Clot waveform analysis of prolonged activated partial thromboplastin time in various disorders

Introduction: The prolongation in APTT reflects various disorders affecting the blood coagulation system. Automated coagulation analyzers such as ACL TOP, help in evaluating the clotting cascade by displaying clot reaction curves or waveforms. The fibrin formation curve forms S-shaped curve showing the changes in the absorbance on X-axis and time in seconds on Y-axis. The clotting data is processed to obtain derivatives.

Materials and methods: This observational study analyzed 80 samples including 20 samples from normal healthy individuals as control. The parameters studied were time (secs), height (mAbs), and width (secs) of first derivative (FD), fibrin clot time at ½ height, height (mAbs), and width (secs) of both first and second peaks of second derivative (SD).

Result and discussion: Hemophilia (n = 13) that consisted of factor VIII deficiency (n = 11) and factor IX deficiency (n = 2) showed biphasic patterns in both first DC and second DC. Cases with thrombosis (n = 8) showed marked elevation in first DC. Various other disorders (n = 39) that consisted of mainly hepatic dysfunction (n = 24) showed prolongation in fibrin formation, first DC, and second DC peak time.

Conclusion: The atypical derivative curve analysis helps in determining the interferences in clotting cascade. It gives significant information and provides direction for further testing.