Diagnostic Ultrasound - Abdomen and Pelvis

Bowel Wall Thickening
Differential Diagnoses: Bowel
DIFFERENTIAL DIAGNOSIS
Common
• Inflammatory Bowel Disease (IBD)
○ Crohn Disease
○ Ulcerative Colitis
• Bowel Neoplasms
○ Adenocarcinoma
○ Lymphoma
○ Carcinoid
○ Gastrointestinal Stromal Tumors
• Diverticulosis/Diverticulitis
• Intussusception
• Intestinal Ischemia
○ Primary
– Acute Arterial Ischemia
– Acute Venous Ischemia
○ Secondary
– Secondary to Closed Loop Obstruction
○ Ischemic Colitis
• Acute Infective Enteritis/Colitis
• Reactive Thickening Adjacent to Inflammatory Process
○ Appendicitis, Cholecystitis
• Chronic Edema
○ Portal Hypertension
○ Hypoproteinemia
• Acute Edema
○ Prestenotic in Acute Bowel Obstruction
Less Common
• Tuberculosis
• Clostridium Difficile Colitis
• Mural Hemorrhage
• Deep Infiltrative Endometriosis
• Post-Radiation Enteritis
• Excess Fat Deposition in Bowel Wall
• Cystic Fibrosis
Rare but Important
• Vasculitis
○ Systemic Lupus Erythematosus
• Graft-vs.-Host Reaction
• Intestinal Amyloidosis
• Systemic Mastocytosis
○ Inflammatory Bowel Disease (Mimic)
• Behçet Disease
○ Crohn Colitis (Mimic)
• Intestinal Lymphangiectasia
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
• Clinical presentation is important
○ Overlapping findings from different causes
• Identify site of involvement
○ Stomach, small bowel, or large bowel
• When there is thickening, map bowel upstream and
downstream
• Comment on
○ Diffuse or focal thickening
○ When diffuse, length involved, and degree of thickening
○ Mural flow and surrounding vascularity with color flow
and power Doppler
• Assess for preservation/absence of mural stratification
• Assess and comment on the perienteric/pericolonic fat
• Observe and comment on peristalsis
• Comment on presence of peritoneal free fluid
• Contrast-enhanced US useful is assessing activity of IBD,
inflammatory thickening, and bowel wall ischemia
Helpful Clues for Common Diagnoses
• Crohn Disease
○ Transmural inflammatory process
○ Most commonly occurs in terminal ileum
○ Usually noncompressible, rigid, and fixed
○ Wall thickening is symmetrical and circumferential
– May be continuous or skipped
○ Hypertrophy of the mesenteric fat
○ Echogenic tissue "creeping fat" extending to
antimesenteric surface of bowel
○ Mural stratification gut signature is usually preserved
– Prominent widened echogenic submucosal layer is
seen due to fibrofatty proliferation
– In some, there is loss of gut signature, which is more
common in active disease
○ Associated luminal narrowing
– Inflammatory or fibrotic
○ Power Doppler useful in showing mural increased
vascularity and engorged vasa recta: Comb sign
○ Bowel fistulation and abscess formation from deep
penetrating ulcers can be detected
○ Involved segment shows aperistalsis or moderately
reduced peristalsis
• Ulcerative Colitis
○ Mucosal inflammatory process
– Thickening is mild with loss of haustra coli
– Mural stratification is preserved
○ Continuous involvement of colon
○ Suspect toxic megacolon when
– Wall thickness reduced, gaseous distension, ascites
• Adenocarcinoma
○ Segmental annular lesion
– Affects short segment
– May be associated with bowel obstruction
○ Focal mass ± ulceration
○ Loss of mural stratification
○ Extra mural tumor infiltration may be visible
• Lymphoma
○ Most commonly occurs in stomach, small intestine,
colon, and esophagus in decreasing order of frequency
○ Loss of gut signature
○ Morphology
– Segmental circumferential, focal mass, or multifocal
bowel wall involvement
– Extramural spread into mesentery
○ Dilatation of bowel lumen may be seen
– Rarely results in bowel obstruction
○ ± hepatosplenomegaly, lymph node enlargement
• Carcinoid
○ Most common small bowel tumor
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