A nurse is collecting data from a client who is taking warfarin and reports observing blood in their stools. Which of the following actions should the nurse take?

A. Prepare the client for a barium enema: A barium enema is a diagnostic imaging procedure used to evaluate structural abnormalities in the colon, but it is not the immediate priority when a client on warfarin reports blood in stools. The focus should first be on assessing coagulation status and risk of bleeding. B. Prepare the client for a colonoscopy: Colonoscopy allows direct visualization of the colon to identify sources of bleeding, but performing an invasive procedure in a client on anticoagulation without assessing clotting parameters first increases the risk of severe hemorrhage. Immediate evaluation of anticoagulation levels is safer. C. Request an aPTT level: Activated partial thromboplastin time (aPTT) is used to monitor heparin therapy, not warfarin. Checking aPTT would not provide accurate information about the client’s anticoagulation status or bleeding risk with warfarin therapy. D. Request an INR level: The international normalized ratio (INR) is the standard laboratory test for monitoring warfarin therapy. An elevated INR indicates increased anticoagulation and a higher risk of bleeding. Assessing the INR provides critical information to guide interventions such as dose adjustment or vitamin K administration.