Association of Marked Prolongation of Prothrombin Time-International Normalized Ratio with Warfarin and Endoscopic Nasobiliary Drainage for Biliary Fistula after Left Hemihepatectomy.

WHAT IS KNOWN AND OBJECTIVE:Vitamin K deficiency is known to cause impaired coagulation. We report a case of marked prolongation of the prothrombin time-international normalized ratio (PT-INR) associated with warfarin and vitamin K deficiency caused by endoscopic nasobiliary drainage (ENBD).CASE PRESENTATION:Oral administration of warfarin was initiated in a 67-year-old man after left hemihepatectomy. He developed a biliary fistula after surgery that was treated by ENBD, which resulted in significant prolongation of the PT-INR.WHAT IS NEW AND CONCLUSION:The effect of warfarin was enhanced in this patient due to reduced absorption of vitamin K as a result of external biliary drainage.