Haemorrhagic disease of the newborn.

1. Big picture

Haemorrhagic disease of the newborn is now more precisely called vitamin K deficiency bleeding (VKDB). It is an important neonatal bleeding disorder because it is preventable, but if missed it can cause life-threatening intracranial hemorrhage, especially in late VKDB.

The key oral-exam idea:

A newborn or young infant with bleeding + normal platelet count + prolonged prothrombin time should make you think of vitamin K deficiency bleeding.

Newborns are naturally vitamin K deficient because:

• vitamin K crosses the placenta poorly
• newborn liver stores are low
• breast milk contains little vitamin K
• neonatal gut flora is immature, so bacterial vitamin K production is low
• hepatic synthesis of vitamin K-dependent clotting factors is immature

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