I have an IJ Tessio catheter and am new to this dalysis center. Recently I noticed that my nurse pulls back blood before flushing the final heparinized saline through. Ofcourse, twice they have had to use retiplase. I tell them not to aspirate but leave the clear heparinized saline in the cath but they claim they have always aspirated. Isn't the problem the blood mixed in with the flush that sits in the line?