Sigmoid Volvulus

Published on 19/07/2015 by admin

Filed under Radiology

Last modified 22/04/2025

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Midline; directed toward RUQ or LUQ; elevation of hemidiaphragm

• Diagnosis: Abdominal radiography, water-soluble contrast enema, CT

Coronal reformatted CT is especially useful in diagnosis

Abdominal radiographs: Supine, upright, prone, and decubitus views

PATHOLOGY

• Major predisposing factors

Diet: Fiber increase → increased bulk of stool, elongation and dilatation of colon

Chronic constipation and obtundation from medications → gaseous distension

• Comorbid disease: 30% with psychiatric disease, 13% are institutionalized at time of diagnosis

CLINICAL ISSUES

• Most common signs/symptoms

Acute or insidious onset

Abdominal pain (< 33%), vomiting, distension, obstipation

• Treatment: Sigmoidoscopic decompression of obstruction ± stabilization via rectal tube insertion

Usually followed by surgical resection of sigmoid colon

DIAGNOSTIC CHECKLIST

• Rule out other causes of distal colonic obstruction

• Dilated sigmoid colon in inverted “U” shape with absent haustra; “beaking,” whirl sign, northern exposure sign

(Left) Supine film of the abdomen shows marked dilation of the sigmoid colon. The sigmoid is folded back upon itself, and the apposed walls of the redundant sigmoid colon form the “seam” of the football (or coffee bean) shape. The sigmoid extends into the upper abdomen above the transverse colon .

(Left) Supine film of the abdomen shows marked dilation of the sigmoid colon. The sigmoid is folded back upon itself, and the apposed walls of the redundant sigmoid colon form the “seam” of the football (or coffee bean) shape. The sigmoid extends into the upper abdomen above the transverse colon .

(Right) Axial CECT in the same case shows the dilated sigmoid lumen with abrupt narrowing at its base .

(Right) Axial CECT in the same case shows the dilated sigmoid lumen with abrupt narrowing at its base .

(Left) Coronal reformatted CT in the same patient shows twisting and displacement of the base of the sigmoid colon and its mesentery . The dilated colonic segments upstream from the volvulus may be easier to distinguish on coronal sections.

(Left) Coronal reformatted CT in the same patient shows twisting and displacement of the base of the sigmoid colon and its mesentery . The dilated colonic segments upstream from the volvulus may be easier to distinguish on coronal sections.

(Right) Another CT section in this case shows the whirl sign of twisted colon and vessels at the base of the sigmoid mesentery.

(Right) Another CT section in this case shows the whirl sign of twisted colon and vessels at the base of the sigmoid mesentery.

TERMINOLOGY

Definitions

• Torsion or twisting of sigmoid colon around its mesenteric axis

IMAGING

General Features

• Best diagnostic clue

Dilated sigmoid colon with inverted “U” configuration and absent haustra

• Location

Midline; directed toward RUQ or LUQ; elevation of hemidiaphragm

Radiographic Findings

• Radiography

Sigmoid volvulus

– Diagnostic in 75% of cases

– Vertical dense white line: Apposed inner walls of sigmoid colon pointing toward pelvis

– Closed loop obstruction: Segment of bowel obstructed at 2 points

– Gas in proximal small intestine and colon; absence of gas in rectum

– Absent rectal gas in spite of prone or decubitus views

– Inverted “U” shape with absent haustra

– Northern exposure sign: Dilated, twisted sigmoid colon projects above transverse colon on supine radiograph

– Apex above T10 vertebra and under left hemidiaphragm; directed toward right shoulder

Compound volvulus

– Dilated sigmoid loop in mid abdomen extending to RLQ with distended small bowel

– Medially deviated distal left colon

Fluoroscopic Findings

• Water-soluble contrast enema

Can use low-pressure barium enema without balloon inflation

“Beaking”: Smooth, tapered narrowing or point of torsion at rectosigmoid junction

Mucosal folds often show corkscrew pattern at point of torsion

Shouldering: Localized wall thickening at site of twist (in chronic or recurrent volvulus)

CT Findings

• CECT

“Beaking”: Progressive tapering of afferent and efferent limbs leading into twist

Whirl sign: Tightly twisted mesentery and bowel near base of volvulus

Compound volvulus: Medial deviation of distal left colon with pointed appearance of medial border

Imaging Recommendations

• Best imaging tool

Abdominal radiography, water-soluble contrast enema, CT

– Supine, upright, prone, and decubitus views of abdomen

– Coronal reformatted CT is especially useful in diagnosis

DIFFERENTIAL DIAGNOSIS

Acute Ileus

• Postop, medication, post-traumatic injury, ischemia

• Dilated large and small bowel with no transition point

• Air-fluid levels without peristalsis

• No colonic obstruction

Functional Megacolon

• Gross constipation without organic cause

• Markedly dilated, ahaustral, air- or stool-filled colon

• Ogilvie syndrome: Nonobstructive dilation of colon

Toxic Megacolon

• Dilated ahaustral transverse colon in patient with known ulcerative or infectious colitis

• “Thumbprinting” due to edematous mucosa

• Mucosal surface is ulcerated or sloughed

Distal Colon Obstruction

• Change in stool caliber over several months

• Gas-filled intestinal loops proximal to obstruction; no distal gas

• Abrupt transition at site of obstruction

• Malignancy

Most common cause of colonic obstruction (55%)

Insidious onset

Weakness, weight loss, anorexia, rectal bleeding

“Apple core” configuration, mucosal destruction

Positive fecal occult blood test highly suggestive of colon cancer

• Stricture secondary to diverticulitis

2nd most common cause of colonic obstruction (12%)

History of recurrent diverticulitis

Other diverticula present

Signs of diverticulitis (e.g., infiltrated mesocolic fat, extraluminal gas or fluid)

PATHOLOGY

General Features

• Etiology

Major predisposing factors

– Diet: Fiber increase → increased bulk of stool, elongation and dilatation of colon

– Chronic constipation and obtundation from medications → gaseous distension

Compound volvulus (ileosigmoid knot)

– Hyperactive ileum winding around narrow pedicle of passive sigmoid colon

Etiology in children

– Malrotation and other mesenteric attachment abnormalities

– Constipation (mental retardation, Hirschsprung disease, cystic fibrosis, aerophagia)

• Associated abnormalities

Comorbid disease: 30% with psychiatric disease, 13% are institutionalized at time of diagnosis

Gross Pathologic & Surgical Features

• Twisted narrow segment with markedly dilated sigmoid loop

Microscopic Features

• Localized thickening of mucosal folds; ischemic and necrotic changes

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

Acute or insidious onset

Abdominal pain (< 33%), vomiting, distension, obstipation

Compound volvulus

– Rapid deterioration (more than with other colonic volvulus types)

– Pain disproportionate to physical findings; absolute constipation

Diagnosis: Radiography is definitive in 75% of cases

Demographics

• Age

60-80 years

• Epidemiology

3rd most common cause of colonic obstruction (10%)

60-75% of colonic volvulus cases involve sigmoid colon

Causes 1-2% of intestinal obstructions in USA

Increased incidence in elderly men and residents of nursing homes &/or mental hospitals (constipation and obtundation)

Significant increase in South America and Africa (increased fiber in diet)

Natural History & Prognosis

• Complications

Closed loop obstruction → strangulation

Ischemia, necrosis (15-20%), and perforation

Ileosigmoid knot → strangulation and gangrene of small bowel within hours

• Prognosis

Uncomplicated: Good

Complicated: Poor

40-50% recurrence after nonoperative reduction

Degree of rotation relative to chance of nonsurgical decompression: 180° (35%), 360° (50%), 540° (10%)

– Twist > 360° does not resolve spontaneously

3% recurrence after nonoperative and operative reduction

Treatment

• Nonoperative

Sigmoidoscopic decompression of obstruction ± stabilization via rectal tube insertion

70-80% success rate

• Nonoperative and operative

Decompression, mechanical cleansing, and elective sigmoid resection

• Complicated cases

Surgical emergency; colonic resection

• Follow-up

Water-soluble contrast enema to rule out underlying colon cancer

DIAGNOSTIC CHECKLIST

Consider

• Acute abdomen; rule out other causes of obstruction

Image Interpretation Pearls

• Dilated sigmoid colon in inverted “U” shape with absent haustra; “beaking,” whirl sign, northern exposure sign

(Left) Axial CECT in a 47-year-old man presenting with a 6-day history of abdominal distension and pain, constipation, and absence of flatus shows the sigmoid volvulus evident in the LLQ with the beaked appearance of the descending loop of the twisted sigmoid colon.

(Left) Axial CECT in a 47-year-old man presenting with a 6-day history of abdominal distension and pain, constipation, and absence of flatus shows the sigmoid volvulus evident in the LLQ with the beaked appearance of the descending loop of the twisted sigmoid colon.

(Right) Coronal CECT in the same patient illustrates a swirled appearance of the mesenteric pedicle at the site of the sigmoid volvulus , characteristic findings in this setting.

(Right) Coronal CECT in the same patient illustrates a swirled appearance of the mesenteric pedicle at the site of the sigmoid volvulus , characteristic findings in this setting.

(Left) Radiograph in a 65-year-old man presenting with abdominal pain and distention demonstrates a dilated redundant sigmoid colon appearing as an inverted “U” loop arising from the pelvis in this typical presentation of a sigmoid volvulus.

(Left) Radiograph in a 65-year-old man presenting with abdominal pain and distention demonstrates a dilated redundant sigmoid colon appearing as an inverted “U” loop arising from the pelvis in this typical presentation of a sigmoid volvulus.

(Right) Supine frontal image from a contrast enema in the same patient demonstrates luminal tapering at the site of stenosis, a.k.a. the bird’s beak sign . This configuration is pathognomonic for sigmoid volvulus.

(Right) Supine frontal image from a contrast enema in the same patient demonstrates luminal tapering at the site of stenosis, a.k.a. the bird’s beak sign . This configuration is pathognomonic for sigmoid volvulus.

(Left) Supine digital scout radiograph in an 89-year-old man who is a long-time resident of a nursing home, presenting with a 2-day history of severe abdominal pain and marked abdominal distension, reveals marked dilation of the sigmoid colon as well as the ascending and descending colon . Note the apposed walls of the sigmoid colon.

(Left) Supine digital scout radiograph in an 89-year-old man who is a long-time resident of a nursing home, presenting with a 2-day history of severe abdominal pain and marked abdominal distension, reveals marked dilation of the sigmoid colon as well as the ascending and descending colon . Note the apposed walls of the sigmoid colon.

(Right) Axial CECT in the same patient illustrates the bird’s beak sign from the volvulus obstructing the massively dilated sigmoid colon .

(Right) Axial CECT in the same patient illustrates the bird’s beak sign from the volvulus obstructing the massively dilated sigmoid colon .

Graphic shows a dilated, twisted, elongated sigmoid colon with venous engorgement and colonic obstruction.

Axial NECT demonstrates sigmoid volvulus. Note the massive dilatation of the sigmoid colon with beaking at the site of volvulus .

Axial NECT demonstrates sigmoid volvulus. Note the massive dilatation of the sigmoid colon with beaking at the site of volvulus .

Frontal radiograph shows a classic case of sigmoid volvulus. Note the classic inverted, U-shaped, massively dilated sigmoid colon directed toward the right hemidiaphragm .

Frontal radiograph shows a classic case of sigmoid volvulus. Note the classic inverted, U-shaped, massively dilated sigmoid colon directed toward the right hemidiaphragm .

Lateral contrast enema in the same patient shows a contrast-filled rectum and “bird’s beak” sign corresponding to luminal narrowing at the site of sigmoid obstruction.

Lateral contrast enema in the same patient shows a contrast-filled rectum and “bird’s beak” sign corresponding to luminal narrowing at the site of sigmoid obstruction.

Axial CECT shows massive colonic redundancy and distention of the large and small bowel. Sigmoid volvulus is evident in LLQ by the beaked appearance of the descending loop of twisted sigmoid colon.

Axial CECT shows massive colonic redundancy and distention of the large and small bowel. Sigmoid volvulus is evident in LLQ by the beaked appearance of the descending loop of twisted sigmoid colon.

Coronal CECT in the same patient demonstrates the classic swirled appearance of the mesenteric pedicle at the site of sigmoid volvulus .

Coronal CECT in the same patient demonstrates the classic swirled appearance of the mesenteric pedicle at the site of sigmoid volvulus .

Axial NECT shows a partially obstructing sigmoid volvulus. Note the “beaking” of the sigmoid at the site of the twist .

Axial NECT shows a partially obstructing sigmoid volvulus. Note the “beaking” of the sigmoid at the site of the twist .

Oblique water-soluble contrast enema of the sigmoid colon in the same patient reveals “beaking” at the site of the volvulus and distal filling of the dilated colon due to partial obstruction.

Oblique water-soluble contrast enema of the sigmoid colon in the same patient reveals “beaking” at the site of the volvulus and distal filling of the dilated colon due to partial obstruction.

Supine radiograph shows dilation of the entire colon. The vertical white line represents the apposed walls of the dilated, inverted sigmoid colon and points toward the mesenteric volvulus.

Supine radiograph shows dilation of the entire colon. The vertical white line represents the apposed walls of the dilated, inverted sigmoid colon and points toward the mesenteric volvulus.

Supine radiograph shows dilated colon. The apex of the sigmoid colon can be seen above the transverse colon, the “northern exposure” sign of sigmoid volvulus.

Supine radiograph shows dilated colon. The apex of the sigmoid colon can be seen above the transverse colon, the “northern exposure” sign of sigmoid volvulus.

Single contrast BE shows a smooth tapered beak obstructing the lumen of the sigmoid colon.

Axial CECT of sigmoid volvulus shows diffuse dilation of the colon. There is a swirl of sigmoid mesocolic blood vessels that converge at the site of the volvulus .

Axial CECT of sigmoid volvulus shows diffuse dilation of the colon. There is a swirl of sigmoid mesocolic blood vessels that converge at the site of the volvulus .

Axial CECT shows a swirl of mesocolic vessels at the base of the volvulus .

Axial CECT shows a swirl of mesocolic vessels at the base of the volvulus .

Supine radiograph shows a dilated, inverted, U-shaped sigmoid colon.

Single contrast BE shows twist and beak at the point of the volvulus with dilated colon beyond the twist.

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