Evaluating the agreement of ultrasound imaging and beta-human chorionic gonadotropin (β-hCG) measurement in confirming completed medical abortion: cross-sectional study

Abstract

Objective: Clinical methods that are generally used to evaluate the completeness of medical abortion are not reliable. Ultrasound imaging and beta-human chorionic gonadotropin (β-hCG) measurements are used to diagnose completed medical abortion, but a precise evaluation of these two methods has shown contradictory results. The purpose of this study is to evaluate the agreement of serum β-hCG measurement and ultrasound imaging to confirm complete medical abortion. Materials and Methods: This study was conducted on pregnant women who had been referred to our center for medical abortion from 2015 to 2017. All cases occurred in the first trimester of pregnancy. They obtained one or two doses of vaginal misoprostol for medical abortion. Success rate of medical abortion was measured by both transvaginal ultrasound imaging and consecutive serum β-hCG measurements two to four weeks after initial treatment. Results: Among the 275 women who completed the study, complete medical abortion was confirmed by serum β-hCG in 231 women (84.3%) and transvaginal ultrasound imaging in 195 women (70.8%) after two weeks. All remaining cases completed the medical abortion after an additional two weeks, confirmed by both transvaginal ultrasound imaging and serum β-hCG. The sensitivity, specificity, positive, and negative predictive values of β-hCG were 95.2%, 86.7%, 84%, and 70%, respectively; and these values for transvaginal ultrasound imaging were 68.5% 64.5%,77%, and 30.%, respectively, for the diagnosis of completed medical abortion. Conclusion: Serum β-hCG measurement is as effective as transvaginal ultrasound imaging to confirm successful medical abortion in early pregnancy.