How often should beta human chorionic gonadotropin (β-hCG) be monitored to confirm a successful medical termination of pregnancy?

From the Guidelines

Beta-human chorionic gonadotropin (bHCG) levels should be monitored every 1 to 2 weeks until levels have normalized, defined as 3 consecutive normal assays, to ensure a medical termination has been successful. This monitoring schedule is crucial because bHCG, produced by placental tissue, has a predictable decline after successful termination. The most recent and highest quality study, 1, recommends this monitoring schedule to confirm a successful abortion and to detect any potential complications, such as an ongoing pregnancy or retained products of conception.

After initial normalization, hCG should be measured twice in 3-month intervals to ensure levels remain normal, as recommended by 1. This is important to detect any potential recurrence of disease, which is rare but can occur. The study also notes that the occurrence of gestational trophoblastic neoplasia (GTN) following hCG normalization is rare after the recommended 6 months of postnormalization hCG monitoring.

It is essential to note that persistent or rising bHCG levels may indicate an ongoing pregnancy or retained products of conception requiring additional intervention. In such cases, additional follow-up testing should be performed, and an ultrasound may be recommended to confirm the presence of any complications. The medication regimen for medical abortion typically includes mifepristone and misoprostol, and the monitoring schedule should be adjusted accordingly.

Some key points to consider when monitoring bHCG levels include:

• A decline of at least 80% from the baseline bHCG level generally indicates success
• If the decline is less than expected or levels plateau or rise, additional follow-up testing should be performed
• An ultrasound may be recommended at 1-2 weeks post-procedure, especially if bHCG results are concerning or if the patient reports continued pregnancy symptoms or heavy bleeding
• A complete abortion is typically confirmed when bHCG levels are undetectable or below 5 mIU/mL, though this may take 4-6 weeks to achieve

Overall, the monitoring of bHCG levels is crucial to ensure a successful medical termination and to detect any potential complications. The recommended monitoring schedule, as outlined in 1, should be followed to minimize the risk of morbidity and mortality.

From the Research

Monitoring bHCG Levels After Medical Termination

To ensure a medical termination has been successful, it is essential to monitor bHCG levels. The frequency of monitoring can vary depending on the individual case and the protocol used.

• According to a study published in 2017 2, serum hCG levels decline rapidly after complete medical abortion, with a mean decline of 70.0% on Day 3 and 91.4% on Day 5.
• Another study from 2023 3 observed a similar trend, with serum beta-human chorionic gonadotropin levels increasing by up to 5.1% within 48 hours of taking mifepristone, followed by a rapid decline on day 10 (by 98.5% compared with initial levels).
• A 2007 study 4 suggested that transvaginal ultrasonographic study and serum beta hCG measurement be performed 14-20 days after the procedure to confirm complete expulsion of intrauterine contents.

Recommended Monitoring Schedule

Based on the available evidence, the following monitoring schedule can be recommended:

• Measure serum hCG levels on the day of mifepristone administration (Day 1)
• Measure serum hCG levels 48 hours after mifepristone administration (Day 3)
• Measure serum hCG levels on Day 5 or 7-14 after mifepristone administration to confirm complete abortion
• Continue to measure serum hCG levels weekly until negative results are attained, usually within 7 weeks post-abortion

Factors Affecting Monitoring

It is essential to consider individual factors that may affect the monitoring schedule, such as:

• Gestational age: Women with earlier gestational ages may require less frequent monitoring 2
• Initial hCG levels: Women with higher initial hCG levels may require more frequent monitoring 2
• Presence of complications: Women with suspected ectopic pregnancies or heavy bleeding may require more frequent monitoring 5, 4