In the case of body piercing, the fistula is the internal "skin tube" that connects the two ends of the piercing. That is, the new skin that forms when the piercing is healed; literally a cylinder of skin, with each end attached to one end of the piercing. A common colloquial term for a fistula is "flesh tube".
A fistula is any connection between an organ, vessel, or intestine and another structure in the body. Fistulas are usually the result of trauma or surgery (i.e. piercings), but can also result from infection or inflammation.
When the body's skin is pierced (or certain types of implants such as transdermals) the healing process involved is the creation of a fistula, or a fleshy tunnel comprised of scar and fibrous tissue that functions as a conduit for drainage during healing as well as a natural encapsulation of the foreign object now lodged in the dermis.
Types of Fistulas
- Blind (Open on one end only, but connects to two structures)
- Complete (Has both external and internal openings, as in a standard piercing with two distinct exit points)
- Horseshoe (Usually occurs when a Connection develops between anus and one or more points on the surface of the skin after going around the rectum as in Crohn's Disease and sever Ulcerative Colitis)
- Incomplete (A tube from the skin that is closed on the inside and does not connect to any internal organ or structure as in a healed transdermal implant).
It is important to note that one's body does not always agree with being pierced, and if one's immune system finds it easier to push out the foreign body rather than encase it in a fistula, rejection is the inevitable outcome.