The primary goal of this standard is to improve and ensure thequality of blood spots collected from newborns. Poor-quality andunsatisfactory specimens place an unnecessary burden on thescreening system. Retesting requires additional follow-up, which,if not completed in a timely manner, could result in missed or latediagnosed cases, and can cause unnecessary trauma to the newbornand anxiety to the parents. Because of the complexity and diversityof the specimens that might be encountered and the influence ofspecimen quality on test results and their interpretation, thespecimen criteria and handling procedures should address the commonvariances. Laboratory staff should immediately request anotherspecimen (or the missing information) when the screening laboratoryreceives a poor-quality specimen (or one missing critical patientinformation). In all newborn screening (NBS) programs (NSPs), theturnaround time for results is critical if treatments to alter theadverse consequences of a condition (such as irreversible braindamage or death) are to commence in a timely manner.
Less-Than-Ideal and Unsatisfactory Specimens
NBS specimens may be collected in less-than-ideal circumstancesand their quality may not be optimal for some, or all, of the NBStest categories. Some typical circumstances considered less thanideal may include specimens that are collected too early, too soonafter a transfusion, before adequate feeding has occurred, or froma sick newborn. Other collection problems, eg, transit delays andmissing information, may also affect the reliability of NBSresults. Individuals responsible for collecting and submittingspecimens should be made aware of these and other potentialproblems that can affect screening results (see Appendix D).
Nomenclature such as less-than-ideal, poor-quality,unsatisfactory, unacceptable, or invalid may be used in describingdried 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 tubespotting; incomplete drying before mailing; or those that areusable to test for some, but not all conditions (see Appendix B).The standard operating procedures of the laboratory should addresswhether DBS specimens that are considered less than ideal("unsatisfactory") meet the established quality criteria. For allless-than-ideal specimens, a second specimen should be requestedimmediately and the request documented and tracked. NBS policiesand protocols relating to submission of less-than-ideal specimensshould seek to eliminate any confusion regarding results that mightarise from such specimens. Similar policies should also exist forthe screening laboratory. Protocols involving less-than-idealspecimens should be carefully followed.
The potential exists for specimens to be deemed "unsatisfactory"for analysis and/or for result reporting for one, many, or allanalytes based on information accompanying the specimen or on thequality and/or amount of specimen received. It is important for theprogram to establish policies governing when and why a specimenshould be considered less than ideal, of poor quality, orunsatisfactory. Data and specimens should be considered bothindependently and in combination when developing such policies.
In cases in which a specimen has been determined to be less thanideal or of poor quality, its analysis could yield unreliable,misleading, or clinically inaccurate results, and appropriatecaution must be exercised. If such a specimen is analyzed, then thelaboratory is acknowledging that the specimen is valuable fortesting and will assume responsibility for the reliability of theanalytical values and whether or not to report such results, andwill track the receipt of a second specimen. Program-specific rulesshould be followed consistently with respect to handling, andanalysis of, these specimens of less-thanideal quality.
Because timely detection of a condition is critical forachieving maximum intervention benefits, testing and reporting ofresults from poor-quality (less-than-ideal) specimens may beconsidered. When testing and reporting results is permitted fromspecimens that deviate from typical quality specimens, thelaboratory should follow established written procedures anddocument the properties of the poor-quality specimen on the datareport. Specimens that are of poor quality (less than ideal) butstill meet the minimum laboratory criteria for analysis should haveresults confirmed by a valid second specimen.4 Poor-quality(less-than-ideal) specimens may be analyzed and/or have theirresults reported only if considered appropriate by the authoritiesoverseeing the NSP. (Adhere to local rules, regulations, andinstitutional policies.) NOTE: Analysis ofpoor-quality specimens should not distract from efforts to educatethose who collect specimens and the constant pursuit of thecollection of high-quality specimens (see Appendix B).
In addition to specimen quality, several patient conditions andtreatments exist that are known to interfere with the reliabilityof NBS results. The tables in Appendix D provide lists of variousconditions and treatments known to interfere with the reliabilityof screening results. For more specific information about theseconditions and treatments, refer to CLSI document NBS03.