Prospective evaluation of clinical characteristics and maternal outcomes of women with pathologically confirmed postpartum retained placental fragments.

Objective: To determine the incidence, risk factors, and short-term maternal outcomes of women with pathologically confirmed retained products of conception (RPOC) following vaginal delivery.

Methods: Prospective cohort study of women with suspicion of RPOC following vaginal delivery, from March 2018 to April 2019. Women were followed for eight weeks postpartum. Women with complete retained placenta were excluded. Women with pathologically confirmed RPOC were compared to those without. Univariate analysis was conducted (ORs; [95% CI]) and was followed by multivariate analysis (aOR; [95% CI]).

Results: During the study period, there were 16,583 vaginal deliveries. A total of 96 women (0.58%) with a suspicion of RPOC were enrolled, of these, 53 women (55%) had pathologically confirmed RPOC. The most significant risk factors for pathologically confirmed RPOC were placental abruption (aOR 5.0 [2.29-11.13]) and Oxytocin augmentation of labor (aOR 1.7 [1.07-2.63]). Pathologically confirmed RPOC were associated with higher rates of prolonged hospitalization (OR 9.2 [2.83-30.05]), postpartum hemorrhage (PPH) (OR 6.6 [3.60-11.98]), hemoglobin drop > 3 g/dl (OR 11.4 [5.49-23.49]), and blood transfusion (OR 8.6 [2.07-38.18]). Women who had exploration of uterine cavity without pathological confirmation of RPOC, still had higher rates of perineal laceration (OR 17.6 [4.93-63.08]), PPH (OR 6.1 [3.05-12.21]), and a hemoglobin drop > 3 g/dl (OR 6.0 [2.13-16.95]).

Conclusions: Pathologically confirmed RPOC following vaginal delivery has unique characteristics and is associated with significantly higher rates of PPH and blood transfusions. These findings may assist in the development of better criteria for selecting women for manual exploration and for preventive measures to reduce PPH and complications.