Herpsss does have a good point. Although I appreciate Robyn's thread in that it describes this unfortunate occurrence, I don't agree with Robyn's comment :
Unless a vet has specifically dealt with that in the past, successfully, it is unlikely they would be all that helpful, so I wouldn't recommend a vet visit as a matter of course.
I recently had to deal with my first hard-belly, and chose to operate on the snake myself. I believe most knowledgeable vets would be more skilled and better equipped than dealing with hard-belly than I was, but I still managed to save his life and he is currently thriving. If I had followed the advice given in this thread, my snake would most likely have died. The hard-belly lump that I extracted was quite a bit larger than the one in the picture and never would have passed through his cloaca.

I'm not opposed to people trying to gently pass the mass out of the cloaca, but if it doesn't work I wouldn't suggest forcing it to the point of tearing the snake. Instead, I would advise seeking out professional help to surgically remove the mass.

Here's the link which describes my experience.