California Newborn Screening Program
Limitations of Screening
Screening is defined by the World Health Organization as "The presumptive identification of unrecognized disease or defect by the application of tests, exams, or other procedures, which can be applied rapidly. These tests sort out apparently well individuals who have a disease from those who probably do not."
Screening programs are, by nature, imperfect. In setting cutoffs, a balance must be struck between time, money, anxiety caused by false positives, and an acceptable number of missed cases. Biological variability and/or human error can result in missed cases. Transfusions can lead to false negative results. Errors can occur at the specimen collection site, when the specimens are in transit, at the laboratory, in computer processing of results, and/or in the reporting process.
For this reason, it is critical for health care providers to remain watchful for any sign or symptoms of these disorders in their patients. The possibility of a disorder should not be ruled out solely on the basis of the newborn screening test result. A newborn screening result should not be considered diagnostic, and cannot replace the individualized evaluation and diagnosis of an infant by a well-trained, knowledgeable health care provider.
The Program has numerous quality improvement, educational and monitoring mechanisms in place to assure that all infants are screened and that the results are valid. Therefore, the possibility of a disorder should never be ruled out solely on the basis of the NBS results. Any signs or symptoms of a disorder should be followed up immediately. To evaluate the completeness and effectiveness of the NBS Program, California Code of Regulations (Title 17) requires that all physicians making a diagnosis of a preventable heritable disorder, for which testing is required, report such diagnosis to the Department of Health Services. If a missed case is called to our attention by this process, the State will investigate the case to determine if changes in policies or procedures are necessary.
Additional Newborn Screening