Mate Whenua-follow-up after early medical abortion: study protocol for a randomized controlled trial.

Background: Early medical abortion (EMA) is safe and effective; an uncommon but crucial adverse outcome is ongoing live pregnancy. The best method of follow-up after EMA to detect ongoing pregnancy is a critical research gap. Few trials compare blood or urine pregnancy tests to ultrasound scans, and no trial compares these tests to each other. The aim is to evaluate the completeness of follow-up of two methods of follow-up after EMA- self-assessment with low-sensitivity urine pregnancy test result or serial serum βhCG blood tests. Secondary aims will evaluate whether self-assessment follow-up is safe and acceptable to patients and clinicians.

Methods: This is a multicentre randomised controlled trial in New Zealand. Eligible women and pregnant people having EMA will be randomised to self-assessment or blood test follow-up. The primary outcome is 'lost to follow-up.' To detect a decrease in 'lost to follow-up' rate from baseline of 15% to 7.5%, with 90% power and a two-sided type 1 error of 0.05, the sample size required is 736 participants, in a 1:1 ratio.

Discussion: If self-assessment reduces lost to follow-up, has additional clinical benefits, and is safe, cost-effective, and acceptable to women and clinicians, we anticipate change in EMA follow-up practice around the world. We think self-assessment will be welcomed as part of a patient-centred package of care following EMA.

Trial registration: This trial was prospectively registered with the Australia New Zealand Clinical Trials Registry (ANZCTR) on 21 August 2023, registration number ACTRN12623000890639; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=384373.