Levator ani muscle (LAM) anatomical volume compared to age and body mass index (BMI) of patients.

Introduction And Hypothesis: The levator ani muscle (LAM) plays an important role in pelvic support. Estimated levator ani subtended volume (eLASV) is an objective measurement of the anatomical volume of the LAM obtained from pelvic MRIs. The aim of this study was to assess the relationship between the anatomical volume of LAM to the age and body mass index (BMI) of a surgical patient based on our previous published cutoff value of increased LAM volume as measured by pelvic MRIs (eLASV > 38.5). We hypothesize that increasing age and BMI will both be correlated with the increasing volumes of LAM.

Methods: We conducted a secondary analysis of an Institutional Review Board-approved retrospective cohort study. Standard protocol pelvic MRI measurements, including the pubococcygeal line, H-line, and M-line, were collected along with the calculated width of the levator ani hiatus (eLASV = - 72.838 + 0.598H-line + 1.217 M-line + 1.136WLH). Comparison to patients' age and BMI was assessed using the Wilcoxon-Mann-Whitney (continuous) and chi-square test (group). Spearman's correlation analysis was used to explore the relationship between age and BMI to eLASV.

Results: Patients with elevated LAM volumes of eLASV were more likely to be older than patients with low volume of LAM, with median age 65 (37, 83) vs. 49.5 (28, 72), respectively (p < 0.001). We observed no difference in median BMI between patients with elevated volumes of eLASV compared with patients with low volumes of eLASV.

Conclusions: Increasing age of women appears to be directly related to elevated volumes for levator ani muscle morphology when measured with eLASV.