Neonatal anaemia, polycythaemia and thrombocytopenia: Case

Case discussion

Diagnosis and immediate assessment

This infant of a diabetic mother presents with plethora, lethargy, poor feeding, respiratory distress, and hypoglycaemia, and a capillary haematocrit of 74 per cent. The first step is to confirm a venous haematocrit. The textbook definition of neonatal polycythaemia is a venous haematocrit above 65 per cent; that cut-off is empirical, not outcome-derived. A numeric 10 to 15 per cent capillary overestimate is not in these papers and should not be recited. ^[2]

Pathophysiology

As venous haematocrit rises above 65 per cent, whole-blood viscosity increases and may compromise organ flow. Blood viscosity increases exponentially at haematocrit at or above 65 per cent. Hyperviscosity can disturb central nervous system function, glucose, renal function, and cardiorespiratory status. A 20 to 40 per cent polycythaemia rate in infants of diabetic mothers is not sourced here; treat this infant on the venous haematocrit and the clinical picture, not on an unsourced percentage. ^[3]

Management

Correct hypoglycaemia immediately. Coexisting hypoglycaemia may worsen long-term outcome. Do not proceed to partial exchange on the capillary value. If partial exchange is performed, normal saline is the best alternative. There is no sourced target haematocrit of 55 per cent, and no sourced 80 to 90 mL per kg exchange formula in these papers. ^[2]

Evidence and controversy

Cochrane review: there are no proven clinically significant short- or long-term benefits of partial exchange in polycythaemic newborns who are clinically well or who have minor hyperviscosity symptoms, and necrotising enterocolitis increased (typical relative risk 11.18). Mimouni: no evidence that partial exchange improves neurodevelopment in asymptomatic polycythaemia; the long-term effect in symptomatic infants has not been studied. This infant is symptomatic, so the decision is not automatic observation, but it is also not an evidence-based mandate to exchange. Discuss the NEC signal, the incomplete follow-up in the trials, and local consultant practice. ^[1]