Retained products of conception in placenta previa without placenta accreta spectrum: who requires transarterial embolization and/or hysterectomy?

Background: To characterize patients with retained products of conception (RPOC) in placenta previa (PP), and to determine who requires transarterial embolization (TAE) and/or hysterectomy after cesarean section (CS). We focused on RPOC in PP without placenta accreta spectrum. Methods: The retrospective cohort study was performed in patients with RPOC in PP between April 2006 and June 2019 in our institute. Results: Of 498 patients with PP, RPOC were observed in 25. The median RPOC length was 4.4 cm (interquartile range: 2.8.-5.7). RPOC hypervascularity was observed in 10 (10/18, 56%) patients. Of the 25 patients, an additional hemostatic intervention (TAE and/or hysterectomy) was required in 12 (48%). The duration between CS and TAE and/or hysterectomy ranged from 0-66 days. Of those, eight (8/12: 67%) patients needed the interventions on the day of surgery (day 0). Univariate analyses showed that patients having received TAE and/or hysterectomy bled more at CS (p = 0.011) and more frequently required blood transfusions at CS (p = 0.011), and were more likely to have hypervascular RPOC (p = 0.036). Conclusion: Hypervascular RPOC and bleeding episodes at CS may predict the requirement of TAE and/or hysterectomy after CS in patients with PP.