Localized collection of pus in liver due to bacterial infectious process with destruction of hepatic parenchyma and stroma

Cluster sign: Cluster of small pyogenic abscesses that coalesce into single large cavity

Early lesions tend to be echogenic and poorly demarcated, evolve into well-demarcated anechoic lesions

May see central gas or fluid level

Nonliquefied abscess may simulate solid tumor

Echogenicity of abscesses

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  Anechoic (50%), hyperechoic (25%), hypoechoic (25%)

Fluid level or debris, internal septa, and posterior acoustic enhancement

CECT: Double target sign

Metastasis (post treatment)

Cholangiocarcinoma (peripheral mass forming)

Biliary cystadenocarcinoma

Hepatocellular carcinoma (hypovascular)

Amebic abscess

Hemangioma (small)

Hemorrhagic simple cyst

Hydatid cyst (echinococcal cyst)

Hepatic infarction in liver transplantation

Development via 5 major routes: Portal vein, biliary tract, hepatic artery, direct extension, trauma

Common organisms: Escherichiacoli , Klebsiella pneumoniae (adult), Staphylococcus aureus (children)

Accounts for 88% of all liver abscesses

Typical presentation: Middle-aged/elderly patient with history of fever, right upper quadrant pain, tender hepatomegaly, leukocytosis

Rule out amebic/fungal liver abscesses, cystic/hypovascular tumors

Check for history of transplantation or ablation/chemotherapy for liver tumor

Demonstration of mobile echogenic debris very helpful in diagnosis

Fluid level or debris, internal septa, and posterior acoustic enhancement are also very helpful clues