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.
Heidelbaugh JJ. Gastroenterology. In: Rakel RE, ed. Textbook of Family Medicine. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 38.