Blood clots in urine have stent from narrow ureter due to tumor. clots passing are painful and blocks my urine. what could be the cause?

Several causes.: The presence of a stent in the urinary tract can cause irritation to the lining of the ureter and bladder causing bleeding. Tumors, besides obstructing, can bleed if they cause any erosion of the ureteral lining. If you are passing large clots and blood, a known risk of stents is the development of a communication between a blood vessel and the ureter. Please see your physicians for evaluation.

Be seen: The stent appears to be causing the bleeding and clots, though it could be from the tumor. Be seen by your urologist for an opinion and exam.

Widely variable ...: Stent is to help healing of mucosa and to avoid blockage by clots or any sizable objects like tumor, clots, or stone, but not without a price. Stent-related symptoms in voiding widely vary among individuals reflecting personal pain threshold of coping ability, degree of procedure-related mucosal injury and inflammation, and length of ureteral stent. In general, the younger, the worse. Best wishes.