Ileocecal valve

The ileocecal valve or ileocaecal valve is a sphincter muscle situated at the junction of the small intestine (ileum) and the large intestine. Its critical function is to limit the reflux of colonic contents into the ileum.

The ileocecal valve is distinctive because it is the only site in the GI tract which is used for Vitamin B12 and bile acid absorption.

Functionally, roughly two liters of fluid enters the colon daily through the ileocecal valve.

Histology
The histology of the ileocecal valve shows an abrupt change in the villous pattern which is mucosa, to the ileocecal valve, there is also thickening of the muscularis mucosa, which is the smooth muscle tissue found beneath the mucosal layer of the digestive tract.

There is also a variable amount of lymphatic tissue found at the valve.

Clinical significance
During colonoscopy, the ileocecal valve is used, along with the appendiceal orifice, in the identification of the cecum. This is important, as it indicates that a complete colonoscopy has been performed. The ileocecal valve is typically located on the last fold before entry into the cecum, and can be located from the direction of curvature of the appendiceal orifice, in what is known as the bow and arrow sign.

Intubation of the ileocecal valve is typically performed in colonoscopy to evaluate the distal, or lowest part of the ileum. Small bowel endoscopy can also be performed by double-balloon enteroscopy through intubation of the ileocecal valve.

Pathology
Tumors of the ileocecal valve are rare, but have been reported in the literature.

Etymology
It was described by the Dutch physician Nicolaes Tulp (1593–1674), and thus it is sometimes known as Tulp's valve.