Neonatal anaemia, polycythaemia and thrombocytopenia: Case

Case discussion

Diagnosis and immediate assessment

This infant of a diabetic mother presents with classic features of neonatal polycythaemia with symptomatic hyperviscosity: plethora, lethargy, poor feeding, respiratory distress, and hypoglycaemia. The first critical step is to confirm the diagnosis with a centrally drawn venous haematocrit, because capillary samples overestimate the true value by up to 10 to 15 per cent. A venous haematocrit above 65 per cent confirms polycythaemia. [1]

Pathophysiology

Chronic fetal hyperinsulinaemia and hypoxia from poorly controlled gestational diabetes drive erythropoietin production and red cell mass expansion, producing polycythaemia rates of 20 to 40 per cent in infants of diabetic mothers. When the haematocrit exceeds approximately 60 per cent, blood viscosity rises exponentially, causing microcirculatory sludging, impaired tissue oxygen delivery, and end-organ hypoperfusion affecting the brain, lungs, gastrointestinal tract, and kidneys. [2]

Management

Given that this infant is symptomatic with respiratory distress, hypoglycaemia, and poor feeding, partial exchange transfusion is indicated to reduce the haematocrit to approximately 55 per cent. The procedure replaces a calculated volume of the infant's blood with normal saline at an estimated blood volume of 80 to 90 mL per kg for a term infant. The exchange volume is calculated as blood volume multiplied by the observed minus desired haematocrit, divided by the observed haematocrit. [1]

The procedure must be performed with careful monitoring of blood pressure, glucose, and temperature. Potential complications include hypoglycaemia, thrombocytopenia, haemodynamic instability, and necrotising enterocolitis. [1]

Evidence and controversy

The role of partial exchange transfusion remains controversial. Systematic reviews have found that while the procedure effectively lowers the haematocrit, it does not consistently improve long-term neurodevelopmental outcomes compared with symptomatic management alone. Current evidence-based practice reserves partial exchange transfusion for symptomatic infants with a confirmed venous haematocrit above 65 per cent, while asymptomatic infants receive supportive care with hydration, glucose monitoring, and observation. [1]

Counselling

The parents should be counselled that polycythaemia is a well-recognised complication of maternal diabetes, that the symptoms are expected to improve as the haematocrit falls, and that the partial exchange transfusion is being performed to relieve the current symptoms. They should be informed about the procedural risks and the need for ongoing glucose monitoring and developmental follow-up. [2]

Disposition and follow-up

After the partial exchange transfusion, the infant requires continued monitoring of haematocrit, glucose, feeding, and neurological status. Cranial ultrasound should be considered if there is any concern about thrombosis or ischaemia. Developmental surveillance is recommended at 6 and 12 months, and the family should be linked with appropriate maternal health services for preconception counselling before any future pregnancy. [3]