Why is it felt in the lower left abdomen, and not in the testicles then?

Sorry for the vagueness....

If anyone here has attempted banding, or self-castration I would suppose they might know. My question doesn't deal with my personal castration- but my attempts at it.

In many of the internet accounts, along with my own personal attempts. There is a huge painful ache in ...

So exactly what is it that is causing the pain in the lower left abdomen during castration.... is it a certain organ, or what is it...and would it still be present if attempted following a vasectomy? Is it caused by the compression of the vas def? or the blood supply?