Thanks for writing.
In most patients with kidney stones, a metallic stent is placed to give passage to the multiple small stone fragments to pass into the urinary bladder
and then out of the urinary tract
. Stents used generally are double J stent with hook like curves at both the ends.
Sometimes, these ends of the stents slip downwards into the upper ureter
to cause slight injury or the end in the bladder can cause bladder wall injury
. Most injuries are slight but can cause severe pain
to the patients.
Also the smaller stone fragments can cause pain as they pass through the ureter.
So what you think is right, stents and smaller stone fragments, both can cause pain.
Hoppe this helps.