Serum human chorionic gonadotropin (hCG) trend within the first few days after medical abortion: a prospective study.

OBJECTIVES

To prospectively describe the decline in serum human chorionic gonadotropin (hCG) in the first 5 days after complete medical abortion and evaluate the influence of initial hCG and gestational duration.

STUDY

DESIGN

We conducted a prospective, physiologic study of women ≤63 days gestation who underwent medical abortion with 200 mg mifepristone and 800 mcg buccal misoprostol. We stratified enrollment into two gestational cohorts, <49 days and 49-63 days, to ensure gestational variability. We collected serum quantitative hCG values on Day 1 (day of mifepristone), Day 3, Day 5 and a routine follow up hCG on Days 7-14. We calculated the percent hCG decline from Day 1 to each repeat measure and evaluated trends based on initial serum hCG level and gestation.

RESULTS

We enrolled 66 women; 59 were protocol-adherent and included in our analysis. Mean gestation on Day 1 was 49 days and mean baseline hCG was 72,332 IU. Fifty-seven subjects (97%) had a complete medical abortion without further intervention. The mean serum hCG decline among subjects with complete medical abortion was 70.0±10.6% [range 36.9-98.6%] on Day 3 and 91.4±4.4% [range 68.4-97.7%] on Day 5. The mean serum hCG decline from Day 1 to routine follow-up on Days 7-9 was 97.1±1.7% [range 92.4-99.2%], from Day 1 to Day 10-11 was 98.5±1.4% [range 94.7-99.6%] and from Day 1 to Day 12-14 was 98.7±2.8% [range 86.7-99.9%]. There was no difference in percent hCG decline stratified by initial hCG or gestation.

CONCLUSIONS

There is a rapid and predictable decline in serum hCG as early as Day 5 after complete medical abortion through 63 days gestation. Rate of hCG decline is not affected by initial hCG or gestational duration.

IMPLICATIONS: For women who require confirmation of complete abortion sooner than 1 week after mifepristone, due to patient preference, logistical constraints or in the setting of pregnancy of unconfirmed location, a single repeat hCG on Day 5 may be clinically useful.