The following question was submitted to the e-network for discussion.

"It is our facility's understanding that cord blood testing should be done only for 48 hours as the EDTA specimen integrity would be poor after that time (the tube manufacturer's recommended time frame). If a physician has requested direct antiglobulin testing after that, we perform a heel stick. The AABB Technical Manual does not address this except to say cord bloods are to be kept for 7 days for further testing.In addition, if we get a positive direct antiglobulin test on an umbilical cord blood sample, we repeat the testing on a heel stick to confirm. What are other facilities doing in this area?"

To which these replies have been received:

1. As a routine, we use cord blood for up to 7 days, with no concerns about RBC grouping, RBC antibody detection or DAT. If we are serious about evaluating an infant for a genuine hematological problem or giving a transfusion, we may begin with the cord blood (e.g., perform an elution), but will get infant blood to confirm things -- since mislabeling is always a potential problem. Also, we prefer cord blood stored no more than 72 hours for acid elution.

2. We use a cord sample up to 72 hours for non-pretransfusion testing, i.e. DAT, and do not use cord samples for pretransfusion testing, except for infant protocol patients (infants who are less than 4 months old and have initial testing on the cord sample, i.e. ABO/Rh and antibody screen (screen is negative) and have units crossmatched. We do not crossmatch again until they are over 4 months of age. We do not use the cord sample past 72 hours for any type of testing. However one interpretation of the Technical Manual is that one could use the cord sample for testing up through 7 days since the it states that the cord samples should be stored for 7 days in case HDN is suspected and then both cord and mother's samples should be tested.

3. The following comment is from a transfusion service that supports a labor and delivery service that delivers about 2500 babies per year."Our cord blood samples are submitted in red top tubes (no additives). We kept them for one week, and if within that week, testing is necessary, the sample is used."

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Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator