Abstract

Background and Aim: Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) are essential tests for diagnosing hemostatic disorders and monitoring anticoagulant therapy. However, delays in processing samples can affect result accuracy. This study aimed to assess the impact of plasma sample processing delays on PT and APTT results.
Methods: An experimental study was conducted at Muhimbili National Hospital, with 100 plasma samples collected from healthy blood donors. Samples were processed within 4 hours (baseline) and stored at -20°C for retesting after 24 and 48 hours. PT and APTT results were compared using one-way ANOVA and non-parametric tests, with a significance threshold of p < 0.05. Data was collected and analyzed in 2024.
Results: PT and APTT values increased with plasma storage time. At baseline, PT and APTT averaged 12.92 seconds and 28.92 seconds, respectively. After 24 hours, PT increased to 15.08 seconds and APTT to 32.28 seconds. At 48 hours, PT reached 17.72 seconds, and APTT was 38.28 seconds. One-way ANOVA showed significant differences in both PT and APTT across storage times (p < 0.001). Correlation analysis revealed a strong positive correlation between storage time and test results (PT: r = 0.852, APTT: r = 0.859). Non-parametric tests confirmed significant differences in PT and APTT between baseline and stored samples at 24 and 48 hours.
Conclusion: Delays in processing plasma samples significantly affect PT and APTT results, emphasizing the need for timely testing within 4 hours to ensure accuracy.

Key words: Plasma storage duration, Prothrombin Time (PT), Activated Partial Thromboplastin Time (APTT), Blood donors, Coagulation tests, Muhimbili National Hospital (MNH), Hemostasis.