Explorative Identification of Anatomical Parameters Associated with Successful Pessary Fitting in Pelvic Organ Prolapse Using Dynamic Magnetic Resonance Imaging

<b>Background:</b> Pelvic organ prolapse (POP) affects many women and is often managed with pessary treatment, yet predicting the success of fitting remains challenging. This study aims to identify anatomical parameters associated with successful and unsuccessful pessary treatment using dynamic magnetic resonance imaging (dMRI). <b>Methods:</b> A cross-sectional study in Maastricht University Medical Centre (MUMC+), the Netherlands. Sixteen women with a cystocele and/or descensus uteri minimal POP-Q stage 2, using pessary treatment, were included. All women underwent a dynamic MRI of the pelvic floor at rest, during contraction and on Valsalva. The anatomical parameters evaluated included various lengths and angles. The association between the anatomical parameters and pessary fitted is assessed using partial least squares regression. The predictive accuracy was tested using cross-validation based on the partial least squares model with the most important variables. <b>Results:</b> Seven of the sixteen women (43.8%) were in the non-fitting group (due to movement, rotation or expulsion of the pessary), and nine women (56.3%) were in the fitting group. Participants in the non-fitting group had a significantly lower body mass index (BMI). Variables such as total vaginal length (TVL) and certain angles were highly predictive of pessary fitting success, with variable importance of projection (VIP) scores indicating their importance. The prediction models showed accuracies ranging from 53.3% to 80.0%. <b>Conclusions:</b> In this explorative study, TVL, cervical length (CL), sacrococcygeal angle and pubococcygeal angle were key variables associated with pessary fitting success. These findings offer valuable insights for optimizing pessary fitting procedures and the development of new pessaries.