Pyogenic Liver Abscess

A pyogenic liver abscess is a bacterial pus collection within the hepatic parenchyma.

Important routes are:

• Ascending biliary infection
• Portal spread from intra abdominal infection
• Haematogenous spread
• Direct extension
• Postoperative or traumatic infection
• Cryptogenic infection

Enterobacterales, particularly Klebsiella pneumoniae and Escherichia coli, streptococci and anaerobes are important pathogens. Abscesses may be polymicrobial.

The central treatment principle is antibiotics plus drainage when the abscess is too large, complex or clinically severe to resolve reliably with antimicrobial therapy alone.

Typical presentation is:

• Fever
• Right upper quadrant pain
• Malaise
• Anorexia
• Weight loss
• Hepatomegaly

Older patients may present predominantly with sepsis, confusion or deterioration of liver biochemistry.

Jaundice suggests significant biliary obstruction or extensive disease.

Metastatic infection, including endophthalmitis or central nervous system infection, can occur with invasive hypervirulent Klebsiella infection.

Contrast CT or ultrasound: confirm the hepatic collection and determine whether it is suitable for aspiration or catheter drainage.

Obtain at least two sets of blood cultures before antibiotics where this does not delay treatment.

Send aspirated pus for aerobic and anaerobic culture and susceptibility testing.

Investigate the source, particularly biliary obstruction, cholangitis or intra abdominal infection.

Start broad antimicrobial treatment promptly.

A practical community acquired regimen is:

Ceftriaxone 2 g IV every 24 hours plus metronidazole 500 mg IV every 8 to 12 hours.

For septic shock, healthcare associated infection or substantial resistant Gram negative risk:

Piperacillin tazobactam 4.5 g IV every 8 hours by extended infusion, adjusted for renal function.

Narrow treatment once blood or abscess cultures return.

Drainage

A small abscess, particularly below approximately 3 cm, can sometimes be treated with antibiotics alone in a stable patient who is improving clinically.

Drain when there is:

• Persistent sepsis
• Larger abscess
• Liquefied accessible cavity
• Impending rupture
• Diagnostic uncertainty
• Failure to improve with antibiotics
• Need for microbiological source identification

For a smaller uncomplicated cavity, image guided needle aspiration may be sufficient.

For an abscess above approximately 5 cm, thick contents or ongoing substantial drainage, percutaneous catheter drainage is usually more reliable than a single aspiration.

Size is not an absolute rule. A 4 cm multiloculated septic abscess may require drainage while a carefully selected larger poorly liquefied lesion may require a different approach.

Surgery

Operate when:

• Percutaneous drainage fails
• Abscess contents are too thick or multiloculated for adequate catheter drainage
• The abscess has ruptured into the peritoneum
• An underlying surgical disease requires correction
• Persistent sepsis continues despite appropriate drainage

Antibiotic duration is longer than for a routine drained intra abdominal abscess because infection lies within hepatic parenchyma. Total treatment commonly lasts approximately 4 to 6 weeks, with IV therapy followed by oral treatment once fever, inflammatory markers and drainage have clearly improved. Evidence for one exact duration is limited, so clinical and radiological response should guide the endpoint.