Jill Durocher

Efficacy of a Low-Sensitivity Urine Pregnancy Test for Identifying Ongoing Pregnancy After Medication Abortion at 64 to 70 Days of Gestation

June 1st, 2022
Medication Abortion
Whitehouse, K.C., Shochet, T., Lohr, P.A.

Recipient of a 2022 Daniel R. Mishell, Jr, MD Outstanding Article Award. Contraception; June 01, 2022; Vol. 110: 21-26; doi:10.1016/j.contraception.2022.02.005. Epub 2022 Mar 4.

Objectives: We assessed whether a low-sensitivity pregnancy test is effective at identifying ongoing pregnancy after medication abortion at 64 to 70 days of gestation.

Study design: From October 2018 to March 2020, we performed a prospective observational study of participants in England and Wales undergoing medication abortion. Participants were scheduled to return to the clinic 14 ± 3 days after mifepristone administration to perform a low-sensitivity pregnancy test (human chorionic gonadotropin threshold of 1000 mIU/mL) and symptom checklist, and state whether they thought the abortion was complete. Clinicians also assessed the low-sensitivity pregnancy test and performed an ultrasound to determine abortion status. We calculated the sensitivity, specificity, negative and positive predictive value of the low-sensitivity pregnancy test (with and without a symptom checklist) for detecting ongoing pregnancy.

Results: We enrolled 757 participants. Thirty-one did not progress to abortion and 558 (76.9%) completed follow-up. Most (79.6%) attended per-protocol; 22 (3.9%) attended earlier than 11 days and 92 (16.5%) later than 17 days. Thirteen participants (2.3%) had an ongoing pregnancy. The low-sensitivity pregnancy test correctly identified all the ongoing pregnancies (sensitivity = 100%; specificity = 84.8%; negative predictive value = 100%; positive predictive value = 13.5%). The symptom checklist alone had a sensitivity of 76.9% and a negative predictive value of 99.4% for identifying ongoing pregnancies. Participants and clinicians agreed on the interpretation of the low-sensitivity pregnancy test 94.6% of the time.

Conclusions: Patient self-assessment of a low-sensitivity pregnancy test after medication abortion between 64- and 70 days' gestation has high sensitivity and negative predictive value for identification of ongoing pregnancy.

Implications: Patients can be offered a low-sensitivity pregnancy test to assess for ongoing pregnancy after medication abortion up to 70 days of gestation thereby reducing the need for in-person visits. Services should be prepared to provide in-person assessments after positive or inconclusive results to ensure early identification of abortion complications.

Keywords: Low sensitivity pregnancy test; Medical abortion; Medication abortion; Mifepristone; Misoprostol Postabortion care.