The plain abdominal radiograph is usually the key to the diagnosis of cecal volvulus. 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 cecum is displaced (see the image below). Depending on the initial bowel position and the length of mobile right colon, the distended cecum may be seen anywhere in the abdomen.
Plain supine abdominal radiograph from an 81-year-old man presenting with abdominal pain and vomiting. The radiograph shows a markedly distended loop of bowel 15-cm in diameter with its axis running from the right lower quadrant to the mid abdomen. This loop of bowel represent a twisted cecum with the caput cecum directed medially (arrows). The haustra within the cecum (C) are effaced. Note the proximal dilated loop of small bowel. The distal colon shows little if any air. At surgery a cecal volvulus was confirmed.
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 (see the first image below). 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 (see the second image below).
A 53-year-old woman presented with clinical features of intestinal obstruction. This plain supine radiograph was performed on the day of admission. It shows a large air-filled viscus (15 cm in diameter), with the axis running from the mid abdomen to the left hypochondrium. No haustra are seen in the air-filled viscus (short arrow). Note that the right iliac fossa is empty (long arrow), but formed feces intermingled with air are noted in part of the ascending colon. The air can be traced up to the rectum. At this stage, no firm radiologic diagnosis was entertained, although the working clinical diagnosis was partial bowel obstruction.
This plain supine radiograph was obtained 24 hours after the radiograph in the previous image (from a 53-year-old woman who presented with clinical features of intestinal obstruction). The position of the air filled viscus has changed and suggests that the air-filled viscus is mobile. The viscus now looks much more like a cecum. The caput cecum is directed toward the right iliac fossa. The twist is outlined by air (arrows).
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 conelike narrowing.
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.
Single contrast barium 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 (see the following images). 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.
This unprepared barium enema examination was obtained 12 hours after the first supine plain radiograph from a 53-year-old woman who presented with clinical features of intestinal obstruction. The image shows a nondilated colon. The barium-filled colon can be traced back to the right iliac fossa where there is a bird-beak cutoff (solid arrow). The dilated cecum lies in the epigastrium .where there is an air fluid level (open arrow). Note that the barium has not entered the cecum
Right oblique image from a barium enema examination in from a 53-year-old woman who presented with clinical features of intestinal obstruction. This image shows a bird-beak appearance (arrow). At surgery, a cecal volvulus was confirmed.
Left: Plain abdominal radiograph from a 48-year-old woman showing a massively distended and medially displaced proximal ascending colon and cecum. The cecal pole is now lying in the left upper abdominal quadrant (C). At least 2 or 3 haustrations are seen in the distended large bowel, which is consistent with cecal volvulus. No air fluid levels were demonstrated in this case. Right: A single contrast barium study of the same patient showing free barium flow through the sigmoid colon in to the mid ascending colon. The proximal ascending colon and the cecum are void of barium due to obstruction at the level of the mid ascending colon
A post evacuation film from the same 48-year-old patient as in the previous images. This image shows a medially pointed end column of the barium (beak sign) in the mid ascending colon. Distally the large bowel is distended with gas and represents the cecal 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, overdistention 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.[9, 11]
Degree of confidence
Plain radiographic findings can be diagnostic of a cecal volvulus in most patients. In others, the findings on the plain images only suggest the diagnosis, and barium enema examination is necessary to confirm the diagnosis.
Rarely, the dilated displaced cecum and ascending colon in the left upper quadrant may be confused with a normal or abnormally distended stomach. A redundant looplike cecal volvulus may be confused with a sigmoid volvulus. In the presence of a double obstruction of the colon (left colon obstruction associated with a cecal volvulus), evaluation of the right colon may not be possible, and the diagnosis of volvulus must be based on plain radiographic findings alone.