Newborn Screening Tests

Screening tests are done to detect health conditions that are not yet causing symptoms. Many serious disorders that are not apparent at birth can be detected by various screening tests. Early diagnosis and prompt treatment can reduce or prevent many disorders that may interfere with an infant's healthy development. In the United States, some tests are done routinely and some are required by the state. When screening tests are positive, further testing is often done.

Typical screening tests include

• Blood tests

• Tests of oxygen level

• Hearing tests

All newborns are evaluated for jaundice (a yellow color of the skin caused by elevated levels of bilirubin in the blood) by looking at the skin and whites of the eyes, using a skin sensor, doing a blood test, or a combination.

The governments of many countries require blood tests in newborns to detect certain inherited disorders that are treatable if discovered early. Common tests include those for phenylketonuria, maple syrup urine disease, galactosemia, congenital adrenal hyperplasia, sickle cell disease, and hypothyroidism. Some organizations also require testing for cystic fibrosis and severe combined immunodeficiency. However, in the United States, different states require different tests. For a list of routine newborn screening tests in the United States by state, see Conditions Screened By State.

Mothers with Rh-negative or type O blood are typically screened for antibodies and potential blood group incompatibility with their fetuses during pregnancy. Testing the newborn is necessary if such screening was not performed during pregnancy, if the mother's antibody screening was positive, or if the newborn develops early or severe jaundice, which might indicate a condition called hemolytic anemia (destruction of red blood cells leading to low red blood cell count).

Infants born to HIV-positive mothers should be tested within the first few days of birth if the mother was not treated with antiviral therapy during pregnancy. Infants may also be tested at later points to confirm a suspected HIV infection or if they are being breastfed (chestfed) by an HIV-positive mother.

Doctors place an oxygen sensor (pulse oximetry) on the newborn's right hand and right foot to measure oxygen levels. Low oxygen levels or significant differences between the hand and foot suggest the possibility of congenital heart disease.

Hearing tests are done to detect hearing loss, which may accompany certain birth defects or infections. Doctors use a handheld device that produces soft clicks and measures the echoes off the newborn's eardrum (called evoked otoacoustic emissions testing), or a device that measures the brain stem's response to sound with an electrode.