Diagnostic Ultrasound - Abdomen and Pelvis

Bowel Wall Thickening
– Distal ileum is most frequent site
○ Initially seen as hypoechoic mass confined to submucosal
layer
– In late stages, extramural tumor extension with
infiltration into mesentery and desmoplastic reaction
giving characteristic "sunburst" pattern
– Mesenteric masses similar echogenicity to primary
□ Can demonstrate calcification
• Gastrointestinal Stromal Tumors
○ Most commonly located in stomach, followed by small
bowel
○ May be seen intraluminal or as exophytic mass
– May show central necrosis with cavitation, which may
be in communication with bowel lumen
– Variable echogenicity on ultrasound
○ Lymph node metastases rare
• Diverticulosis/Diverticulitis
○ Thickened muscularis propria
○ Presence of diverticula
– Thin-walled outpouching containing gas or feces
○ Diverticulitis
– Thick-walled diverticulum
– Surrounding inflamed echogenic fat
– Increased mural and peri colonic vascularity
• Intussusception
○ Telescoping of proximal segment of bowel into adjacent
distal segment of bowel
○ Bowel within bowel appearance
– Target sign in cross section
○ Proximal bowel dilatation may be seen
– Complete obstruction rare
• Intestinal Ischemia
○ Clinical findings important
○ Long segment involved
○ Mural stratification preserved (unless becoming
hemorrhagic)
○ Assess adjacent structures, mesenteric vasculature,
obstruction, predisposing conditions
• Acute Infective Enteritis/Colitis
○ Clinical presentation important with microbiologic
confirmation
○ Edematous bowel wall; mural stratification preserved
○ Usually long segment involved
○ Findings overlap with radiation enteritis, reactive
thickening, & prestenotic edema
Helpful Clues for Less Common Diagnoses
• Tuberculosis
○ Preferential thickening of cecum and ileocecal valve
○ Necrotic lymph nodes
○ Inflammatory mass or stricturing
○ Loss of mural stratification
• Clostridium Difficile Colitis
○ Usually pancolitis
○ Marked mural edema with widened submucosal layer
○ Pronounced haustral pattern; accordion sign
• Mural Hemorrhage
○ Long segment involved
○ Homogeneous hypoechoic symmetric thickening
○ Associated with luminal effacement
○ Mural stratification may or may not be preserved
○ Vascularity variable from normal to absent on Doppler
assessment
○ Causes
– Anticoagulant treatment, vasculitis, ischemic bowel,
coagulation disorders
• Deep Infiltrative Endometriosis
○ Rectosigmoid, appendix, caecum, and distal ileum
○ Focal eccentric thickening & widening of muscular layer
SELECTED REFERENCES
1. Muradali D et al: US of gastrointestinal tract disease. Radiographics. 35(1):50-
68, 2015
2. Razzaq R et al: Ultrasound diagnosis of clinically undetected Clostridium
difficile toxin colitis. Clin Radiol. 61(5):446-52, 2006
3. Di Mizio R et al: Small bowel Crohn disease: sonographic features. Abdom
Imaging. 29(1):23-35, 2004
4. O'Malley ME et al: US of gastrointestinal tract abnormalities with CT
correlation. Radiographics. 23(1):59-72, 2003
Differential Diagnoses: Bowel
Crohn Disease
Crohn Disease
(Left) Oblique axial US
through the right iliac fossa
shows an inflamed thickened
segment of the distal ileum
from Crohn disease. Note
symmetrical thickening with
preservation of the gut
signature. Prominent
echogenic submucosal layer
ſt is seen. (Right) Short axis
US of an inflamed segment of
bowel with Crohn disease
shows a target-like
appearance due to the
preserved mural stratification
(gut signature). The echogenic
layer ſt represents thickened
submucosal layer from
fibrofatty proliferation.
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