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You are called to review a healthy term neonate on the postnatal ward whose mother's blood group is O Rhesus D (RhD)-negative and whose own blood group (determined from umbilical cord blood) is A RhD-positive. A direct Coombs test is ‘2+ positive’. According to departmental protocol, the neonate should be started on oral folic acid 500 μg daily from discharge until weaning, supposedly to reduce the risk of late haemolytic anaemia. You wonder as to the value of this intervention.
Structured clinical question
In a neonate with a positive direct Coombs test (patient), does folic acid supplementation until weaning (intervention) compared with placebo (control) reduce the incidence or severity of anaemia (outcome)?
Secondary sources: None.
Primary sources: Medline and Embase were searched using the Ovid interface (1946 and 1974, respectively, to current date) in June 2016. The following keywords were used: (‘Coombs test’ or ‘anti*globulin test’ or allo*immuni*ation or iso*immuni*ation or erythroblastosis or ‘h*emolytic disease’) and (‘folic acid’ or folate) and an*emia. The results were limited to English language and the age groups infant and child. The search retrieved 39 individual articles, of which two were relevant primary sources (summarised in table 1). Further indirect evidence was obtained from a review article retrieved in the search and its references.
The direct Coombs (or …