduce complications resulting from suture placement. It is recommended sutures to be fixed 2 centimeters from the ischial spine, on the upper edge of the ligament, not crossing its entire thickness. Our results suggested that high BMI provides greater safety in performing this procedure. The distances from the fixation point to the pudendal artery and nerve were directly proportional to the BMI. The higher the BMI, the greater the distances. We suppose that the increase of weight the structures end up being furhter one from the other and consequently enlarging the distances. However, the limited number of evaluated cadavers, with only one obese individual, does not allow drawing this conclusion.

There was no difference in the measurements obtained in the anterior and posterior vaginal approaches. A direct correlation between BMI and the distances to the pudendal artery and pudendal nerve was found.