The methods outlined below are only to be used in extraordinary circumstances when a heel-stick cannot be performed. The heel-stick is the preferred method for optimal laboratory results for the newborn screen.
Important Note: These methods often result in a specimen that is caked, clotted, layered, scratched or contaminated and have an increased risk of being deemed unsatisfactory to test, which would require a re-draw. This could result in critical delays in testing, disorder identification and in the health of the infant. Please consider these potential problems before opting to collect the Newborn Screen by one of the following methods.
Capillary Tube Collection
Blood collection using capillary tubes is discouraged because it increases the risk of a clotted, layered specimen or a torn or chafed card. If capillary tube collection becomes necessary due to clinical circumstances:
- For each circle to be filled, use a sterile, plain tube. Anti-coagulants such as EDTA, citrate, and heparin will interfere with analysis.
- Touch the tip of the capillary tube to the blood drop from the heel and allow the blood to flow into the tube. (The tube may fill better by holding it in a near horizontal position as it touches the drop of blood).
- Immediately after filling the capillary tube, apply the contents to the center of the first circle on the newborn screening card, allowing the blood to flow out and fill one circle.
- Waiting too long may allow the blood and plasma to separate and interfere with test analysis.
- Do not touch the tube to the filter paper.
- Do not dab the blood on or “color in” the circle.
- Apply blood to only one side of the filter paper.
- Do not apply multiple capillary specimens to the same circle.
- Continue the steps above for each circle on the filter paper.
Venous Blood Collection
Although discouraged, if circumstances warrant venous blood collection:
- Avoid drawing from an extremity where an IV is in place.
- Using appropriate pediatric blood drawing techniques, obtain the sample through a butterfly (winged) blood collection set.
- Remove or shorten catheter length so the blood can flow freely onto all the filter paper circles.
- Syringe collection of the blood is discouraged because the lack of anticoagulant and time delays can cause clot formation and separation of the specimen.
Keep in mind:
- Test results may be affected if collected from a site other than the heel.
- Veins may be needed for IV fluids.
- Venous blood collection is more invasive than a heelstick.
Umbilical Catheter Collection
- To avoid contamination from substances previously infused through the line, draw off 2-2.5 cc’s before collecting the newborn screen specimen.
- Collect the blood in a syringe and apply it to the circles immediately to avoid blood clots that would make the specimen unsatisfactory.
- Fill all circles.
- Do not re-apply blood to a circle that has already dried.