This test is used only in certain circumstances and is usually used only when amniocentesis or chorionic villus sampling would not be adequate. It provides the most accurate information and the most rapid results. A needle is inserted through the mother's abdominal wall, into the amniotic cavity and into the fetal umbilical cord. The PUBS procedure increases your risk of fetal loss by about 2%. The procedure requires considerable skill and should be done only at referral centers.

Concerns about genetics do not end when the baby is born. Every newborn in the United States is checked for two genetic disorders: phenylketonuria and hypothyroidism. When these disorders are diagnosed at birth, they can be treated and mental retardation avoided. Several states require screening for two to four additional disorders, such as cystic fibrosis and maple syrup urine disease. Some children need to be evaluated by a geneticist. These are children born with an obvious birth defect or genetic disorder, or children who do not develop normally.

Clinical geneticists are physicians skilled in the diagnosis, management, treatment, and counseling of persons and families affected by genetic disorders. Their examination usually involves a detailed medical history, a family history and pedigree, and a thorough physical exam of the patient and often other family members. Sometimes chromosome, DNA, or biochemical studies are required. These usually involve samples of blood and possibly a tissue biopsy.