Disorders of coagulation

Published on 23/06/2015 by admin

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11.3 Disorders of coagulation

Evelyn Doyle

Essentials

1 Haemophilia and von Willebrand disease account for the majority of inherited coagulation disorders.
2 A positive family history of a bleeding disorder should be sought when a coagulation disorder is suspected.
3 Establishing disease severity (assayed factor levels), past history of bleeding, the nature of this bleed and presence of inhibitors will help guide replacement therapy in haemophilia.
4 Always consider ‘hidden’ potentially life-threatening bleeding: intracranial bleeding is a major cause of mortality in the haemophiliac patient.

Haemophilia

Introduction

Haemophilia A and B are coagulation disorders usually transmitted by X-linked recessive inheritance (70% of cases) but can occur as spontaneous gene mutations (30% of cases). Haemophilia A results from factor VIII deficiency and Haemophilia B (Christmas disease) is caused by factor IX deficiency. Acquired haemophilia is rare and occurs when autoantibodies develop against factor VIII.

Clinical presentation

Haemophilia A and B are clinically indistinguishable. Disease severity correlates well with assayed factor levels: severe disease occurs with factor levels <1% of normal, moderate and mild disease occur with levels between 1–5% and above 5%, respectively. In the absence of a positive family history, disease may go undetected for a variable period, depending on disease severity, with some cases of mild disease being diagnosed in adulthood.

Bleeding can occur in any tissue and may occur spontaneously or with minimal trauma. Most neonates, even those with severe disease, are born without significant bleeding, though intracranial haemorrhage may occur. As a child starts to ambulate bleeding episodes becomes more frequent. Unlike disorders of platelet function where mucosal bleeding typically occurs, bleeding into joints and soft tissues is characteristic, with large joints of the knee, ankle, hip, elbow, wrist and shoulder involved most frequently.

Other significant and potentially life-threatening bleeding can occur and should be considered in the haemophiliac patient: intracranial haemorrhage occurs with increased frequency after head trauma, retroperitoneal haematoma may occur spontaneously or following trauma and may mimic appendicitis, soft tissue haemorrhage in the head or neck is potentially life threatening due to the risk of airway obstruction. Gastrointestinal haemorrhage is a less common manifestation of haemophilia in children. Haematuria may be macroscopic or microscopic.

In the current paediatric haemophiliac population, transfusion-borne viruses including hepatitis B and C and human immunodeficiency virus are rare, as most cases of transmission occurred prior to 1985.

Investigations

Haemophilia A and B both cause a prolonged activated partial thromboplastin time (aPTT) with a normal prothrombin time and platelet count. Individual factor assays can then be performed to confirm the diagnosis. Haemophiliacs presenting with suspected intracranial or retroperitoneal bleeds need computerised tomography (CT) scanning. Plain radiographs will exclude fractures associated with traumatic haemarthroses.

Treatment

The primary treatment goal is control of bleeding by replacement of clotting factor. Factor concentrates are available as virus-inactivated plasma-derived product and recombinant factor concentrates. When available and expense allows, recombinant factor concentrates should be used. Factor replacement may be given following a confirmed bleed or as prophylaxis against potential bleeding; for example, prior to dental extraction. Prophylactic factor replacement, usually given two to three times a week at home, with increased doses given for any breakthrough bleeds, has led to a marked reduction in the number and severity of bleeding episodes.

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