Monday, May 29, 2017

Introduction to Liver Abscess

A liver abscess occurs when bacteria or protozoa destroy hepatic tissue, producing a cavity, which fills with infectious organisms, liquefied liver cells, and leukocytes. Necrotic tissue then walls off the cavity from the rest of the liver.

Liver abscess occurs equally in men and women, usually in those older than age 50. Death occurs in 15% of affected patients despite treatment.
Underlying causes of liver abscess include benign or malignant biliary obstruction along with cholangitis, extrahepatic abdominal sepsis, and trauma or surgery to the right upper quadrant. Liver abscesses also occur from intra-arterial chemoembolizations or cryosurgery in the liver, which causes necrosis of tumor cells and potential infection.
The method by which bacteria reach the liver reflects the underlying causes.
Biliary tract disease is the most common cause of liver abscess. Liver abscess after intra-abdominal sepsis (such as with diverticulitis) is most likely to be caused by hematogenous spread through the portal bloodstream. 

Hematogenous spread by hepatic arterial flow may occur in infectious endocarditis. 

Abscesses arising from hematogenous transmission are usually caused by a single organism; those arising from biliary obstruction, by mixed flora. 

Patients with metastatic cancer to the liver, diabetes mellitus, or alcoholism are more likely to develop a liver abscess. 

The organisms that predominate in liver abscess are gram-negative aerobic bacilli, enterococci, streptococci, and anaerobes. 

Amebic liver abscesses are caused by Entamoeba histolytica.
Signs and symptoms
Signs and symptoms of liver abscess depend on the degree of involvement. Some patients are acutely ill; in others, the abscess is recognized only at autopsy, after death from another illness.
With a pyogenic abscess, the onset of symptoms is usually sudden; with an amebic abscess, it’s more insidious. Common signs and symptoms include abdominal pain, weight loss, fever, chills, diaphoresis, nausea, vomiting, and anemia. Symptoms of right pleural effusion, such as dyspnea and pleural pain, develop if the abscess extends through the diaphragm. Liver damage may cause jaundice.

Ultrasonography and computed tomography (CT) scan with contrast medium can accurately define intrahepatic lesions and allow assessment of intra-abdominal pathology. Percutaneous needle aspiration of the abscess can also be performed with diagnostic tests to identify the causative organism. Contrast-aided magnetic resonance imaging may also become an accurate method for diagnosing hepatic abscesses.
Abnormal laboratory values include elevated levels of serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and bilirubin; an increased white blood cell count; and decreased serum albumin levels. With pyogenic abscess, a blood culture can identify the bacterial agent; with amebic abscess, a stool culture and serologic and hemagglutination tests can isolate E. histolytica.


Antibiotic therapy along with drainage is the preferred treatment for most hepatic abscesses. Percutaneous drainage either with ultrasound or CT guidance is usually sufficient to evacuate pus. Surgery may be performed to drain pus in patients with an unstable condition and continued sepsis (despite attempted nonsurgical treatment) and in patients with a persistent fever (lasting longer than 2 weeks) after percutaneous drainage and appropriate antibiotic therapy.
Before the causative organism is identified, an antibiotic should be started to treat aerobic gram-negative bacilli, streptococci, and anaerobic bacilli, including Bacteroides species. A combination may be used. When the causative organisms are identified, the antibiotic regimen should be modified to match the patient’s sensitivities. An I.V. antibiotic should be administered for 14 days and then replaced with an oral preparation to complete a 6-week course

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