Early pregnancy loss: Pretreat with mifepristone?

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Yes. While medical management of early pregnancy loss with misoprostol frequently results in treatment failure, pretreating with mifepristone can increase efficacy.


Pretreat patients with oral mifepristone prior to using vaginal misoprostol to increase the efficacy of medical management of early pregnancy loss over that with misoprostol alone.


B: Based on a single, well-executed, randomized controlled trial.1

Schreiber CA, Creinin MD, Atrio J, et al. Mifepristone pretreatment for the medical management of early pregnancy loss. N Engl J Med. 2018;378:2161-2170.




Jenny is a 29-year-old G2P1001 woman who presents to your clinic for a missed period. Her last menstrual period was about 10 weeks ago. She is found to have a positive pregnancy test in the office. On examination, her uterus is nontender and consistent in size with gestation of 7 weeks. She denies any bleeding or cramping. On ultrasound, you see a gestational sac measuring 28 mm and no embryo. You confirm early pregnancy loss. Jenny is sad about this diagnosis. She does not wish to proceed with expectant management and is hopeful to avoid a surgical procedure. How do you counsel her regarding medical management?

Early pregnancy loss or first trimester miscarriage is estimated to occur in about 1 million women in the United States annually and is the most common complication of early pregnancy.2,3 Early pregnancy loss is defined as a nonviable, intrauterine pregnancy with either an empty gestational sac or a gestational sac containing an embryo or fetus without fetal heart activity within the first 12 weeks 6 days of gestation.4

Once early pregnancy loss is confirmed by ultrasound, expectant management with no intervention is an acceptable treatment option. Women generally prefer active management, either medically or with surgical evacuation.5,6 Misoprostol 800 mcg administered vaginally or orally has been the accepted medication regimen for medical management.5 However, failure rates with misoprostol have been reported to be as high as 40%, particularly among women with a closed cervical os, who then require repeat dosing of misoprostol or surgical evacuation.6


Mifepristone before misoprostol improves efficacy for early pregnancy loss

The PreFaiR (Comparative Effectiveness of Pregnancy Failure Management Regimens) study was a randomized trial that took place at 3 US centers. The study was designed to assess the safety and efficacy of pretreatment with oral mifepristone prior to use of vaginal misoprostol for the medical management of early pregnancy loss.1

This is the first high-quality, randomized trial to demonstrate the safety and efficacy of oral mifepristone Tx prior to vaginal misoprostol administration in the medical management of early pregnancy loss.

Three hundred women, ≥ 18 years and undergoing medical management for early pregnancy loss, were randomized to receive misoprostol 800 mcg vaginally alone or mifepristone 200 mg orally followed by misoprostol 800 mcg vaginally 24 hours later.

Inclusion and exclusion criteria. Women who showed a nonviable intrauterine pregnancy at 5 to 12 weeks’ gestation by ultrasound were eligible for the study. Exclusion criteria included incomplete or inevitable abortion, contraindications to either study drug, viable or ectopic pregnancy, hemoglobin < 9.5 g/dL, current use of anticoagulants or the presence of a clotting disorder, and pregnancy with an intrauterine device in place.

Outcomes. The primary outcome was gestational sac expulsion by the first follow-up visit and no additional interventions within 30 days of treatment. Secondary outcomes included acceptability of treatment, adverse events, and clinical characteristics associated with successful expulsion.

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