Background: Considering that there is no general agreement on use of misoprostol as the best method for the termination of pregnancy in first trimester, this study aimed to compare the vaginal ultrasonography and serum β-hCG in the confirming of a complete abortion.

Materials and Methods: This study was performed on 133 patients with a missed abortion or the blighted ovum diagnosed by vaginal ultrasonography, and a 12 week gestational sac admitted to Shabih-Khani hospital of Kashan in 2010. The patients' serum β-hCG levels were measured. They were assessed for the tissue discharge (abortion) after taking one or two doses of vaginal misoprostol suppositories and the oral contraceptive pills prescribed after confirming the abortion. Then vaginal ultrasonography and the serum β-hCG measurement were performed to diagnose the complete abortion in the second and fourth weeks of pregnancy.

Results: Among 133 patients, a complete abortion was diagnosed for 116 (87.2%) and 80 cases (60.15%) based on β-hCG level and vaginal ultrasonography, respectively in the second week of pregnancy. In other cases, a complete abortion was diagnosed using both β-hCG level and vaginal ultrasonography in the fourth week. Therefore, β-hCG level was more effective (98.75%) than the vaginal ultrasonography to diagnose a complete abortion in the second week of pregnancy. The accordance between the two methods was 0.327 at the end of the second week of pregnancy.

Conclusion: The measurement of β-hCG level and vaginal ultrasonography are equally effective to confirm a complete abortion. Hence, to diagnose the complete abortion, determining the β-hCG level followed by clinical examination is recommended.