Laboratory evaluation of hemostatic disorders is vital across multiple medical specialties. Basic screening tests include a complete blood count, prothrombin time (PT), activated partial thromboplastin time (aPTT), platelet function assay, thrombin time, peripheral blood smear review, and fibrinogen. The bleeding time test was initially developed to evaluate patients’ ability to control bleeding before surgery or in those suspected of having a bleeding disorder caused by platelet dysfunction. It is unreliable and insensitive; if used, it should be combined with a thorough family and clinical history and other hemostasis screening tests, such as platelet count and morphology. PT evaluates the function of the extrinsic pathway. It is very useful for identifying deficiencies in coagulation factors, whether qualitative or quantitative, within the extrinsic and common pathways. Additionally, it aids in monitoring vitamin K antagonist anticoagulants such as warfarin and detecting liver disease, vitamin K deficiency, FX deficiency due to amyloidosis, disseminated intravascular coagulation, the presence of direct oral anticoagulants in a dose-dependent manner, or antibodies against factors of the extrinsic pathway. APTT is a clotting test that detects deficiencies or inhibitors of clotting factors in the intrinsic and common pathways of coagulation. Along with a normal prothrombin time, it is the most useful screening test for identifying deficiencies in factors VIII, IX, XI, and XII. The aPTT can also be prolonged in deficiencies affecting the common pathways (factors V, X, II, and fibrinogen) and when inhibitors are present. Additionally, some therapeutic anticoagulants, such as heparin, can also extend aPTT.