What is Peri-implant Effusion in a Silcone Breast Implant?

That is a new term to me, but it sounds like what I would call a "seroma".  Usually an "effusion" is a fluid collection somewhere, I just have never heard it mentioned in the context of breast implants.  Fluid (seroma) can accumulate around breast implants.  It usually does not amount to any problem and probably goes undiagosed unless there is a lot of fluid (very rare).  It may need to be drained if it is a problem.  Best of luck to you.