Enlargement of the levator hiatus in female pelvic organ prolapse: cause or effect?

AIM This study was undertaken to investigate whether female pelvic organ prolapse repair changes levator hiatal biometry. METHODS Retrospective analysis of clinical and translabial ultrasound volume data of women who underwent prolapse surgery at a tertiary urogynaecological unit between March 2005 and April 2009. Data sets of 81 women were analysed who had undergone an interview, clinical assessment using POP-Q staging and 3D translabial ultrasound before and after prolapse surgery. Imaging data were obtained preoperatively and 3-12 months postoperatively to determine potential changes in levator hiatal dimensions. Type of surgery, mesh use, symptoms of recurrent prolapse, age, significant recurrent prolapse and length of follow-up were tested in linear regression as potential confounders. RESULTS The mean preoperative hiatal area on Valsalva was 31.9 cm(2) (range 13.5-58.1 cm(2), SD 10.0 cm(2)). Mean postoperative hiatal area on Valsalva was 28.9 cm(2) (range 13.9-47.4 cm(2); SD 7.3 cm(2)), which implies a significant reduction of 9% (P = 0.001). None of the tested potential confounders were found to be significantly associated with a perioperative change in hiatal area on Valsalva on linear regression analysis. CONCLUSIONS Surgery for female pelvic organ prolapse is associated with a small but significant reduction in hiatal area, but abnormal hiatal distensibility persists in most cases. This suggests that excessive hiatal distensibility is more likely the cause rather than the effect of prolapse.