Pelvic floor support changes in postpartum pelvic organ prolapse with involvement of single and multiple compartments

To investigate longitudinal changes in pelvic floor support in primiparous women with pelvic organ prolapse (POP) after vaginal delivery, focusing on single- and multiple-compartment involvement.

Two hundred primiparas after vaginal delivery were prospectively enrolled and underwent pelvic floor MRI at six weeks postpartum. POP was diagnosed and classified into subgroups (single or multiple compartments involved) based on MRI findings. Primiparas with POP underwent repeat MRI at four months postpartum. Pelvic floor measurements, including injury score and functional parameters of the levator ani muscle (puborectal hiatus line, H line; muscular pelvic floor relaxation line, M line; levator hiatus area, LHA; iliococcygeus angle, ICA; levator plate angle, LPA), were assessed on MRI. Measurements were compared among POP subgroups and a normal control group (without POP) at six weeks postpartum. Additionally, changes between six weeks and four months postpartum were analyzed within POP subgroups.

Based on MRI criteria, approximately 41.5% of primiparas were diagnosed with POP, predominantly cystoceles commonly associated with uterine prolapse. Functional parameters of the levator ani, except for LPA at rest, were significantly increased in POP subgroups compared to controls. At four months postpartum, M line, H line, and LPA significantly decreased, and prolapsed organs were elevated in cases with multiple compartments involved, compared to six weeks postpartum. No significant changes were observed in cases with single-compartment involvement during follow-up.

A substantial proportion of primiparas experienced postpartum POP. Impaired levator ani function contributed to POP. Pelvic floor support improved during early postpartum in cases with multiple-compartment involvement.