Twist and shout in the large intestine.
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RADIOLOGIC DIAGNOSIS: Type II cecal volvus.
INTERPRETATION OF IMAGES
Figure 1 details a gaseous distended "kidney shaped" loop of large bowel located within the left upper quadrant. Figures 2 and 3 demonstrate a tapered column of gastrograffin contrast near the proximal ascending colon/cecum as imaged on a gastrograffin enema study consistent with a "bird beak sign." Figures 4, 5, and 6 demonstrate twisting of the mesentery and mesenteric vessels without any evidence of contrast seen within the small bowel on this intravenous and rectal contrast computed tomographic examination consistent with a "whirl" or "swirl" sign.
As the third most common cause of large bowel obstruction after diverticulitis and malignancy, volvulus is a life threatening condition that must be considered in any patient presenting with an acute abdomen. While sigmoid volvulus is slightly more common, cecal volvulus is an equally important and significant pathologic process whose mortality ranges from 12%-17%. (1)
Cecal volvus may be classified as Type I and II, where Type I is referred to as a cecal bascule which is an nonobstructive process, and Type II cecal volvus is consistent with obstructive processes.1,7 In most patients with a Type II cecal volvulus, the torsion is located in the ascending colon above the ileocecal valve. In general a partial malrotation, long mesentery, and poor fixation of the right colon is necessary for a cecal volvulus to occur as the cecum and also parts of the ascending colon are involved. Early diagnosis is essential to reduce the high mortality rate reported with this condition as Type II cecal volvulus is essentially a closed-loop obstruction that may lead to vascular compromise with consequent gangrene and perforation. (1,2) Patients presenting with a cecal volvus may experience an abdominal compartment syndrome where the increase in abdominal pressures causes cardiac and respiratory compromise. (7)
The final position of the cecum in adults is the result of several developmental processes including rotation, descent, and mesenteric fixation of the intestinal midgut. A retroflexed, anteflexed, or medially placed cecum are regarded as normal anatomic variants and are frequently seen at barium enema examination. (1,4)
Etiologies of a Type II cecal volvulus include sudden distention by trauma, pressure, constipation, or distal colonic obstruction. As a result, studies of patients with a cecal volvulus have focused on the possibility of a volvulus of the right colon occurring in association with obstructive colonic lesions. (1,7) The most common distal colonic lesions associated with a cecal volvulus are colon cancer and diverticulitis. (1)
Axial torsion is the most common form of a volvulus and occurs with the development of a twist of 180[degrees]-360[degrees] along the longitudinal axis of the ascending colon. Consequently the cecal volvus caused by longitudinal axis rotation is associated with a high mortality rate as the obstructive process is associated with significant vascular compromise leading to strangulation of the arterial and venous vessels along the antimesenteric border with subsequent perforation. (3)
In patients with a cecal bascule (Type I cecal volvulus), the cecum folds anteromedial to the ascending colon in a cephalad direction with the production of a flap-valve occlusion at the site of flexion. This form of torsion occurs in a transverse plane and is associated with marked distension of the cecum, which is often displaced into the center of the abdomen. As many as a third of the patients with a cecal volvulus have a cecal bascule where reduction of the cecal bascule is reported after an enema examination. With a cecal bascule the ileum may passively twist with the cecum and not be obstructed. A constant feature of cecal bascule is the presence of a constricting band across the ascending colon which may be found at laparotomy. (5,7)
Plain film or a kidney-ureter-bladder (KUB) scan of the abdomen may be excellent in diagnosing and elucidating a Type II cecal volvulus. When diagnostic, a large dilated ovoid air-filled cecum is usually visualized in the upper left abdomen as the hypermobile cecum has rotated upward and to the left around the ileocolic vessels and is often referred to as a "kidney shaped" gaseous distended loop of bowel. (7) Conversely, a sigmoid volvulus is more likely to have large dilated loops of bowel with the apex in the left lower quadrant and the convexity in the right upper quadrant. (1) Approximately 10% of cases of cecal volvulus are the cecal bascule (Type I cecal volvus). A gastrograffin or barium enema can be diagnostic in up to 88% of cases of a Type II cecal volvulus but is contraindicated in suspected cases of intestinal gangrene. Computed tomography findings in cases of a Type II cecal volvulus include a whirl pattern (similar to the widely-used hurricane symbol) and a bird-beak appearance of the afferent and efferent colonic segments. (1,7) Colonic haustra may become effaced from edema and the proximal small bowel dilates while the distal colon collapses. In fact, CT is fast becoming the standard for diagnosing volvulus as it can also show signs of perforation or strangulation.
(1.) Ballantyne GH, Brandner MD, Beart RW Jr, et al. Volvulus of the colon. Incidence and mortality. Ann Surg 1985;202:83-92.
(2.) Rivo M, Farrell GE, Schauffer IA. The association of volvulus of the cecum and ascending colon with obstructive colonic lesions. Am J Roentgenol 1957;78:587-590.
(3.) Rabinovici R, Simansky DA, Kaplan O, et al. Cecal volvulus. Dis Colon Rectum 1990;33:765-769.
(4.) Taylor J. Intestinal obstruction. In: Stehr W (editor). The Mont Reid Surgical Handbook: Mobile Medicine Series, 6th edition. Philadelphia: Saunders Elsevier; 2008:253-264.
(5.) Catalano O. Computed tomographic appearance of sigmoid volvulus. Abdom Imaging 1996;21:314-318.
(6.) Delabrousse E, Sarlieve P, Sailley N, et al. Cecal volvulus: CT findings and correlation with pathophysiology. Emerg Radiol 2007;14:411-415.
(7.) Dahnert W. Radiology Review Manual, 6th edition. Lippincott Williams and Wilkins; 2007:815-816.
Sean Moore, BS; Jagan D. Gupta, MD; and Harold R. Neitzschman, MD (Section Editor)
Mr. Moore is a third year medical student at Tulane School of Medicine in New Orleans, Louisiana. Dr. Gupta is a first year radiology resident at Tulane University Health Sciences Center in New Orleans, Louisiana. Dr. Neitzschman is a professor of radiology and chairman of the Department of Radiology at Tulane University Health Sciences Center in New Orleans. Donald Olivares is the digital imaging specialist and graphic designer for the Department of Radiology at Tulane University Health Sciences Center in New Orleans.
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|Title Annotation:||Radiology Case of the Month|
|Author:||Moore, Sean; Gupta, Jagan D.; Neitzschman, Harold R.|
|Publication:||The Journal of the Louisiana State Medical Society|
|Date:||Jul 1, 2010|
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