摘要：The purpose of this study was to describe levator ani (LA) anatomy in postterm nulliparas using 3- dimensional (3- D) magnetic resonance (mR). Study design: Nulliparas (n = 84) with uncomplicated, postterm pregnancies underwent an mR (4 mm slices, 0 gap) of the uterus and pelvis. LA volume and morphometry were assessed using 3- D post-processing software. Results: LA insertion into the symphysis was visible in 93% , and the iliococcygeus muscle assumed a convex shape (arch) in the 92% of the 84 women. The LA shape was characterized as “ U” in 53% and “ V” in 47% . mean LA volume was 13.5 (3.7) cm3. There was a positive association between LA volume and higher fetal station (P = .02) and increasing BmI (P < .001). However, no relationship between LA volume and station was found after adjusting for BmI. Conclusion: BmI was correlated with LA volume in postterm nulliparas. LA insertion into the symphysis and the iliococcygeus arch were well-preserved overall and morphometry was variable.