The transplant operation involves placing a new kidney and ureter in the lower abdomen. The arteries and veins of the new kidney is then attached to your blood vessels and bladder. Unless your old kidneys are too large, causing infection, or high blood pressure, they are left in your body. When your new kidneys are attached, they will begin to form urine just like your own kidneys did when they were functioning normally. A catheter may be inserted for a few days to help drain the urine made by the new kidney. In some cases, dialysis may be needed until your new kidneys can function independently.