Antenatal Maternal Serum IAT Titer and Fetal Outcome in Rh Isoimmunized Pregnancies

The incidence of Rh negativity in India is about 1-5 % and the rate of Rh sensitization to be approximately 0.79 % of live births. This study evaluated the role of antenatal maternal serum Indirect Antiglobulin Test (IAT) titre in predicting the feto-neonatal outcome. The study was conducted from Jan 2007 to Dec 2012 at our centre in Pune, Maharashtra, India. This study reports our experience with 75 IUTs carried out for 42 cases of severe Rh isoimmunization. IAT was performed by ID gel cards and test tube method was utilized for titration. Results were analysed by odds ratio (OR) with 95 % Confidence Interval. IAT titre was found to have a direct correlation with the maternal parity, requirement of number of IUT's and adverse fetal outcome. Of the 42 cases of severe Rhisoimmunization who underwent IUT, 11 (26.2 %) had hydropic fetus resulting in 08 (73 %) live babies, two intrauterine and one neonatal death. The remaining 31 (73.8 %) non-hydropic fetuses who received IUT, one intrauterine and one neonatal death were observed. In the 11 hydropic cases, who received IUTs, two intrauterine and one neonatal death were observed in which the IAT titre was ≥512, which was found statistically significant with OR of 9.77 & P value of 0.05. The overall survival rate was 37/42 (88.1 %). Severity and fetal outcome in Rh isoimmunized pregnancies, showed a significant association with antenatal maternal serum IAT titre. More the antibody titre more would be the fetal and/or neonatal severity with respect to immune hemolytic anemia. Requirement of multiple IUTs are also associated with high antenatal serum IAT titre.