Cord Blood Specimens from OB

[Mary Ann]

Hi Malcom! Tell me about tile,is that another word for tube? I find you so fascinating it would be a real treat for me if I could someday visit your lab,I still can't get over the fact you knew Coombs.Happy Thanksgiving from Austin,Tx Ya'll:cool:

[Malcolm Needs ☆]

Hi Mary Ann,

Thank you for yoyr comments, and it would be a delight to have you visit the laboratory if you possibly can.

I wouldn't claim that I "knew" Prof Coombs, but I certainly met him and conversed with him quite a few times.

The tile technique we used to use was as follows.

Two aliquots of serum/plasma were mixed with one aliquot of red cells suspended to about 3% in saline in a tube, mixed and incubated at 37oC for an hour.

The red cells were then washed in saline for a minimum of four times, and then the tube is centrifuged again and the very last drop of saline is removed.

A white opaque tile is then scrubbed clean (this is VERY important) and dried.

The cells from the tube are then placed on the tile and a drop of AHG is added.

The AHG and cells are mixed together using the edge of a slide or a wooden stick (or anything else that is inert) and the tile is then gently swirled by hand for 5 minutes.

Agglutination can be fairly clearly seen, as can a negative.

There is a (not very good) photograph in the article about the history of the antiglobulin test (on page 5) that I posted in the library section under education.

Malcolm

Edited November 24, 2011 by Malcolm Needs

[Auntie-D]

Macolm - I much prefer tiles for rapid groups, rather than tubes but all of my staff are reluctant...

[Malcolm Needs ☆]

Yes, I can understand, but I think it is a perception thing (or, more accurately, a mis-perception thing) with a lot of people that, because tile techniques are old techniques (and I think the same applies to other "old techniques"), they don't work.

Nothing could be further from the truth.

[Auntie-D]

Malcolm - agreed fully!

The reason I prefer tiles is that it's so much easier to see even the smallest agglutination on them. I did my HNC project (way back lol) on weak-D idnetification between tube, tile and gel. Turned out that tile is almost as sensisitive as gel, and both are hugely more sensitive than tube. I feel it is operator sensitivity that is the key - how many, when using tube, do a microscopic examination of any negatives for micro-agglutination?

Tile is sooooo much easier to see tiny agglitinations.

[Malcolm Needs ☆]

If it's any consolation, when I did my HNC we used to write our essays on stone tablets!

[Liz]

hahahahha you are a riot Malcolm.

But that tile business is amazing, I imagined it as you described it .. with a bit more movement.

[Liz]

Were the tiles like white ceramic wall tiles? or do you mean slides!! no don't disappoint me, please...

[Malcolm Needs ☆]

No - not white ceramic wall tiles, because you needed to shine a light through them to see the reaction.

Perhaps I should have said, semi-opaque. As I recall it, they were sort of glass oblongs, with one side "painted" white (but not so "painted" that some light could get through them). I suppose that you could say that it was a bit like the semi-opaque plastic you get on light boxes, only it was glass.

Edited November 24, 2011 by Malcolm Needs

[AMcCord]

I'm thinking that it would be what we call 'frosted'. I've done slide types, but never antibody testing. Cool!

[webersl]

6 mL EDTA in plastic only.

Can someone explain why some labs are some getting clot tubes for cord immunohematology? Seems like extra work and irritation - getting the timing right, washing, working with just a few cells at the bottom of the clot. I've done it both ways and VERY much prefer EDTA.

Edited November 28, 2011 by webersl

[Mabel Adams]

Eons ago we used to get clot tubes of cord blood to hold for TORCH serological studies if needed. They never were so we finally quit collecting them.

[Mabel Adams]

What's HNC stand for?

We got cells of clots mostly after the clot retracted but also by using a pipet to suck and squirt serum around the clot until some red cells were rinsed off of it.

Many in the US went to using gel for AHG tests but kept doing tube blood types. It's faster and used to be cheaper.

[Malcolm Needs ☆]

Hi Mabel,

There used to be two exams that had to be passed (well, actually more than two) but the basic ones were ONC, which stood for Ordinary National Certificate and HNC, which stood for Higher National Certificate. After that, we had to do the "Special" examination, which lead to Fellowship of the Institute of Biomedical Science.

All of these exams have now been replaced by more "modern" exams (i.e. those that rely almost entirely on theoretical knowledge, and that have little or no practical based teaching whatsoever - and what do we do on the bench? Oh, practical work)!!!!!!!!!!!!

[tbostock]

We use EDTA plastic tubes for our cord bloods and we put them on our Tango analyzer (front type only, and DAT IgG). No washing needed, but we do check the samples for clots before we put them on...works beautifully.

[mollyredone]

Most of our NB samples come in a glass 10 ml clot tube. They don't want to switch to plastic because they want to sterilze the tubes with the surgical tray. Although we have been getting a few EDTA plastic tubes. I'll have to check and see if I can find a sterile kit that they could order.

[Sara Iloilo]

Please refer to AABB and CAP standards. but for us we use 7 ml EDTA tube.

[LisaM]

Just a completely dumb question here but if the sample is clotted how do you group the babies?

Edit - we get EDTA only

I've wondered that myself, too--we get the 10 ml red top tubes for cord samples, and usually if there's a clot, there seems to be enough cells floating around in the serum, too, to suck out a sample and wash the heck out of it, because they stuff the tubes very full in our L+D department.

[Malcolm Needs ☆]

I've wondered that myself, too--we get the 10 ml red top tubes for cord samples, and usually if there's a clot, there seems to be enough cells floating around in the serum, too, to suck out a sample and wash the heck out of it, because they stuff the tubes very full in our L+D department.

Ummm, excuse me for being thick here, but if you've got red cells for a forward group and (if you must) serum for a reverse group, what is the problem? For many, many years, clotted samples were the only samples that were allowed in the Blood Bank because of the "need" for complement.

[AMcCord]

Clotted cord blood samples are a bit yucky to work with, but there is no problem doing a type using them - plenty of free cells. I hate to admit it, but I am old enough to remember using clotted samples. When I trained, the only test we did on an EDTA sample was a DAT. Everything worked just fine off of those red tops.