A small sample of villi are retrieved. Can be done at 8-14 weeks. Villi in the chorion frondosm are believed to reflect fetal chromosome, enzyme, and DNA content, thereby permitting early diagnosis of abnormalities. Quicker determination of anomalies is possible because the sample is direct fetal tissue. Can be used for intrauterine transfusion.
Infant is given O negative blood.
Risks include transiet fetal bradycardia, bleeding, infection. Maternal Blood Assessment Coombs test. Can be measures at 35 weeks. Present at 36 weeks. Delta Optical Density.