Performing a Minor Crossmatch
Posted: Wednesday, December 15th, 2021 | Updated: Sunday, March 3rd, 2024
Posted: Wednesday, December 15th, 2021 | Updated: Sunday, March 3rd, 2024
Overview
A minor crossmatch mixes the recipient red blood cells with the donor's plasma.
From the Recipient
Ideally obtain about 1-2 ml of blood and place into an EDTA tube. Centrifuge the tube and carefully separate the plasma from the red blood cells. Place the plasma into a glass red top tube. Place 0.2 ml of red blood cells into 4.8 ml of saline in a glass red top tube. Place 0.1 ml of this sample into 3 separate red glass top tubes. Alternatively, you may choose to place some blood into an EDTA tube and the rest in a clot tube. Serum is also able to be used in a crossmatch
From the Donor
Obtain anticoagulated blood either from the blood product line itself or directly from the donor. If a fresh sample is collected from the donor, obtain about 2 ml of blood and place into an EDTA tube as noted above. Centrifuge the tube portion and/or EDTA tube to carefully separate the plasma from the red blood cells once more. You may place the plasma in a glass red top tube. Place 0.1 ml of plasma into each of the 3 separate red glass top tubes created above
Sample Analysis
Let one sample sit at room temperature, another warmed at 37 degrees C, and the last refrigerated for approximately 15 minutes. Centrifuge the samples and then evaluate each tube for hemolysis and/or agglutination. If either is present, the sample does not crossmatch. You may have to microscopically examine some samples if unsure about the status. Some patients may already show hemolysis prior to starting the crossmatch. They may also be autoagglutinating severely. If this is the case, performing an accurate crossmatch may be very difficult or next to impossible
Alternative Analysis
You may also label three glass slides as follows: donor control, minor crossmatch, and recipient control. From there you'll place a drop of donor rbc suspension with a drop of the donor plasma onto the donor control. You'll place a drop of donor plasma with a drop of recipient rbc suspension onto the minor crossmatch slide. Finally, you'll place a drop of recipient rbc suspension with a drop of recipient plasma onto the last slide. Alternatively, if you choose not to create a rbc suspension, you may place 2 drops of serum or plasma onto the slides instead of a single drop. Gently rock each slide and look for any agglutination. If agglutination or hemolysis is present, the samples are considered incompatible
Agglutination Scale
0 = no agglutination, 1+ = small amount of agglutination or small agglutinates, 2+ = moderate amount of agglutination or moderately sized agglutinates, 3+ = severe amount of agglutination dispersed into a few large agglutinates, 4+ = severe amount of agglutination in one solid clump
A minor crossmatch mixes the recipient red blood cells with the donor's plasma.
From the Recipient
Ideally obtain about 1-2 ml of blood and place into an EDTA tube. Centrifuge the tube and carefully separate the plasma from the red blood cells. Place the plasma into a glass red top tube. Place 0.2 ml of red blood cells into 4.8 ml of saline in a glass red top tube. Place 0.1 ml of this sample into 3 separate red glass top tubes. Alternatively, you may choose to place some blood into an EDTA tube and the rest in a clot tube. Serum is also able to be used in a crossmatch
From the Donor
Obtain anticoagulated blood either from the blood product line itself or directly from the donor. If a fresh sample is collected from the donor, obtain about 2 ml of blood and place into an EDTA tube as noted above. Centrifuge the tube portion and/or EDTA tube to carefully separate the plasma from the red blood cells once more. You may place the plasma in a glass red top tube. Place 0.1 ml of plasma into each of the 3 separate red glass top tubes created above
Sample Analysis
Let one sample sit at room temperature, another warmed at 37 degrees C, and the last refrigerated for approximately 15 minutes. Centrifuge the samples and then evaluate each tube for hemolysis and/or agglutination. If either is present, the sample does not crossmatch. You may have to microscopically examine some samples if unsure about the status. Some patients may already show hemolysis prior to starting the crossmatch. They may also be autoagglutinating severely. If this is the case, performing an accurate crossmatch may be very difficult or next to impossible
Alternative Analysis
You may also label three glass slides as follows: donor control, minor crossmatch, and recipient control. From there you'll place a drop of donor rbc suspension with a drop of the donor plasma onto the donor control. You'll place a drop of donor plasma with a drop of recipient rbc suspension onto the minor crossmatch slide. Finally, you'll place a drop of recipient rbc suspension with a drop of recipient plasma onto the last slide. Alternatively, if you choose not to create a rbc suspension, you may place 2 drops of serum or plasma onto the slides instead of a single drop. Gently rock each slide and look for any agglutination. If agglutination or hemolysis is present, the samples are considered incompatible
Agglutination Scale
0 = no agglutination, 1+ = small amount of agglutination or small agglutinates, 2+ = moderate amount of agglutination or moderately sized agglutinates, 3+ = severe amount of agglutination dispersed into a few large agglutinates, 4+ = severe amount of agglutination in one solid clump
Sources:
Nusbaum, Rebecca. "Blood Transfusions in Anemic Dogs and Cats". Today's Veterinary Nurse. vol. 4, no. 3. Summer 2021. pp. 49-59.
On The Job Training and Routine Practices
Nusbaum, Rebecca. "Blood Transfusions in Anemic Dogs and Cats". Today's Veterinary Nurse. vol. 4, no. 3. Summer 2021. pp. 49-59.
On The Job Training and Routine Practices