Nearly all babies will have a simple blood test to check for disorders that are not immediately apparent after delivery. Some of these disorders are genetic, metabolic, blood, or hormone related. Each state in the United States requires screening tests, but the specific tests performed vary among the states.
Some disorders are more common in some states, making testing more important.
A heel-prick is usually used to sample the baby s blood. The blood drops are collected in a small vial or on a special paper. The blood is then sent for testing. The baby s heel may have some redness at the pricked site, and some babies may have bruising, but this usually disappears in a few days. It is estimated that one baby in 10,000 to 25,000 is born with PKU in the United States.