Caecal volvulus
A caecal volvulus accounts for 11% of all intestinal volvulus. It generally occurs between 30 - 60 years of age. Although there is an association with prior surgery, adhesions and bands they are not essential for a volvulus to occur.
In 10% of the population deficient peritoneal fixation of the caecum and ascending colon allowing abnormal mobility. Depending on the length of the mobile segment of right colon a variety of obstructive bowel patterns may result.
Two types of caecal volvulus are described:
- axial torsion type
- caecal bascule type
In practice, differentiation between the types is not clinically important because the clinical presentation and treatment is the same. However, the radiographic appearances are different.
Radiographic features
Plain film (AXR)
Axial torsion
In axial torsion, the image may show a markedly distended loop of large bowel with its long axis extending from the right lower quadrant to the epigastrium or left upper quadrant, the most common site to which the caecum is displaced. Depending on the initial bowel position and the length of mobile right colon, the distended cecum may be seen anywhere in the abdomen. Despite the varying positions of the distended cecum, the plain radiographic features of a cecal volvulus are characteristic, and the caput cecum can typically be identified. The colonic haustral pattern is generally maintained, although some effacement may be present if superimposed ischemia is present. When shorter segments of the colon and cecum are involved, the distended cecum may be found in the normal location. In most patients, obstruction is almost complete; thus, the distal colon is usually empty and the small bowel is frequently distended. Occasionally, a long-axis torsion may be associated with signs of incomplete obstruction. Rarely, small-bowel loops are identified to the right of the distended cecum and ascending colon. The ileocecal valve may possibly be identified, and on occasion, the point of torsion may be outlined by gas, as an area of cone-like narrowing.
Caecal bascule
In the cecal bascule form of volvulus, the distended air filled cecum is located more centrally. With this variant, the ileum can passively twist with the cecum and small bowel is not obstructed. If the appendix is filled with gas and in an unusual location attached to a distended cecum, the diagnosis can be made readily.
Contrast enema
Single-contrast barium or water soluble contrast enema examination is generally adequate for the evaluation of cecal volvulus. A double-contrast barium enema study does not confer any significant advantage, because no fine detail is necessary to make the diagnosis. The administration of glucagon is often necessary because patients may have considerable colonic spasm and find it difficult to retain the contrast agent.
The barium enema study shows a nondilated distal colon to the point of twist. If the obstruction is not complete, some barium may trickle past the site of obstruction, and the twist may be visualized in more detail. If the twist occurs along the transverse axis, the obstruction appears relatively smooth, and no spiral twist is usually seen. In a cecal bascule, a rounded termination of the barium column may be seen. This, when seen near a distended gas-filled viscus, should alert the radiologist to the diagnosis of a volvulus.
As little barium as possible should be allowed to flow proximal to the site of obstruction because flooding the bowel proximal to the obstruction site might precipitate a complete obstruction. When the barium enema is administered, overdistension should also be avoided because this can lead to perforation. An attempt should always be made to reduce the volvulus. This reduction may be achieved during colonic filling by barium, but reduction occasionally occurs during barium evacuation. With an intermittent volvulus, the barium enema results may be normal, but a postevacuation radiograph may reveal the twist.
CT
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