What is the most likely diagnosis for a child with umbilical bleeding, normal Prothrombin Time (PT), normal activated Partial Thromboplastin Time (aPTT), normal platelet count, and normal platelet function, but increased clot lysis, and a family history of similar condition?

Factor XIII Deficiency

The most likely diagnosis is Factor XIII deficiency, given the characteristic presentation of umbilical bleeding with normal PT, aPTT, platelet count, and platelet function, but with increased clot lysis and a positive family history. 1

Diagnostic Reasoning

Why Factor XIII Deficiency Fits Perfectly

• Umbilical cord bleeding is the hallmark presentation of Factor XIII deficiency in neonates, distinguishing it from other bleeding disorders 1, 2
• Normal PT and aPTT are characteristic because Factor XIII acts after clot formation to stabilize fibrin, not during the coagulation cascade measured by these tests 3
• Increased clot lysis (prolonged clotting time by 5 minutes) reflects the unstable clot formation that occurs when Factor XIII cannot cross-link fibrin properly 1
• Autosomal recessive inheritance explains the family history pattern with a relative having the same condition 1
• Normal platelet count and function exclude platelet disorders and von Willebrand disease 1

Why the Other Options Are Excluded

• Von Willebrand disease (Option A) is ruled out because it would show prolonged bleeding time due to impaired platelet adhesion, and the platelet function is explicitly normal in this case 4
• Bernard-Soulier syndrome (Option B) is excluded because it presents with thrombocytopenia and abnormal platelet function, neither of which are present here 3
• Congenital alloimmune thrombocytopenia (Option C) is eliminated because the platelet count is normal 3

Immediate Management Priorities

Critical First Steps

• Administer fresh frozen plasma (FFP) at 10-20 mL/kg every 12 hours immediately to stop active umbilical bleeding, as Factor XIII deficiency responds rapidly to plasma replacement 1
• Avoid all intramuscular injections, including vitamin K, until Factor XIII levels are corrected, as these can cause large intramuscular hemorrhages 1
• Do not assume vitamin K deficiency based on umbilical bleeding alone; vitamin K deficiency would show prolonged PT, which is absent in this case 1

Diagnostic Confirmation

• Order Factor XIII activity assay for definitive diagnosis, as this is the only way to confirm the deficiency 3
• The euglobin lysis test may show increased fibrinolysis, though this is less specific than direct Factor XIII measurement 1
• Avoid all invasive procedures including venipuncture and circumcision until diagnosis is confirmed and Factor XIII levels are corrected 1

Common Pitfalls to Avoid

• Do not delay treatment waiting for confirmatory testing - the clinical presentation is sufficiently characteristic to warrant immediate FFP administration 1
• Do not confuse this with vitamin K deficiency - the normal PT/aPTT pattern is completely different from vitamin K deficiency, which would prolong both PT and aPTT 5
• Do not overlook the family history - the autosomal recessive inheritance pattern is a critical diagnostic clue that should prompt immediate consideration of Factor XIII deficiency 1

Long-Term Management

• Prophylactic dosing consists of FFP 10-20 mL/kg every 2-4 weeks or Factor XIII concentrate at manufacturer-recommended intervals 1
• Before any surgical intervention, ensure Factor XIII levels are corrected to >10% activity 1
• Provide genetic counseling regarding autosomal recessive inheritance to the family 1
• Collaborate immediately with pediatric hematology for ongoing management and monitoring 1