From the Guidelines
Retained Products of Conception (RPOC) on ultrasound are defined as echogenic material within the endometrial cavity after pregnancy, typically appearing as heterogeneous tissue with variable vascularity, and can also be referred to as residual products of conception. The most reliable ultrasound findings include an endometrial thickness greater than 10mm, presence of an intrauterine mass, and vascularity detected on color Doppler imaging, as noted in the study by 1. The vascularity is particularly important, as it helps distinguish RPOC from blood clots or debris. Some key points to consider when evaluating RPOC on ultrasound include:
- Endometrial thickness: an endometrial thickness greater than 10mm is a reliable indicator of RPOC, as seen in the study by 1.
- Intrauterine mass: the presence of an intrauterine mass can indicate RPOC, as noted in the study by 1.
- Vascularity: vascularity detected on color Doppler imaging can help distinguish RPOC from blood clots or debris, as seen in the study by 1. Additional findings might include an irregular endometrial-myometrial border and the presence of a gestational sac or fetal parts in some cases. These ultrasound criteria are most accurate when combined with clinical history of recent pregnancy (delivery, miscarriage, or abortion) and symptoms such as abnormal bleeding or pain, as noted in the study by 1. The appearance can vary depending on the time elapsed since pregnancy, with vascularity typically decreasing over time. Accurate identification is crucial as RPOC requires treatment, usually surgical evacuation, to prevent complications like hemorrhage and infection, as seen in the study by 1. It's also worth noting that some panelists suggested removing “retained” in RPOC, as it may imply the tissue is fixed, leading to unnecessary intervention, while the decision to treat is based on clinical factors or a persistent gestational sac, as noted in the study by 1. However, given that RPOC is used in all trimesters and relays useful information to pathologists when provided as the clinical indication for histologic evaluation, removing “retained” may pose unforeseen challenges, as seen in the study by 1. Residual may be a softer adjective to “retained,” possibly decreasing the implication that tissue is fixed, as noted in the study by 1. Therefore, residual products of conception is another alternate phrase in this lexicon preserving the acronym RPOC, which is in common use, as seen in the study by 1.
From the Research
Definition of RPOC on Ultrasound
RPOC (Retained Products of Conception) can be defined on an ultrasound as a thickened endometrial echo complex (EEC) or a discrete mass in the uterine cavity 2. The detection of vascularity in a thickened EEC or an endometrial mass at color or power Doppler US increases the positive predictive value for the diagnosis of RPOC 2, 3.
Key Ultrasound Findings
Some key ultrasound findings that suggest RPOC include:
- A thickened endometrial echo complex (EEC) 2
- A discrete mass in the uterine cavity 2
- An endometrial mass, which is the most sensitive (79%) and specific (89%) sonographic feature for RPOCs 3
- Complex fluid in the endometrial canal 3
- A thick endometrium measuring greater than 10 mm 3
- Detection of vascularity in a thickened EEC or an endometrial mass at color or power Doppler US 2, 3
Diagnostic Criteria
The diagnosis of RPOC can be made based on a combination of symptoms, endometrial thickness, endometrial irregularity, and blood flow indicative of placental tissue seen on Doppler ultrasound 4. The absence of an endometrial mass or complex fluid and an endometrial thickness of less than 10 mm are considered normal findings and make RPOCs extremely unlikely 3.