[Severe coagulation abnormality during treatment for ischemic enteritis in an older patient taking a direct oral anticoagulant].

An 85-year-old woman hospitalized for rehabilitation after cerebral infarction developed persistent bloody diarrhea and was transferred to our hospital (day 1). Contrast-enhanced computed tomography of the abdomen showed edematous thickening extending from the left side of the transverse colon to the rectum, with decreased mucosal enhancement. She was diagnosed with ischemic enteritis. She fasted and was treated with fluids and antibiotics. The bloody diarrhea stopped, and she was restarted on the direct oral anticoagulant (DOAC) edoxaban on day 5. Endoscopy on day 11 showed linear ulceration and severe mucosal edema in the rectum. The diarrhea was persistent, so fasting and fluid therapy were continued. A blood test on day 18 showed significant prolongation of the prothrombin time (≥100 s), International Normalized Ratio (14.03), and activated partial thromboplastin time (87.5 s), as well as a significant increase in protein induced by vitamin K absence-II (12,469 mAU/mL). Her condition was diagnosed as a coagulation abnormality due to vitamin-K deficiency. A vitamin-K preparation was administered immediately, and her coagulation abnormality improved rapidly. In general, DOACs do not require routine monitoring with blood tests. However, frequent monitoring of the coagulation function is required in fasting patients on DOACs because acute coagulation abnormalities can be induced rapidly by vitamin-K deficiency. Given that non-valvular atrial fibrillation and ischemic enteritis are among the most prevalent diseases affecting older people, the likelihood of encountering these diseases in daily clinical practice will increase with the aging of the population. We herein report this instructive case suggesting that a severe coagulation abnormality may develop during treatment for ischemic enteritis in older people taking a DOAC.