Patient characteristics
In total, 3545 consecutive patients who underwent pelvic MRI from July 2018 to June 2019 were reviewed. Of these patients, 2931 met the exclusion criteria, and 614 cases remained in the final analysis (Fig. 2). The study sample had a median age of 43 [range: 17 to 76] years and a median body mass index of 22.4 [range: 15.6 to 38.8] kg/m2. In total, 63.5% (390/614) of the patients had laparoscopic or transabdominal surgery records. The enrolled patients were stratified by age, with 120 patients aged ≤ 30 years, 282 patients aged between 31 and 49 years, and 212 patients aged ≥ 50 years old. The differences in height, weight, BMI and position of uterus among these three groups were limited as shown in Table S1. However, the parity times significantly differed among the groups (p < .001). The women aged ≥ 50 years had the highest rate of multiparity (49.1%, 104/212) and highest rate of vaginal delivery (92.9%, 197/212) but the lowest rate of nullipara (0.9%, 2/212). The women aged between 31 and 49 years were mostly primiparous (59.6%, 168/282), and the vaginal delivery rate was 52.8% (149/282), while the women aged ≤ 30 years were mostly nulliparous (79.2%, 95/120), and the vaginal delivery rate was only 12.5% (15/120). These findings are presented in Table S1.