Invasive procedure to obtain fetal blood generally performed after 18 weeks of gestation. Procedural risk of fetal loss is approximately 1 " “2%.
Use
Usually performed when diagnostic information cannot be obtained through amniocentesis, chorionic villus sampling (CVS), ultrasound examination, or following an inconclusive result from one of these tests
Provides fetal material for chromosome (cytogenetic) testing, biochemical testing, and molecular DNA-based testing for inherited disease
Chromosome analysis faster than with either amniocentesis or CVS because less culture time required; therefore, useful for late presentations
Used to assess fetal isoimmunization (e.g., Rhesus factor, Kell), anemia, platelet count, hemolytic disease, and infection (e.g., toxoplasmosis, rubella, or CMV)
May also be used to administer medication to the fetus
Limitations
Riskier procedure than amniocentesis of CVS performed late in pregnancy, limiting pregnancy termination options