The medication combination of mifepristone and misoprostol, referred to as “abortion pills,” is highly effective for early abortion and early pregnancy loss. Typically, when patients have not yet had an intrauterine pregnancy confirmed by ultrasonogram, they are followed with serial blood tests (hCG) and a repeat ultrasonogram to ‘rule out’ ectopic pregnancy — a life threatening condition in which a fertilized egg has implanted outside the uterus and will not be viable. In a retrospective cohort study, researchers from the Brigham compared the safety and efficacy of immediately starting the medication combination after a person has a positive pregnancy test versus waiting to initiate treatment until a diagnosis of ectopic pregnancy has been ruled out. 

The researchers found that administering the pills as early as possible could be done safely and could also help the patient determine if their pregnancy was an ectopic pregnancy or not faster than if they had waited for an ultrasonogram. Researchers found no evidence of an increase in the rates of serious adverse events, emergency department visits, or nonadherence with follow-up.

However, the team did see a higher failure rate for the pills when given early, meaning that patients with an undesired pregnancy who are treated early may need to re-initiate a medical abortion.

“This study should encourage clinicians to shift clinical practice to meet the demand of patients and facilitate an approach of ‘the sooner, the better,’ which is what many patients want,” said corresponding author Alisa Goldberg, MD, MPH, of the Department of Obstetrics and Gynecology. “Our data suggest that there is no reason to mandate that patients with pregnancies of unknown location delay initiating abortion to first obtain a definitive diagnosis. In contrast, there is diagnostic and therapeutic benefit to administering abortion medications to patients with undesired pregnancy of unknown location.”