Ascending colon

The origin of the ascending colon is well defined as it starts just cranial to the ileocecal valve and it continues to the hepatic flexure where there is no definite defining border between the two.  It is retroperitoneal in its location and is slightly narrower in diameter than the cecum and measures up to 20-25 cm long.

The ascending colon is supplied by the right colic artery which is a branch of the SMA and it is drained by the right colic vein which drains into the SMV.


Ascending colon
The ascending colon in this patient is relatively short in this projection.  It starts just above the ileocecal valve and ends in an ill defined region under the liver at the hepatic flexure.

Courtesy Ashley Davidoff MD




Structural Differences Between the Ascending and Descending Colon as Shown by CT colonography
75365 ascending colon descending colon size character shape folds normal anatomy Ct colonography Virtual colonoscopy CTscan Courtesy Ashley Davidoff MD Scott Tsai MD

Applied Anatomy

Angiodysplasia of the colon is an acquired arteriovenous malformation, occurs most commonly in the cecum and ascending colon.  It is not an uncommon cause of lower GI bleeding.  When diverticuli bleed, they usually bleed from right sided diverticulosis even though in Western cultures the sigmoid colon is far more frequently involved with diverticulosis.   TB of the colon usually affects the right side of the colon (eMedicine)

The radiological distinction between Crohn’s disease, carcinoma and TB may be difficult to differentiate.  While carcinoma is described as having apple core shape, TB is said to have a shape that is more reminiscent of an hourglass.

Other diseases that occur on the right side of the colon are relatively universal to the colon as a whole and include diverticulitis, ischemia and carcinoma.


Long stricture in the ascending colon
Barium enema of a 29 year old male from India who presented with intermittent small bowel obstruction. TB was thought to be more likely but carcinoma and Crohn’s disease was in the differential diagnosis. The shape of the lesion seemed to be more like an hourglass than an apple core and so we favored TB.  At surgery colon carcinoma was diagnosed – go figure.

A classical apple core lesion is demonstrated in the sigmoid colon section below.

Courtesy Ashley Davidoff MD



                        Figure 1                                                               Figure 2.

Hypervascular lesion in ascending colon
The angiogram from a 45 year old man shows a hypervascular lesion in the mid portion of the ascending colon.  The right colic artery supplies the lesion and is enlarged as seen in Fig 1 and a large right colic draining vein is seen in Fig 2 draining into the portal vein and into the liver.

Courtesy Laura Feldman MD.