Estimated Levator Ani Subtended Volume (eLASV): A Novel Assay for Predicting Surgical Outcomes in Pelvic Organ Prolapse

Pelvic floor disorders affect millions of women within the United States daily, with nearly 25% of all women currently have some form of pelvic floor dysfunction [1]. An estimated 200,000 women undergo surgery annually for pelvic organ prolapse [4-6], and recent projections estimate that the number will increase to approximately 250,000 by year 2050 [7]. Up to 30% of these women, will undergo a second surgical procedure for recurrence of prolapse following their first surgery [2]. Astoundingly, resulting in 60,000 - 75,000 women a year undergoing a second advanced gynecological surgical procedure for pelvic organ prolapse consequently increasing the patients' perioperative risk and the overall cost of women's healthcare nationwide.

Levator ani muscle plays an important role in pelvic support. Weakening or direct trauma to the muscle is currently the best-defined pathogenesis for development of pelvic organ prolapse and for the recurrence of prolapse after surgical repair [7-13]. Levator ani avulsion has been demonstrated to be a clinical predictor of cystocele recurrence following anterior colporrhaphy with native tissue and with mesh augmentation [11,12]. However, further studies are warranted to investigate of levator ani muscle integrity as a predictor for surgical outcomes after more advance surgical procedures.

The investigators demonstrated an objective measure of levator ani muscle integrity (eLASV) calculated from standard 2D dynamic pelvic MRI measurements (H-line and M-line) obtained directly from radiology reports along with one 2D linear measurement that is easily obtained from radiographic images [13-15]. The novelty of eLASV as a measurement of the entire muscle integrity, separates it methodology from the solitary of diagnosing partial trauma or defects as previously published within the literature. eLASV is a novel objective measurement of levator ani muscle integrity and measures all three portions of the muscle (puborectalis, pubococcygeus, and iliococcygeus) as a whole complex. Transvaginal and transperineal ultrasonography along with CT scans or xRays of the pelvic floor are unable to image at the high level resolution imperative for complete reconstruction of the entire levator ani muscle.

Each woman's levator ani muscle anatomical shape is unique to her as a result of her own individual lifetime risk for developement of pelvic floor dysfunction. Consider the levator ani muscle as a kitchen bowl varying in different shapes and sizes for each individual woman. Now consider filling these varying shapes and sizes of the kitchen bowls with water, eLASV is the objective three dimensional measurement of the volume of water contained within each different muscle complex.

When the volume of eLASV is elevated, it represents a measurable change in the anatomical shape of the muscle as a result of loss of the muscle integrity for support of the pelvic floor. As Decreased support of the levator ani muscle within the pelvic floor will result in an increased strain on the supportive ligament structures within the female pelvis [16,17]. Increased strain on the supportive structures including the uterosacral ligament, sacrospinous ligament, paravaginal support, etc., could result in an increased risk of recurrence for prolapse following advance pelvic reconstructive surgery.