Hi, Thanks for writing in. Research shows that ureteric injury is a feared complication in colorectal surgery, with a reported incidence of 0.2%–7.6%. This can be decreased by ureteric catheter placement that gives the surgeon the advantage of facilitating intraoperative ureter identification and assisting in immediate injury recognition and repair. Also this decision is controversial because of fear of ureteric damage during catheter insertion and postoperative urinary complications such as obstructive oliguria and urinary tract infection. I suppose there has been little injury to the urinary tract due to the stent placement in your father during surgery. It was an action keeping in mind the complication associated with the surgery. Further research done in 2012 shows that ureter stent placement is safe and justified in most cases. Unfortunately the stent has caused a little scratch in your father. The injury should heal soon. Hope this helps.