Dr. Ross attempts to give the dying Palenko a blood transfusion without apparently testing his blood type. He does this by using O-Negative blood, which can be given to any recipient. It was crucial to try and stabilise Palenko who was suffering massive blood loss. Had he survived a bit longer, they could then take the time to do a blood test and transfuse the appropriate blood type.
One of very few episodes not written by show's creator Horowitz