An anastomosis is a surgical connection between two structures. It usually means a connection that is created between tubular structures, such as blood vessels or loops of intestine.
For example, when part of an intestine is surgically removed, the two remaining ends are sewn or stapled together (anastomosed), and the procedure is referred to as an intestinal anastomosis.
Examples of surgical anastomoses are colostomy (an opening created between the bowel and the abdominal skin) and arterio-venous fistula (an opening created between an artery and vein) for hemodialysis.
A pathological (caused by disease) anastomosis can result from trauma or infection and may involve veins, arteries, or intestines. These are usually referred to as fistulas.
Traumatic fistulas usually occur between an artery and vein. Traumatic intestinal fistulas usually occur in two ways: