Conditions · Gastroenterology and hepatology

Pyogenic liver abscess !

A pocket of pus in the liver caused by bacteria, often spreading from the bile ducts or the bowel. It causes fever and right upper abdominal pain.

Updated 2026-11-01

Structures involved

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Why it happens

What it is

A collection of pus within the liver caused by bacterial infection. It most often arises from infection of the biliary tree or spreads through the portal vein from an abdominal infection, and it can be single or multiple.

Who gets it

The most common type of liver abscess in high-income countries, mostly in adults over 50. In Colombia and other tropical areas amoebic abscess is also frequent, so both must be considered in every patient with a liver abscess.

Causes

Biliary: cholangitis from stones, strictures, tumours or after ERCP (most common)
Portal: appendicitis, diverticulitis, inflammatory bowel disease or bowel perforation
Arterial: bacteraemia from a distant source such as endocarditis
Direct spread from the gallbladder or trauma; cryptogenic in many cases
Organisms: Escherichia coli, Klebsiella pneumoniae, streptococci (Streptococcus anginosus group) and anaerobes, often mixed

Risk factors

Diabetes mellitus (especially for Klebsiella)
Biliary disease and previous biliary procedures
Liver or pancreatic cancer and colorectal cancer
Older age, immunosuppression and liver transplant
Chemoembolisation or ablation of liver tumours

Pathophysiology

Bacteria reach the liver through the bile ducts, the portal vein or the hepatic artery. Local infection causes tissue necrosis and a walled-off pus collection, most often in the right lobe because it receives more portal flow. Hypervirulent Klebsiella can spread to the eye, lung and brain.

Classification

Single versus multiple abscesses
By route: biliary, portal, arterial, contiguous, cryptogenic
By size: small (<3–5 cm) versus large

Symptoms and signs

Fever, chills and night sweats, often the main complaint
Right upper quadrant pain and tender hepatomegaly
Malaise, anorexia, nausea and weight loss
Jaundice, especially with biliary origin
Right shoulder pain or cough from diaphragmatic irritation

Diagnosis

Clinical: Fever with right upper quadrant pain in a patient with biliary or abdominal infection, diabetes or a recent procedure; the classic triad is often incomplete.
Tests: Leukocytosis, high CRP, raised alkaline phosphatase and low albumin. Blood cultures (positive in about half) and culture of aspirated pus guide antibiotics. Amoebic serology is done to rule out amoebic abscess, especially in endemic areas such as Colombia.
Imaging: Ultrasound is the first test; contrast CT is the most sensitive, shows a rim-enhancing lesion and looks for the source. Colonoscopy is considered in cryptogenic Klebsiella or streptococcal abscess to exclude colorectal cancer.

Differential diagnosis

Amoebic liver abscess
Infected hydatid cyst
Necrotic liver tumour or metastasis
Acute cholecystitis or cholangitis
Right lower lobe pneumonia

Goal of treatment

Drain the pus, eradicate the bacteria with prolonged antibiotics and treat the source, while managing sepsis.

Treatment

Procedure: Percutaneous drainage guided by ultrasound or CT, by needle aspiration or catheter, for most abscesses larger than about 3–5 cm.
Medical: Empirical broad-spectrum antibiotics covering Gram-negative bacteria, streptococci and anaerobes (for example a third-generation cephalosporin with metronidazole, or a beta-lactam/beta-lactamase inhibitor), adjusted to cultures and continued for several weeks.
Acute: Sepsis care: blood cultures, early antibiotics, intravenous fluids and close haemodynamic support.
Surgical: Surgical drainage or resection for rupture, multiloculated abscesses that fail percutaneous drainage, or when the source needs surgery; ERCP for biliary obstruction.
Follow-up: Temperature curve, drain output, inflammatory markers and follow-up imaging until resolution; blood glucose control in diabetes.

Complications

Sepsis and septic shock
Rupture into the peritoneum, pleura or pericardium
Pleural effusion or empyema
Metastatic infection (endophthalmitis, meningitis) with hypervirulent Klebsiella
Portal or hepatic vein thrombosis

Prognosis

With drainage and antibiotics, mortality has fallen to under about 10%. Outcome is worse with multiple abscesses, biliary malignancy, shock, older age and delayed diagnosis.

Prevention

Prompt treatment of biliary and abdominal infections
Good diabetes control

Test yourself

Think of the answer, then tap the question to see it.

What is the most common source of pyogenic liver abscess?

The biliary tree (cholangitis from stones, strictures or tumours).

Which organism is linked to liver abscess in diabetics and can spread to the eye?

Klebsiella pneumoniae (hypervirulent strains), which can cause endophthalmitis.

Which lobe of the liver is most often involved and why?

The right lobe, because it is larger and receives more portal venous blood.

How does management differ between pyogenic and amoebic liver abscess?

Pyogenic abscess usually needs drainage plus weeks of antibiotics; amoebic abscess usually responds to metronidazole alone.

Why is colonoscopy considered after a cryptogenic Klebsiella or streptococcal liver abscess?

Because it can be the first sign of an underlying colorectal cancer.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: Pyogenic liver abscess: MedlinePlus Medical Encyclopedia (MedlinePlus (U.S. National Library of Medicine), 2024).

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Representative model, for educational purposes only.

Liver highlighted on the Durgical 3D model