الواقع والحياد
18-04-2007, 01:03 AM
Grading Agglutination Reactions
PRINCIPLE
The degree of red cell agglutination observed in any blood bank test procedure is significant and should be recorded. The degree of agglutination gives an indication of the amount of antigen or antibody present. The manner in which the cell buttons are resuspended and reactions are read is critical for accurate results.
PROCEDURE
1-Read only one tube at a time, using the lighted agglutination viewer.
http://www.cksu.com/vb/uploaded/6488/1176846802.gif
2-Before resuspending, observe the supernate for hemolysis. If hemolysis is observed, this is a positive reaction and should be noted on the worksheet.
3-Grasp the tube lightly at the top, and hold vertically so that the cell button is facing toward you when viewed in the mirror.
4-VERY GENTLY shake the tube (shake from the wrist) to dislodge the cell button. Continuously observe the cells as they come off the cell button.
5-When the cell button is about one-half broken up, gently tip the tube horizontally and observe for agglutination.
6-Return the tube to the upright position and continue gently shaking until the entire cell button is dislodged.
7-Tilt the tube once more and immediately grade and record the reaction. Consult the reaction grading scheme below.
NOTE:
-Overshaking can break up fragile agglutinates, resulting in a false negative reaction.
-Failure to completely resuspend the cell button may result in a mixed-field reaction being missed.
GRADING SYSTEM FOR REACTIONS
Macroscopic:
4+ One solid aggregate or clump of cells.
3+ Several large aggregates, clear background.
2+ Small to medium sized aggregates, clear background.
1+ Small aggregates, turbid reddish background.
+W Tiny aggregates, turbid reddish background.
MF Mixed Field – Any degree of agglutination in a sea of unagglutinated cells.
Hem - Hemolysis is interpreted as a positive reaction and may be graded as complete or partial. Both hemolysis and agglutination may be recorded on the same tube.
Ø Negative - no agglutination, smooth reddish background.
Microscopic:
+ Positive - aggregates of at least 3-5 cells.
Ø Negative - no agglutination.
http://www.cksu.com/vb/uploaded/6488/1176847681.gif
REFERENCE
AABB Technical Manual 13th Ed. (1999)
matc\gradrxn.lab
Author: Peggy Schroeder, revised by Peggy Jensen
PRINCIPLE
The degree of red cell agglutination observed in any blood bank test procedure is significant and should be recorded. The degree of agglutination gives an indication of the amount of antigen or antibody present. The manner in which the cell buttons are resuspended and reactions are read is critical for accurate results.
PROCEDURE
1-Read only one tube at a time, using the lighted agglutination viewer.
http://www.cksu.com/vb/uploaded/6488/1176846802.gif
2-Before resuspending, observe the supernate for hemolysis. If hemolysis is observed, this is a positive reaction and should be noted on the worksheet.
3-Grasp the tube lightly at the top, and hold vertically so that the cell button is facing toward you when viewed in the mirror.
4-VERY GENTLY shake the tube (shake from the wrist) to dislodge the cell button. Continuously observe the cells as they come off the cell button.
5-When the cell button is about one-half broken up, gently tip the tube horizontally and observe for agglutination.
6-Return the tube to the upright position and continue gently shaking until the entire cell button is dislodged.
7-Tilt the tube once more and immediately grade and record the reaction. Consult the reaction grading scheme below.
NOTE:
-Overshaking can break up fragile agglutinates, resulting in a false negative reaction.
-Failure to completely resuspend the cell button may result in a mixed-field reaction being missed.
GRADING SYSTEM FOR REACTIONS
Macroscopic:
4+ One solid aggregate or clump of cells.
3+ Several large aggregates, clear background.
2+ Small to medium sized aggregates, clear background.
1+ Small aggregates, turbid reddish background.
+W Tiny aggregates, turbid reddish background.
MF Mixed Field – Any degree of agglutination in a sea of unagglutinated cells.
Hem - Hemolysis is interpreted as a positive reaction and may be graded as complete or partial. Both hemolysis and agglutination may be recorded on the same tube.
Ø Negative - no agglutination, smooth reddish background.
Microscopic:
+ Positive - aggregates of at least 3-5 cells.
Ø Negative - no agglutination.
http://www.cksu.com/vb/uploaded/6488/1176847681.gif
REFERENCE
AABB Technical Manual 13th Ed. (1999)
matc\gradrxn.lab
Author: Peggy Schroeder, revised by Peggy Jensen