Liver Abscess

REF: Feldman: Sleisenger & Fordtran's Gastrointestinal and Liver Disease, 6th ed., 1998

Pathogenesis

Infections of the biliary tract (e.g., cholangitis, cholecystitis) are the most common source of liver abscess.
In some cases, direct infection of the liver may occur along a penetrating vessel or from an adjacent septic focus.

Less commonly, liver abscess is a complication of bacteremia arising from underlying abdominal disease, such as diverticulitis, perforated or penetrating peptic ulcer, gastrointestinal malignancy, inflammatory bowel disease, or peritonitis.

In approximately 50% of cases of liver abscess, no obvious source can be identified. Oral flora have been proposed to be a potential source in such cases, particularly in patients with severe periodontal disease.

Microbiologic Evaluation

Most pyogenic liver abscesses are polymicrobial.
The most frequently isolated organisms are Escherichia coli and Klebsiella, Proteus, Pseudomonas, and Streptococcus species.
The number of cases found to be caused by anaerobic organisms has increased. The most commonly identified anaerobic species are Fusobacterium necrophorum, Bacteroides fragilis, and other Bacteroides species.
Recurrent pyogenic cholangitis may be caused by Salmonella typhi. Clostridium and Actinomyces species are uncommon causes of liver abscess, and rare cases are caused by Yersinia enterocolitica, septic melioidosis, Pasteurella multocida, and Listeria species.
Liver abscesses caused by Staphylococcus aureus infection are most common in children and patients with septicemia or impaired host resistance. Fungal abscesses of the liver may occur in immunocompromised hosts, particularly in those with a hematologic malignancy.

Diagnosis

Symptoms:

In the past, patients with a pyogenic liver abscess typically presented with acutely spiking fevers, pain in the right upper quadrant, and, in many cases, shock.
Since the introduction of antibiotics, the presentation of pyogenic liver abscess has become less acute, often insidious, and characterized by malaise, low-grade fever, and dull abdominal pain that may increase with movement. Symptoms may be present for one month or more before a diagnosis is made.
Multiple abscesses are typical when biliary disease is the source and associated with a more acute systemic presentation than solitary abscesses, often with sepsis and shock. When an abscess is situated near the dome of the liver, the patient may experience pain in the right shoulder or a cough as a result of diaphragmatic irritation or atelectasis.

Physical examination:

Fever (low-grade or high spiking)
Hepatomegaly and liver tenderness, which is accentuated by movement or percussion.
Splenomegaly is unusual, except with a chronic abscess.
Ascites is rare, and, in the absence of cholangitis, jaundice is present only late in the course of the illness.
Portal hypertension may follow recovery if there has been thrombosis of the portal vein.

Diagnostic Tests/Procedures

Lab: anemia, leukocytosis, an elevated erythrocyte sedimentation rate, and abnormal liver function tests, especially an elevated serum alkaline phosphatase level. Blood cultures may identify the causative organism in 50% of cases.
Ultrasound of Abdomen
Ultrasound-Guided Aspirate for Culture and Special Stains - Cultures of aspirated material are positive in 90% of cases.
CT Scan of Abdomen - accurate, with a sensitivity approaching 100%
Entamoeba histolytica Serology
MRI, Cholangiography, and arteriography may each be of value in selected clinical situations.

Differential Diagnosis: Hepatocellular carcinoma; echinococcal cyst

Prevention and Treatment

Pyogenic liver abscesses are best prevented by prompt treatment of acute biliary and abdominal infections and by adequate drainage of infected intra-abdominal collections under appropriate antibiotic coverage.

Treatment of a hepatic abscess requires

Antibiotic therapy directed at the causative organism(s)
Initial antibiotic coverage, pending culture results, should be broad-spectrum and include a penicillin, an aminoglycoside, and either metronidazole or clindamycin to cover anaerobic organisms. For streptococcal infections, the use of high-dose oral antibiotics for six months may be preferable.
Antibiotics should be administered intravenously for two weeks and then orally for six weeks.
If amebiasis is suspected, metronidazole therapy should be started before aspiration is performed.
Drainage of the abscess, usually percutaneously under radiologic guidance. Placement of an indwelling drainage catheter in the abscess may be necessary until the cavity has resolved. Surgical drainage is rarely required. With multiple abscesses, only the largest abscess may need to be aspirated; smaller lesions often resolve with antibiotic treatment alone, but rarely, each lesion may need to be drained.
Biliary decompression is essential when a hepatic abscess is associated with biliary obstruction and may be accomplished through the endoscopic or transhepatic route.

Prognosis

The mortality rate for patients with hepatic abscesses treated with antibiotics and percutaneous drainage is 16%. A worse prognosis may be expected when there is a delay in diagnosis; multiple organisms cultured from blood; jaundice; hypoalbuminemia; a pleural effusion; or other associated medical diseases. Complications of pyogenic liver abscess include empyema, pleuropericardial effusion, portal or splenic vein thrombosis, rupture into the pericardium, thoracic and abdominal fistula formation, and sepsis.

See also Amebic (Entamoeba histolytica ) Liver Abscess (under construction)
Amebiasis occurs worldwide but is most common in tropical and subtropical regions. In the United States, it is a disease of young, often Hispanic, adults. Endemic areas include Africa, Southeast Asia, Mexico, Venezuela, and Colombia.

03042002

Selected Readings

Dull JS, Topa L, Balgha V, et al, "Non-surgical Treatment of Biliary Liver Abscesses: Efficacy of Endoscopic Drainage and Local Antibiotic Lavage With Nasobiliary Catheter," Gastrointest Endosc, 2000, 51(1):55-9.

Lam YH, Wong SK, Lee DW, et al, "ERCP and Pyogenic Liver Abscess,"Gastrointest Endosc, 1999, 50(3):340-4.

Rustgi AK and Richter JM, "Pyogenic and Amebic Liver Abscess," Med Clin North Am, 1989, 73(4):847-58.

Seeto RK and Rockey DC, "Amebic Liver Abscess: Epidemiology, Clinical Features, and Outcome," West J Med, 1999, 170(2):104-9.