Sonographic evaluation of retained products of conception within 48 h following delivery: a retrospective cohort study

Objective: Early diagnosis of retained products of conception (RPOC) is critical for directing clinical management and for preventing associated complications. This study aimed to evaluate the utility of post-delivery ultrasound in patients with risk factors for RPOC. Study design: A retrospective cohort-study was conducted in a single tertiary university-affiliated hospital (January 2016–September 2022). Sonographic evaluation, including endometrium thickness measurement and color Doppler, were reviewed of women with risk factors for RPOC: postpartum hemorrhage, a hemoglobin drop > 4 g/dl, manual removal of the placenta, and suspicious placenta. Results of early postpartum ultrasound (within 48 h), misoprostol administration and hysteroscopies were evaluated. Results: Of the 591 women included, RPOC was suspected in 141 (24%). Endometrial thickness > 5 mm was associated with sonographic RPOC diagnosis in 58%. Suspected sonographic RPOC was concluded for 100%, 92% and 7% of the women with marked, moderate, and undetectable vascularity, respectively, p < 0.001. Misoprostol 1000 mcg per rectum (PR) was administered to 86% of those with suspected RPOC; only 11% of them needed an operative hysteroscopy for removal of the RPOC. RPOC on a pathology report was confirmed for 71% of those who underwent hysteroscopy. Conclusions: Postpartum transabdominal ultrasonography within 48 h of delivery was effective for assessing RPOC. For appropriate triage, color Doppler grading increased the accuracy of RPOC diagnosis. Misoprostol treatment was successful in 88% of women with suspected sonographic RPOC. The combination of sonographic evaluation and misoprostol treatment for suspected RPOC might lower the rate of unnecessary invasive procedures.