National Consensus Statements for the Prevention of Maternal Rhesus (RhD) Alloimmunization and Management of Alloimmunized Pregnancies: A Modified Delphi Process.

Objective: National stakeholders developed guidance statements regarding controversial aspects of perinatal testing and management of pregnancies at risk of or affected by alloimmunization. The objective was to create national, standardized recommendations to guide testing practices, reduce unnecessary testing, optimize resources and improve patient care.

Methods: 46 multidisciplinary Canadian experts participated in an iterative Delphi process to reach consensus on 47 practices regarding all aspects of screening and management of pregnant persons at risk of alloimmunization. The panel rated their agreement on a 5-point Likert scale. After each round, panelists revoted on the statements until consensus was achieved, defined as Cronbach's alpha >0.95 or a maximum of three voting rounds. Fifteen of the forty-seven statements pertaining to High-Risk obstetrical scenarios are presented.

Results: 46 experts completed all rounds of voting. Consensus was achieved after 3 survey rounds (Cronbach's alpha = 0.94) for all statements. The 15 statements reaching consensus addressed general issues pertinent to the evaluation of the high-risk patient including antibody testing of clinically significant antibodies (e.g. Kell), antibody titration frequency, paternal phenotyping, fetal genotyping, multidisciplinary care,) and administration of RhIG following clinical situations: ectopic and molar pregnancy and following invasive fetal testing and therapeutics.

Conclusions: The consensus document provides guidance regarding best practices in prevention and management of alloimmunization to RhD and clinically significant antibodies to optimize RhIG usage and support clinical units. To effect practice change, knowledge translation of this consensus will require a broad educational program involving clinical offices, hospital emergency rooms and birthing units.