Liver Abscesses & Cysts

Overview – Liver Abscesses & Cysts

Liver abscesses and hepatic cysts are uncommon yet clinically significant liver lesions. Liver abscesses often result from bacterial infection and can range from asymptomatic to life-threatening sepsis, with E. coli and anaerobes as typical culprits. Hydatid cysts, by contrast, are parasitic infections caused by Echinococcus granulosus, particularly in endemic regions and associated with animal exposure. Early identification and targeted treatment—including antibiotics, aspiration, or antiparasitic agents—are essential to preventing complications such as rupture, sepsis, or biliary obstruction. This page outlines both liver abscesses and hydatid disease for final-year medical students, focusing on diagnosis, investigations, and treatment.

Liver Abscesses

Definition

• Liver abscess = A pus-filled cavity in the liver caused by infection, most commonly pyogenic in nature.

Aetiology

• Infective causes, often polymicrobial:
  • E. coli, anaerobes, and other gut flora
• Source of infection:
  • Intra-abdominal sepsis (e.g. appendicitis, diverticulitis)
  • Biliary sepsis, especially in the elderly

Morphology / Pathophysiology

• Pyogenic abscess = Walled-off area of necrosis and purulence
• May be solitary or multiple
• Multiple abscesses are associated with a significantly higher mortality rate

Clinical Features

• Variable presentation – from asymptomatic to acutely unwell
• Symptoms:
  • Malaise, fever, rigors
  • Anorexia, weight loss
  • Vomiting
  • Right upper quadrant (RUQ) abdominal pain
• Signs:
  • Pyrexia, jaundice
  • Septic appearance
  • Tender hepatomegaly

Investigations

• Bloods:
  • ↑ ALP and bilirubin (cholestatic pattern)
  • Positive blood cultures
• Imaging:
  • Abdominal ultrasound → diagnostic
  • CT abdomen → assess extent and exclude malignancy (e.g. hepatocellular carcinoma)

Management

• Drainage:
  • USS-guided aspiration for diagnosis and decompression
• Antibiotics:
  • Empiric cover: Metronidazole + Gentamicin (adjust based on culture)

Prognosis

• Solitary abscess → generally favourable prognosis
• Multiple abscesses → poor prognosis (≈80% mortality)

Hydatid Cysts (Hydatid Disease)

Definition

• Hydatid disease = Parasitic liver cysts caused by Echinococcus granulosus

Aetiology

• Transmission from dogs or sheep (definitive hosts) to humans (intermediate host)
• Ingestion of eggs leads to larval cyst formation, especially in the liver

Morphology / Pathophysiology

• Classic three-layered cyst:
  • Outer: fibrous layer from host
  • Middle: laminated membrane
  • Inner: germinal layer that generates daughter cysts
• Most commonly found in right lobe of liver

Clinical Features

• Often asymptomatic
• May present with dull RUQ ache
• Risk of rupture or secondary infection

Investigations

• Ultrasound or CT → visualise cyst architecture and daughter cysts
• Serology for Echinococcus antibodies (may assist diagnosis)

Management

• Antiparasitic therapy:
  • Albendazole
• Surgical removal or aspiration:
  • Percutaneous fine-needle aspiration
  • Open surgery if large or complicated

Summary – Liver Abscesses & Cysts

Liver abscesses and cystic lesions of the liver are important differential diagnoses in patients with fever and RUQ pain. Pyogenic liver abscesses are usually bacterial in origin, diagnosed via imaging, and treated with antibiotics and aspiration. In contrast, hydatid cysts arise from parasitic infection and require antiparasitic medication or surgical management. Early recognition is key to avoiding sepsis, rupture, or hepatic dysfunction. For a broader context, see our Gastrointestinal Overview page.