Appearance of the levator ani muscle subdivisions in endovaginal three-dimensional ultrasonography.

Abstract

To formulate an evaluation system and authenticate the levator ani subdivisions visible on endovaginal three-dimensional ultrasonography. A three-dimensional endovaginal ultrasound examination was performed on five fresh-frozen female pelves. The location of the pubovaginalis, puboperinealis, puboanalis, puborectalis, and iliococcygeus muscles was identified. Three-dimensional endovaginal ultrasound scans of 22 nulliparous women with normal pelvic floors were obtained, and a three-level evaluation system was constructed. Level 1 contained the muscles as they insert into the perineal body. Level 2 evaluated the insertions into the retropubic area and typically contained the pubovaginalis, puboperinealis, puboanalis, and puborectalis. Level 3 contained muscles that were cephalad to the pubic bone. Two blinded reviewers assessed levator ani subdivision visualization at each level and individual muscle visualization by the origin-insertion points. There was 98%, 96%, and 92% agreement for levels 1, 2, and 3 muscles, with 95% confidence intervals (CIs) of 0.92-1, 0.95-0.99, and 0.88-0.95, respectively. Kappa values (95% CI) for agreement were calculated for individual muscles as follows: superficial transverse perinei and puborectalis were seen by both raters 100%, puboperinealis, pubovaginalis, and puboanalis 0.645 (0.1-1), and iliococcygeus 0.9 (0.6-1). The location of the pubovaginalis, puboperinealis, puboanalis, puborectalis, and iliococcygeus as seen by three-dimensional endovaginal ultrasonography was confirmed through anatomic dissection of fresh-frozen pelves. Subdivisions of the levator ani muscle were visualized reliably with three-dimensional ultrasonography using a systematic approach. III.