Discrepancy in optical & mechanical method in coagulation tests in a turbid sample.

Automated coagulation analyzers have replaced manual methods to meet the ever-increasing test load in many laboratories. Of the different methods, two distinct methods exist based on optical and mechanical clot detection (magnetic steel ball method). In optical method the detection of clot formation is measured by a change in optical density (OD) of a test sample. Mechanical clot detection technology, involves monitoring the movement of a steel ball within the test solution using a magnetic sensor. There are limited studies comparing both these methods and they have conflicting results regarding the effect of plasma turbidity on the final result. We report a case where a plasma factor (lipemia) caused prolongation of both PT and APTT, as measured by the photo optical method.