Diagnosis of Hypofibrinogenemia in Infants
The diagnosis of hypofibrinogenemia in infants requires measurement of fibrinogen levels from umbilical cord blood at birth, with collaboration between neonatal and pediatric bleeding disorder teams to confirm the diagnosis before performing any elective invasive procedures. 1
Diagnostic Approach
Initial Evaluation
- For infants with suspected hypofibrinogenemia (especially those with family history):
- Draw fibrinogen level from umbilical cord blood immediately after birth 1
- This initial sample reflects the baby's true fibrinogen level before any interventions
Laboratory Testing
- Fibrinogen activity level measurement is the primary diagnostic test 1
- Fibrinogen antigen level should be measured when available 1
- Additional coagulation tests that may show abnormalities:
- Prolonged thrombin time
- Prolonged partial thromboplastin time (APTT)
- Prolonged prothrombin time (PT) 2
Interpretation Challenges
- Critical pitfall: Adult reference ranges cannot be applied to newborns and infants 3
- Age-specific reference ranges must be used:
- Mean fibrinogen values are typically within adult range at birth
- PT values reach adult range by day 4 of life
- APTT values remain higher than adult range even at 11-20 days of life 3
Classification of Severity
Fibrinogen disorders are classified based on fibrinogen levels:
- Afibrinogenemia: Complete absence of fibrinogen
- Severe hypofibrinogenemia: Very low fibrinogen levels
- Moderate hypofibrinogenemia: Low but detectable levels
- Mild hypofibrinogenemia: Levels ≥1 g/L to lower limit of normal 1
Clinical Presentation
Infants with hypofibrinogenemia may present with:
- Umbilical cord bleeding 2
- Ecchymoses
- Subcutaneous hematomas
- Hemarthroses (especially following traumatic delivery)
- Gastrointestinal bleeding 2
Management Considerations
Immediate Post-Diagnosis Care
- Delay all elective invasive procedures (including venipuncture and circumcision) until diagnosis is confirmed 1
- Establish collaboration between neonatal and pediatric bleeding disorder teams 1
Precautions During Procedures
- For infants with confirmed afibrinogenemia or severe hypofibrinogenemia:
- Avoid invasive procedures when possible
- If procedures are necessary, maintain fibrinogen levels ≥1.5 g/L 1
Special Considerations
Maternal-Fetal Implications
- When both parents are heterozygous for hypofibrinogenemic mutations:
- 25% chance of having a child with afibrinogenemia
- Prenatal diagnosis may be considered to assess fetal bleeding risks 1
- Plan appropriate mode of delivery to minimize trauma
Delivery Planning
- For infants suspected to have afibrinogenemia or severe hypofibrinogenemia:
- Avoid fetal scalp monitoring
- Avoid forceps or vacuum-assisted delivery
- Consider early recourse to cesarean section, especially with prolonged second stage of labor 1
By following this diagnostic approach and taking appropriate precautions, clinicians can minimize bleeding complications and optimize outcomes for infants with hypofibrinogenemia.