Washing Cord Blood for ABO Typing
A colleague in Florida notes that traditionally “4 or more” washes are recommended when performing ABO typing on cord blood. Are there any specific references stating this requirement? And has the wash procedure ever been validated or is validation necessary at each facility? In addition, the AABB Technical Manual (17th Edition p 634) states that “cord blood should be collected using a needle and syringe, which avoids contamination with Wharton’s jelly and the need for additional washing of the cells.” How does the transfusion service know whether or not the cord blood specimen was collected with a needle and syringe and whether washing is necessary?
The following comments have been received.
ADDENDA Oct. 25, 2012
- Daniel Kettler, Blood Bank Supervisor at Delano Regional Medical Center responds:
Routine washing of cord blood samples prior to ABO typing assumes that every cord blood sample is contaminated with Wharton’s jelly to the extent that false-positive test results will be produced.
You can easily determine if routine washing of cord red blood cells is necessary in your facility by parallel testing 20-40 cord blood samples with and without washing prior to ABO/Rh typing. Evaluate your results and design your process accordingly. I stopped routine washing of cord red blood cells prior to ABO/Rh typing over 30 years ago. I have always included an Rh control test with standard tube testing or gel. We do not wash cord blood samples prior to testing on the ORTHO ProVue®.
ADDENDA Oct. 27, 2012
- A blood banker from a Midwestern medical center responds that he too stopped performing extra pre-washes for cord blood testing long ago. Since the cord blood workup is usually ABO, Rh, and DAT and the DAT needs 3-4 washes anyway, he makes a 3% dilution of the cord cells and wash tubes with one drop apiece for each of the 3 tests, then washes 3 times.
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