Paediatrics: Haemophilia A

Haemophilia A

Haemophilia A is a congenital bleeding disorder due to defective produc-tion of factor VIII (FVIII), with X-linked recessive inheritance. Incidence is 1:10,000–14,000 males. One-third have no family history. Carrier females are rarely symptomatic, but may have a low FVIII level. Genetic testing may be necessary to confirm carrier status. Severity depends on degree of FVIII deficiency:

·  <1% activity = severe disease, with ‘spontaneous’ haemathroses, significant bleeding if cut, mucosal bleeds, and lumpy (pea-sized) bruises as infants. Most require prophylaxis with FVIII concentrate (see Management, p.636).

·  2–5% = moderate disease. Bleeding rarely occurs, and tends to involve muscles and soft tissues, secondary to trauma. Requires FVIII concentrate when bleeding occurs but no prophylaxis.

·  5–20% = mild disease. Rarely bleed. May present after surgery or trauma. Prophylaxis with DDAVP or FVIII concentrates for surgery.

Presentation

·  Rare in the neonate: severe forms present in infancy with intracranial bleeds or after circumcision: most present as they start to mobilize.

·  Easy bruising. In younger children often get pea-sized lumpy bruises.

·  Bleeding into joints (haemarthroses): knees > ankles > elbows > hips > wrists. The joint is painful, swollen, tender, warm, with severe limitation of movement, +/– unable to weight bear. Uncontrolled recurrent bleeding can lead to degenerative joint disease.

·  IM bleeds: can be difficult to differentiate between muscle strain and bleed. May lead to compartment syndrome, nerve compression, or ischaemic contracture.

·  Intracranial bleeds: may be extradural, subdural, or intracerebral. Usually follows minor head trauma. All patients should seek medical attention, and those with severe disease need immediate FVIII.

Investigations

·  APTT ‘rise’and FVIII ‘fall’ (PT, von Willebrand factor and PFA all n).

·  Perform cranial CT scan if any suspicion of intracranial bleed.

·  US scans are useful for possible joint bleeds and muscle haematomas.

Management

·  Prophylaxis: in severe disease, most require prophylaxis with alternate day IV FVIII concentrates to prevent spontaneous bleeds. Children with moderate or mild disease do not require regular prophylaxis.

·  Major bleeds: treat with recombinant FVIII product except in those with FVIII inhibitors. The dose depends on bleeding site, child’s weight and serum half life of FVIII (usually 710hr). In those with severe disease on prophylactic therapy, regular screens are made to assess exactly how much FVIII is required to treat a joint or a major bleed. The dose for joint bleed aims to get FVIII to 40–50%, whilst for head injury to 100%, i.e. treat intracranial bleeds with twice the dose used for a joint bleed.

·Major surgery: preparation with a haematologist to plan timing and dose of factor. Give analgesia as required, but not NSAIDs (d platelet function).

·Minor surgery or persistent bleeds: IV, SC, or intranasal DDAVP in those with moderate/mild haemophilia may suffice.

·Mouth bleeding: tranexamic acid suspension/tablets (20–25mg/kg tds).

·Avoid IM injections: including vitamin K at birth, if disease suspected (give IV). All vaccinations should be given subcutaneously.

·Educate family: about PRICE guidelines for supportive care of a bleed: Pressure dressing, Ice (bag of frozen peas), Rest (non-weight bearing), Compress (cold if possible), Elevation of limb.

·Daily physiotherapy: following a bleed is important to avoid muscle weakness or contractures once joint bleeding has resolved.

·Home FVIII treatment: parents, and in due course the boys themselves, should be trained to give IV FVIII concentrates. Central venous ‘ports’ are only used when peripheral access is deemed impossible.

Complications

·Chronic arthropathy: s to recurrent joint bleeds.

·Transmission of hepatitis B, hepatitis C, HIV: now rare since virally inactivated plasma concentrates and recombinant FVIII concentrate is given. All children should be vaccinated against hepatitis B.

·FVIII inhibitor development: is suggested by bleeds not responding to treatment. Measure FVIII inhibitor titre. Difficult to treat but most are started on immune tolerance induction with high dose FVIII. Acute bleeds are treated with increased FVIII dose or other products, e.g. rFVIIa or FEIBA.

Prognosis

Excellent. Life expectancy is now normal with current recombinant thera-py (prophylaxis and treatment).