Postpartum Changes in Levator Plate Shape and Genital Hiatus Size After Vaginal Delivery

Vaginal delivery is a risk factor for pelvic organ prolapse. We sought to quantify changes in level III pelvic support measurements at 7 weeks and 8 months following vaginal delivery.

This secondary analysis included primiparous women who underwent pelvic MRI and clinical examinations at 7 weeks and 8 months after vaginal delivery. Demographics and obstetrical data were abstracted. Mid-sagittal resting MRIs were used to perform level III measurements including urogenital hiatus (UGH), levator hiatus (LH), and mid-sagittal levator area (LA), and to trace the levator plate (LP). Using principal component analysis, 7-week and 8-month principal component scores (PC1s) and MRI measurements were compared using paired t test. If the PC1 score change from 7 weeks to 8 months was > 0, women were considered to have a more dorsally oriented LP shape.

Of 76 participants, POP-Q values did not significantly differ between 7 weeks and 8 months, but MRI measurements improved (UGH: 3.9 ± 0.8 vs 3.5 ± 0.8, p < 0.001; LH: 5.4 ± 0.8 vs 5.2 ± 0.8, p = 0.01; LA: 18.0 ± 6.0 vs 15.2 ± 6.5, p < 0.001). Approximately 30% (22 out of 76) had a more dorsally oriented LP shape and larger level III measurements at 8 months than women with a more ventrally oriented LP shape (LA: 86.4% vs 1.9%, p < 0.001; LH: 16% vs 12%, p < 0.001; UGH: 59.1% vs 3.7%, p < 0.001).

After vaginal delivery, most women had "recovery" of level III support-defined by smaller UGH, LH, and LA measurements-and a more ventrally oriented LP shape. However, nearly 30% had larger level III measurements and a more dorsally oriented LP shape, indicating "impaired recovery" of support.