Mechanical Failure??

Just out of curiosity, what is really the definition of a "mechanical failure" when it comes to any form of bariatric surgery?  Maybe more specifically the Roux-en-Y?  I'm curious as to if this is determined on a case by case or if most surgeon's use a criteria determining if a revision is the next step??  Any thoughts and comments would be appreciated, thanks!

 

 

With the RNY 2 things come to mind, the pouch stretching and the stoma stretching.  I assume that there are certain measurments that they go by that are the maximum and if they are bigger then it is considered mechanical failure.  I am sure there are other causes but those are the 2 that come to mind.