Vitamin K Deficiency (Answer: C)
The most likely diagnosis is Vitamin K deficiency, given the combination of umbilical stump bleeding, prolonged PT and PTT, normal platelet count, and delayed clot time in a newborn.
Laboratory Pattern Analysis
The key to this diagnosis lies in understanding which coagulation factors are affected:
- Prolonged PT and PTT together indicate deficiency of factors in the common pathway affecting both extrinsic and intrinsic pathways, which is the hallmark of Vitamin K deficiency affecting factors II, VII, IX, and X 1
- Normal platelet count explicitly excludes thrombocytopenia (option D) and makes platelet-related disorders unlikely 1
- Delayed clot time reflects the inability to form stable clots due to multiple vitamin K-dependent factor deficiencies 1
Why Not the Other Options?
Hemophilia A (Option A) - Excluded
- Hemophilia A would prolong only the PTT, not the PT, since factor VIII is part of the intrinsic pathway only 1
- The presence of prolonged PT rules out isolated factor VIII deficiency 2
Von Willebrand Disease (Option B) - Excluded
- Von Willebrand disease typically presents with prolonged bleeding time due to impaired platelet adhesion 1
- It is not reliably detected by PTT screening and typically does not cause severe umbilical stump bleeding in newborns 2
- Normal platelet function (implied by normal platelet count and specific bleeding pattern) makes this unlikely 3
Thrombocytopenia (Option D) - Excluded
- The platelet count is explicitly stated as normal, which by definition excludes thrombocytopenia 2
Classic Clinical Presentation
- Umbilical stump bleeding is a classic presentation of vitamin K deficiency in newborns, along with bleeding from circumcision, generalized ecchymoses, and intramuscular hemorrhages 1
- The absence of vitamin K prophylaxis at birth is a significant risk factor for Vitamin K Deficiency Bleeding (VKDB) 1
- Breast-feeding is a primary risk factor for VKDB, as breast milk contains insufficient vitamin K 1
Diagnostic Confirmation
- Rapid correction of PT/PTT within 2-4 hours after vitamin K administration confirms the diagnosis 1, 4, 5
- A prompt response (shortening of the prothrombin time in 2-4 hours) following administration of vitamin K is usually diagnostic of hemorrhagic disease of the newborn 4
- Measurement of proteins induced by vitamin K absence (PIVKA-II) can provide additional confirmation 1
Immediate Management
The American Academy of Pediatrics recommends:
- Administer 1 mg vitamin K intramuscularly or intravenously immediately while awaiting confirmatory laboratory correction 1, 4
- For treatment of hemorrhagic disease of the newborn, vitamin K 1 mg should be given either subcutaneously or intramuscularly 4
- Consider fresh-frozen plasma for immediate factor replacement in life-threatening bleeding 1
- Whole blood or component therapy may be indicated if bleeding is excessive 4
Critical Pitfall to Avoid
Factor XIII deficiency can present with umbilical stump bleeding and delayed cord separation but has normal PT, PTT, and platelet count 3, 6, 7. However, this case explicitly states prolonged PT and PTT, which rules out Factor XIII deficiency and confirms vitamin K deficiency as the diagnosis 3.