A 4-year-old boy presents with delayed umbilical stump bleeding at birth and prolonged bleeding after minor trauma. PT, aPTT, platelet count, and bleeding time are all normal. A clot solubility test in 5M urea shows rapid dissolution of the clot. Which factor is deficient?

• A Factor XIII ✓
• B Factor VIII
• C Factor VII
• D Factor IX

Explanation

Factor XIII cross-links fibrin to stabilize the clot. Its deficiency produces a classic pattern: all routine coagulation tests (PT, aPTT, BT, platelet count) are normal, yet the clot dissolves rapidly in 5M urea or monochloroacetic acid because it lacks cross-linking. Factor VIII or IX deficiency would prolong aPTT, and factor VII deficiency would prolong PT.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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