We measure   PT and PTT tests with using sysmex (CA50) or Coalaser (DiaLAB) analysers  using Biolab reagents. Both instruments measure the tests according turbidometric method. We encounter a "NC error" (PT>60 sec and PTT>180 sec) for about each 20 tests in non turbid patient's plasma. However, when we measure these samples with manual methods or by other instrument even with turbidometric method ( ACL analyser) and using the same reagents, the test results is normal/ mild to moderate increase.  How could resolve this problem?

I suggest you call the analyzer company's technical specialist with this question.  We have IL analyzers that use the optical method.  I know that on those, if there is anything that causes the clot curve to look abnormal, we will see a "no clot" result.  On those analyzers, we have to check the curve for that particular test to see if the curve is a typical "extended" no-clot, or there is something else wrong that might cause an abnormal curve.

 

I would ask why 1 out of 20 tests are failing like this.  It seems like that's way too many false extended results for any analyzer.

 

Scott