The term volvulus is derived from the Latin word volvere (“to twist”). A colonic volvulus occurs when a part of the colon twists on its mesentery, resulting in acute, subacute, or chronic colonic obstruction. The main types of colonic volvulus are sigmoid volvulus and cecal volvulus. [1, 2]
See Can't-Miss Gastrointestinal Diagnoses, a Critical Images slideshow, to help diagnose the potentially life-threatening conditions that present with gastrointestinal symptoms.
Before the 19th century, management of patients with volvulus was largely expectant. Gradually, as nonintervention became associated with a high mortality, early surgical treatment became a widely accepted practice.
By 1920, three surgical approaches (ie, open detorsion and mesenteric plication, resection with colostomy, and resection with anastomosis) were widely used for the surgical treatment of patients with sigmoid volvulus. Emergency resection carried a mortality of well over 50%. The Mikulicz operation, the Hartmann procedure, and sigmoidopexy combined with partial resections were also attempted, with variable results.
In 1947, the technique of transanal deflation of the volvulus using sigmoidoscopy was described. This method of treatment was supported by subsequent studies,  but nonoperative detorsion as the only treatment was found to be associated with a high recurrence rate. Consequently, elective resection after a few days of decompression of the colon was adopted, and this approach remains the current surgical treatment of patients with sigmoid volvulus.
Surgical treatment of cecal volvulus paralleled that of sigmoid volvulus. Before the early 19th century, expectant management was widely practiced; as experience accrued, surgical treatment became accepted. Detorsion and cecopexy were commonly performed, as was placement of cecostomy tubes. The high recurrence and complication rates led to the adoption of right hemicolectomy for the treatment of cecal volvulus, which remains the accepted approach. Cecostomy is reserved for patients who are too debilitated to withstand resection.
The embryonic right colon typically has a mesentery that eventually fuses to the parietal peritoneum; this fusion results in adherence to the posterior abdominal wall. Developmental variations in the degree of fusion lead to differences in the mobility of the ascending colon and the cecum (see the image below). Hendrick, in a review of cadaver studies, found that 10-25% of the general population had a propensity for cecal volvulus on the basis of the length of the colonic mesentery.  The long mesentery of the ascending colon results in a mobile cecum.
Two conditions must be present for the development of a cecal volvulus: (1) an abnormally mobile segment of cecum and colon and (2) a fixed point around which the mobile segment can twist. The second condition is created through normal ileocolic attachments, as well as through abnormal adhesions after surgery or appendicitis.
The Jackson veil is an abnormal membrane that passes anterior to the ascending colon and permits the cecum to be mobile around the lower point of the fixation permitted by the membrane (see the image below).
At the level of the iliac crest, the descending colon becomes the sigmoid colon. The mesosigmoid has variable attachments to the posterior body wall; most often, it is attached diagonally downward toward the right. Cadaver studies in the United States found the average length and breadth of the sigmoid mesentery to be 7.9 cm and 5.6 cm, respectively (see the image below).  Cadaver studies from the Middle East reported a mesenteric breadth of 15.2 cm. This difference may be developmental or may reflect differences in diet.
Resection of the colon is based on the arterial supply to its various anatomic divisions (see the image below). The ascending colon and cecum are supplied by the superior mesenteric artery via the ileocolic and right colic arteries. Adjacent to the colonic wall, these arteries form arcades that give off the vasa recta. The vasa recta divide into short and long branches that supply the medial and lateral aspects of the colon, respectively.
The middle colic artery forms an arcade with the left colic artery, which is a branch of the inferior mesenteric artery. This arcade, termed the marginal artery of Drummond, lies in the mesenteric border adjacent to the colonic wall. The marginal artery gives off vasa recta to the transverse colon, the splenic flexure, and the descending colon. The sigmoid colon is supplied by branches of the left colic artery, as well as by two to four sigmoidal arteries, which are branches of the inferior mesenteric artery.
In 3-5% of the population, the right colic and ileocolic arteries do not anastomose, creating an area of poor blood supply. Similarly, the point of Griffith is an area of poor blood supply in the region of the splenic flexure.
The critical point of Sudeck was previously considered to be a similar watershed area of poor blood supply at the junction of the rectum with the sigmoid colon. Because of the extensive and intramural submucosal plexus of arteries formed by the branches of the superior, middle, and inferior rectal arteries, the rectum and distal sigmoid colon are well vascularized. In contrast, the vasa recta (the end arteries in the colon wall) are not well vascularized. For this reason, the clinical implications of the critical point of Sudeck are not as important.
To avoid injuring the ureters, the surgeon must always be aware of the location of these structures in the retroperitoneum. The ureter is easily identified at the pelvic brim where it crosses over the external iliac artery. It is visible as a white structure that, on gentle compression, demonstrates characteristic propulsive movement.
Chronic constipation in Western society and a high-fiber diet in developing nations lead to an overloaded sigmoid colonic loop. The weight of this loaded sigmoid colon makes it susceptible to torsion along the axis of the elongated mesentery. The presence of a gravid uterus or a large pelvic mass alters the relative positions of the intra-abdominal organs, also predisposing to formation of volvulus.
As a result of repeated subacute attacks of torsion, the base of the sigmoid mesocolon becomes foreshortened. The associated mild, chronic inflammation at the base of the mesentery and the two limbs of the sigmoid colon loop leads to the formation of adhesive tissue. This causes the sigmoid loop to become chronically fixed into a paddlelike configuration, which, in turn, predisposes to recurrence of the torsion (see the image below).
Cecal volvulus may be organoaxial (true cecal or cecocolic volvulus) or mesentericoaxial (cecal bascule). The former involves the distal ileum and ascending colon twisting around each other, in much the same way as a sigmoid volvulus. Compared with sigmoid volvulus, in which the torsion is in a counterclockwise direction, cecal volvulus usually occurs in a clockwise direction.
Incomplete cecal and ascending colonic fixation occurs because of a lack of embryologic development of the dorsal mesentery. The lack of development predisposes the patient to clockwise torsion of the cecum, terminal ileum, and ascending colon (see the images below). Vascular compromise is common because of mesenteric torsion.
In contrast, a cecal bascule occurs when the malfixed cecum folds anteriorly over the ascending colon (see the image below) in an axis at right angles to the mesentery. Because no torsion of the ileocolic mesentery is present, vascular compromise of the cecum rarely occurs. Vascular compromise occurs more commonly in cases in which significant distention is present, which prevents the cecum from unfolding into its normal position.
A complete volvulus leads to the development of a closed-loop obstruction of the affected colonic segment. Increased dilation of the bowel loop compromises the vascular supply of the bowel, eventually leading to ischemic gangrene and bowel wall perforation.
The presence of a long mesentery with a narrow base of fixation to the retroperitoneum and elongated, redundant bowel predisposes to the formation of volvulus. Volvulus can develop in any portion of the large bowel. However, it is most common in the sigmoid colon because of the mesenteric anatomy. Less commonly, volvulus develops in the right colon and terminal ileum (cecal or cecocolic volvulus) or the cecum alone (termed a cecal bascule). In rare cases, volvulus may develop in the transverse colon or the splenic flexure.
Sigmoid volvulus may occur because of sigmoid elongation, resulting in a redundant loop. Most commonly, this is the result of chronic constipation and the progressive dilatation and lengthening of the sigmoid colon and its mesentery.
Institutionalized patients with neuropsychiatric disorders often develop sigmoid volvulus. A higher incidence of the condition is observed in patients with Parkinson disease, multiple sclerosis, or spinal cord injury. Psychotropic drugs interfere with colonic motility and are etiologically implicated in the high incidence observed in patients in psychiatric institutes.
Patients in nursing homes also commonly develop sigmoid volvulus. This association may be a manifestation of the prolonged recumbency and chronic constipation that patients in chronic care facilities experience. Not surprisingly, the excessive use of laxatives, cathartics, and enemas is highly associated with the development of sigmoid volvulus.
In developing countries, a high-fiber diet leads to overloading of the sigmoid colon, which twists around its mesentery and results in volvulus. Megacolon, either congenital or acquired through Chagas disease, predisposes to the development of sigmoid volvulus. In areas of South America where Chagas disease is endemic, the development of sigmoid volvulus in affected patients is reported to be as high as 30%.
The presence of a pelvic mass also increases the risk of developing sigmoid volvulus. The mass displaces the sigmoid colon sufficiently to result in torsion of the mesentery and subsequent volvulus. The association of pregnancy and large ovarian tumors with sigmoid volvulus is well known. In Western societies, as many as 45% of pregnant patients with intestinal obstruction have sigmoid volvulus.
Less common conditions resulting in sigmoid volvulus include postoperative adhesions, internal herniations, intussusceptions, omphalomesenteric abnormalities, intestinal malrotations, and carcinoma. A rare condition in patients with abnormally long mesenteries of the stomach, splenic flexure, and sigmoid colon has been described as traveling volvulus. The abnormal mesenteric fixation of intraperitoneal organs predisposes these patients to recurrent spontaneous torsion and detorsion.
Whereas sigmoid volvulus is usually an acquired condition, cecal volvulus is due to congenital incomplete dorsal mesenteric fixation of the cecum or ascending colon associated with an abnormally elongated mesentery distal to this area of absent mesentery. In autopsy studies, marked mobility of the right colon occurs in an estimated 15-20% of the population.
Other anomalies that predispose to cecal volvulus include undescended right colon and previous surgical mobilization of the cecum, both permitting sufficient mobility for volvulus. Appendicitis, with resultant formation of adhesions, predisposes to cecal volvulus as well.
As in sigmoid volvulus, a pelvic space-occupying lesion (eg, a gravid uterus or an ovarian tumor) may precipitate an episode of cecal volvulus by altering the relative positions of the intra-abdominal organs. Gaseous dilation of the sigmoid colon and cecum after colonoscopy has also been described as a cause of volvulus.
United States statistics
Colonic volvulus ranks after cancer and diverticulitis as a cause of large-bowel obstruction in the United States; it is responsible for approximately 5% of all cases of intestinal obstruction and 10-15% of all cases of large-bowel obstruction. In these populations, the most common site of large-bowel torsion is the sigmoid colon (80%), followed by the cecum (15%), the transverse colon (3%), and the splenic flexure (2%). 
In Western societies, the average age of patients with sigmoid volvulus is in the eighth decade, and the two sexes are equally affected. Various series have reported that of all patients diagnosed with volvulus, 25-35% are admitted to an acute care facility from a neuropsychiatric care institution, and 10-15% are admitted from a long-term nursing care facility.
Worldwide geographic variations in the incidence of sigmoid volvulus are well described. Much higher frequencies are reported in African, Asian, Middle Eastern, Eastern European, and South American countries. In all of these regions, the inhabitants consume a high-fiber diet, which is considered a predisposing factor for the development of sigmoid colon volvulus. In these endemic areas, patients are younger and predominantly male.
In the “volvulus belt” of Africa and the Middle East, nearly 50% of large-bowel obstructions are a result of volvulus, almost exclusively of the sigmoid colon. Cecal volvulus is much less common than sigmoid volvulus, accounting for 10-15% of all cases of volvulus and predominately affecting women in the sixth decade of life.
Delay in diagnosis and treatment of sigmoid and cecal volvulus is associated with substantial morbidity and mortality. Studies report a mortality of 30-40% in patients in whom diagnosis and treatment of cecal volvulus are delayed.
The suggested interval between endoscopic decompression and definitive surgical intervention is 48-72 hours. This is adequate time for resuscitation, investigation, and intervention to further reduce surgical risk.
Even when volvulus is adequately treated with endoscopic decompression and surgical resection, mortality is in the range of 12-15%, according to various studies. In part, these figures reflect the poor general health of this patient population. A retrospective review of patients in Veterans Affairs (VA) hospitals with sigmoid volvulus quoted a mortality of 24% for emergency procedures and a mortality of 6% for elective procedures (after decompression). 
As many of 50% of patients who undergo endoscopic decompression alone experience recurrence. Endoscopic decompression alone for sigmoid volvulus carried a recurrence rate of 40-50%, with a mortality of 25-30% after surgical treatment of the recurrent volvulus.
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