title: Three examples of Rh haemolytic disease of the newborn with a negative direct antiglobulin test.
abstract: Typically the serological diagnosis of alloimmune haemolytic disease of the newborn (HDN) includes a positive direct antiglobulin test on the infant's red cells, and the presence of an IgG red cell alloantibody in both maternal and cord sera. HDN with a negative direct antiglobulin test has been reported with anti-A and anti-B, but not with other red-cell alloantibodies. In this report we describe four examples of HDN in infants whose red cells had a negative direct antiglobulin test. The first case was diagnosed retrospectively when the infant was admitted to hospital aged 3 weeks with severe anaemia and cardiac failure, and subsequently died. Maternal and infant sera were both shown to contain anti-C: however, the direct antiglobulin test on the infant's red cells was negative. Approximately 1 year later the mother of this infant gave birth to triplets: soon after birth one of the triplets required an exchange transfusion, one had hyperbilirubinaemia, and the third was unaffected. Anti-C and anti-e were detectable in the maternal serum at this time. The most probable Rh genotypes of the two affected infants were R1R2 (CDe/cDE), while the Rh genotype of the unaffected infant was R2R2 (cDE/cDE). Anti-c was implicated as causing HDN in a fourth infant (from a different family) who was a hydropic stillborn. The direct antiglobulin test on fetal blood was negative and other causes of non-immune hydrops were excluded. These four infants provide evidence that the direct antiglobulin test may be negative in some severely affected and even fatal cases of HDN.
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
authors.forename: N M
authors.initials: NM
authors.lastname: Heddle
authors.forename: P
authors.initials: P
authors.lastname: Wentworth
authors.forename: D R
authors.initials: DR
authors.lastname: Anderson
authors.forename: D
authors.initials: D
authors.lastname: Emmerson
authors.forename: J G
authors.initials: JG
authors.lastname: Kelton
authors.forename: M A
authors.initials: MA
authors.lastname: Blajchman
mesh_terms: D003298:Coombs Test; D004899:Erythroblastosis, Fetal / Q000175:diagnosis* / Q000276:immunology / Q000401:mortality; D004912:Erythrocytes / Q000276:immunology*; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D012189:Retrospective Studies; D012204:Rh-Hr Blood-Group System / Q000276:immunology*
chemical_list: D012204:Rh-Hr Blood-Group System