Liver Abscesses: Treatment Options and Outcomes

• Study notes on Liver Abscesses

Treatment Options and Outcomes for Pyogenic Hepatic Abscess

• Percutaneous catheter drainage has a higher success rate (100%) vs. aspiration
• Aspiration has a success rate of 60%
• Success rates were similar between aspiration alone and aspiration plus catheter drainage, in terms of treatment success rate, hospital stay, antibiotic duration, and mortality
• The aspiration-only group required more aspirations than the catheter drainage group, with 40% needing two aspirations and 20% needing three
• Catheter drainage is the preferred treatment, but an initial single aspiration is worth considering
• Some reports show success with antibiotics alone, but most of these patients had a diagnostic aspiration or partial drainage
• Antibiotic treatment without drainage may result in high mortality (59%-100%)
• For patients not fit for surgery or refusing invasive procedures, antibiotic treatment may be attempted but isn't generally recommended
• Liver resection is occasionally needed, such as for infected hepatic malignant neoplasms, hepatolithiasis, or intrahepatic biliary stricture; some patients may benefit from resection if there is severe hepatic destruction

Trends in Mortality

• Mortality from pyogenic hepatic abscess has greatly decreased in the last 70 years
• Before the use of surgical drainage, the condition was uniformly fatal
• Surgical drainage and IV antibiotics reduced mortality to around 50% until the early 1980s
• Since the 1980's mortality rates have fallen to 10% to 20%
• The 1990s saw mortality below 10%
• Memorial Sloan-Kettering Cancer Center (MSKCC) reported a 3% mortality in their recent series

Factors Affecting Prognosis

• Presence of malignant disease
• Factors linked to malignant disease (e.g., jaundice, high LFT results)
• Signs of sepsis all indicate a poor prognosis
• Chronic disease signs like hypoalbuminemia often indicate a poor outcome
• Severe infection signs: leukocytosis, Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, abscess rupture, bacteremia, and shock indicates mortality
• Two thirds of percutaneous and surgical case series show effective success and mortality rates

Amebic Abscess Epidemiology

• Amebiasis is a common disease in tropical and developing countries
• It is also an issue in developed countries with significant immigration and travel
• Common in Mexico, India, Africa, and parts of Central and South America
• The World Health Organization (WHO) estimated 40 to 50 million people in 1995 had amebic colitis or liver abscess and that resulted in 40,000 to 100,000 deaths each year
• Previous estimates didn't differentiate between E. histolytica (pathogenic) and Entamoeba dispar (nonpathogenic)
• Male homosexuals, previously thought to be frequently infected with E. histolytica, actually have E. dispar

Amebic Abscess Pathogenesis

• E. histolytica is a protozoan within the Entamoeba genus
• Not all E. histolytica strains are pathogenic
• Ingestion of E. histolytica cysts causes amebiasis through contaminated water, vegetables, or human contact
• Cysts pass to the intestines and then to the colon, infecting the mucosa
• Trophozoites thought to enter the portal venous system, causing necrosis by lysing tissues through cell adherence, activation, and protein hydrolysis
• This process results in localized hepatic necrosis and accumulating debris with amebic trophozoites
• Early development is associated with these
• Antiamebic antibodies, particularly IgA, are developed, but do not halt progression
• A cell-mediated mechanism is now believed to be key

Amebic Abscess Pathology

• Hepatic amebic abscess is enzymatic necrosis, producing liquefied liver tissue, with the appearance of "anchovy sauce"
• Bacterial infection isn't usually present unless there has been a perforation
• Hydrolysis continues until Glisson's capsule, resistant to this process, is reached, forming a cavity that is typically limited by the peritoneum
• It has no real fibrous capsule