Liver abscess

Overview
A liver abscess is a pus-filled mass inside or attached to the liver. Common causes are an abdominal infection such as appendicitis or diverticulitis. With treatment, the death rate is 10-30%.

General Characteristics of Liver Abscess

 * Biliary tract disease is the most common cause but no cause identified in the majority of patients.
 * Nonspecific clinical findings - high degree of suspicion required for diagnosis
 * Most often single, rather than multiple foci
 * Hyperbilirubinemia and elevated alkaline phosphatase in the majority of patients, but low specificity.
 * E. coli the most prevalent organism, followed by Klebsiella, Streptococcus, and Bacteroides species.
 * Rare cause is bowel perforation following foreign body ingestion
 * Therapy for solitary liver abscess from causes other than bowel perforation is intravenous antibiotics and percutaneous US- or CT-guided drainage
 * Therapy for liver abscess caused by bowel perforation or foreign body is open surgical drainage
 * Amebic liver abscess occurs in 94% of cases of amebiasis
 * Liver abscess is a relatively infrequent (1.7% according to Cho, D. et. al.), although possible, complication of percutaneous radiofrequency ablation of hepatic tumors.

Types
There are 3 major forms of liver abscess, classified by etiology:


 * 1) Pyogenic abscess, which is most often polymicrobial, accounts for 80% of hepatic abscess cases in the United States.
 * 2) Amebic abscess due to Entamoeba histolytica accounts for 10% of cases.
 * 3) Fungal abscess, most often due to Candida species, accounts for less than 10% of cases.

Clinical Features

 * Symptoms
 * Pain Right Hypochondrium referred to Right shoulder
 * Pyrexia (100.4 F)
 * Profused sweating and Rigors
 * Loss of Weight
 * Earthy Complexion


 * Signs
 * Pallor
 * Tenderness and rigidity in right hypochondrium
 * Palpable Liver
 * Intercostal Tenderness
 * Basal Lung Signs

Diagnosis

 * Blood CP
 * Haemoglobin Estimation
 * Stools Examination (Trophozoites and Cysts)
 * Radiography
 * Aspiration Exploratory
 * Medical ultrasonography and CT Scanning
 * Sigmoidoscopy
 * Liver function tests
 * Serological Tests

Diagnostic Findings

 * Right pleural effusion, elevated right hemidiaphragm, and subsegmental atelectasis on chest radiography
 * Findings on abdominal radiography nonspecific in 87% of cases
 * US and CT are critical imaging tools
 * US may demonstrate a peripheral echo-free halo, distal acoustic enhancement, and progressive change over a short period of time.
 * On CT, abscesses may be single or multipe, round or oval, have an enhancing rim, complete or incomplete rim of edema, have smooth or nodular margins, intraabscess hemorrhage, peripheral biliary ductal dilatation, and may contain internal septations. Patterns are variable.
 * Pretreatment amebic liver abscess appears as a heterogeneously low-signal intensity mass with sharp borders on T1 and as a hyperintense region with hyperintensity extending to the liver surface, corresponding to edematous hepatic parenchyma.
 * Progression of edema is followed with T2-weighted imaging.
 * Posttreatment amebic liver abscess becomes homogeneously hypointense on T1-weighted images.
 * Maturation of the abscess wall during and after treatment is characterized by the appearance of concentric rings.
 * Differential for MR findings for amebic liver abscess also includes bacterial abscess, hematoma and necrotic tumor.

(Images shown below are courtesy of RadsWiki)

Etiology

 * Streptococcus milleri
 * E. coli
 * Streptococcus fecalis
 * Klebsiella
 * Proteus vulgaris
 * Opportunistic Pathogens (Staphylococcus)

Clinical features

 * Acute abscess
 * Fever
 * Lethargy
 * Discomfort in Right Upper Quadrant of abdomen
 * Anorexia
 * Enlarged and Tender Liver
 * Pleural effusion


 * Chronic Abscess
 * Fever
 * Abdominal discomfort
 * Enlarged Liver

Treatment

 * Antibiotics
 * Penicillins
 * Aminoglycosides
 * Metronidazole
 * Cephalosporins


 * Percutaneous Drainage under USG or CT Control
 * Laparotomy in intraabdominal disease

Additional Resources

 * Dongil Choi, Hyo K. Lim, Min Ju Kim, Suk Jung Kim, Seung Hoon Kim, Won Jae Lee, Jae Hoon Lim, Seung Woon Paik, Byung Chul Yoo, Moon Seok Choi, and Seonwoo Kim. Liver Abscess After Percutaneous Radiofrequency Ablation for Hepatocellular Carcinomas: Frequency and Risk Factors. Am. J. Roentgenol., Jun 2005; 184: 1860 - 1867.
 * Dewbury, K.C., Joseph, A.E., Millward Sadler, G.H., and Birch, S.J. Ultrasound in the diagnosis of the early liver abscess. Brit. J. of Radiol. 1980;53, 635: 1160-1165.
 * Drnovsek, V., Fontanez-Garcia, D., Wakabayashi, M.N., Plavsic, B.M. Gastrointestinal Case of the Day, Radiographics, 1999;19:820-822.
 * Elizondo, G., Weissleder, R., Stark, D.D., Todd, L.E., Compton, C., Wittenberg, J., and Ferrucci, J.T. Amebic Liver Abscess: Diagnosis and Treatment Evaluation with MR Imaging. Radiology, 1987; 165:795-800.
 * Radin, D.R., Ralls, P.W., Colletti, P.M., and Halls, J.N. CT of amebic liver abscess. Am. J. Roentgen. 1988; 150, 6: 1297-1301.

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