What about if you have bursitis and you don't drain it?

Depends: Many cases of bursitis do not need to be drained. Often, rest, anti-inflammatories, ice, compression can relieve and diminish the swelling/fluid. If a bursa is infected though, it needs to be drained/evaluated. An infected bursa will be red, will hurt, can limit motion, can drain, can cause fevers or malaise, and do not get better.

Can't always drain: Not all types of bursitis can be drained. There may be inflammation but no fluid. We try to drain any fluid collection in the body and get cell counts, cultures, chemistries and and review the fluid under a microscope. It is important to drain fluid to look for infection. Usually infection, pain relief and the desire to get a diagnosis of the fluid are the main reasons to drain it.