Some patients have anatomy that poses a risk for fluid extravasation or inadequate flow and peripheral IVs should be avoided in these situations. Examples include extremities that have massive edema, burns or injury. For the patient with severe abdominal trauma it is preferable to start the IV in an upper extremity because of the potential for injury to vessels between the lower extremities and the heart. For the patient with cellulitis of an extremity, the area of infection should be avoided when starting an IV because of the risk of inoculating the circulation with bacteria. As well, extremities on the side of a mastectomy or that have an indwelling fistula should be avoided because of concerns about adequate flow.