scope:

Specimen Quality

The primary goal of this standard is to improve and ensure the quality of blood spots collected from newborns. Poor-quality and unsatisfactory specimens place an unnecessary burden on the screening system. Retesting requires additional follow-up, which, if not completed in a timely manner, could result in missed or late diagnosed cases, and can cause unnecessary trauma to the newborn and anxiety to the parents. Because of the complexity and diversity of the specimens that might be encountered and the influence of specimen quality on test results and their interpretation, the specimen criteria and handling procedures should address the common variances. Laboratory staff should immediately request another specimen (or the missing information) when the screening laboratory receives a poor-quality specimen (or one missing critical patient information). In all newborn screening (NBS) programs (NSPs), the turnaround time for results is critical if treatments to alter the adverse consequences of a condition (such as irreversible brain damage or death) are to commence in a timely manner.

Less-Than-Ideal and Unsatisfactory Specimens

NBS specimens may be collected in less-than-ideal circumstances and their quality may not be optimal for some, or all, of the NBS test categories. Some typical circumstances considered less than ideal may include specimens that are collected too early, too soon after a transfusion, before adequate feeding has occurred, or from a sick newborn. Other collection problems, eg, transit delays and missing information, may also affect the reliability of NBS results. Individuals responsible for collecting and submitting specimens should be made aware of these and other potential problems that can affect screening results (see Appendix D).

Nomenclature such as less-than-ideal, poor-quality, unsatisfactory, unacceptable, or invalid may be used in describing dried blood spot (DBS) specimens that are not properly collected. Such specimens are those with insufficient quantity of blood; clotting; smearing or contamination; inadequately filled circles; oversaturation with blood; scratching or abrading by capillary tube spotting; incomplete drying before mailing; or those that are usable to test for some, but not all conditions (see Appendix B). The standard operating procedures of the laboratory should address whether DBS specimens that are considered less than ideal ("unsatisfactory") meet the established quality criteria. For all less-than-ideal specimens, a second specimen should be requested immediately and the request documented and tracked. NBS policies and protocols relating to submission of less-than-ideal specimens should seek to eliminate any confusion regarding results that might arise from such specimens. Similar policies should also exist for the screening laboratory. Protocols involving less-than-ideal specimens should be carefully followed.

The potential exists for specimens to be deemed "unsatisfactory" for analysis and/or for result reporting for one, many, or all analytes based on information accompanying the specimen or on the quality and/or amount of specimen received. It is important for the program to establish policies governing when and why a specimen should be considered less than ideal, of poor quality, or unsatisfactory. Data and specimens should be considered both independently and in combination when developing such policies.

In cases in which a specimen has been determined to be less than ideal or of poor quality, its analysis could yield unreliable, misleading, or clinically inaccurate results, and appropriate caution must be exercised. If such a specimen is analyzed, then the laboratory is acknowledging that the specimen is valuable for testing and will assume responsibility for the reliability of the analytical values and whether or not to report such results, and will track the receipt of a second specimen. Program-specific rules should be followed consistently with respect to handling, and analysis of, these specimens of less-thanideal quality.

Because timely detection of a condition is critical for achieving maximum intervention benefits, testing and reporting of results from poor-quality (less-than-ideal) specimens may be considered. When testing and reporting results is permitted from specimens that deviate from typical quality specimens, the laboratory should follow established written procedures and document the properties of the poor-quality specimen on the data report. Specimens that are of poor quality (less than ideal) but still meet the minimum laboratory criteria for analysis should have results confirmed by a valid second specimen.4 Poor-quality (less-than-ideal) specimens may be analyzed and/or have their results reported only if considered appropriate by the authorities overseeing the NSP. (Adhere to local rules, regulations, and institutional policies.) NOTE: Analysis of poor-quality specimens should not distract from efforts to educate those who collect specimens and the constant pursuit of the collection of high-quality specimens (see Appendix B).

In addition to specimen quality, several patient conditions and treatments exist that are known to interfere with the reliability of NBS results. The tables in Appendix D provide lists of various conditions and treatments known to interfere with the reliability of screening results. For more specific information about these conditions and treatments, refer to CLSI document NBS03.