The PT and PTT panel is a comprehensive coagulation screening test that evaluates both the extrinsic and intrinsic pathways of blood clotting. This panel includes Prothrombin Time (PT), which measures clotting through the extrinsic pathway and is used to monitor warfarin therapy and evaluate vitamin K-dependent clotting factors. It also includes Activated Partial Thromboplastin Time (aPTT), which measures clotting through the intrinsic pathway and is used to screen for bleeding disorders like hemophilia and monitor heparin therapy. The panel provides a complete evaluation of the coagulation system, helping to identify deficiencies in various clotting factors, detect bleeding disorders, and monitor anticoagulant therapy. This comprehensive approach is essential for preoperative screening, evaluating unexplained bleeding, and monitoring patients on blood thinners.