My 91 Year Old Uncle Has A Swollen Left Arm,

My 91 year old uncle has a swollen left arm, from the elbow down through his hand, it is also bluish/ purple in color. There is tenderness on the underside of this arm, just below the elbow. I took him to Med Express yesterday where the doctor diagnosed edema, wrapped it in an ace bandage, told him to keep it elevated, & put in an order for an ultrasound to rule out a blood clot. However, we have not received a call yet to order the ultrasound which I was hoping would be done tomorrow. My uncle is on the blood thinner, Eliquis. I am not a doctor, but I have never seen a case of edema that looks like this. Should I wait for the hospital to call to schedule the test, or should I take him to the ER tonight?