Serum β-HCG Level in Women Diagnosed as Having Retained Products Of Conception: A Prospective Cohort Study.

Study Objective: Retained products of conception (RPOC) may occur after delivery or abortion, often necessitating operative hysteroscopy for their removal. A preoperative diagnosis of RPOC by ultrasonography is not always accurate and may lead to unnecessary surgical procedures. We sought to evaluate whether serum level of β-human chorionic gonadotropin (β-HCG) may aid in the preoperative diagnosis of RPOC.

Design: A prospective cohort study.

Setting: Gynecology department in a university affiliated medical center.

Patients: Women undergoing operative hysteroscopy for removal of RPOC between December 2019 and January 2021.

Interventions: Operative hysteroscopy for RPOC removal. Serum β-HCG levels were obtained on the day of surgery, and level ≥5.0 mIU/mL was considered positive. All operative specimens were evaluated by pathology for the presence of trophoblastic tissue.

Measurements And Main Results: Of the 105 women recruited to the study, the operative pathology showed trophoblastic tissue in 81 cases (77.1%), and they were included in the data analysis. The β-HCG level was positive in 16 of those 81 cases (19.8%). Positive β-HCG level was significantly associated with RPOC after an abortion (surgical or medical) compared with RPOC after delivery. In addition, the mean RPOC mass was larger in the β-HCG-positive group than the β-HCG-negative group (29.1 ± 9.5 mm vs 23.8 ± 8.9 mm, respectively, p = .004), and the interval from termination of pregnancy to surgery was shorter (4.8 ± 1.7 weeks vs 7.5 ± 2.1 weeks, respectively, p <.001). Relatively high β-HCG level (352 mIU/mL and 3561 mIU/mL) were found in 2 cases in which the RPOC mass was implanted on a previous cesarean section scar.

Conclusion: β-HCG level is noncontributory to the preoperative diagnosis of RPOC.