Cervical angle as a possible predictor of abnormal placental position in women with endometriosis

Background We aimed to examine the effects of endometriosis on the rate of abnormal placentation by comparing the data of pregnant women with and without endometriosis. Methods A case–control study was conducted to compare the perinatal outcomes between women with and without endometriosis. In the subgroup analysis, magnetic resonance imaging (MRI) scans of pregnant women with placenta previa were used to measure the cervical angle and its relationship with endometriosis. The cervical angle was measured as the angle between the cervical glands and the line perpendicular to the spinal column in each sagittal MRI section. Results We retrospectively analyzed data from 3453 cases of singleton deliveries between 2015 and 2019 at two study facilities. Among them, 159 had clinically or surgically confirmed endometriosis. The odds ratio (OR) for abnormal placental position was significantly higher in pregnant women with endometriosis (OR. 2.82; 95% confidence interval [CI], 1.58–5.04). The OR was 3.21 (95% CI, 1.57–6.55) in the endometriosis‐surgery group (91 patients) and 2.32 (95% CI, 0.91–5.88) in the non‐surgery group (68 patients). Furthermore, 44 women who underwent pelvic MRI after 30 weeks of gestation were included to examine the cervical angle. Then, we compared the date of pregnant women with (n = 6) and without endometriosis (n = 38). Regardless of placental attachment position, the cervical angle was significantly lower in the group with than in the group without a history of endometriosis. Conclusion Pregnant women with a history of endometriosis may have stronger uterine retroversion, which could potentially contribute to abnormal placental positioning.