Ala LEE, Senior Medical Technologist

[leewc]

Do anyone experience false positive reaction in antibody screening using gel Coombs card due to the presence of rouleaux formation? If so, how to distinguish it from genuine positive reaction?

[donellda]

I haven't used gel for a few years but I did use it for about 5 years before I came to my present employer. I remember getting reactions in gel that looked very faintly positive. The button would be on the bottom of the tube with a few cells trailling down. We never investigated to see if it was rouleux but when we did get these types of reactions it often disappeared when we repeated them. Why don't you call Ortho customer service and see if they have had anyone else with a similar problem and see if they have a solution.

[Jane]

Yes- If you have the book from Ortho titled, "Interpretation Guide" it has pictures of samples with rouleaux listed under that and under haze. If we have a patient with rouleaux (verified by hematology or by us looking under the microscope) we do the tube antibody screen. After washing and adding AHG, rouleaux shouldn't be a problem anymore.

Hope this helps!

[S.Hunt]

We do come accross patient's with rouleaux and it appears just like the pictures in th ORTHO Gel literature. However, more often than not we are aware of the Rouleaux before the Gel card antibody screen is completed in the reverse grouping which we do with tubes.

More recently we have been encountering more Rouleaux than ususal and it appears to be due to a pharmacy formulary change for antibiotics.

We repeat the testing using PEG (which has it's own set of problems) and in 98% of the cases the problem is resolved.

Good Luck

[Melanie]

Rouleaux formation in gel usually looks "mixed field" with a faint ring around the top and some shadow along the sides with a button on the bottom. We repeat the screen using a different method (usually peg) and go from there.