Expert opinion on best practice in programmed frozen embryo transfers: a Delphi consensus

RESEARCH QUESTION: How can outcomes in programmed frozen embryo transfers (FET) be improved, and what are the key areas where more research is needed? DESIGN: Using a Delphi-consensus framework, a scientific committee comprising five experts and a Scientific Coordinator formulated 17 literature-supported and expert opinion-supported statements, which were presented to an Extended Panel of international experts (five scientific committee members, excluding the Scientific Coordinator, and an additional 22 experts) who voted on their level of agreement or disagreement with each statement using a 5-point Likert-type scale (1 = Absolutely agree; 2 = More than agree; 3 = Agree; 4 = Disagree; 5 = Absolutely disagree). Consensus was reached if over 66% of participants agreed or disagreed. RESULTS: All statements exceeded the threshold for agreement after one round of voting. The statements covered aspects such as the decision-making process for choosing a programmed FET cycle; the route, dose and duration of oestrogen supplementation, and the benefit of monitoring serum oestrogen, LH and progesterone concentrations; the route and duration of progesterone treatments; the use of combination progesterone therapy; the duration and cessation of luteal phase support; and pregnancy outcomes from different FET protocols. CONCLUSIONS: The decision to undergo a programmed FET cycle should be made jointly between the patient and the physician and should be individualized according to the documented advantages (predictability and flexibility) and disadvantages (adverse obstetric and neonatal outcomes).