[Histonet] CYP.07680 - cytology cross contamination

[Jeter, Brent]

Hi Brandi,

The clean, blank slide is some times inserted between cases in the staining rack to determine if floaters are present.  It's sort of a retroactive test - if you see cells on the blank slide, then you already have cross-contamination and you need to re-prep and restain the cases separately.  Some people feel that you've caught the floaters on your clean slide and the problem is solved, but there's no guarantee others won't be present on your specimen slides, too.

Toluidine blue is an example of a stain you could use to determine cellularity; another option often used is a modified Wright Giemsa stain such as Diff-Quik.  You're not looking to make a final diagnosis, but to make a quick preparation and use a simple stain just to see if there are a lot of cells present.  This is a more proactive test.  The idea is that highly cellular specimens have an increased likelihood of shedding cells into the stains and contaminating other cases; it also can be used to identify obviously malignant cases, which should definitely be stained separately.

If you're using a rapid stain to look for high cellularity, you need to centrifuge and concentrate the specimen(s) first, just as you would in regular prep.  The Diff-Quik stain is a Romanovsky stain and is used on air-dried slides, so there's no need for fixation.

Hope that helps - 


Brent Jeter
Anatomic Pathology Supervisor
The George Washington University Hospital
202-715-5076 (phone)
202-715-4691 (fax)
brent.jeter <@t> gwu-hospital.com
________________________________________
From: histonet-bounces <@t> lists.utsouthwestern.edu [histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Brandi Higgins [brandihiggins <@t> gmail.com]
Sent: Tuesday, May 11, 2010 2:55 PM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] CYP.07680 - cytology cross contamination

Hello all,

For CAP policy CYP.07680 for "procedures to prevent cross-contamination of
specimens during processing and staining" - what are your labs doing?

 I work in a small lab so the histotechs process the cytology specimens and
the pathologists read the slides (we have no PA's or cytoprep techs or
cytotechs to screen slides).  We also process only non-GYN, so we don't have
to worry about GYN/non-GYN cross contamination.

The notes under this policy say procedures must prevent cross-contamination
between highly cellular specimens and suggest the screening method of
toluidine blue stain to determing if specimens are highly cellular.

Does anyone use the toluidine blue for this purpose?  If so could you tell
me the procedure for toluidine blue you use?  And how do you determing which
specimens you stain with toluidine blue and what qualifies as highly
cellular.  If so do you retain these toluidine blue slides for any period of
time?

CAP policy also suggests inserting a clean blank slide in each stain run and
examine for contamination.  Is anyone doing this?

We have been inspected before with no problems with this CAP question, but I
just want to make sure we are doing everything we can to prevent
cross-contamination.

Thanks in advance for your input!
Brandi Higgins, HT (ASCP)
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