Diagnostic Ultrasound - Abdomen and Pelvis

Appendicitis
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Diagnoses: Bowel
Ileocolitis
• Mural thickening of cecum and terminal ileum; increased
mural flow on color Doppler
○ Crohn disease
○ Infectious (e.g., Campylobacter, Yersinia, tuberculosis)
Appendicular Mucocele
• Well-encapsulated cystic mass, ± wall calcification
• No periappendiceal inflammation
• Onion skin appearance of mucus in lumen
Normal Appendix With Mucosal Lymphoid
Hyperplasia
• Associated with infectious/inflammatory GI tract conditions
• Appendix may be thick walled; thick, smooth, inner
hypoechoic band; no luminal distension
• Absent periappendiceal inflammatory changes/no
hyperenhancement in wall
Appendiceal/Cecal Carcinoma
• Soft tissue density mass infiltrating &/or occluding
appendicular lumen
• Usually little surrounding inflammatory infiltration
• Local and regional enlarged lymph nodes
Pelvic Inflammatory Disease
• Complex adnexal/tubo-ovarian mass
• Dilated fallopian tube with fluid-fluid level (pyosalpinx)
Ruptured Right Adnexal Ectopic Pregnancy
• Echogenic tubal ring and increased tubal mural vascularity,
± fetal pole (± cardiac activity)
Segmental Omental Infarction (SOI)/Epiploic
Appendagitis (EA)
• Mass-like echogenic omentum in SOI, smaller echogenic
mass in EA with focal tenderness
• Absent or minimal adjacent bowel wall changes
Meckel Diverticulitis
• Imaging findings may overlap with acute appendicitis
• No association with cecum
PATHOLOGY
General Features
• Etiology
○ Multifactorial
– Ischemic mucosal damage, bacterial overgrowth,
luminal obstruction (appendicolith or Peyer patches)
○ Secondary/reactive appendicitis
– Crohn disease, reactive to adjacent inflammation
Staging, Grading, & Classification
• Could be obstructive or nonobstructive
• Gangrenous when there is necrosis
Gross Pathologic & Surgical Features
• Thickened appendix, which may or may not be distended
○ Appendicolith may be present
Microscopic Features
• Leukocyte infiltration of appendiceal wall
• Mucosal ulceration, necrosis if gangrenous
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Periumbilical pain migrating to RLQ; peritoneal irritation
at McBurney point; atypical signs in 1/3 patients
○ Anorexia, nausea, vomiting, diarrhea, fever
• Clinical profile
○ White blood cells may or may not be elevated
Demographics
• Age
○ All ages affected
• Gender
○ M = F
• Epidemiology
○ 7% of all individuals in Western world develop
appendicitis during their lifetime
Natural History & Prognosis
• Treatment
○ Surgery if nonperforated or if minimal perforation
○ Antibiotic therapy alternative to surgery in
nonobstructive appendicitis in some centers
○ Percutaneous drainage if well-localized abscess > 3 cm
○ Antibiotic therapy if periappendiceal soft tissue
inflammation and no abscess
• Complications
○ Gangrene and perforation; abscess formation
○ Peritonitis; septicemia; liver abscess, pyelophlebitis
○ Bowel obstruction; hydronephrosis
• Prognosis
○ Excellent with early surgery
DIAGNOSTIC CHECKLIST
Consider
• Appendicitis in right clinical context when inflamed fat is
seen in RLQ
○ Use graded compression to identify inflamed appendix
○ Nonvisualization of inflamed appendix does not rule out
appendicitis
• Other possible causes when no features to suggest
appendicitis
• Perforated appendicitis when there is inflamed echogenic
fat with fluid collection in right iliac fossa
Image Interpretation Pearls
• Blind-ended, aperistaltic, thick-walled tubular structure with
gut signature
○ May or may not be distended
• Sonographic McBurney sign with focal pain over appendix
• Presence of appendicolith associated with periappendiceal
inflammation is diagnostic of appendicitis
SELECTED REFERENCES
1. Park NH et al: Ultrasonography of normal and abnormal appendix in
children. World J Radiol. 3(4):85-91, 2011
2. Pinto Leite N et al: CT evaluation of appendicitis and its complications:
imaging techniques and key diagnostic findings. AJR Am J Roentgenol.
185(2):406-17, 2005
3. Andersson RE: Meta-analysis of the clinical and laboratory diagnosis of
appendicitis. Br J Surg. 91(1):28-37, 2004