[Prevalence of immunohematologic tests at birth and the incidence of hemolytic disease in the newborn].

UNLABELLED: The administration of anti-D globulin to the mothers has decreased the incidence of Rh hemolytic disease but the improvement of technologic assays has made it possible to identify several hemolytics diseases of the newborn.

BACKGROUND

To identify the prevalence of immunohematologic tests demonstrated by indirect (IC), direct (DC) and elution tests; to identify the incidence of hemolytic disease and its treatment (phototherapy and/or exchange transfusion) in neonates with hemolytic disease. This is a retrospective cohort-study performed from January 1st 1996 to July 1st 1998.

METHODS

This is a descriptive study of the immunohematologic profile of 1698 mothers and their offsprings, as risk factors for developing hemolytic disease. The inclusion criteria were the positivity of the indirect (IC) and direct (DC) Coombs tests and elution tests. Based on the inclusion criteria three group of infants were analyzed: Group I was composed of 149 offsprings of Coombs-positive mothers (IC+) with antibodies associated with neonatal hemolytic disease. This group was further divided into two groups: Group I-A (IC+DC+) was composed of 83 Coombs-positive offsprings (DC+) of Coombs-positive mothers (IC+) and Group I-B (IC+DC-) was composed of 66 Coombs-negative offsprings (DC-) of Coombs-positive mothers (IC+); Group D was composed of 736 Coombs-positive offspring's of Coombs-negative mothers (IC-); and Group E was composed of 807 Coombs-negative and elution-positive offspring's of Coombs-negative mothers.

RESULTS

This study shown that the overall prevalence of immunohematologic tests associated with hemolytic disease was 9.07% (3212/35429), 0.43% (154/35429) among offsprings of Coombs-positive mothers, 4.10% (1453/35429) among Coombs-positive infants, and 4.53% (1605/35429) among elution-positive infants. The overall incidence of hemolytic disease was 36.23% (613/1692), 33.56% (50/149) among offspring's of Coombs-positive mothers, 44.43% (327/736) among Coombs-positive infants, and 29.24% (236/807) among elution-positive infants. The overall incidence of phototherapy among infants with hemolytic disease was 36.23% (613/1692), 49.40% (41/83) in group I-A (IC+DC+), 13.64% (9/66) in group I-B(IC+DC-), 44.43% (327/736) in group D, and 29.24% (236/807) in group E. The overall incidence of exchange transfusion among infants with hemolytic disease was 0.88% (15/1692), 14.46% (12/83) in group I-A (IC+DC+), 0% (0/66) in group I-B (IC+DC-), 0.27% (2/736) in group D, and 0.12% (1/807) in group E.

CONCLUSIONS

The results of this study allowed us to conclude that the overall prevalence of immunohematologic tests associated with hemolytic disease was 9.07% (3212/35429) and the overall incidence of hemolytic disease was 36.23% (613/1692) in this study-group. The highest incidences of hemolytic disease and phototherapy were observed among Coombs-positive offsprings of Coombs-positive mothers.