Abstract
The term infant is remarkably resistant to bleeding despite physiologically low levels of procoagulant proteins. However, because of their unique haemostatic systems, neonates are vulnerable to haemorrhagic disorders. The prevention of early vitamin K deficiency bleeding (VKDB) of newborn by oral or parenteral administration of vitamin K has been well established. However, rarely, a newborn can present with bleeding manifestations even after routine vitamin K prophylaxis at birth. A 2-day-old healthy male baby presented with catastrophic pulmonary haemorrhage with severely deranged coagulation profile even after receiving vitamin K prophylaxis at birth. His presentation, initial laboratory findings and course in the hospital were very much in favour of haemophilia B, but follow-up factor IX level and clinical exome sequencing did not confirm it. However, protein induced in vitamin K absence-II was found to be raised just before the discharge, and we concluded this case as a rare presentation of classical VKDB.