-Original-

Cases of Retroverted Uterus Involving Placenta Previa and Low-Lying Placenta Previa Are Significantly Associated with Endometriosis

Eika Harigane¹, Takashi Matsushima¹, Asako Watanabe¹, Hiroki Shinmura¹, Ryuhei Kurashina¹, Daisuke Shigemi² and Shunji Suzuki²

¹Department of Obstetrics and Gynecology, Nippon Medical School Musashi Kosugi Hospital, Kanagawa, Japan
²Department of Obstetrics and Gynecology, Nippon Medical School Hospital, Tokyo, Japan

Background: The purpose of this study was to determine whether cases of placenta previa and low-lying placenta previa in patients with retroverted uterus are significantly associated with endometriosis.
Methods: Participants were patients who underwent cesarean section at our hospital with a diagnosis of placenta previa or low-lying placenta previa within a 7-year period from January 2015 to December 2022. Of these, patients with multiple pregnancies and those without a complete uterine image in the medical record at less than 12 weeks' gestation were excluded. Included patients were divided into two groups according to the presence or absence of endometriosis. The presence of endometriosis was determined based on intraoperative findings. A retrospective case-control study was conducted by examining the presence or absence of retroverted uterus during early pregnancy and the presence or absence of posterior placenta.
Results: A total of 110 patients were included, 32 in the group with endometriosis and 78 in the group without endometriosis. There were 15 (46.9%) cases of retroverted uterus in the group with endometriosis and 17 (21.8%) in the group without endometriosis, indicating significantly more cases in the group with endometriosis (P=0.01). There were 15 (46.9%) cases of retroverted uterus with posterior placenta in the group with endometriosis and 16 cases (20.5%) in the group without endometriosis, indicating significantly more cases in the group with endometriosis (P=0.009).
Conclusion: Placenta previa and low-lying placenta previa in cases of retroverted uterus are significantly associated with endometriosis.

J Nippon Med Sch 2025; 92: 22-28

Keywords
endometriosis, low-lying placenta previa, placenta previa, posterior extrauterine adhesions, retroverted uterus

Correspondence to
Eika Harigane, Department of Obstetrics and Gynecology, Nippon Medical School Musashi Kosugi Hospital, 1-383 Kosugi-cho, Nakahara-ku, Kawasaki, Kanagawa 211-8533, Japan
641se@nms.ac.jp

Received, April 24, 2024
Accepted, September 30, 2024