Alterations in pelvic floor muscles and pelvic organ support by pregnancy and vaginal delivery in squirrel monkeys.

INTRODUCTION AND HYPOTHESIS: The objective of this study was to measure the effects of pregnancy and parturition on pelvic floor muscles and pelvic organ support.

METHODS

Levator ani, obturator internus, and coccygeus (COC) muscle volumes and contrast uptake were assessed by MRI of seven females prior to pregnancy, 3 days, and 4 months postpartum. Bladder neck and cervix position were measured dynamically with abdominal squeezing.

RESULTS

The sides of three paired muscles were similar (p > 0.66). COC volumes were greater (p < 0.004) after parturition than before pregnancy or after recovery. COC contrast uptake increased (p < 0.02) immediately after delivery. Bladder neck position both in the relaxed state and abdominal pressure descended (p < 0.04) after delivery and descended further (p < 0.001) after recovery. Cervical position in the relaxed state before delivery was higher (p < 0.001) than postpartum but was unchanged (p = 0.50) with abdominal pressure relative to delivery.

CONCLUSION

In squirrel monkeys, coccygeus muscles demonstrate the greatest change related to parturition, and parturition-related bladder neck descent seems permanent.