Hi All, 

Quick question for the gel users.  We use gel as one of our back ups to our ECHO, I personally have never performed DATs in gel.  At my current facility they perform only cord blood DATs in gel. I've noticed that when the techs prepare the 0.8% cell suspension they are WAY off when compared to commercially made Ortho cells (the cell button after spinning is like 1/2 the size it should be).  In our procedure manual someone hand wrote in to wash the cells four times, when I grabbed the technical manual it states that the advantage to column technology is that you do not need to wash for anti-globulin tests.

 

I've been so ingrained to wash for DATs, I find it hard to believe you wouldn't for gel.

 

So to wash or not to wash? That's my question.

 

Thanks!

Have done DAT's cord blood sample in gel (manual and automated) for more than 15 years without washing.   Stopped washing cord blood samples routinely prior to tube testing in the 80's. 

We don't wash cord bloods for DATs in gel, haven't since we switched many years ago. 

 

There should be a procedure how to make 0.8% cell suspensions - Ortho had one which is really closer to 1%  10uL packed cells added to 1mL diluent. 

  We don't wash our cord bloods for gel. We spin the tube to get packed cells and use the  Ortho procedure that David has mentioned. Works great!

Where in the 18th edition of the technical manual does it state that the advantage to column technology is that you do not need to wash for anti-globulin tests.

Thanks!

Thanks everyone! Im actually relieved bc I can just tell them not to wash and it'll be an easy fix.

We do use that calculation to make the 0.8% from packed cells, the problem is that people are washing the cord blood four times in the cell washer and it doesn't leave enough red cells to get 10 microliters of true packed cells.

 

Anorris, page 377 last paragraph.   

First of all, there is NOT a need to wash the red cells, whether they be cord cells or red cells from any other source; that is rather the point of the gel technique (read Lapierre's original paper for an explanation, as to why - because it is really too long and complicated to explain here in one post - except to say that the plasma (and, therefore, the free antibodies, do not pass through the gel, whereas the red cells do, unless they are sensitised, and are agglutinated by the AHG in the gel).

 

Secondly, the red cell suspension should ALWAYS be made by automated pipette (or something similar that is accurate), because the human eye is NOT accurate, and will mess up the whole technique.

Thank you Malcom, that was a good explanation.  Its funny that you said the human eye is not always accurate because one of the blood bankers told me they eyeball it, and I said the same exact thing that you said. How do you eyeball a 0.8% suspension?! 

No washing for gel. A few years ago we even validated cord blood testing on the Provue as all of our BB samples are EDTA tubes. Works great. The techs were resistant at first but anything you can automate is usually better all around.