Intussusception

Published on 19/07/2015 by admin

Filed under Radiology

Last modified 22/04/2025

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 Outer layer = intussuscipiens; inner layer = intussusceptum

image “Coiled spring” appearance on small bowel follow-through or enteroclysis
• CT: Alternating layers of mesenteric fat and soft tissue density bowel walls

image Enhancing mesenteric vessels accompany intussusceptum
image CT may identify lead mass
image Short segment, nonobstructing intussusceptions  are commonly seen, rarely significant
• US: “Target,” “doughnut,” or bull’s-eye sign

TOP DIFFERENTIAL DIAGNOSES

• Primary bowel tumor
• Metastases and lymphoma
• Endometrial implant
• Meckel diverticulum

PATHOLOGY

• Tumor-related lead point

image Benign: Polyp, leiomyoma, lipoma
image Malignant: Primary (more common in colon), metastases and lymphoma (more common in SB)
• Physical cause, but no neoplasm

image Postoperative causes are most common (e.g., adhesions, anastomoses)
• Intussusception in children

image Usually attributed to lymphoid hyperplasia in distal SB

CLINICAL ISSUES

• Obstruction and ischemia are more common in long-segment intussusception with lead mass
image
(Left) Graphic shows an ileocolic intussusception with a tumor in the bowel wall image as the lead mass. Note the vascular compromise and ischemia of the intussusceptum image.

image
(Right) Coronal CECT shows invaginated mesenteric fat image and vessels image from an ileocolonic intussusception. The lead mass proved to be carcinoma.
image
(Left) Transverse color Doppler ultrasound of SB intussusception shows vascular flow within an intraluminal mass image and 2 echogenic submucosal rings representing intussusceptum image and intussuscipiens image.

image
(Right) Transverse power Doppler ultrasound in the same patient reveals marked hyperemia image within the mass, which proved to be a metastatic melanoma.

TERMINOLOGY

Definitions

• Invagination or telescoping of proximal segment of bowel (intussusceptum) into lumen of distal segment (intussuscipiens)

IMAGING

General Features

• Best diagnostic clue

image Bowel-within-bowel, “coiled spring” appearance
• Location

image Ileoileal > ileocolic > colocolic
image Usually small bowel (SB) in adults, ileocolic in children
image Colon: Malignant tumors more common than benign
image SB: Benign tumors more common than malignant

Radiographic Findings

• Radiography

image Air-fluid levels, proximal bowel dilatation, absence of gas in distal collapsed bowel

Fluoroscopic Findings

• Barium study

image Classic “coiled spring” appearance

– Trapping of contrast between folds of intussusceptum and intussuscipiens
image Bowel obstruction, proximal dilatation, distal collapsed loops

CT Findings

• “Bowel-within-bowel” appearance

image Outer layer represents intussuscipiens, inner layer represents intussusceptum
image Alternating layers of mesenteric fat and soft tissue density bowel walls
image Enhancing mesenteric vessels accompany intussusceptum
• Reniform or sausage-shaped mass
• Features of intestinal obstruction

image Air-fluid levels, proximal bowel distension
image Obstruction and ischemia are more common in long-segment intussusception with lead mass

– CT may identify lead mass
• Short segment, nonobstructing intussusceptions 

image Commonly seen on CT
image Usually of no clinical significance

MR Findings

• “Bowel-within-bowel” or “coiled-spring” appearance
• Best seen on turbo spin-echo T2WI

Ultrasonographic Findings

• Grayscale ultrasound

image Transverse US: “Target,” “doughnut,” or bull’s-eye sign

– Peripheral hypoechoic halo: Edematous wall of intussuscipiens
– Intermediate hyperechoic area: Space between intussuscipiens and intussusceptum
– Internal hypoechoic ring: Wall of intussusceptum
image Longitudinal US: Pseudokidney or hay fork sign

– Multiple, thin, parallel, hypoechoic and echogenic stripes
• Color Doppler

image Mesenteric vessels dragged between entering and returning wall of intussusceptum

Imaging Recommendations

• Best imaging tool

image Depends on patient age/presentation
image Sonography may be sufficient for diagnosis in children
image Multiplanar CT is optimal in adults

– Better depiction of presence, cause, and clinical significance of intussusception

DIFFERENTIAL DIAGNOSIS

Primary Bowel Tumor

• May cause or simulate intussusception
• Carcinoid tumor, adenocarcinoma, gastrointestinal stromal tumor (GIST), lipoma, adenoma
• Enteroclysis or CT/MR enterography: Best for detecting mass

Metastases and Lymphoma

• Non-Hodgkin lymphoma (more common)

image Distribution: Stomach (51%), small bowel (33%)
image Nodular, polypoid, infiltrating, invading mesentery
image Sausage-shaped thickening of affected bowel wall 

– May cause or simulate intussusception
• Metastases (SB): Malignant melanoma, lung and breast cancer

image Melanoma in SB often presents as intussusception

– Usually multifocal, intramural masses
image Lung and breast metastases more often cause obstruction

Endometrial Implant

• Endometrial tissue outside myometrium
• Common location: Pelvic organs; bowel involved in 37% of cases
• Crenulation of folds, plaque-like deformities
• High- or low-grade SB obstruction, usually due to fibrosis, rarely intussusception

Meckel Diverticulum

• Most frequent congenital anomaly of GI tract
• Ileal outpouching (∼ 2 feet from ileocecal valve)
• May cause SB obstruction or intussusception

image SB spasm due to Meckel diverticulitis
image Diverticulum “inverted” into bowel lumen may cause intussusception

PATHOLOGY

General Features

• Etiology

image Most adult intussusceptions are short segment, transient, nonobstructing, not associated with lead mass

– Idiopathic or underlying SB disorder (e.g., celiac-sprue)
– Intussusception in children is much more common, and usually attributed to lymphoid hyperplasia within bowel wall
image Tumor-related lead point: Benign and malignant masses

– Benign: More common in SB

image Polyps such as lipoma, leiomyoma
– Malignant

image Carcinoma: Much more common in colocolic intussusception
image GIST, carcinoid, others
– Metastases and lymphoma

image More common in SB intussusception
image Postoperative risk factors (more common in SB)

– Suture lines, ostomy closure sites
– Adhesions, long intestinal tubes
– Bypassed intestinal segments
– Appendiceal stump granuloma
– Abnormal bowel motility, electrolyte imbalance
– Chronic dilated loop
image Meckel diverticulum; celiac and Whipple diseases
image Colitis (usually infectious)
image Epiploic appendagitis

Staging, Grading, & Classification

• Short-segment, nonobstructing intussusception

image Usually self-limited, without lead mass
• Long-segment, obstructing intussusception; mass is more likely

Gross Pathologic & Surgical Features

• 3 layers seen

image Intussusceptum: Entering/inner tube and returning/middle tube
image Intussuscipiens: Sheath or outer tube

Microscopic Features

• Early: Inflammatory changes
• Late: Ischemic necrosis, mucosal sloughing

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

image Adults: Intermittent pain, vomiting, red blood in stool
image Children: Acute pain, palpable oblong abdominal mass; “red currant jelly” stools

Demographics

• Age

image Any age group; children > adults
• Gender

image M = F
• Epidemiology

image Uncommon in adults, much more common in children

– 95% of all intussusceptions occur in children
– 2nd most common cause of acute abdomen in children

image Idiopathic in 90% of cases
image Often attributed to lymphoid hyperplasia in SB wall

Natural History & Prognosis

• Complications: Obstruction, infarction, hemorrhage, perforation, peritonitis
• Prognosis

image Early: Good after reduction or surgical resection; recurrence very rare
image Late: Poor due to risk of severe vascular compromise, gangrene, perforation

Treatment

• None for transient, nonobstructing intussusception
• Resection for ileocolic, ileocecocolic, and colocolic
• Children: Hydrostatic or pneumatic reduction

image Surgical reduction or resection usually reserved for complicated cases (e.g., with bowel ischemia)

DIAGNOSTIC CHECKLIST

Consider

• Short-segment, nonobstructing intussusceptions are common in adults; no treatment required

Image Interpretation Pearls

• Barium fluoroscopy

image “Coiled spring” appearance due to barium between intussusceptum and intussuscipiens
image Lead point: Lobulated mass etched in white
• CT: Bowel-within-bowel

image Alternating layers of bowel walls, mesenteric fat and vessels

image
(Left) Axial CECT in a patient with ileocolic intussusception shows an outer ring intussuscipiens image of the colon wall, while the intussusceptum is a small intestinal segment image. Mesenteric fat and vessels image accompany the intussuscepted small bowel (SB) segment.
image
(Right) Axial CECT shows a reniform (kidney-shaped) SB image due to jejunal intussusception. Note the intussuscepted mesenteric fat and vessels image.
image
(Left) Axial CT shows an intussusceptum image with its mesenteric fat image within the contrast opacified lumen of the ascending colon, the intussuscipiens in this case.

image
(Right) Axial CT in the same case shows that the lead mass of the intussusception is a low-density, spherical mass image with a calcified rim, a characteristic appearance of an appendiceal mucocele. Long-segment, obstructing intussusceptions such as this often have a lead mass when seen in adults.
image
(Left) Coronal CT image in the same case shows the long-segment intussusception image and the mucocele image as the lead mass.

image
(Right) The resected specimen in the same case, consisting of the terminal ileum and ascending colon, shows the mucocele of the appendix image and the intussusception image.
image
Transverse power Doppler ultrasound shows a colocolonic intussusception from ileocecal carcinoma. Note the echogenic mass image with accompanying mesenteric fat and vessels image.

image
Pathology specimen of the same patient reveals a large ileocecal carcinoma image.
image
Transverse grayscale sonogram shows small bowel intussusception from metastatic melanoma. Sonographic imaging of LUQ reveals a hypoechoic mass involving the small bowel image.
image
Transverse color Doppler ultrasound in the same patient demonstrates an echogenic submucosal bowel wall layer of intussusceptum image and intussuscipiens image. Note the invaginated mesenteric vessels image.
image
Axial CECT shows ileocecal intussusception from cystic fibrosis. Note the invaginated mass with mesenteric fat image.
image
Anteroposterior single contrast barium enema demonstrates an obstructing mass from intussusception within the transverse colon image. At surgery, the lead mass was due to inspissated mucoid material within the terminal ileum.
image
Small bowel follow through shows the “coiled spring” with “bowel-in-bowel” appearance of this small bowel intussusception. The lead mass was melanoma metastatic to the bowel wall.
image
Axial NECT following small bowel follow through in a patient with metastatic melanoma shows the “bowel-in-bowel” appearance image of the intussusception.
image
Axial CECT in a patient with cystic fibrosis shows a short-segment, nonobstructing small bowel intussusception image.
image
Axial CECT shows a small bowel intussusception image with an accompanying crescent of mesenteric fat. The bowel lumen is dilated due to sprue, not obstruction.
image
Axial CECT shows a sausage-like mass within the lumen of the terminal ileum due to an inverted, intussuscepting Meckel diverticulum.

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