Diagnostic Ultrasound - Abdomen and Pelvis

Diverticulitis
Diagnoses: Bowel
Colitis
• Presence of inflammatory colonic thickening typically in
absence of diverticula
• Etiology infectious, inflammatory, or ischemic
• Thickened long segment of colon with exaggeration of gut
signature surrounded by echogenic inflamed fat
Acute Appendicitis
• In clinical context, findings of thickened and distended
appendix ± calcified appendicolith are diagnostic
• Blind-ending, noncompressible tubular structure (> 7 mm in
caliber) arising from cecum with surrounding echogenic fat
seen on ultrasound
• CT: Dilated, thick-walled appendix with periappendiceal fat
stranding
Acute Epiploic Appendagitis (AEA) and Segmental
Omental Infarction (SOI)
• Localized infarction of appendices epiploicae (AEA) or
greater omentum (SOI) secondary to torsion, trauma, or
venous occlusion
• AEA typically in antimesenteric border of colon and SOI in
greater omentum
• Typically between 1-4 cm in AEA and larger (> 7 cm) in SOI
with significant focal tenderness
• Ultrasound: Echogenic mass without any adjacent bowel
wall thickening
• CECT: Ovoid fat density lesion with marked surrounding fat
stranding and relative sparing of colonic wall
• Recognizing AEA and SOI on imaging is crucial because
these are self-limiting and management is conservative
PATHOLOGY
General Features
• Acute diverticulitis
○ Impacted fecalith in diverticulum triggers localized
inflammation and microperforation
○ Progressive pericolic inflammation and infection result in
abscess formation
○ Perforation can also lead to generalized peritonitis
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Acute lower abdominal pain
– Localization of pain dependent on site of
inflammation
□ Typically left iliac fossa pain in classic acute sigmoid
diverticulitis
○ Fever, diarrhea, rectal bleeding (due to proximity of
inflamed diverticula to perforating vessels)
• Other signs/symptoms
○ Diverticulosis typically asymptomatic
Demographics
• Ethnicity
○ Prevalent in Western society associated with low dietary
fiber intake and has multifactorial etiology
○ Right-sided diverticulum; more common in young adults
and in Asian population
• Epidemiology
○ Diverticulosis; increases with age; < 5% before 40 years
to > 65% by 80 years of age
○ ~ 25% with diverticulosis will become symptomatic
○ Diverticulosis of right colon occurs at rate of 6-14%
Natural History & Prognosis
• Acute diverticulitis
○ Majority settle with conservative management
• Complications
○ Abscess, fistula, stricture, obstruction, perforation with
purulent or fecal peritonitis
Treatment
• Acute, uncomplicated diverticulitis
○ Conservative: Intravenous antibiotics and analgesia
• Radiological intervention; US or CT guided
○ To drain abscess and control localized sepsis
• Surgery
○ Decision based on clinical status and findings on CT
– Perforation with generalized peritonitis usually
Hinchey stage 3 and 4 disease
○ Considered in mechanical large bowel obstruction or
fistula
DIAGNOSTIC CHECKLIST
Consider
• Acute diverticulitis
○ Differential diagnosis of acute abdomen presenting with
lower abdominal pain
○ Cause of generalized peritonitis or pneumoperitoneum
○ Cause of pelvic abscess ± evidence of fistula in pelvic
viscera
○ Source of liver abscess secondary to ascending portal
pyemia
Image Interpretation Pearls
• Ultrasound
○ Pronounced hypoechoic muscular layer of colonic wall
containing diverticula with surrounding inflamed
echogenic fat accompanied with localized tenderness
• CT: Thick-walled colon containing diverticula with
surrounding fat stranding
Reporting Tips
• Look for complications
• Beware of carcinoma in background of diverticulosis
SELECTED REFERENCES
1. Klarenbeek BR et al: Review of current classifications for diverticular disease
and a translation into clinical practice. Int J Colorectal Dis. 27(2):207-14, 2012
2. Puylaert JB: Ultrasound of colon diverticulitis. Dig Dis. 30(1):56-9, 2012
3. Goh V et al: Differentiation between diverticulitis and colorectal cancer:
quantitative CT perfusion measurements versus morphologic criteria--initial
experience. Radiology. 242(2):456-62, 2007
4. West AB et al: The pathology of diverticulosis coli. J Clin Gastroenterol. 38(5
Suppl):S11-6, 2004
5. Pereira JM et al: Disproportionate fat stranding: a helpful CT sign in patients
with acute abdominal pain. Radiographics. 24(3):703-15, 2004
6. O'Malley M et al: Ultrasound of gastrointestinal tract abnormalities with CT
correlation. RadioGraphics. 23(1):59-72, 2003
7. Horton KM et al: CT evaluation of the colon: inflammatory disease.
RadioGraphics. 20(2):399-418, 2000
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