INTRODUCTION
A previously healthy infant presented at several weeks of age with irritability and cutaneous bleeding. Laboratory testing demonstrated a profound coagulopathy with markedly prolonged prothrombin and activated partial thromboplastin times. Coagulation factor studies demonstrated the classic pattern of vitamin K deficiency, with significantly reduced vitamin K-dependent factors (II, VII, X) and preserved factor V and VIII. Neuroimaging demonstrated an intracranial hemorrhage. After parenteral phytonadione (vitamin K1), coagulation tests substantially corrected, consistent with vitamin K deficiency bleeding (VKDB). Despite escalation of care, the infant died. Intramuscular (IM) vitamin K prophylaxis had been refused at birth.
In this scenario, which represents a composite and anonymized case, this presentation should not be a diagnostic mystery. VKDB is a hemorrhagic disorder of infancy caused by inadequate vitamin K-dependent coagulation factors. VKDB is typically classified as early-onset (within the first 24 hours of birth), classical (2 days to 1 week after birth), or late-onset (1…