Static and dynamic MRI features of the levator ani and correlation with severity of genital prolapse

To describe the static and dynamic MRI features of the levator ani, and evaluate whether they are associated with the MRI evaluation of the severity of genital prolapse.

Static and dynamic MRI of 40 patients, referred for evaluation prior to genital prolapse surgery, were reviewed retrospectively. Prolapse severity was evaluated on MRI at maximal straining by descent of the bladder neck under the pubococcygeal line for the anterior compartment, by descent of the uterine cervix under the pubococcygeal line for the middle compartment, and by anterior bulging of the rectum for the posterior compartment. For evaluation of the levator ani, the following parameters were recorded: (1) at rest: thinning or defects in both puborectalis and iliococcygeus muscles, (2) at rest and at straining: urogenital hiatus length and width, M line, iliococcygeal and levator plate angles. The levator ani features were tested for potential associations with the MRI evaluation of prolapse severity.

Bladder neck descent at straining was correlated with the levator plate angle at rest (p=0.001), and with the hiatus length at rest (p=0.02), and at straining (p=0.008). Uterine cervix descent at straining was correlated with the hiatus length (p=0.0005), and width (p=0.014) at straining, M line (p=0.002) and levator plate angle (p=0.007) at straining, whereas anterior rectal bulging at straining was paradoxically inversely correlated with the hiatus width at rest (p = 0.04).

In a population of women with genital prolapse, MRI evaluation of the levator ani was associated with MRI evaluation of the severity of genital prolapse.