Levator ani muscle volume and architecture in normal vs. muscle damage patients using 3D endovaginal ultrasound: a pilot study

Introduction and hypothesis: This study aimed to compare the difference in levator ani muscle (LAM) volumes between 'normal' and those with sonographically visualized LAM defects. We hypothesized that the 'muscle damage' group would have a significantly lower muscle volume. Methods: The study included patients who had undergone a 3D endovaginal ultrasound. The normal (NM) and damage (DM) muscle groups’ architectural changes were evaluated based on anterior-posterior (AP), left-right (LR) diameter, and minimal levator hiatus (MLH) area. The puboanalis-puboperinealis (PA), puborectalis (PR), and pubococcygeus-iliococcygeus (PC) were manually segmented using 2.5 vs. 1.0 mm to find the optimal sequence and to compare the volumes between NM and DM groups. POPQs were compared between the NM and DM groups. Results: The 1.0-mm segmentation volumes created superior volume analysis. Comparing NM to the DM group showed no significant difference in LAM volume. Respectively, the mean total LAM volumes were 17.27 cm³ (SD = 3.97) and 17.04 cm³ (SD = 4.32), p = 0.79. The mean MLH measurements for both groups respectively were 10.06 cm² (SD = 2.93) and 12.18 cm² (SD = 2.93), indicating a significant difference (p = 0.01). POPQ analysis demonstrated statistically significant differences at Ba and Bp parameters suggesting that the DM group had worse prolapse (p = 0.05, 0.01, respectively). Conclusions: While LAM volumes are similar, there is a significant difference in the physical architecture of the LAM and the POPQ parameters in muscle-damaged patients compared to the normal group.