What is coagulopathy?

What is Coagulopathy?

Coagulopathy is a life-threatening condition characterized by impaired blood clot formation that can manifest as either excessive bleeding or, paradoxically, thrombosis depending on the clinical context. 1, 2

Core Definition

Coagulopathy represents a dysfunction in the body's hemostatic mechanisms that prevents normal blood clotting. 3 The term encompasses a spectrum of disorders affecting:

• Platelet function and number - critical for initial clot formation 4
• Coagulation factor activity - essential proteins in the clotting cascade 4
• Fibrinolytic pathways - systems that break down clots 5

Clinical Manifestations

Bleeding Presentation

When coagulopathy manifests as bleeding, patients typically exhibit:

• Oozing from mucosal surfaces, venipuncture sites, or surgical wounds 1
• Clinical bleeding unexplained by local or surgical factors 6
• Deep hemorrhagic shock with signs of ongoing hemorrhage 1

Thrombotic Presentation

In certain conditions (such as COVID-19 infection during pregnancy), coagulopathy can paradoxically increase thrombotic risk despite impaired clot formation. 7

Pathophysiology: The Multifactorial Nature

Primary Mechanisms

In trauma settings, coagulopathy develops early and is present in 25-36% of patients upon emergency department admission. 8 The condition results from:

• Bleeding-induced shock - tissue hypoperfusion triggers anticoagulant pathways 8, 1
• Tissue injury-related thrombin-thrombomodulin complex generation - activates protein C anticoagulant pathway 8, 1
• Activation of fibrinolytic pathways - excessive clot breakdown 8, 1
• Endothelial glycocalyx degradation - marked by elevated syndecan-1 levels 8, 1

Contributing Factors: The "Lethal Triad" and Beyond

Acidosis severely compromises coagulation:

• A pH decrease from 7.4 to 7.0 reduces prothrombin activation by 70% 8
• Impairs both coagulation enzyme and platelet function 1

Hypothermia causes profound coagulation impairment:

• Decreases platelet and coagulation enzyme activities 8
• Standard laboratory tests underestimate this effect as samples are rewarmed to 37°C before testing 8

Dilutional coagulopathy results from:

• Large volume infusion of crystalloids, colloids, or blood products 8
• Dilution of coagulation factors and platelets 1

Hypoperfusion contributes to:

• Tissue hypoxia and metabolic acidosis 1
• Impaired citrate metabolism in massive transfusion 9

Coagulation factor consumption depletes available clotting factors through ongoing hemorrhage and activation of coagulation cascades. 1

Diagnostic Criteria for Severe Coagulopathy

Laboratory parameters that define severe coagulopathy include:

• PT ratio >1.2 (or PT >15.5 seconds) - associated with significantly higher mortality and transfusion requirements 1
• Platelet count <100,000/μL - indicates severe coagulopathy 1, 6
• Markedly elevated D-dimer levels (3-4 fold increase) - indicates increased thrombin generation 1
• Decreased fibrinogen levels - associated with poor outcomes 1

Thromboelastography (TEG) provides functional whole blood coagulation assessment at the bedside, offering advantages over standard tests. 1

Epidemiology and Clinical Impact

Approximately one-third of severely injured trauma patients present with coagulopathy upon hospital admission. 8, 1 This subset experiences:

• Significantly increased mortality beyond that expected from injury severity alone 8
• Higher incidence of multiple organ failure 8
• Increased transfusion requirements 1

In intensive care populations, laboratory evidence of coagulopathy is common, with PT ratio ≥1.5 found in 66% of patients and thrombocytopenia in 38%. 6

Distinction from Other Conditions

Acute traumatic coagulopathy is distinct from disseminated intravascular coagulation (DIC) as described in other medical conditions. 8, 5 Various terms describe this entity including Acute Traumatic Coagulopathy, Early Coagulopathy of Trauma, and Trauma-Induced Coagulopathy. 8

Common Pitfalls

Standard coagulation tests (PT, PTT) significantly underestimate the true extent of coagulopathy because:

• Samples are rewarmed to 37°C, masking hypothermia effects 8
• They don't reflect in vivo coagulation on cell membranes 8
• Platelet dysfunction is not routinely monitored 8

Vitamin K deficiency is the most common cause of prolonged PT in ICU patients (20% of cases with PT ratio ≥1.5), yet is often overlooked. 6