Association between pelvic floor muscle trauma and contraction in parous women from a general population

Objective To study possible associations between pelvic floor muscle contraction, levator ani muscle (LAM) trauma and/or pelvic organ prolapse (POP) >= Stage 2 in parous women recruited from a general population. Methods This was a secondary analysis of data from a cross-sectional study of 608 parous women from a general population examined using the POP quantification system (POP-Q) and three-dimensional/four-dimensional transperineal ultrasound for identification of LAM macrotrauma (avulsion) and microtrauma (distension of levator hiatal area > 75th percentile on Valsalva maneuver). Muscle contraction was assessed using the modified Oxford scale (MOS), perineometry and ultrasound measurement of proportional change of anteroposterior hiatal diameter and levator hiatal area at rest and on pelvic floor muscle contraction. The Mann-Whitney U-test was used to study associations between pelvic floor muscle contraction, LAM trauma and POP. Results Women with macrotrauma (n = 113) had significantly weaker median pelvic floor muscle contraction, as measured using MOS and perineometry, than did women with an intact LAM (n = 493) (contraction strength was 1.5 (range, 0.0-5.0) vs 3.5 (range, 0.0-5.0) on MOS, and vaginal squeeze pressure was 15.0 (range, 0.0-78.0) cmH(2)O vs 28.0 (range, 0.0-129.0) cmH(2)O on perineometry; P < 0.001). This was also demonstrated by ultrasound measurement, with a proportional change in hiatal area of 19.9% (range, 4.1-48.0%) vs 34.0% (range, 0.0-64.0%) (P < 0.001) and proportional change in anteroposterior diameter of 16.2% (range, -5.7 to 42.6%) vs 26.0% (range, -3.4 to 49.4%) (P < 0.001). No statistically significant difference between women with (n=65), and those without (n=378), microtrauma was found after excluding women with macrotrauma. Women with POP had weaker muscle contraction than those without; in those with POP-Q >= 2 (n = 275) compared with those with POP-Q < 2 (n = 333), muscle contraction strength was 3.0 (range, 0.0-5.0) vs 3.5 (range, 0.0-5.0) on MOS, vaginal squeeze pressure was 21.0 (range, 0.0-98.0) cmH(2)O vs 28.0 (range, 3.0-129.0) cmH(2)O on perineometry, proportional change in hiatal area was 29.6% (range, 0.0-60.9%) vs 33.8% (range, 0.0-64.4%) and proportional change in anteroposterior diameter was 22.8% (range, -5.7 to 49.4%) vs 25.7% (range, -3.4 to 49.4%) (P < 0.001 for all). Conclusions LAM macrotrauma was associated with weaker pelvic floor muscle contraction measured using palpation, perineometry and ultrasound. Women with POP had weaker contraction than did women without POP. Copyright (c) 2018 ISUOG. Published by John Wiley & Sons Ltd.