A client with deep vein thrombosis (DVT) in the left leg is on a heparin protocol. Which intervention is most important for the nurse to include in this client's plan of care?

A. Encourage mobilization to prevent pulmonary embolism. While mobilization can be important in preventing further DVT development, initial bed rest is often recommended to avoid dislodging the clot. Mobilization should be carefully managed based on the provider's recommendations. B. Measure each calf's girth to evaluate edema in the affected leg. Measuring calf girth is useful for monitoring the extent of the DVT, but it is not the most critical intervention compared to monitoring for complications of heparin therapy. C. Observe for bleeding side effects related to heparin therapy. This is the correct intervention. Heparin is an anticoagulant, and monitoring for signs of bleeding (such as in the gums, urine, stool, and bruising) is crucial to prevent serious complications. D. Assess blood pressure and heart rate at least every 4 hours. While important, frequent monitoring of vital signs is secondary to the need to vigilantly observe for bleeding, which is a direct and significant risk of heparin therapy.