March of Dimes
Collection of Screening Specimens
  Invalid Specimens

Certain types of specimens are known to give erroneous laboratory results. In accordance with laboratory regulations, these cannot be tested and are termed invalid. This delays the screening of the newborn, and requires that the submitter repeat the collection procedure.

Simple Spot Check provides examples of unacceptable specimens. You will need Adobe Acrobat Reader to view Simple Spot Check. To download a free copy of Acrobat Reader, click here.
Simple Spot Check (PDF 40KB)


Causes of Invalid Specimens

The New York State testing laboratory classifies unsuitable specimens into eight categories based on the following criteria:
Invalid Specimens
Possible Causes
Quantity of blood insufficient 1) Filter paper circle incompletely filled or not saturated.
2) Blood applied with needle or capillary tube.
3) Contamination of surface of filter paper circle.
4) Failure to obtain any blood.
Blood spots appear scratched or abraded Blood applied improperly with capillary tube or by other means.
Blood spots wet or discolored Specimen not properly dried before mailing.
Blood spots appear supersaturated Excess blood applied (usually with capillary tube or needle). Blood applied to both sides of filter.
Blood spots appear diluted 1) Puncture site squeezed or "milked" to expel blood.
2) Exposure of blood spots to direct heat.
3) Contamination of filter paper before or after blood collection by gloved or ungloved hands or by substances such as alcohol, feeding or antiseptic solutions, hand lotion or powder.
Blood spots exhibit "serum rings" 1) Alcohol not wiped off puncture site before skin puncture is made.
2) Allowing filter paper to come in contact with alcohol, water, hand lotion, etc.
3) Squeezing the area around the puncture site excessively.
4) Drying the specimen improperly.
5) Applying blood to filter paper with a capillary tube.
Blood spots appear clotted or layered Touching the same filter paper circle to a blood drop several times. Filling the circle from both sides of the filter paper.
Specimen delivered to the laboratory more than 14 days after collection 1) Specimen held at the hospital before mailing.
2) Delivery delayed by the post office or other delivery service.


The information contained in this section does not constitute the endorsement of any specific state policy or procedure by the March of Dimes. Content is based on the New York State Department of Health manual “Newborn Screening in New York State: A Guide for Health Professionals,” provided by the Newborn Screening Program, Wadsworth Center, New York State Department of Health. The material has been modified for a national audience, and additional information has been added by the March of Dimes. 		 
  © 2008 March of Dimes Birth Defects Foundation. All rights reserved. The March of Dimes is a not-for-profit organization recognized as tax-exempt under Internal Revenue Code section 501(c)(3). Our mission is to improve the health of babies by preventing birth defects and infant mortality.