Hemostasis System in Children

Clinical Types of Hemorrhagic Syndrome

Physical examination and a thorough history taking allow for a preliminary determination of the nature of disorders in the hemostasis system:

• Microcirculatory (platelet) type: ecchymoses appear asymmetrically and painlessly, hemarthroses are absent.
• Hematoma type (coagulopathies): characterized by painful soft tissue hematomas and hemarthroses. A specific sign is the delayed onset of bleeding after trauma or surgical interventions. A burdened family history plays a crucial role.
• Vasculitic-purpuric type: manifests as raised, symmetric, papular-petechial rash, which is most commonly localized on the buttocks and extensor surfaces of the extremities. Frequently accompanied by articular, renal, and abdominal syndromes.

In rare hereditary coagulopathies (deficiencies of factors II, VII, X), hemarthroses are less common than in classic hemophilia. Bleeding from mucous membranes (epistaxis, gingival bleeding, tooth extraction sites), menorrhagia, and hematuria come to the fore. Central nervous system hemorrhages, gastrointestinal bleeding, and retroperitoneal hematomas are considered life-threatening.

Laboratory Differentiation

Basic tests evaluating various links of hemostasis are used to accurately verify the diagnosis.

Hemophilia and Coagulopathies

The diagnosis of hemophilia is based on three blocks of data: hereditary transmission pattern, specific changes in the coagulogram, and exclusion of other pathologies.

Typical coagulogram pattern: isolated prolongation of aPTT and total clotting time with normal values of prothrombin time (PT), thrombin time (TT), and fibrinogen. The vascular-platelet link is not affected (platelets and bleeding time are normal). In the occult course of mild hemophilia, aPTT may remain within normal limits.

Confirmation of the diagnosis requires at least 2 of 3 criteria:

1. Absence of acquired coagulopathies.
2. Decrease in the activity of FVIII or FIX factors below 50%.
3. Presence of mutations in the corresponding genes.

Specific diagnostics include assessing the activity of plasma hemostasis factors (FVIII, FIX, XI, XII), as well as von Willebrand factor antigen and properties (ag-vWF, vWF:RCo). In severe cases, factor levels drop to critical 0–20 IU/L. Additionally, the activity of inhibitors to factors is investigated using the Bethesda method to monitor treatment efficacy.

Neonatal considerations: for the expected birth of a child with hemophilia, an atraumatic delivery method is chosen. Blood for analysis is taken from the umbilical cord, and any invasive manipulations (including capillary blood sampling and venipuncture) are postponed until the diagnosis is clarified.

Thrombocytopenias and Thrombocytopathies

Platelet link pathologies are divided into quantitative and qualitative.

In immune thrombocytopenia (ITP), the leading sign is an isolated drop in platelets below 100×10⁹/L with normal erythrocytes and leukocytes. In the myelogram, the megakaryocyte count remains normal or compensatorily increased, which proves the peripheral nature of cell destruction. Differential diagnosis of ITP is carried out with conditions where platelets are destroyed secondarily (against the background of systemic lupus erythematosus, viral infections, DIC syndrome) or their production is impaired (acute leukemia, aplastic anemia).

Hereditary thrombocytopenias are classified by cell size:

• With microthrombocytopenia: Wiskott–Aldrich syndrome (combined with severe immunodeficiency and eczema) and X-linked thrombocytopenia.
• With normocytopenia: TAR syndrome (combined with absent radii), congenital amegakaryocytic thrombocytopenia.
• With macrothrombocytopenia: Bernard–Soulier syndrome, DiGeorge syndrome, gray platelet syndrome.

In thrombocytopathies (e.g., Glanzmann thrombasthenia), the platelet count remains normal, but their function is impaired: bleeding time is prolonged, and endothelial tests are positive. A specific marker of Glanzmann thrombasthenia is a sharp decrease in aggregation to standard inducers (ADP, collagen, adrenaline) with preserved response to ristocetin. This distinguishes it from Bernard–Soulier syndrome, where ristocetin aggregation is precisely what is impaired.

Hemorrhagic Vasculitis and Secondary Syndromes

In IgA vasculitis (Henoch–Schönlein purpura), the microvasculature is primarily affected. The disease is more common in boys aged 4–8 years. Laboratory coagulation and platelet links remain intact; diagnostics are based on assessing capillary status (tourniquet and pinch tests, capillaroscopy).

In clinical practice, it is extremely important to distinguish primary hemostatic pathologies from secondary (symptomatic) hemorrhagic syndrome. For example, in leukemias or severe liver diseases, the bleeding mechanism is combined: the synthesis of plasma factors is impaired, the bone marrow megakaryocytic lineage is depressed, and the vascular wall is damaged due to hypoxia or leukemic infiltration.

Class and exam questions

What else to study on this topic

• Detailed algorithm for the differentiation of thrombocytopathies based on ristocetin aggregation (Bernard–Soulier syndrome and von Willebrand disease).
• Classification of the severity of hemorrhagic syndrome in immune thrombocytopenia according to WHO criteria.
• Clinical features of Wiskott–Aldrich syndrome and X-linked thrombocytopenia (WASP gene mutations).
• Methodology for determining the activity of inhibitors to clotting factors (Nijmegen-modified Bethesda method).
• Differential diagnosis of primary hemostatic disorders and secondary syndrome in leukemias and bone marrow failure.

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