Recommendation grades (A-C) and levels of evidence (Ia-IV) are defined at the end of the "Major Recommendations" field.
Recommendations for Samples and Request Forms
- Samples for antenatal screening are identified to the same standard as pre-transfusion samples. (Good Practice Point [GPP])
- Samples should be dated, labelled and signed by the person taking them, in the presence of the patient who should be asked to confirm demographic details. Any labels pre-printed away from the phlebotomy procedure, e.g., Addressograph labels, should not be accepted on the specimen [Chapman et al., 2004]. (Level IV, Grade C)
Recommendations for Laboratory Testing
- ABO and D grouping must be performed in accordance with the guidelines for compatibility procedures in blood transfusion laboratories [Chapman et al., 2004].(Level IV, Grade C)
- All pregnant women found to be D negative should be issued with blood group cards to inform them, and those responsible for their care, of the D negative status and the need for prophylactic anti-D. (Level IV, Grade C)
- The screening cells and methods used for red cell antibody screening should comply with the guidelines for compatibility procedures in blood transfusion laboratories [Chapman et al., 2004]. (Level IV, Grade C)
Antenatal Testing Protocols
See also the clinical algorithm in the original guideline document.
- All pregnant women should be ABO and D typed and screened for the presence of red cell antibodies early in pregnancy and at 28 weeks gestation [National Collaborating Centre for Women's and Children's Health, 2003]. (Level III, Grade B)
- Blood transfusion laboratories should keep a record of anti-D administration to provide a basis for distinguishing between immune and prophylactic anti-D. (Level IV, Grade C)
- Cases of anti-D, anti-c and anti-K [unless the father is confirmed K negative] should be assessed at monthly intervals to 28 weeks gestation and at fortnightly intervals thereafter. Such cases must be referred to a specialist fetal medicine unit if the antibody reaches the critical level and/or the level is rising significantly. (Grade B)
- Clinically significant antibodies, other than anti-D, -c or -K, should be assessed, and other antibodies excluded, at 'first appointment' and at 28 weeks gestation. (Level IIb Grade B)
- All women who have previously had an infant affected by haemolytic disease of the newborn (HDN) should be referred before 20 weeks to a specialist unit for advice and for assessment of fetal haemolysis, irrespective of antibody level. (Level IIa Grade B)
Reports of Laboratory Investigation
- Women with clinical significant red cell antibodies should be issued with a card giving details of the antibody. (GPP)
Action at Time of Birth
- All infants born to women who have clinically significant antibodies should be closely observed for evidence of HDN. A direct antiglobulin test (DAT) should be performed and if positive, haemoglobin and bilirubin levels should be measured. (Level IV, Grade C)
Definitions:
Level of Evidence
Ia Evidence obtained from meta-analysis of randomised controlled trials
Ib Evidence obtained from at least one randomised controlled trial
IIa Evidence obtained from at least one well-designed controlled study without randomization
IIb Evidence obtained from at least one other well-designed quasi-experimental study
III Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies and case–control studies
IV Evidence obtained from expert committee reports or opinions and/or clinical experience of respected authorities
Grade of Recommendation
Grade A (evidence levels Ia, Ib) Requires at least one randomised controlled trial as part of the body of the literature of overall good quality and consistency addressing the specific recommendation
Grade B (evidence levels IIa, IIb, III) Requires availability of well-conducted clinical studies but no randomised clinical trials on the topic of recommendation
Grade C (evidence level IV) Requires evidence from expert committee reports or opinions and/or clinical experience of respected authorities. Indicates absence of directly applicable studies of good quality
