Essence and purpose of the test
The screening test of the blood coagulation system, traditionally referred to as a coagulogram, is a vital tool in daily clinical practice. The primary goal of this laboratory testing is the timely diagnosis of various hemostatic disorders.
In addition, the study provides the clinician with the opportunity to make an accurate prognosis regarding the risk of perioperative bleeding. In clinical practice, this is particularly critical when planning any surgical interventions, as well as during initial screening of patients with severe systemic pathology. Evaluating coagulation parameters helps prevent complications associated with inadequate function of the clotting system.
Essential and extended parameters
When performing a basic hemostasis assessment, a number of essential parameters are distinguished. The standard test protocol must invariably include the following markers:
- Prothrombin and International Normalized Ratio (INR).
- Activated partial thromboplastin time (aPTT).
- Plasma fibrinogen level.
- Thrombin time.
The extended profile, which is highly relevant for an in-depth assessment of perioperative risks, additionally includes such parameters as prothrombin index (PTI) or prothrombin time (PT), antithrombin III activity, and D-dimer concentration. Recording the D-dimer level, along with determining antithrombin III activity, is necessary for diagnosing conditions with pathological activation of the coagulation cascade.
Coagulogram in aHUS and DIC syndrome
Special clinical attention should be given to the interpretation of the coagulogram in patients with atypical hemolytic uremic syndrome (aHUS). In a typical, uncomplicated clinical presentation of aHUS, the parameters of the screening hemostasis test remain completely unchanged.
The situation changes radically in a complicated course of the disease, when DIC syndrome (disseminated intravascular coagulation syndrome) manifests against the background of aHUS. This complication develops due to the pathological mutual activation of the complement system and the hemostatic system. In this situation, the laboratory picture vividly demonstrates signs of consumption coagulopathy:
- There is a marked prolongation of clotting time parameters.
- The concentration of fibrinogen in the blood drops critically.
- Antithrombin III activity decreases.
- D-dimer levels naturally and sharply increase.
Role of the test in infective endocarditis
According to current clinical guidelines, performing a coagulogram is strongly recommended for all patients without exception with suspected or confirmed infective endocarditis (IE).
Blood sampling for this test should be carried out as soon as possible—directly as part of the initial examination upon admission of the patient to the hospital. The main goals in this scenario are the early diagnosis of hemostatic disorders and the most accurate prognosis of bleeding risk, which directly determines the safety of further patient management.
How to remember the picture of DIC syndrome: "The system is depleted, time is dragged out, debris accumulates." Factors are consumed (decreased fibrinogen and AT III), reactions slow down (prolonged time parameters), and breakdown products accumulate (increased D-dimer).
Class and exam questions
Does the coagulogram change in the typical course of aHUS?
No, in the uncomplicated, typical course of atypical hemolytic uremic syndrome, the parameters of the screening hemostasis test remain unchanged.
How do coagulation parameters change with the development of DIC syndrome?
Consumption coagulopathy is observed: clotting time parameters are prolonged, fibrinogen and antithrombin III levels are decreased, while the D-dimer concentration increases.
Why is a coagulogram prescribed for all patients with infective endocarditis?
The test is performed upon initial admission to diagnose potential hemostatic disorders and assess the prognosis of bleeding risk.
For what purpose is hemostasis assessed before surgery?
The primary goal of the preoperative screening hemostasis test is to predict the risk of perioperative bleeding and prevent complications.
What else to study on this topic
- Mechanisms of mutual activation of the complement system and hemostatic system in aHUS.
- Pathogenesis of consumption coagulopathy in DIC syndrome.
- Diagnostic significance and principles of calculating the International Normalized Ratio (INR).
- The role of antithrombin III as a natural anticoagulant in the blood coagulation system.
- Differences between prothrombin time (PT) and prothrombin index (PTI).
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