Ileocecal valve

Ileocecal valve
Interior of the cecum and lower end of ascending colon, showing colic valve. ("Colic valve" is an older term for the ileocecal valve.)
Endoscopic image of cecum with arrow pointing to ileocecal valve in foreground.
Latin	valva ileocaecalis
Gray's	subject #249 1179
Artery	ileocolic artery
Vein	ileocolic vein
MeSH	Ileocecal+valve

The ileocecal valve, or ileocaecal valve, is of a bilabial papilla structure with physiological sphincter muscle situated at the junction of the small intestine (ileum) and the large intestine, with recent evidence indicating an anatomical sphincter may also be present in humans)^[1] Its critical function is to limit the reflux of colonic contents into the ileum.^[2]

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.^{[citation needed]}

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

Histology

The histology of the ileocecal valve shows an abrupt change from a villous mucosa pattern of the ileum to a more colonic mucosa. A thickening of the muscularis mucosa^{[citation needed]}, which is the smooth muscle tissue found beneath the mucosal layer of the digestive tract. A thickening of the muscularis externa is also noted^[1].

There is also a variable amount of lymphatic tissue found at the valve.^[3]

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.^[4]

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.^[5]

Pathology

Tumors of the ileocecal valve are rare, but have been reported in the literature.^[6][7]

Etymology

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

References

1. ^ ^{a b} Pollard, MF; Thompson-Fawcett, MW; Stringer, MD (2011). "The human ileocaecal junction: anatomical evidence of a sphincter". Surg Radiol Anat [Epub ahead of print]. PMID 21863224. 
2. ^ Barret KE. "Lange Gastrointestinal Physiology". The McGraw-Hill Companies, 2006.
3. ^ Burkitt HG, Young B, Heath JW. Wheater's Functional Histology: a text and colour atlas. Churchill Livingstone, London, 1993.
4. ^ Cotton PB, Williams CB. Practical Gastrointestinal Endoscopy Blackwell Publishers, London, 1996
5. ^ Ross, AS; Waxman, I; Semrad, C; Dye, C (2005). "Balloon-assisted intubation of the ileocecal valve to facilitate retrograde double-balloon enteroscopy". Gastrointestinal endoscopy 62 (6): 987–8. doi:10.1016/j.gie.2005.09.002. PMID 16301054. 
6. ^ Yörük, G; Aksöz, K; Buyraç, Z; Unsal, B; Nazli, O; Ekinci, N (2004). "Adenocarcinoma of the ileocecal valve: report of a case". The Turkish journal of gastroenterology : the official journal of Turkish Society of Gastroenterology 15 (4): 268–9. PMID 16249985. 
7. ^ Song, HJ; Ko, BM; Cheon, YK; Ryu, CB; Lee, JS; Lee, MS; Shim, CS (2005). "Isolated ileocecal lymphoma". Gastrointestinal endoscopy 61 (2): 293–4. PMID 15729248. 

External links

• Diagram at amatsu.co.uk
• largeintestine at The Anatomy Lesson by Wesley Norman (Georgetown University) (cecuminside)