Hi Northwoods,
Great question. Male Ureters are normally 3–4 mm in diameter. The Male Urethra is 6 mm diameter. Remember these structures have a bit of stretch in them.
Thanks for asking.
~Tuck
To be honest, I'm not sure what the actual answer to your question is. What I can tell you is that I've had surgery to remove stones and I've had to have a stent due to my ureter having to be cut in order to get the bigger stone(s) out, but the "last leg" was only severely irritated which was evidenced by the bad burning sensation I experienced when urinating for a few days afterwards.The internal irritation was due to the surgical instruments the Urologist was using going in and out during surgery. Since those same instruments and the stone itself went through both the ureter and the "last leg" and only the ureter needed the stent while healing, I would therefore bet that either the "last leg" is larger or has more elasticity and therefore able to ultimately open wider and not be cut. That's my common sense answer from my experience.