<prompt> Prolonged prothrombin time is seen in ?Haemophilia AHaemophilia BThrombocytopeniaFactor VII deficiency  <response>: Prothrombin time evaluates extrinsic factors and common pathway factors factors 1,2,5,7,10.Prolongation of PT time occurs with deficiency of these factors. Haemophilia A is due to factor 8 deficiency, which is an intrinsic factor.So no PT prolongation Haemophilia B due to factor 9 deficiency. No PT Prolongation Thrombocytopenia due to decreased platelet number. so no PT prolongation . Factor 7 is an extrinsic factor .So its deficiency causes prolongation of PT Ref. Robbins and Cotran Pathologic basis of disease.South Asia Edition volume 1.page no.657,662,663 Harsh Mohan textbook of pathology 7th edition.Pg no.307 