Written by Chris Thom
Spoon Feed
In this retrospective analysis, pelvic POCUS had moderate sensitivity and high specificity for the diagnosis of retained products of conception (RPOC).
Another application in the books for POCUS
This was a single institution study of 645 patients presenting to the ED from 2017 to 2023 who had a pelvic POCUS that did not identify an intrauterine pregnancy (IUP). A subcohort of 265 patients with a history concerning for RPOC was also analyzed. Two ultrasound fellowship trained physicians reviewed the pelvic POCUS examinations to determine if there were findings of RPOC present (defined as heterogeneous endometrium > 10 mm). Gold standard was radiology ultrasound diagnosis or OB/GYN diagnosis. Nearly all of the POCUS exams were transabdominal in nature, with only 7% receiving a transvaginal examination.
Pelvic POCUS had a sensitivity of 79% (95%CI 66.1-88.6) and specificity of 93.8% (95%CI 90-96.6) for the diagnosis of RPOC in the subcohort of patients with a history suggestive of RPOC. Several of the 22 false-positive POCUS studies were from potentially viable pregnancies, though only one patient went on to have a viable birth.
How will this change my practice?
This is the first study to evaluate the test characteristics of POCUS for RPOC. The authors note that the high specificity suggests this would be an appropriate first line test, as the diagnosis can be made quickly with bedside POCUS. Understanding the patient’s diagnosis at the initial point of history and exam can greatly streamline the patient’s ED course and improve time to intervention. It also affords the physician the benefit of cognitive unloading, given the diagnosis becomes known at that early point. I agree with the authors’ decision to analyze the subcohort of patients with symptoms suspicious for RPOC, as this is the group of patients where we benefit from exploration of pelvic POCUS test characteristics.
POCUS pro-tips and clips:
Obtaining high-quality transabdominal pelvic POCUS images involves application of firm pressure to displace bowel and bring the probe closer to the object of interest. A full urinary bladder is often helpful at providing an acoustic window to the uterus. With RPOC, we are looking for a thickened endometrium, which can be identified by its hyperechoic appearance in the middle of the uterus. Adding color doppler may increase diagnostic accuracy of RPOC, though this was not done in the pelvic POCUS exams from this study. Keep in mind that an anteverted uterus on a thinner patient can often be well imaged with the linear transducer, instead of the more standard curvilinear approach (1).
Source
Accuracy of point-of-care ultrasound in diagnosing retained products of conception. Am J Emerg Med. 2025 Jan 13;90:65-70. doi: 10.1016/j.ajem.2025.01.032. Epub ahead of print. PMID: 39826241
Additional References
Tabbut M, Harper D, Gramer D, Jones R. High-frequency linear transducer improves detection of an intrauterine pregnancy in first-trimester ultrasonography. Am J Emerg Med. 2016;34(2):288-291.
