Excerpt from Cecal Volvulus

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Background

The term cecal volvulus is a misnomer because, in most patients with cecal volvulus, the torsion is located in the ascending colon above the ileocecal valve. In general, a partial malrotation is necessary for cecal volvulus to occur, because 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, which is essentially a closed-loop obstruction that may lead to vascular compromise with consequent gangrene and perforation.¹

The diagnosis is mostly based on plain abdominal radiographic findings aided by those of single-contrast barium enema examination. CT is useful in identifying signs of ischemia, which include mural thickening, infiltration of the mesenteric fat, and pneumatosis intestinalis. Treatment is surgical, but reduction of the volvulus has been reported after barium enema examination. Colonoscopy may be considered for the purpose of decompression.^{9, 12, 13, 14, 15}

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Pathophysiology

Wolfer et al described defective peritoneal fixation of the ascending colon and cecum in 10% of the population.² This fixation permits abnormal mobility of the ascending colon and cecum, making displacement of the right colon into any part of the abdominal cavity possible. Depending on the length of the mobile ascending colon, a variety of obstructive bowel patterns may result. Many authors have described an association with adhesions, membranes, and bands, which may provide a nodal point around which the mobile ascending colon may twist. Although these conditions are frequently present, they are not essential for a volvulus to occur.

To explain the discrepancy between the relatively high incidence of a mobile right colon and the rarity of cecal volvulus, other predisposing causes have been implicated. Associations with colonic atony, partial distal large-bowel obstruction, traction due to disease of the appendix, meteorism that occurs with air travel in a nonpressurized plane, colonoscopy, pregnancy, postpartum abdomen, postoperative abdomen (especially after closed segmental resection of the left colon, presumably with stenosis), and colonic ileus (pseudo-obstruction) have been reported.^{3, 4, 5} The role of these factors in the genesis of cecal volvulus is not clear.

Many studies of cecal volvulus have focused on the possibility of volvulus of the right colon occurring in association with obstructive lesions, usually in the left colon.³ The most common distal colonic lesions associated with cecal volvulus are colonic carcinoma and diverticulitis.

Two types of cecal volvulus are described: axial torsion type and the cecal bascule type. In practice, differentiation between the 2 types is not clinically important because the clinical presentation and treatment is the same. However, the radiographic appearances are different, and recognition of these differences is important for diagnosis.

Axial torsion, the most common form of volvulus, occurs with the development of a twist of 180-360^o; along the longitudinal axis of the ascending colon. This form has a high mortality rate because the obstructive process is associated with vascular compromise, which can lead to gangrene and perforation, often on the antimesenteric border, where the ischemic changes may be most pronounced.

In the cecal bascule type of volvulus, the cecum folds anteromedial to the ascending colon, 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 cecal volvulus have this variety, and reduction of cecal bascule after barium enema examination is reported. 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; this may be found at laparotomy. Whether these bands are inflammatory in origin, related to past abdominal surgery, or congenital is not certain.¹¹

Urticaria of the bowel has been reported in association with a cecal volvulus. Biopsy of these bowel lesions has revealed submucosal edema and cellular infiltrate. Whether the urticaria is secondary to ischemia has not been confirmed.

Frequency

International

Cecal volvulus represents 1-3% of cases of intestinal obstruction in adults.

Mortality/Morbidity

The high mortality rate is related to the degree of obstruction and vascular compromise that lead to gangrene and perforation.

• In elderly patients, the mortality rate is 20-40%.
• Delay in diagnosis and attempts at conservative management may result in a 100% mortality rate.
• Delay in surgical treatment in the presence of increasing cecal distention can result in cecal perforation.

Sex

A slight male predominance may exist.

Age

Although all persons in all age groups may be affected, the incidence peaks in those aged 20-40 years. The condition is unusual in children.⁶

Anatomy

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. Retroflexed, anteflexed, and medially placed ceca are regarded as normal anatomic variants and are frequently seen at barium enema examination. If the cecum fails to descend beyond the peritoneal fold, which normally anchors the cecum in the right iliac fossa, it may instead pass across the duodenal loop and cause neonatal intestinal obstruction. The degree of neonatal duodenal and/or intestinal obstruction is variable, but any intestinal obstruction in a neonate or infant should be investigated with a sense of urgency. The mesentery of the small bowel in such instances is represented by a narrow band, which allows volvulus of the entire small bowel to occur.

Occasionally, diaphragmatic interposition of the right colon (Chilaiditi syndrome) occurs. This is related to redundancy of bowel rather than defective fixation. The right side of the colon may have a defective fixation and abnormal mobility; therefore, it may be located anywhere in the abdomen, including beneath the right hemidiaphragm. This motility may allow the right side of the colon and cecum to herniate into the inguinal and femoral canals. Most of these abnormalities of fixation can be diagnosed radiologically.

Nonspecific abdominal symptoms occasionally occur with abnormalities of fixation. Traction on the superior mesenteric artery with partial compression of the duodenum, gallbladder, pylorus, or kidneys has been implicated. The most important complication of the abnormalities of fixation is a volvulus of the right side of the colon and/or cecum.

Clinical Details

The common presentation of a cecal volvulus is an acute abdomen, with colicky abdominal pain of sudden onset. Most cases of cecal volvulus reportedly occur in patients with a mobile, defectively fixed right colon while they are asleep. Normal movement of the patient from side to side during sleep may result in displacement of the right colon to an ectopic or abnormal location. When gaseous distention occurs, the displaced right colon is trapped, resulting in symptomatic acute volvulus.¹⁶

The site of cecal volvulus in the mid abdomen or left upper quadrant suggests a simple 180° twist. Some have suggested that such a displacement may occur when the patient is recumbent. Abdominal pain, vomiting, borborygmus, and dehydration are common. Electrolyte levels may be disturbed, and leukocytosis may be present.⁷

Preferred Examination

The preferred examinations are plain abdominal radiography, barium enema examination (usually with a single contrast agent), and CT.^{8, 9}

Limitations of Techniques

Bowel gas patterns on a plain abdominal radiograph may not be characteristic because the right colon and/or cecum may be displaced to any part of the abdominal cavity. A redundant looplike cecal volvulus may be confused with a sigmoid volvulus. In the presence of a closed-loop obstruction of the colon, evaluation of the 2 sites of obstruction may not be possible with barium enema examination.

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