Early Options: Monitoring Medical Abortion

Early Options - A Provider's Guide to Medical Abortion

This page contains the following sections:

hCG Testing
Tissue Inspection and Physical Examination
Post-Abortion Ultrasound

The primary purpose of monitoring patients during medical abortion is to confirm that complete abortion has occurred without complications. Follow-up generally occurs within 2 weeks after administration of the first medication (mifepristone or methotrexate). Because of the teratogenic potential of medical abortion regimens, detection of a continuing pregnancy at the 2-week follow-up visit warrants surgical evacuation of the uterus.

Several approaches can be used to confirm termination of pregnancy, including hCG testing, tissue inspection (with patients who abort in a clinical setting), history of bleeding combined with evidence of involuted uterus on pelvic examination, and ultrasonographic evaluation. Click here to view Figure 4.

hCG Testing
Human chorionic gonadotropin testing is one means of monitoring medical abortion outcomes. Following abortion, hCG levels decline rapidly at first and then decrease more gradually, at a rate of about 50% every 2 days. Schaff and colleagues²⁹ conducted a study of 100 women ≤ 56 days' gestation who underwent medical abortion with methotrexate and misoprostol. They found that ß-hCG levels declined by at least 50% within a week of initiating treatment in women who aborted.

Based on data aggregated from multiple studies using methotrexate/misoprostol, Creinin³⁰ concluded that complete abortion is unlikely in a patient whose serum ß-hCG level does not decline by at least 50% within 24 hours of misoprostol administration. However, it may take weeks for the level to decline to a normal (nonpregnant) value. Creinin and Vittinghoff³¹ reported that it took between 24 and 28 days following abortion with methotrexate/misoprostol for ß-hCG levels to decline to ≤ 10 IU/L.

In a study³² involving 217 women at 49 days LMP or less (confirmed by ultrasound) who received 600 mg mifepristone, followed 2 days later by 400µg oral misoprostol, researchers found that β-hCG levels at the follow-up visit (scheduled between treatment day 6 and 18 based on patient preference) dropped to a mean of 3% of the pre-treatment β-hCG level in cases of successful medical abortion (S.D. 3, range 1-44% of the initial value, with only 3 cases above 27%). Further analysis revealed that there is a positive predictive value of 0.995 for successful medical abortion if 20% of the pretreatment value is used as a cut-off criterion.

Tissue Inspection and Physical Examination
When the abortion occurs in the clinical setting, direct observation of the products of conception can confirm pregnancy expulsion.

A bimanual examination in 1 to 2 weeks that confirms uterine involution in a patient who reports bleeding after misoprostol comparable to that of a menstrual period may also be adequate in selected situations.

After reading this section, you should be able to answer the following question:
If a preabortion ultrasound confirmed the presence of an intrauterine pregnancy, which sonographic findings indicate a completed medical abortion?

Post-Abortion Ultrasound
Possible outcomes of medical abortion include complete abortion, incomplete abortion (clinical presentation consistent with the diagnosis of persistent nonviable gestational sac on ultrasound), and ongoing pregnancy.

When using transvaginal ultrasonography to assess the outcome after medical abortion, the primary objective is to determine whether the gestational sac is absent. The evaluation is performed after the woman experiences heavy bleeding. This imaging study may be done as soon as 4 hours after administration of misoprostol if the patient remains for monitoring in the clinical setting, the next day if she takes misoprostol at home, or at the first follow-up visit within 2 weeks after the initiation of the treatment regimen.

Interpretation of a follow-up ultrasound will depend, in part, on whether or not the patient underwent ultrasonography prior to the abortion. If the patient had a preabortion sonogram identifying an intrauterine pregnancy, then the absence of a gestational sac at follow-up indicates that the abortion is complete.

If the patient had no initial study, but reports heavy bleeding after taking the abortion medications, then absence of a gestational sac at follow-up most likely indicates a successful medical abortion.

However, if the patient had no initial scan to confirm an intrauterine pregnancy and she reports no significant bleeding, then absence of the sac on follow-up may indicate ectopic pregnancy or very early pregnancy (less than about 4 weeks) not visible by ultrasonography.

Typically, a sonogram of a complete medical abortion will show some amount of intrauterine debris. There may be clots and retained trophoblastic tissue, but the gestational sac is absent. A thickened decidual stripe without a gestational sac will be visible in this case. Click here to view Figure 5A.

These findings are normal following expulsion of the gestational sac in a medical abortion patient. In a stable patient, no intervention would be required.

Indeed, a study³³ involving a chart review of 525 women who received 200mg mifepristone followed 24-72 hours later by 800 µg vaginal misoprostol through 63 days gestation examined whether ultrasonographic findings at the follow-up visit were predictive of the need for clinical interventions. The mean endometrial thickness at the follow-up visit (within 17 days of initiation of mifepristone) was 4.10 +/- 1.80mm with a range of 0.67-13.4mm. There was no correlation between the gestational age at the initiation of treatment and endometrial thickness at follow-up. The researchers analyzed possible cutoff points for endometrial thicknesses at which one might institute universal treatment and found there was no acceptable point at which false-positive and false-negative rates are minimized. The authors concluded "[e]ndometrial thickness after administration of a single dose of mifepristone and misoprostol for medical termination should not dictate clinical intervention. The decision to treat should be based on the presence of a persistent gestational sac or compelling clinical signs and symptoms."

In contrast to a generalized thickened endometrium, a persistent nonviable gestational sac appears as an empty, or anechoic, intrauterine fluid collection. Click here to view Figure 5B. The edges of the sac are typically a little "ragged" in appearance, and there may be a small hemorrhage in the choriodecidual area. Management can either be expectant or involve a repeat dose of misoprostol or aspiration curettage.

Watch a video clip about this subject.

Continuing pregnancy is an unusual occurrence following early medical abortion with mifepristone/misoprostol.³⁴ This condition is diagnosed when the ultrasound reveals a viable intrauterine pregnancy as indicated by embryonic cardiac activity 2 weeks after initiation of treatment. Click here to view Figure 5C. Because of the teratogenic risk posed by the medical abortion regimen, aspiration curettage would be indicated.

Click here to check your understanding.

Proceed to Recognizing Abnormal Pregnancy.

References for this module