What is the likely cause of a 5-day-old neonate's bleeding from the umbilicus and blood streaks in the skin, born to a mother with epilepsy controlled by Phenytoin (phenytoin)?

Vitamin K Deficiency

The most likely cause of bleeding from the umbilicus and blood streaks in the skin in this 5-day-old neonate is vitamin K deficiency bleeding (VKDB), specifically related to maternal phenytoin use during pregnancy. 1

Mechanism of Phenytoin-Induced Neonatal Bleeding

Maternal phenytoin exposure during pregnancy causes a potentially life-threatening bleeding disorder in newborns due to decreased levels of vitamin K-dependent clotting factors. 1 This occurs because:

• Phenytoin crosses the placenta and interferes with fetal vitamin K metabolism 2
• The fetal liver is immature and fetal levels of vitamin K-dependent coagulation factors are already physiologically low 2
• Neonates exposed to phenytoin in utero require higher doses of vitamin K after birth to prevent bleeding 2

Clinical Presentation Consistent with VKDB

This neonate's presentation at 5 days of age fits the "classic" form of VKDB, which occurs between days 2-7 of life 3, 4:

• Bleeding from the umbilicus is a characteristic manifestation of VKDB 2
• Blood streaks in the skin (petechiae/purpura) represent cutaneous bleeding 2
• The timing (day 5) falls within the classic VKDB window 4

Why Not Sepsis

While sepsis can cause bleeding through disseminated intravascular coagulation (DIC), several factors make this less likely:

• The question specifically highlights maternal phenytoin use, which is a known risk factor for VKDB 1
• VKDB presents with bleeding symptoms without the systemic signs of sepsis (fever, lethargy, poor feeding, hemodynamic instability) 2
• In DIC from sepsis, you would expect thrombocytopenia, whereas VKDB presents with normal platelet counts and isolated prolongation of PT/PTT 2, 4

Why Not Physiologic

Physiologic bleeding does not occur in healthy neonates:

• Normal newborns do not bleed from the umbilicus or develop spontaneous cutaneous bleeding 3
• While vitamin K-dependent factors are physiologically lower in all neonates, this does not cause clinical bleeding in the absence of vitamin K deficiency 5

Diagnostic Confirmation

The diagnosis of VKDB in this setting would show:

• Grossly prolonged PT and PTT (often >70 seconds for PT and >110 seconds for PTT) 4
• Normal platelet count (distinguishing it from ITP or sepsis-related thrombocytopenia) 2, 4
• Normal fibrinogen level 6
• Rapid correction of coagulation parameters within 6-12 hours after vitamin K administration 4

Prevention Strategy

This drug-induced condition can be prevented with vitamin K administration to the mother before delivery and to the neonate after birth. 1 Specifically:

• Antenatal maternal prophylaxis: 10-20 mg/day orally for 15-30 days before delivery prevents early VKDB in infants of mothers on phenytoin 5
• Neonatal prophylaxis: Higher doses of vitamin K are required at birth for infants exposed to phenytoin in utero 2
• These infants should receive intramuscular vitamin K (not oral) and may require repeated doses 5

Critical Pitfall

The most dangerous complication of VKDB is intracranial hemorrhage, which occurs in up to 50% of affected neonates and carries high mortality and morbidity. 3, 4 Any neonate with VKDB presenting with bleeding symptoms requires urgent neuroimaging to exclude intracranial hemorrhage, even without obvious neurological signs 4.