Defecation versus pre- and post-defecation Valsalva maneuvers for dynamic MR assessment of pelvic floor dysfunction

To compare prevalence and severity of multi-compartment pelvic floor dysfunction between supine magnetic resonance defecography with defecation (MRD) and supine dynamic MRI during Valsalva, both with and without rectal distention.

This was an IRB-approved, HIPAA-compliant retrospective review of consecutive patients referred for MR Defecography. MRD protocol included imaging at rest, during pre-defecation Valsalva (Pre-DV), defecation (Def), and post-defecation Valsalva (Post-DV). The Post-DV images were performed after complete evacuation either during the defecation acquisition or, in cases where patient was unable to defecate during the examination, in a conventional toilet. Size of cystocele, vaginal prolapse, anorectal (AR) descent, and enterocele were measured on all acquisitions relative to the pubococcygeal line. Rectocele size was recorded in anteroposterior dimension. The presence or absence of rectal intussusception (RI) was documented. The prevalence, absolute size, and grades of prolapse, rectocele, and RI were compared between the acquisitions using pair-wise ANOVA, Friedman, Dunn pair-wise, and Cochran-Mantel-Haenszel tests.

30 patients were included in the final analysis. Higher prevalence of cystocele, vaginal prolapse, enterocele, AR descent grade 2 or higher, rectocele grade 2 or higher, and RI were seen on Def compared to Post-DV and Pre-DV. Cystocele, vaginal prolapse, enterocele, AR descent, and rectocele sizes were significantly larger on Def compared to Post-DV by 0.7-1.95 cm (p ≤ 0.007). Prolapse in all compartments and rectocele size were significantly larger on Def compared to Pre-DV (p < 0.0001). Cystocele, vaginal prolapse, and enterocele sizes were significantly larger on Post-DV compared to Pre-DV (p < 0.0001). There were significant differences in grading of all types of prolapse and rectocele between the various acquisitions of MRD (p < 0.0001). Cystocele, AR descent, and rectocele grades were significantly higher on Def compared to Post-DV (p range ≤ 0.0002). Grading of all types of prolapse and rectocele was significantly higher on Def compared to Pre-DV (p < 0.0001). Cystocele, vaginal prolapse, and enterocele grades were all significantly higher on Post-DV compared to Pre-DV (p  ≤ 0.0007).

Defecation images during supine MRD elicit higher prevalence and size of prolapse of all pelvic compartments in comparison to both pre- and post-defecation Valsalva images. Post-defecation Valsalva images show larger size of anterior and middle compartment prolapse than pre-defecation Valsalva images. Functional evaluation of pelvic floor dysfunction with MRI should include image acquisition during defecation. If Valsalva images are acquired, these should be performed after the defecation acquisition and without rectal distention.