Preadmit Specimens with positive antibody screens

[Malcolm Needs ☆]

Love the ironic humour Eoin!

[Mabel Adams]

We do pre-admit specimens up to 2 weeks before the procedure if the patient has not been pregnant or transfused in the past 3 months.  We have been willing to use the specimen to do gel crossmatches until 3 days after the procedure (might be as much as 17 days from collection but usually isn't that long).  We usually set up the units the day before surgery (on all pre-admits, not just those with antibodies) so as not to tie them up unnecessarily.  We could have to set up additional units in the few days after surgery too. We do not freeze the samples.  This policy was in place before I came here and was probably created with negative antibody screens in mind.  The reason we all do AHG xms in patients with antibodies is as a double-check on our unit antigen typing and to catch antibodies to low -frequency antigens, right? So how long will antibodies remain active enough in the sample to cause an incompatible crossmatch with that mis-typed unit or the one with the low-incidence antigen?  Does anyone have data on how long the usual antibodies we identify tend to remain stable in a refrigerated specimen?  And do you know how long antibodies to low-frequency antigens can be trusted to remain stable?  Obviously any antibody can do whatever it wants and it depends on the original strength.  I know that Kidd system antibodies tend not to store well, while Rh antibodies do.  What's a reasonable rule of thumb that will prevent patient harm?  Must we do all gel xms before the specimen is 3 days old, 7 days old or???? Our manufacturer's instructions seem to be getting more vague over time. I don't see anything in them that would say we can't use the specimen at 17 days.

[cthherbal ☆]

We do pre-admit specimens up to 2 weeks before the procedure if the patient has not been pregnant or transfused in the past 3 months.  We have been willing to use the specimen to do gel crossmatches until 3 days after the procedure (might be as much as 17 days from collection but usually isn't that long).  We usually set up the units the day before surgery (on all pre-admits, not just those with antibodies) so as not to tie them up unnecessarily.  We could have to set up additional units in the few days after surgery too. We do not freeze the samples.  This policy was in place before I came here and was probably created with negative antibody screens in mind.  The reason we all do AHG xms in patients with antibodies is as a double-check on our unit antigen typing and to catch antibodies to low -frequency antigens, right? So how long will antibodies remain active enough in the sample to cause an incompatible crossmatch with that mis-typed unit or the one with the low-incidence antigen?  Does anyone have data on how long the usual antibodies we identify tend to remain stable in a refrigerated specimen?  And do you know how long antibodies to low-frequency antigens can be trusted to remain stable?  Obviously any antibody can do whatever it wants and it depends on the original strength.  I know that Kidd system antibodies tend not to store well, while Rh antibodies do.  What's a reasonable rule of thumb that will prevent patient harm?  Must we do all gel xms before the specimen is 3 days old, 7 days old or???? Our manufacturer's instructions seem to be getting more vague over time. I don't see anything in them that would say we can't use the specimen at 17 days.

Currently we use 10 day prior to surgery samples up to 3 days post-surgery (so 13 days total), but I've worked as a large university hospital that used 30 day old samples to crossmatch units for the patient on day of surgery only, then requried a new sample the following day.

[Brenda K Hutson]

But the last sentence specifies "frozen" retention for a longer period of time; so I think it is going back to specimen integrity on these antibody.

Brenda

 

 Thanks for the reference!  We will have to check the standard itself, as it appears that this is a response to a question about specimen retention, not specimen acceptability regarding age and testing. The last sentence seems to refer only to how long a specimen should and can be retained. 

 

There is no quoting of the complete JCAHO standard here, so I am wondering if the sense of the actual standards may say something else about specimens collected for Pre-admit testing.

 

Scott