Neonatal Thrombocytopenia

 

Reviewed by Alan Groves and Carl Kuschel
April
2003
Clinical Guidelines Back Newborn Services Home Page
Background Incidence Aetiology Risks of Thrombocytopenia
Platelet Transfusion Guidelines References

Please see also Neonatal Alloimmune Thrombocytopenia

Background

Incidence

Aetiology

Causes of thrombocytopenia are best separated by time of presentation into fetal, early <3 days) and late.

Timing Most Common Aetiology Less Common Aetiology
Fetal
  • Alloimmune
  • Congenital infection (e.g. CMV, toxoplasma, rubella)
  • Aneuploidy (e.g. trisomies 18, 13, 21, or triploidy)
  • Autoimmune (e.g. ITP, SLE)
  • Severe rhesus disease
  • Congenital/inherited (e.g. Wiskott-Aldrich syndrome)
Early-Onset Neonatal
(<72 hours)
  • Placental insufficiency (e.g. GPH, IUGR, diabetes)
  • Perinatal asphyxia
  • DIC
  • Alloimmune
  • Autoimmune
  • Congenital infection (e.g. CMV, toxoplasma, rubella)
  • Thrombosis (e.g. aortic, renal vein)
  • Bone marrow replacement (e.g. congenital leukaemia)
  • Kasabach-Merritt syndrome
  • Metabolic disease (e.g. propionic and methylmalonic acidaemia)
  • Congenital/inherited (e.g. TAR, Congenital Amegakaryocytic Thrombocytopenia [CAMT])
Late-Onset Neonatal
  • Late-onset sepsis
  • NEC
  • Congenital infection (e.g. CMV, toxoplasma, rubella)
  • Autoimmune
  • Kasabach-Merritt Phenomenon
  • Metabolic disease (e.g. propionic and methylmalonic acidaemia)
  • Congenital/inherited (eg TAR, CAMT)

Fetal Thrombocytopenia

Is most commonly due to Neonatal Alloimmune Thrombocytopenia. Congenital infection and chromosomal abnormalities are the other principal considerations.

Early-Onset Neonatal Thrombocytopenia

This is common in preterm infants following pregnancies complicated by impaired placental function or fetal hypoxia (which may impair fetal/infant platelet production). These infants show a typical pattern of low/low-normal platelet counts at birth (100-200 x 109/L), with levels falling to a nadir of 50-100 x 109/L at 4-5 days. Counts generally return to normal at 7-10 days. Clinically stable preterm infants following this pattern have only a very low risk of bleeding if platelet count remains above 50 x 109/L.

Early-onset neonatal thrombocytopenia without an obvious precipitant is much more of a concern, and may be due to Neonatal Alloimmune Thrombocytopenia, with its high risk of haemorrhage. Neonatal Autoimmune Thrombocytopenia is due to maternal platelet autoantibodies (i.e. mothers are also at risk of thrombocytopenia), principally from ITP and SLE. Infants with this disorder are at only low risk of significant haemorrhage (<1%), but should have platelet count monitored daily. If count falls to <30 x 109/L, consider intravenous immunoglobulin therapy.

Late-Onset Neonatal Thrombocytopenia

In such cases platelet count often drops rapidly, and to levels of 50 x 109/L or below. Once the precipitant is controlled levels rise again over 5-7 days. These infants are at significant risk of haemorrhage, though the benefit of transfusing with platelets isn’t clear-cut (see platelet transfusion guidelines)

Risks of Thrombocytopenia

Thrombocytopenia increases the risk of bleeding, but this risk is hard to quantify for individual infants. A few factors guide decision to transfusion:

Platelet Transfusion Guideline

Many centres have developed consensus-based guidelines for platelet transfusion while awaiting strong evidence for timing of intervention.1

Platelet Count (x109) Action
<30
  • Transfuse if bleeding
  • Consider transfusion in all other cases
30-49
  • Transfuse if bleeding
  • Consider transfusion if:
    • <1000g and <7 days
    • Clinically unstable (e.g. fluctuating BP)
    • Previous major bleeding (e.g. Grade 3-4 IVH, pulmonary haemorrhage)
    • Current minor bleeding
    • Concurrent coagulopathy
    • Requiring surgery or exchange transfusion
50-99
  • Transfuse only if bleeding
>99
  • Do not transfuse



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References

1 Roberts, I.A. and N.A. Murray, Thrombocytopenia in the newborn. Curr Opin Pediatr, 2003. 15(1): p. 17-23.
2 Murray, N.A., Evaluation and treatment of thrombocytopenia in the neonatal intensive care unit. Acta Paediatr Suppl, 2002. 91(438): p. 74-81.
3 Sola, M.C., A. Del Vecchio, and L.M. Rimsza, Evaluation and treatment of thrombocytopenia in the neonatal intensive care unit. Clin Perinatol, 2000. 27(3): p. 655-79.