What are the initial tests and management strategies for patients requiring coagulation studies?

From the Guidelines

Initial coagulation studies for patients requiring coagulation studies should include Activated Partial Thromboplastin Time (aPTT), Thromboplastin Time (TT), Prothrombin Time (PT), INR, and anti-Xa levels to assess early anticoagulants exposure in the trauma setting.

Initial Tests

The following tests are recommended:

• Activated Partial Thromboplastin Time (aPTT)
• Thromboplastin Time (TT)
• Prothrombin Time (PT)
• International Normalized Ratio (INR)
• Anti-Xa levels These tests are essential for evaluating patients with anticoagulant drugs in a trauma setting, as stated in the 2023 WSES guidelines 1.

Management Strategies

Management strategies for patients with coagulation disorders depend on the underlying cause and clinical context.

• For patients anticoagulated with oral vitamin K antagonists, a reversal agent should be administered in cases of bleeding, not responding to supportive measures, major life-threatening bleeding, or needing urgent surgical or invasive procedures 1.
• The recommended reversal protocol for vitamin K antagonists includes intravenous four-factor prothrombin complex concentrates (4F-PCCs) and 5 mg intravenous vitamin K for life-threatening bleeding and/or urgent surgical procedures 1.
• For patients receiving direct oral anticoagulants (DOACs), an early assessment of laboratory coagulation tests and direct measurements of DOAC levels is recommended before deciding on reversal due to the thromboembolic risk 1.
• Reversal agents for DOACs, such as idarucizumab for dabigatran and andexanet alfa for rivaroxaban or apixaban, should be administered only in critically ill patients with dosable plasma DOAC levels and presenting with hemorrhagic shock not responding to resuscitation 1.

Ongoing Monitoring

Ongoing monitoring of coagulation parameters is essential to assess response to treatment and adjust management strategies as needed.

• The timing and selection of interventions should be tailored to the clinical urgency, with more aggressive correction needed for active bleeding or before invasive procedures compared to incidental laboratory abnormalities.
• Regular assessment of coagulation studies and clinical parameters, such as base excess level, arterial lactates dosage, urine output, and neurologic assessment, is crucial for managing trauma patients, especially the elderly and frail population 1.

From the FDA Drug Label

OVERDOSAGE Signs and Symptoms Suspected or overt abnormal bleeding (e.g., appearance of blood in stools or urine, hematuria, excessive menstrual bleeding, melena, petechiae, excessive bruising or persistent oozing from superficial injuries) are early manifestations of anticoagulation beyond a safe and satisfactory level Treatment Excessive anticoagulation, with or without bleeding, may be controlled by discontinuing warfarin sodium tablets therapy and if necessary, by administration of oral or parenteral vitamin K1.

The initial tests for patients requiring coagulation studies are not explicitly stated in the provided drug label. However, for patients on warfarin therapy, monitoring of PT/INR is implied to be crucial in assessing the risk of bleeding due to anticoagulation.

• Discontinuation of warfarin and administration of vitamin K1 are management strategies for excessive anticoagulation.
• In cases of minor to major bleeding, parenteral vitamin K1 (5 to 25 mg, rarely up to 50 mg) may be given.
• For severe hemorrhage, options include administering fresh whole blood, fresh frozen plasma, or commercial Factor IX complex 2.

From the Research

Initial Tests for Coagulation Studies

• Prothrombin time (PT) and activated partial thromboplastin time (APTT) are the most widely used tests to investigate coagulation abnormalities 3
• PT results can be reported as clotting time, percentage activity, PT-ratio, or international normalized ratio (INR) 3
• APTT is sensitive to contact factor deficiencies, including factor XII, prekallikrein, and high-molecular-weight kininogen, as well as liver disease, vitamin K deficiency, and disseminated intravascular coagulation 4

Management Strategies

• The APTT can be used for monitoring unfractionated heparin (UFH) therapy, screening lupus anticoagulant (LA), or assessing thrombosis risk 4
• A good knowledge of factor sensitivity is usually needed to explain the reasons for a prolonged APTT in a given patient 4
• Beriplex, a prothrombin complex concentrate (PCC), can be used for rapid reversal of oral anticoagulation with warfarin 5
• Interpretation of abnormal PT, APTT, and bleeding time (BT) results requires consideration of the underlying clinical context and may involve reflexive testing or subspecialty consultation 6

Considerations for Test Interpretation

• The INR scale has limitations when used in clinical settings other than monitoring vitamin K antagonists 3
• APTT reagents may vary in their sensitivity to heparin, LA, and clotting factors, which can impact test interpretation 4
• Normal reference ranges for PT and APTT should be established and verified for each laboratory 4