What is the approach to a newborn with bleeding, normal prothrombin time (PT) and partial thromboplastin time (PTT), and hepatomegaly?

Approach to a Newborn with Bleeding, Normal PT/PTT, and Hepatomegaly

This clinical presentation is most consistent with vitamin K deficiency bleeding (VKDB), and you should immediately administer vitamin K 1 mg IM or IV while simultaneously investigating the hepatomegaly as a potential contributing factor. 1, 2

Immediate Management

Administer vitamin K 1 mg intramuscularly or intravenously immediately without waiting for additional laboratory confirmation. 1, 2, 3 The normal PT and PTT in a bleeding newborn is paradoxically diagnostic of early VKDB, as the coagulation cascade remains partially functional while vitamin K-dependent factors (II, VII, IX, X) are critically depleted. 2

• If bleeding is life-threatening (intracranial hemorrhage, massive gastrointestinal bleeding, or hemodynamic instability), immediately give fresh frozen plasma (FFP) 10-20 mL/kg in addition to vitamin K for immediate factor replacement while awaiting vitamin K effect (2-4 hours). 1, 2, 4, 3
• The presence of hepatomegaly does not contraindicate vitamin K administration and may actually indicate hepatic dysfunction contributing to decreased synthesis of vitamin K-dependent factors. 1

Diagnostic Confirmation

Rapid correction of PT/PTT within 30 minutes to 2-4 hours after vitamin K administration confirms VKDB. 1, 2, 3 This response is both therapeutic and diagnostic. 3

• Measurement of PIVKA (proteins induced by vitamin K absence) can confirm the diagnosis retrospectively, particularly in patients already treated with vitamin K or FFP. 1
• Never delay vitamin K administration while awaiting coagulation studies—the diagnosis is clinical and treatment is both safe and diagnostic. 2

Critical History and Risk Factor Assessment

Verify whether vitamin K prophylaxis was administered at birth, as compliance varies and some institutions/states do not mandate it. 1, 2

• Determine if the infant is exclusively breastfed, as breast milk contains insufficient vitamin K and is a primary risk factor for VKDB. 1, 2
• Obtain maternal history regarding anticoagulant use, as higher vitamin K doses may be necessary if the mother received oral anticoagulants. 3

Hepatomegaly-Specific Evaluation

The hepatomegaly requires parallel investigation as it may represent:

Congenital infection (TORCH infections), which can present with both bleeding and hepatomegaly. 5 Look for:

• Petechiae, purpura, or other skin manifestations
• Microcephaly or other dysmorphic features
• Jaundice beyond physiologic neonatal jaundice

Liver dysfunction or failure, which impairs synthesis of coagulation factors. 5 Assess:

• Bilirubin levels (direct and indirect)
• Transaminases (AST, ALT)
• Albumin and synthetic function markers
• Ammonia if encephalopathy suspected

Metabolic storage diseases (particularly lysosomal storage diseases), though these typically present later. 6

Hematologic malignancy or infiltrative process, though rare in newborns. 6

Additional Laboratory Evaluation

Obtain complete blood count with differential to assess for: 5, 7

• Thrombocytopenia (which would suggest DIC, sepsis, or immune-mediated destruction rather than isolated VKDB)
• Anemia (suggesting ongoing blood loss or hemolysis)
• Neutropenia or leukocytosis (suggesting infection)

If platelet count is <50,000/mm³ with active bleeding, consider platelet transfusion 10-20 mL/kg. 1, 4

Rare but Critical Differential: Homozygous Protein C Deficiency

If the infant fails to respond to vitamin K within 2-4 hours or presents with purpura fulminans-like skin lesions, consider homozygous protein C deficiency. 8, 4

• Treatment requires FFP 10-20 mL/kg every 12 hours or protein C concentrate 20-60 units/kg until lesions resolve (Grade 1A recommendation). 8, 4
• This is a life-threatening condition requiring immediate hematology consultation and long-term anticoagulation or liver transplantation. 8

Common Pitfalls to Avoid

• Do not assume vitamin K was given at birth without explicit verification in the medical record. 1, 2
• Do not delay treatment waiting for coagulation studies to "confirm" the diagnosis—normal PT/PTT with bleeding in a newborn is pathognomonic for VKDB. 2
• Do not attribute all bleeding to VKDB if hepatomegaly is present—pursue parallel investigation of liver dysfunction and infectious etiologies. 5
• Do not use adult FFP doses—neonates require 10-20 mL/kg, and all blood products should be CMV-negative. 4

Monitoring and Follow-up

• Reassess PT/PTT 2-4 hours after vitamin K administration. 3
• If coagulopathy does not correct, pursue further evaluation for inherited bleeding disorders with hematology consultation. 1
• Continue investigation of hepatomegaly etiology with appropriate imaging (ultrasound) and infectious/metabolic workup as clinically indicated. 5, 6