Special Considerations

For the purpose of newborn screening, a transfusion is defined as receipt of red blood cells (such as PRBCs or whole blood). This includes the receipt of intrauterine transfusions before birth. You may indicate “no” for transfusion status on the newborn screening card if an infant has only received fresh frozen plasma (FFP) and/or platelets.

If possible, the newborn screen sample should be collected prior to a red blood transfusion, even if the infant is less than 24 hours old. Blood transfusions are known to affect the results of screening for the hemoglobinopathies and galactosemia. Infants who are affected with one of these disorders may be missed if they have a transfusion prior to their screen because the donor blood interferes with the screen.

Pre-transfusion sample obtained less than 24 hours of age:

If a pre-transfusion sample is taken at less than 24 hours of age, a second sample is required between 24-48 hours of age, to ensure sufficient screening for all diseases.

• Collecting a pre-transfusion sample allows you to adequately screen for:
  • Galactosemia, since the test relies on measurement of the Galactose-1-Phosphate Uridyltransferase enzyme activity in red blood cells.
  • Hemoglobinopathies, since the adult hemoglobin from the transfused blood may mask an abnormal hemoglobin pattern.
• However, other diseases may be missed if the sample is collected too early, i.e. before 24 hours of age.
• In some cases, NSO may request an additional repeat sample 4-6 months after the infant’s most recent transfusion, for example, if the initial sample was unsatisfactory.

Pre-transfusion sample not obtained:

It may not always be possible to obtain a sample prior to a red cell transfusion. If a pre-transfusion sample is not obtained:

• Collect the newborn screening sample between 24 and 48 hours of age.
• A repeat sample will be required 4-6 months from the infant’s most recent transfusion.
• Advise the parents/guardians, and/or the infants primary care provider of the need for this 4-6 month repeat screen.

The health care provider who submitted the initial sample is responsible to arrange for the repeat sample to be obtained. It is recommended that each submitter develops their own internal process on how these cases are handled. All correspondence with parents/guardians and/or their primary health care provider should be documented.

Note: When completing the newborn screening card for these infants, please ensure to indicate the date and time of the initial and most recent transfusions.

Amino acid solutions administered as part of TPN are a common reason for false positive newborn screening results for some amino acid diseases. When possible, NSO recommends holding the administration of TPN for 3 hours prior to newborn screening sample collection. Only the amino acid component of the TPN needs to be held. Our recommended protocol for infants receiving TPN provides further details.

When completing the newborn screening card for these infants, check off the TPN circle on the blood spot collection card and indicate the number of hours TPN was held. This helps NSO interpret the infant’s results.