Levator defects affect perineal position independently of prolapse status

Abstract

Objective Determine the effect of levator defects on perineal position and movement irrespective of prolapse status. Study Design Forty women from an ongoing study were divided into two groups of 20 women with and without severe levator defects. Prolapse status was matched between groups with 50% having stage III or greater anterior wall prolapse. Perineal structure locations were measured against standard axes on MR scans at rest, maximum contraction (Kegel), and maximum Valsalva. Differences in location were calculated and compared. Results In women with levator defects, independent of prolapse status: (1) at rest the perineal body was 1.3 cm and the anal sphincter 1.0 cm more caudal (p≤ 0.01); at maximum contraction the perineal body and the anal sphincter were both 1.2 cm more caudal (p≤ 0.01); with maximum Valsalva the perineal body was 1.3 cm more caudal and the anal sphincter was 1.2 cm more caudal (p≤ 0.01). (2) At rest the levator hiatus was 0.8 cm larger and the urogenital hiatus was 1.0 cm larger (p≤ 0.01). (3) At rest the bladder was 0.07 cm more posterior (p≤ 0.02) and with maximum contraction 1.9 cm lower (p≤ 0.02). (4) With maximum Valsalva the bladder was 1.5 cm lower and displaced further caudally (p≤ 0.03). Conclusions Controlling for prolapse, women with levator defects have a more caudal location of their perineal structures and larger hiatuses at rest, maximum contraction, and maximum Valsalva.

Mobility of the perineal body and anorectal junction before and after childbirth

“…Advanced dynamic imaging is needed to assess movement and function of this structure in live women. While MRI can define the perineal body, the low resolution of dynamic MR limits its usefulness in this regard [5,9].…”

“…Avulsion of the puborectalis muscle, i.e., trauma to the insertion of this muscle on the os pubis, is a common consequence of vaginal childbirth, especially a first vaginal delivery [8]. In an MRI study in women with levator defects, the perineal structures were found to be located more caudally at rest [9]. Since an enlarged hiatal area compromises the support of all pelvic organs, vaginal delivery is likely to increase the mobility of perineal body and anorectal junction.…”

Comparison of muscle fiber directions between different levator ani muscle subdivisions: in vivo MRI measurements in women

“…Two functional characteristics of the LA muscle have been described: its ability to lift (vertically in the standing posture) the pelvic organs, and its action in squeezing the levator hiatus closed (horizontally in the standing position) [14, 15]. It is unclear, at present, how much each component of the levator contributes to each of these two actions.…”

Relevance of open magnetic resonance imaging position (sitting and standing) to quantify pelvic organ prolapse in women

“…Likewise, a study by DeLancey and Hurd 44 also reported that uroginal hiatus size is related to prolapse size. 47 In this study, MRO images displayed significant elongation in dimensions of H and M lines that was seen in all POP patients in standing and supine positions but not in the control group. We recognize that the ongoing debate over reference lines applied to MRI is a limitation that impacts our study.…”