Polycythaemia (a venous haematocrit above 0.65) is relatively common. Most babies are asymptomatic, though a small proportion of babies develop clinical signs related to hyperviscosity, which include:
- Poor suck and feeding
- Tachypnoea and tachycardia
A partial exchange is usually indicated if the haematocrit is either more than 0.7 in an asymptomatic infant or more than 0.65 in a symptomatic infant.
Reference: Rennie & Roberton’s Textbook of Neonatology, 5th Ed, 2005. London: Churchill.