Transperineal ultrasound of the levator hiatus following minimally invasive sacrocolpopexy

Objectives: To evaluate the impact of minimally invasive sacrocolpopexy (MISC) on transperineal ultrasound (TPUS) pelvic floor measurements, specifically the levator hiatal area (LHA) pre- and postoperatively. We hypothesized that women who undergo MISC will have a significantly smaller LHA postoperatively compared to preoperative measurements.

Methods: This is a pilot study which was a sub-aim of a randomized, controlled trial (MERIT) within a large, academic urogynecology practice. Females with pelvic organ prolapse and an enlarged genital hiatus (≥4cm but < 7.5cm) and planning MISC were randomized to concomitant posterior colporrhaphy and/or perineorrhaphy (PR) or no concomitant PR. Subjects had TPUS preoperatively and 6 months postoperatively. The primary outcome was change in LHA. Secondary outcomes included changes in: levator hiatal circumference (LHC), levator hiatal diameter (LHD), levator hiatal volume (LHV), perineal body length (PB), and the distance between the pubic symphysis to posterior hymen (PSPH). TPUS images were obtained by specialized ultrasound technicians using a GE Voluson 3D transperineal probe with subjects in dorsal lithotomy position and an empty bladder. The probe was held in the longitudinal position to obtain an image in the midsagittal plane. All measurements were obtained in the plane of minimal dimensions at rest, contraction and strain, Figure. Paired t tests were used for pre- and post-operative comparisons and confirmed with Wilcoxon Signed rank; to compare measurements between randomization assignments, independent t tests were used (JMP Pro 16).

Results: Six subjects completed pre- and postoperative ultrasounds with median age 61.5 years and median BMI 30.3 kg/m². All subjects identified as White and non-Hispanic with a median vaginal parity of 2.5. All had preoperative prolapse stage 2 or stage 3 (n=3, n=3). The study MISC was their first prolapse reconstruction for 5 of 6 patients. Four subjects were randomized to no additional repair, and all received treatment as randomized.

For the primary outcome, mean LHA showed a significant decreased from preoperative to postoperative only with strain (-5.7cm², p=0.02), Table 1A. Concomitant PR was not associated with change in LHA, Table 1B. The length of the PB was significantly increased at rest after MISC (mean difference 0.32cm, p=0.03), but not with strain or contraction, Table 1A. Similarly, concomitant PR was not associated with change in PB Table 1B. The LHD, LHC, LHV, and PSPH all showed significant decreases between pre and post TPUS on straining measurements, Table 1A.

Conclusions: MISC results in identifiable changes to pelvic floor muscle measurements as visualized on straining TPUS. Performing a concomitant PR did not seem to impact pelvic floor measurements, although we are limited by a very small sample size. Additional research is needed to confirm these findings and assess clinical relevance.