Saturday, March 1, 2008


Volvulus describes the condition in which the bowel becomes twisted on its mesenteric axis, a situation that results in partial or complete obstruction of the bowel lumen and a variable degree of impairment of its blood supply.
The condition most commonly affects the colon.
Although colonic volvulus is relatively rare in the United States, ranking behind cancer and diverticulitis, it is responsible for approximately 5% of cases of large bowel obstruction.
However, in Russia volvulus accounts for approximately half of all causes of colonic obstruction, and it is a common cause of colonic obstruction in Iran, India, and some parts of Africa.
Any portion of the large bowel can torse if that segment is attached to a long and floppy mesentery that is fixed to the retroperitoneum by a narrow base of origin.
However, the mesenteric anatomy is such that volvulus is most common in the
sigmoid colon,
with less frequent occurrences involving the right colon and terminal ileum (usually referred to as cecal volvulus),
the cecum alone (the condition permitted by a highly mobile cecum, called a cecal bascule, that is mobile in a caudad to cephalad direction),
and, most rarely, the transverse colon.

Sigmoid volvulus accounts for two thirds to three fourths of all cases of colonic volvulus.
· The condition is permitted by an elongated segment of bowel accompanied by a lengthy mesentery with a very narrow parietal attachment, a situation that allows the two ends of the mobile segment to come close together and twist about the narrow mesenteric base.
· Associated factors include chronic constipation and aging, with the average age at presentation being in the seventh to eighth decade of life.
· There is an increased incidence of the condition in institutionalized patients afflicted with neuropsychiatric conditions and treated with psychotropic drugs.
· These medications may predispose to volvulus by affecting intestinal motility.
· The increased incidence of volvulus in third world countries has been attributed to a diet high in fiber and vegetables.
· Patients with sigmoid volvulus may present as acute or subacute intestinal obstruction with signs and symptoms indistinguishable from those caused by cancer of the distal colon.
· There is usually a sudden onset of severe abdominal pain, vomiting, and obstipation.
· The abdomen is usually markedly distended and tympanitic, with the distention often more dramatic than would be associated with other causes of obstruction.
· There is always the possibility that the condition can be associated with ischemia caused either by mural ischemia associated with the increased tension of the distended bowel wall or by arterial occlusion caused by torsion of the mesenteric arterial supply; therefore, severe abdominal pain, rebound tenderness, and tachycardia are ominous signs.
· There may be a history of previous episodes of acute volvulus that spontaneously resolved, and in such circumstances marked abdominal distention may occur with minimal tenderness.
· The radiographic findings are often dramatic and enable prompt diagnosis and treatment.
· They usually reveal a markedly dilated sigmoid colon with the appearance of a “bent inner tube” with its apex in the right upper quadrant.
· An air-fluid level may be seen in the dilated loop of colon, and gas is usually absent from the rectum.
· CT reveals a characteristic mesenteric whirl, although the diagnosis can usually be established on the basis of the clinical presentation and the plain film of the abdomen.
· A contrast enema typically demonstrates the point of obstruction with the pathognomonic “bird’s beak” deformity revealing the obstructing twist that obstructs the sigmoid lumen.

Treatment of the sigmoid volvulus begins with appropriate resuscitation, and in most cases involves nonoperative decompression.
Decompression relieves the acute problem and allows resection as an elective procedure that can be accomplished with reduced morbidity and mortality.
Patients with signs of colonic necrosis are not eligible for nonoperative decompression.
Decompression can occur with placement of a rectal tube through a proctoscope or with the use of a colonoscope.
Often, a soft rectal tube can be inserted under direct vision through the twist of the volvulus while the patient is in the emergency department.
Decompression results in a sudden gush of gas and fluid, with a decrease in the abdominal distention.
The reduction should be confirmed with an abdominal radiograph.
The rectal tube should be taped to the thigh and left in place for 1 or 2 days to allow continued decompression and to prevent immediate recurrence of the volvulus.
The bowel can then be cleansed with cathartics and a complete colonoscopic examination performed.
If a rectal tube cannot be passed as described, detorsion of the volvulus with the colonoscope should be attempted.
If detorsion of the volvulus cannot be accomplished with either a rectal tube or colonoscope, laparotomy with resection of the sigmoid colon (Hartmann’s operation) is required.
Even if detorsion of the sigmoid is successful, elective sigmoid resection is indicated in most cases because of the extremely high recurrence rate (which approaches 50%).
The operation can be conducted through a small left lower quadrant incision or by a laparoscopic approach.
Because the elongated colon and mesentery require virtually no mobilization, resection with primary anastomosis is easily accomplished.
Colonoscopy should be performed before elective resection to exclude an associated neoplasm.

Although the term cecal volvulus is ingrained in the literature, true volvulus of the cecum probably never occurs.
There is a well-recognized condition in which the cecum folds in a cephalad direction anteriorly over a fixed ascending colon.
Although gangrene may develop, this is exceedingly rare because there is not major vessel obstruction.
This “cecal bascule” commonly causes intermittent bouts of abdominal pain as the mobile cecum permits intermittent episodes of isolated cecal obstruction that are spontaneously relieved as the cecum falls back into its normal position.

The condition commonly referred to as cecal volvulus is actually a cecocolic volvulus and consists of an axial rotation of the terminal ileum, cecum, and ascending colon with concomitant twisting of the associated mesentery.
This is a relatively rare condition, accounting for less than 2% of all cases of adult intestinal obstruction and approximately a fourth of all cases of colonic volvulus in the United States.
Cecocolic volvulus is possible because of a lack of fixation of the cecum to the retroperitoneum.
Studies on cadavers have shown that between 11% and 22% of people have a right colon that is sufficiently mobile to allow a volvulus to occur.
Factors that have been implicated in causing a cecal volvulus include previous surgery, pregnancy, malrotation, and obstructing lesions of the left colon.
Cecocolic volvulus is somewhat more common in women, whereas sigmoid volvulus occurs with equal frequency in both sexes.
Cecocolic volvulus affects a younger age group (most common in the late 50s) compared with sigmoid volvulus.
The typical presentation of patients with cecocolic volvulus is the sudden onset of abdominal pain and distention.
In the early phases of a cecocolic volvulus, the pain is mild or moderate in intensity.
If the condition is not relieved and ischemia occurs, the pain increases significantly.
Physical examination my reveal asymmetrical distention of the abdomen, with a tympanitic mass palpable in either the left upper quadrant or mid abdomen.
Plain radiographs of the abdomen reveal a dilated cecum that is usually displaced to the left side of the abdomen.
The distended cecum usually assumes a gas-filled “comma” shape, the concavity of which faces inferiorly and to the right.
Occasionally the distended cecum will appear as a circular shape with a narrow, triangular density pointing superiorly and to the right.
Haustral markings in the distended loop indicate that the dilated bowel is colon.
The torsion results in obstruction of the small bowel, and the radiographic pattern of dilated small intestine can cause diagnostic difficulty.
Although there have been reports of detorsion of cecocolic volvulus with a colonoscope, most cases will require operation to correct the volvulus and prevent ischemia.
If ischemia has already occurred, immediate operation is obviously required.
Contrast enema is helpful to confirm the diagnosis and to exclude a carcinoma of the distal bowel as a precipitating cause of the volvulus.
Right colectomy is the procedure of choice.
Primary anastomosis is usually preferred unless the volvulus has resulted in frankly gangrenous bowel, when resection of the gangrenous bowel with ileostomy is a safer approach.
There have been many reports of correcting cecocolic volvulus with cecopexy, which should avoid the complication associated with an anastomosis.
However, the operation to provide fixation of the cecum is actually quite extensive, entailing elevating and attaching a flap of peritoneum over the surface of the cecum and ascending colon.
The recurrence rates are high with cecopexy, and right colectomy remains the procedure of choice for most surgeons.

Volvulus of the transverse colon is extremely rare and tends to be associated with other abnormalities, such as congenital bands, distal obstructing lesions, and pregnancy.
Clinical features are indistinguishable from other causes of large bowel obstruction.
Radiologic examination is not particularly useful, because many cases are misdiagnosed as sigmoid volvulus.
A contrast study may show a “bird’s beak” deformity indicating a volvulus.
In such cases colonoscopic reduction may result in detorsion and relief of obstruction.
Elective resection should follow to prevent recurrence.

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