Vitamin K deficiency bleeding of the newborn

Vitamin K deficiency bleeding of the newborn (VKDB) refers to spontaneous bleeding in a newborn caused by a deficiency of vitamin K dependent-coagulation factors. As vitamin K does not cross the placental barrier, is not present in breast milk, and is not synthesized in the sterile gut of a newborn, vitamin K levels are low in all neonates. VKDB is rare in industrialized countries because most children receive a vitamin K injection at birth. VKDB is categorized as early-onset (within 24 hours after birth), classic (within 4 weeks), or late-onset (between 2–8 months). Bleeding is usually intracranial, subgaleal, gastrointestinal, or nasal. Treatment is focused on managing the bleeding with, e.g., transfusions and restoring bleeding homeostasis by administering vitamin K.

• Without prophylaxis: affects 0.25–1.7% of newborns ^[1]

Epidemiological data refers to the US, unless otherwise specified.

The underlying cause is always a deficiency of vitamin K, which can be due to various factors:

• Exclusive breastfeeding: low vitamin K levels in breast milk (most important in late-onset VKDB)
• Low liver storage capacity
• Poor placental passage of vitamin K
• Vitamin K deficiency in the mother (e.g., because of anticonvulsant therapy; most important in early-onset VKDB; maternal malnutrition)
• Underdeveloped intestinal flora (which produces vitamin K), e.g., due to premature birth
• Chronic diarrhea of the newborn
• Long-term antibiotic treatment in newborns
• Cholestatic diseases (e.g., biliary atresia)

References:^[2]

• Early onset: within 24 hours after birth; intracranial bleeding common
• Classic: : within 1 week after birth; intracranial bleeding rare
• Late onset: between 2–8 months after birth; intracranial bleeding common

• Easy bruising
• Bleeding and signs of blood loss (e.g., pale skin)
• Hematuria, hematochezia

Coagulation studies:

• ↑ Prothrombin time (PT)
• Normal or ↑ activated partial thromboplastin time (PTT)
• Normal bleeding time
• ↓ Factors II, VII, IX, and X

• Transfusions as necessary
• Administration of vitamin K

In the US, all newborns receive intramuscular vitamin K (0.5–1 mg) at birth.