Diagnostic Ultrasound - Abdomen and Pelvis

Pyogenic Hepatic Abscess
Diagnoses: Liver
• More irregular and complex wall and septations
• Hepatic capsular retraction
Biliary Cystadenoma/Cystadenocarcinoma
• Rare, multiseptated cystic mass
• No surrounding inflammatory changes in liver parenchyma
Hepatocellular Carcinoma (Hypovascular)
• More heterogeneous; irregular infiltrating border
• Background liver cirrhosis
Amebic Abscess
• Peripheral location, abuts liver capsule
• Most often solitary (85%), rarely multiseptated
• Affects right lobe (72%) > left (13%)
• More common in recent immigrants or patient with travel
history
Hemangioma (Small)
• Hyperechoic on US
• Often indistinguishable from small abscess on CECT/MR
Hemorrhagic Simple Cyst
• Hemorrhage may produce internal debris/septa/wall
thickening within preexisting cyst
• Cyst may appear multiloculated
Hydatid Cyst (Echinococcal Cyst)
• Large cystic liver mass with peripheral daughter cysts
• ± curvilinear or ring-like pericyst calcification
• ± dilated intrahepatic bile ducts: Due to mass effect or
rupture into bile ducts
Hepatic Infarction in Liver Transplantation
• Hepatic and biliary necrosis due to hepatic artery
thrombosis
• Peripheral, wedge-shaped or geographic, segmental
distribution
• No capsule or septal enhancement
PATHOLOGY
General Features
• Etiology
○ Portal vein route
– Pylephlebitis from appendicitis, diverticulitis,proctitis,
inflammatory bowel disease
– Right colon infection spread: Superior mesenteric vein
→ portal vein → liver
– Left colon infection spread: Inferior mesenteric vein →
splenic vein → portal vein → liver
○ Biliary tract route
– Ascending cholangitis from
choledocholithiasis,benign or malignant biliary
obstruction
○ Hepatic artery route
– Septicemia from bacterial endocarditis, pneumonitis,
osteomyelitis
○ Direct extension
– Perforated gastric/duodenal ulcer, subphrenic
abscess, pyelonephritis
○ Traumatic cause
– Blunt or penetrating injuries or following
interventional procedures
○ Most commonly bacterial organisms
– Adult: Escherichia coli, Klebsiella pneumoniae
– Children: Staphylococcus aureus
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Fever, RUQ pain, rigors, malaise
○ Nausea, vomiting, weight loss, tender hepatomegaly
○ If subphrenic then atelectasis & pleural effusion possible
• Clinical profile
○ Middle-aged/elderly patient with history offever, RUQ
pain, tender hepatomegaly, leukocytosis
• Lab data: Increased leukocytes & serum alkaline
phosphatase
• Diagnosis by fine-needle aspiration cytology
Demographics
• Epidemiology
○ Accounts for 88% of all liver abscesses
○ Incidence increasing in Western countries due to
ascending cholangitis & diverticulitis
Natural History & Prognosis
• Complications: Spread of infection to subphrenic space
causes atelectasis & pleural effusion
• Prognosis: Good after medical therapy & aspiration
Treatment
• Antibiotics
• Percutaneous aspiration
• Catheter or surgical drainage
DIAGNOSTIC CHECKLIST
Consider
• Rule out amebic/fungal liver abscesses, cystic tumors
• Check for history of transplantation or
ablation/chemotherapy for liver tumor
Image Interpretation Pearls
• "Cluster" sign: Small abscesses coalesce into big cavity
• Presence of central gas or fluid level
• Nonliquefied abscess may simulate solid tumor
SELECTED REFERENCES
1. Bonder A et al: Evaluation of liver lesions. Clin Liver Dis. 16(2):271-83, 2012
2. K C S et al: Long-term follow-up of pyogenic liver abscess by ultrasound. Eur
J Radiol. 74(1):195-8, 2010
3. Benedetti NJ et al: Imaging of hepatic infections. Ultrasound Q. 24(4):267-
78, 2008
4. Doyle DJ et al: Imaging of hepatic infections. Clin Radiol. 61(9):737-48, 2006
5. Kim KW et al: Pyogenic hepatic abscesses: distinctive features from
hypovascular hepatic malignancies on contrast-enhanced ultrasound with
SH U 508A; early experience. Ultrasound Med Biol. 30(6):725-33, 2004
6. Mortelé KJ et al: The infected liver: radiologic-pathologic correlation.
Radiographics. 24(4):937-55, 2004
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