NON-INVASIVE PRENATAL DIAGNOSIS OF FETAL RHD BLOOD GROUP STATUS FOR D NEGATIVE PREGNANT WOMEN: NEW STRUCTURES FOR CLINICAL MANAGEMENT

Aims To report on the accuracy and clinical application of non-invasive prenatal diagnosis for fetal RHD genotyping. Methods Blood samples (n = 788) were collected from n = 603 non-selected RhD negative pregnant women, gestation age 7–38 weeks (median age 19 weeks). Samples from n = 110 isoimmun-ised D negative pregnant women were referred from across Australia. Cell free fetal DNA was isolated and qPCR used to amplify fetal RHD sequences from exons 4,5 and 10. Test outcomes were measured against cord blood serology. Results Among the 788 samples the predicted fetal RHD assignment was negative in 292 (37.1%), positive in 485 (61.5%) and inconclusive in 11 (1.4%). Cord blood RhD results for n = 758 showed a strong association between genotype and phe-notype (p Discussion The maternal blood test is safe and accurate for assessing fetal RHD status. It has been used to guide clinical management of isoimmunised D negative pregnant women from across the country.