[Foetal-maternal alloimmunizations in the South-East area of the Venice province].

BACKGROUND: This study report the results obtained in a retrospective analysis of the foetal-maternal alloimmunizations observed from 1993 to 1999 in the South-East area of the Venice province.

METHODS: The data concerning 17,000 pregnancy observed in this area from 1993-1999 have been collected. For each pregnancy data concerning maternal ABO, Rh, Kk and IAT as well as foetal ABO, Rh, Kk and DAT were available. Further data (mainly antibodies concentration and specificity) were available if a foetal-maternal alloimmunization was detected and if transfusional support was given after the birth.

RESULTS: The authors observed 465 alloimmunizations (prevalence 2.7%): 381 (82%) of these were due to an ABO foetal-maternal incompatibility, 23 due to D incompatibility and the other 61 due to other blood groups antigens. Only 6 cases needed transfusional support: 5 exchange transfusion (a patient needed 2 exchanges) and a delayed transfusion.

CONCLUSIONS: Foetal-maternal alloimmunizations are today a rare but not exceptional event (about 3% of pregnancy), the great majority of these alloimmunizations are due to an ABO incompatibility. Despite the prevention of alloimmunization in D negative women by using Rh immune globulin, anti-D alloimmunization is still observed. A great number of other blood groups antigens are involved in foetal-maternal alloimmunization mainly within the Rh system (CcEe, etc.). In the authors' experience the great majority of foetal-maternal alloimmunizations were clinically silent, only 6 cases (1.3% of patients with a positive DAT) needed transfusional therapy.