Early serum human chorionic gonadotropin (hCG) trends after medication abortion.

OBJECTIVES

Despite increased reliance on human chorionic gonadotropin (hCG) for early pregnancy monitoring, there is limited information about hCG trends soon after medication abortion. The purpose of this study was to determine if there is a predictable decline in serum hCG values shortly after medication abortion.

STUDY

DESIGN

This is a retrospective study of women with early intrauterine pregnancies who underwent medication abortion with mifepristone and misoprostol and had a serum hCG level on Day 1 (day of mifepristone) and a repeat value on Day 2 to 6. The percent hCG decline was calculated from baseline to repeat measure, with repeat values from the same patient accounted for through repeated measure analysis of variance.

RESULTS

Eighty-eight women with a mean gestational age of 5.5 weeks and median baseline hCG of 5220 IU met study criteria over a 3-year period. The mean decline (±SD) in hCG from the Day 1 baseline value was 56.9%±29.5% on Day 3, 73.5%±38.6% on Day 4, 86.1%±8.8% on Day 5, and 92.9%±3.4% on Day 6. Eighty-two women (93% of the cohort) had a complete abortion without further intervention. The least square means hCG decline among these women was 57.6% [95% confidence interval (CI): 50.3-64.9%] on Day 3, 78.9% (95% CI: 75.0-82.8%) on Day 4 and 86.2% (95% CI: 81.3-91.1%) on Day 5.

CONCLUSION

There is a rapid decline in serum hCG within the first few days after early medication abortion. Further research is needed to delineate how soon after medication abortion this decline may be specific enough to confirm abortion completion.

IMPLICATIONS: This study provides the largest cohort of patients followed with serial hCG values in the first few days after medication abortion. Our findings demonstrate the trend in hCG decline in this population, which may be predictable by Day 5.