Ultrasound Assessment of Retained Products of Conception (RPOC): Insights from the Current Literature

Retained products of conception (RPOC) represent a significant cause of morbidity in the post-abortive and postpartum periods, potentially leading to abnormal uterine bleeding, pelvic pain, infections, and intrauterine adhesions. Accurate diagnosis is crucial to avoid unnecessary surgical interventions and to preserve future fertility. Transvaginal ultrasound constitutes the primary imaging modality for identifying RPOC, but the lack of standardized diagnostic criteria complicates clinical decision-making. This narrative review explores the current literature on sonographic findings associated with RPOC, focusing on the diagnostic value of endometrial thickness (ET), the presence of intrauterine echogenic masses, and the use of Color Doppler imaging. Although an ET ≥15 mm is frequently used to suspect RPOC, the variability in cut-off thresholds and limited specificity reduce its diagnostic reliability. The detection of an echogenic intrauterine mass appears to be the most sensitive and specific sonographic feature. Color Doppler assessment, particularly the presence of enhanced myometrial vascularity (EMV) and classification systems like the Gutenberg score, offers further insight by stratifying hemorrhagic risk and guiding therapeutic choices. However, vascular parameters such as peak systolic velocity (PSV) and resistive index (RI) demonstrate a substantial overlap between benign and pathological conditions, limiting their stand-alone utility. The review also addresses the differential diagnosis of RPOC, including blood clots, arteriovenous malformations, placental polyps, gestational trophoblastic disease, and endometrial osseous metaplasia. The role of three-dimensional ultrasound remains limited in clinical practice, offering no significant advantage over two-dimensional imaging. Finally, the timing of follow-up ultrasound after medical treatment with misoprostol is critical: delayed assessment reduces overtreatment by allowing time for spontaneous resolution. In conclusion, despite advances in ultrasound technology, the diagnosis of RPOC remains challenging due to heterogeneity in imaging findings and inter-observer variability. A multimodal approach integrating grayscale and Doppler ultrasound with clinical evaluation is essential for optimal management.