Weak D antigen - Revisited.

D antigen is the most immunogenic antigen in the complex Rh blood group system discovered in the year 1939. There is a lot of polymorphism in its phenotype due to genetic heterogeneity. Certain mutations and /or deletions lead to a weak phenotype defined by decreased density of antigen sites which require the use of anti human globulin for detection. The need for detection of the weak D antigen was to prevent alloimmunization by this blood if transfused to a D negative patient especially to women in child bearing age group. This contention is however, controversial and not proven beyond doubt. Moreover, the use of potent monoclonal D typing antisera detects low density of weak D antigens thus obviating the use of anti human globulin. We have assessed the incidence of Rh negative and weak D blood groups in the Garhwal region of Uttarakhand and reviewed the literature regarding the controversies in the clinical significance of weak D antigen.

Prevalence of Rh negative pregnant women who attended the antenatal clinic and delivered in Rajavithi Hospital: 2000-2005.

OBJECTIVE: To assess the prevalence of Rh-negative pregnant women who attended the antenatal clinic and delivered in Rajavithi Hospital. MATERIAL AND METHOD: A descriptive retrospective study in Rh-negative pregnant women was done. The present study included the general characteristic of cases, anti-D immunoglobulin prophylaxis administration, fetal anemia and neonatal jaundice. RESULTS: During the study period, 147 Rh-negative pregnant women delivered at Rajavithi Hospital. The prevalence of Rh-negative pregnant women in Rajavithi hospital was 0.31%. Fetal anemia and neonatal jaundice were detected in 21.9% and 37.2%, respectively, and 68.14% of cases received antenatal anti-D immunoglobulin. Anti-D immunoglobulin prophylaxis significantly reduced the incidence of neonatal jaundice (p < 0.05). CONCLUSION: The prevalence of Rh-negative pregnant women was 0.31%.

Freqüências dos grupos sangüíneos e incompatibilidades ABO e RhD em puérperas e seus recém-nascidos / Frequencies of blood groups, ABO and Rh D incompatibility in post-delivery women and their liveborn

OBJETIVO: Determinar as freqüências fenotípicas e predizer o risco de incompatibilidade e aloimunização materna RhD na população da Zona Oeste de São Paulo, Brasil. MÉTODOS: Estudo descritivo no qual avaliamos 2372 puérperas e seus recém-nascidos vivos, no período de um ano, tipificadas para os sistemas ABO e RhD por meio de teste de aglutinação em tubo. RESULTADOS: O estudo mostrou os seguintes percentuais: grupo sangüíneo O, 50,67 por cento; A, 32,17 por cento; B, 13,45 por cento; AB, 3,71 por cento; RhD(+), 90,34 por cento e RhD(-), 9,66 por cento. A ocorrência de incompatibilidade materno-fetal foi de 18,4 por cento para o sistema ABO e de 7 por cento para o RhD. CONCLUSÃO: O contingente da população Rh negativa com alto risco para aloimunização RhD foi estimado em 82 por cento, denotando a importância da profilaxia da aloimunização RhD.

OBJECTIVE: This study aimed to assess the frequency of different blood phenotypes and to predict the risk of Rh D alloimmunization and maternal-fetal incompatibility in a Brazilian population living in the West zone of the city of São Paulo - Brazil. METHODS: This descriptive study evaluated 2,372 post-delivery women and their liveborn during one year. Blood types were analyzed by means of tube agglutination tests. RESULTS: The blood type frequencies were: 50.67 O, 32.17 A, 13.45 B, 3.75 AB, 90.34 Rh D(+) and 9.66 Rh D(-). ABO maternal-fetal incompatibility was detected in 18.4 percent and Rh D incompatibility in 7 percent. CONCLUSION: The fraction of Rh D(-) population at high risk for Rh D alloimmunization was 82 percent, emphasizing the importance of Rh D alloimmunization profilaxis.

Incidence of Rh immunization between 1981 and 1992.

BACKGROUND. The Institute of Immunohaematology has had an Rh clinic at the Nowrosjee Wadia Maternity Hospital since 1957. Between then and 1977, 5% Rh-negative women produced Rh antibodies. Between 1978 and 1980, the rate of immunization was reduced to 3.3%. In the present study we determined the incidence of Rh immunization between 1981 and 1992. METHODS. ABO and Rh grouping was carried out by standard methods on 139,635 samples collected from antenatal women. Six thousand nine hundred and fourteen (5%) Rh-negative women were screened for Rh antibodies using an enzyme technique. Analysis was carried out by dividing the data into four groups, each of three years duration. RESULTS. The number of women attending the antenatal outpatients increased steadily but the frequency of Rh-negativity remained at approximately 5%. The rate of Rh immunization among Rh-negative women declined from 3.1% during 1981-83 to 1.7% during 1990-92. The rate among pregnant women dropped from 0.16% to 0.09% and this was statistically significant (p < 0.05). The incidence of Rh immunization among Rh-negative women increased from 0.4% in the first pregnancy to 17.5% after four or more pregnancies (p < 0.01). Only 15 out of 167 Rh immunized women had received anti-D immunoglobulin previously. CONCLUSIONS. The incidence of Rh immunization has declined during the last 12 years possibly due to family planning and extensive use of anti-D immunoglobulin. However, complete eradication of Rh haemolytic disease of the newborn will be possible only if a comprehensive Rh prophylaxis programme is instituted.

Riesgo y prevalencia de isoinmunización en madres Rh negativas / Risks and prevalence of isoimmunization in rh negative mothers

Se estudiaron 2518 madres que se desembarazaron en el Servicio de Obstetricia del Hospital Dr. Luis E. Aybar en el período comprendido entre el 1 de Junio al 31 de Diciembre 1992, de las cuales 119 resultaron ser Rh neg, para una prevalencia de 4.7//. De estas 119 madres, 3 resultaron con el Test de Coombs indirecto positivo, para una prevalencia de isomunización de 2.5//. De estas 119 madres, 49 que tuvieron hijos Rh pos, pudieron ser seguidas por 6 meses post parto y 4 de ellas al término de este período resultaron con el test de Coombs indirecto positivo, para una prevalencia de 8.1//de isoinmunización y un riesgo de p=0.08