Ileocaecal valve

The ileocaecal valve (TA: ostium ileale), also known as Bauhin valve or Tulp valve, separates the terminal ileum from the caecum and functions to regulate flow between these two structures and prevent reflux from the caecum into the small intestine. 

Terminology

There are a large number of additional synonyms for the ileocaecal valve, which include Tulpius valve (variant of Tulp valve), valve of Varolius, ileal papilla, ileocaecal eminence and colic valve .

Gross anatomy

The ileocaecal valve consists of two muscular layers of ileum, an upper and lower lip, that are covered by mucosa and protrude into the lumen of the caecaum supported by mucosal folds called frenula. This forms the opening of the terminal ileum into the medial caecum and delineates the upper margin of the caecum from the ascending colon.

The morphology of the ileocaecal valve has be described on endoscopy as ^1,3,4:

• labial-type: slit-like opening (most common)
• papillary-type: dome-shaped
• lipomatous: significant amount of fat demonstrated in the lips

Variant anatomy

• lateral (~7.5%) or posterior opening (~5%) of the terminal ileum ^2,4

Radiographic appearance

Fluoroscopy

• ileocaecal valve is identified on barium enema as an oval or triangular-shaped filling defect with smooth or lobulated surfaces ⁴

CT

• ileocaecal valve is best viewed on supine imaging
• mixed density structure at the junction of the ileum and caecum with an average density of -25 HU (range -60 HU to +18 HU) ⁴

History and etymology

Costanzo Varolius (1543-1575) was an Italian and papal anatomist who is famously remembered for his contributions to neuroanatomy, including being the first to describe the pons; hence its historical monicker, pons Varolli ^6,7.

Caspar Bauhin (1560-1624) was a Swiss anatomist, although best remembered for his botanical works. Both his father and brother, John, were also physicians ⁵. Bauhin glands, a synonym of the anterior lingual salivary glands were also named for him ⁶.

Nicolas Tulp (1593-1674), a.k.a. Nicolas Tulpius, was a Dutch physician ⁶.

Related pathology

• lipomatosis of the ileocaecal valve
• ileocaecal valve incompetence