I received a message from a piercee who couldn't figure out why her old, established piercings were acting up:

I have several piercings all different ages some for as many as 10 years or more and not had any problems. Recently they have all began to migrate and reject and I don't understand why. Can you tell me why this would happen all of the sudden and at such volume after years of no problems at all?

My response:
Are you experiencing some kind of excessive stress right now? Stress can cause problems with healed piercings. If not, I'd suggest a visit to a doctor for a thorough check up. After a long history of stability, if your piercings are acting up that could indicate a health problem of some sort. The far-reaching effects of stress on the body are well-documents. I've definitely seen extremely well-healed, old piercings act up, and reject as a result of elevated levels of stress (both acute and chronic).  

Please keep me posted!
 

She did just that, and contacted me again about three months later:

I emailed you a while ago regarding my migrating piercings. After some observation and doctor visits it was in fact due to high stress levels as you suspected.

I lost my eyebrow, nose, & hood piercings completely. Well, I took the hood jewelry out because I began to notice similarities in how the ones that rejected felt. I was able to save my nipple piercings. I however have a microdermal that almost completely came out but is still hanging on by a thread. Just haven't wanted to deal with the removal after losing the others.

Do you think that I would be safe to have them redone?

First you should take care of your "hanging" surface anchor (the preferred terminiology of the Association of Professional Piercers.) Piercings that are left in the body during rejection can heal with more scar tissue than if you remove the jewelry once it becomes clear the piercing is no longer viable.

I can't evaluate you well without inspecting the tissue in person. But if you have your stress under control and there is no excessive scar tissue present, then it may be possible. If you are experiencing hardened, lumpy, or dense scar tissue, I'd suggest waiting until that diminishes before considering repiercing. Try out some scar reduction options to help it along.

Note also, that in many cases surface anchors tend to be temporary at best, anyway--so you may want to stick with the other more traditional piercings.