Fetal Blood Sampling (Percutaneous Umbilical Blood Sampling [PUBS], Cordocentesis)

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