iSTAT BhCG False positives

Hi!
We recently had one.  It was very high.  Urine BhCG was neg.  It was immediately suspect as patient stated she did not sleep with men, only women.  It was repeated on our Orthos and was negative.  Both original sample and Ortho sample were repeated with iSTAT BhCG.  Both were still very positive.  Patient was having ovarian cyst issues but no cancer reported.  Pathology and POC review all turned up nothing suspect with our final assumption that it was some sort of interference for that specific patient.  If we get another, I'll report to Abbott and here. Thanks! Mary

YES!!! This has always occurred for us here and there, but has drastically increased lately.  We are currently investigating the issues.  I have not called into Abbott yet, but I can certainly do so.  Most of ours are patients that are in the 5.0-25.0 range and then when sent to Main Lab, they are negative.  There have been some over the >25.0 value, but not as many.  We did see in the limitations that "Partially clotted samples can result in elevated hCG results as well as quality check codes. To prevent clotting in samples collected in heparinized tubes, the sample should be inverted gently at least 10 times to ensure even dissolution of the heparin anticoagulant."  We know our ED department doesn't mix tubes so well as we see microclots on the GEM analyzer in the same area.  We were attributing it to this, but since the increase, we are taking a harder look.  The list of limitations and interferences on this test is LONG.

We also had one a month or so ago. iSTAT result was in the low 5.0-25.0 range but repeated negative twice when sent to the lab for confirmatory testing. This is the only one of these I've seen, so I assumed it was a weird one-off. Maybe not though...?