Ortho Gel, well 6

[HWalker]

Is anyone else having sporadic false positives in well 6 of the gel cards?

It seems to occur on the last box or 2 of a lot. There's no 'rhyme nor reason' to it. For example, we'll do qc on the cards using a dilute anti-C with the Ortho 3 cell surgiscreen. Well #1 is 3+, well 2 & 3 negative.

If we do it twice on the card well 6 will be a weaker 2-3+ with cells streaming all through the column.

columns 1 2 3 4 5 6

surgiscrn 1 2 3 1 2 3

Results 3+ 0 0 3+ 0 2+

:confused::confused:

Hope that made sense.

We centrifuge the cards before use.

This has happened with the last 2 lots we've used. I haven't called Ortho yet.

Thanks for any input!

[David Saikin]

I have not noticed this - - - are you certain there is no drying in the gel? I have noticed that phenomenon in the past, ie, drying in the gel itself towards the end of the box.

[TimOz]

Hi HWalker,

I have seen exactly this many years ago. Are the liquid levels OK in the cards? Are they "splashed". In my case there seemed to be a dispensing issue but it was never nailed down. Changed batch of cards fixed it. A quick way to determine if it is really a specific well issue is to repeat the test with the cards flipped around (so well 1 well is now well 6). The false positives should be obvious. Take some photos and refer it to OCD Tech support.

[Juliane]

I have had some experiences with false positives due to age of reagents (near expiration) getting caught in the gel but not necessarily part of the reactivity.

Also, are you storing cards at room temp? the preferred storage is refrigerated, but only if you have the room. If you do I highly recommend changing your storage to refrigerated and it will certainly prevent having to respin them before use, and keep the cards from drying or intra-well evaporation. I would call ortho.

are you using a ProVue? Or just Manual.... We have not had this problem with our weak D (2-3+) pos control.

[TimOz]

Hi HWalker,

Just a suggestion. Could you add where you are from in your profile? I just realised my comments above refer to Ortho BioVue that is NOT the gel ID-MTS system available in the US and is not a gel but silica bead based. Ortho BioVue likes to be stored at 2-8oC and will eventually evaporate if stored at higher temperatures or on a bench in the sun where it can warm up. Ortho ID-MTS gel is similar but not the same as the DiaMed ID-MTS system we have here. It does not like to be chilled and should be stored at RT. You will get more accurate advice if we are not confused about what you are actually using.

[Juliane]

Contact Ortho for USA MTS Gel products, and they will tell you refrigeration is the preferred storage for their gel cards, as the storage range is 2-25'C. So it is perfectly acceptable to be stored at 2-8'C, actually is is better to do so....

[TimOz]

Hi Juliane,

Note that In my post above I typed 2 hyphen 8oC but it has not displaying correctly!!!!!!!

This is true in Australia, Europe and the whole world - except the US.

From the current pace inserts in front of me:

DiaMed ID-MTS LISS/Coombs Poly - "Storage requirements 18 - 25oC . Do not store near any heat, air conditioning sources or ventilation outlets".

Ortho Clinical Diagnostics BioVue Anti-IgG, C3d; polyspecific - "Storage requirement: Store cassettes upright at 2 to 25oC. Do not store in a self defrosting refrigerator/freezer. Do not store cassettes near any heat source (i.e Heat Block, radiator, large instrumentation, refrigerator, freezer, etc., or in any area receiving direct sunlight."

OCD will tell customers to store tham at 2 to 8oC if they have room in the cold room and bring out the cassettes for use and leave them at RT as long as they are not heated in any way - see above.

The US is different as you have OCD ID-MTS gel system and neither product above is available . Like I said, this gets confusing if the geography is not defined or the exact product used is clear. DiaMed Gel and Ortho gels are similar but not the same. Many people outside the US call the Ortho BioVue product a gel as they use this as a generic term and it is not correct.

[Mabel Adams]

I have lived in two places using Ortho gel that are both dry climates. We keep our gel cards in the fridge except for a small stock at RT that will be used quickly. At my prior facility we noticed drying out of the cards if stored at RT for longer periods--I assume because of the dry climate. Not sure if that is the cause of any problems with false positives, but thought I'd throw it out there.

[rravkin@aol.com]

HWalker,

Why do you prespin the gel card? I am concerned that this step enacted on an aged gel card will alter the gel producing your false positive, although I would think you would see false positives sporadically and not isolated to one or two wells.

[TimOz]

I agree with rravkin.

OCD at one staged advised to prespin BioVue cards (these are not ID-MTS) if they were splashed in transport BUT this is a silica bead system. I understand the plastic (gel) beads can "pack down" in spinning and alter the reactions. I have not seen data to support this but I would check.

[macarton]

We store our gel cards in the refrigerator and it has cut down on the number of issues such as this. Our sister hospital using the same lot as ours had a similar issue, and it was from a dirty dispensor. It was more pronounce toward the end of the bottle. Apparently some one was documenting cleaning, but wasn't or not cleaning it correctly. Mary