Consensus definition and essential reporting parameters of selective fetal growth restriction in twin pregnancy: a Delphi procedure.
Twin pregnancies complicated by selective fetal growth restriction (sFGR) are associated with increased perinatal mortality and morbidity. Inconsistences in the diagnostic criteria for sFGR employed in existing studies hinder the ability to compare or combine their findings. It is therefore challenging to establish robust evidence-based management or monitoring pathways for these pregnancies. The main aim of this study was to determine, by expert consensus using a Delphi procedure, the key diagnostic features of and the essential reporting parameters in sFGR.
A Delphi process was conducted among an international panel of experts in sFGR in twin pregnancy. Panel members were provided with a list of literature-based parameters for diagnosing sFGR and were asked to rate their importance on a 5-point Likert scale. Parameters were described as solitary parameters (sufficient to diagnose sFGR, even if all other parameters are normal) and contributory parameters (those that require other abnormal parameter(s) to be present for the diagnosis of sFGR). Consensus was sought to determine the cut-off values for accepted parameters, as well as parameters used in the monitoring, management and assessment of the outcome of twin pregnancies complicated by sFGR. The questions were presented in two separate categories according to chorionicity.
A total of 72 experts were approached, of whom 60 agreed to participate and entered the first round; 48 (80%) completed all four rounds. For sFGR irrespective of chorionicity, one solitary parameter (estimated fetal weight (EFW) of one of the twins less than the third centile) was agreed. For monochorionic (MC) twin pregnancy at least two out of four contributory parameters (EFW less than the 10th centile of one of the twins, abdominal circumference (AC) of one twin less than the 10th centile, EFW discordance of 25% or more, and umbilical artery (UA) pulsatility index (PI) of the smaller twin above the 95th centile) were agreed. For sFGR in dichorionic (DC) twin pregnancy, at least two out of three contributory parameters (EFW of one twin less than the 10th centile, EFW discordance of 25% or more, and UA PI of the smaller twin above the 95th centile) were agreed.
Consensus-based diagnostic features of sFGR in both MC and DC twin pregnancies, as well as cut-off values for the parameters involved, were agreed upon by a panel of experts. Future studies are needed to validate these diagnostic features before they can be used in clinical trials of interventions.