- Clinical science
A pyogenic liver abscess is a rare disease characterized by solitary/multiple collections of pus within the liver. The infection is caused by bacteria and is usually polymicrobial, with E. coli and K. pneumoniae being the common causative organisms. The majority of cases are caused by ascending infection from a biliary tract pathology (e.g., cholangitis due to choledocholithiasis, i.e. biliary strictures). Due to the liver's dual blood supply from the portal vein and the hepatic artery, an infectious focus in the gastrointestinal tract or bacteremia exposes the liver to high bacterial loads. Patients, typically middle-aged/elderly males, present with non-specific symptoms, such as fever, malaise, and weight loss. Right upper quadrant pain and tender hepatomegaly are specific features of a liver abscess but are often absent. Diagnosis is confirmed on abdominal imaging (ultrasound or CT), which demonstrates intrahepatic fluid-filled lesions with surrounding edema. Broad-spectrum IV antibiotics (ampicillin + sulbactam) and percutaneous/surgical drainage of the abscess cavity is the mainstay of treatment. Complications include sepsis, pneumonia, and abscess rupture into the peritoneum/thorax. Advancements in diagnostics and treatment have reduced the complications and mortality rates of pyogenic liver abscesses.
- Incidence: 2–3 cases per 100,000 people in the United States
- Peak incidence: 50–60 years
- Sex: Slight male predominance
Epidemiological data refers to the US, unless otherwise specified.
Etiology by source
Biliary tract (∼ 60%): Most common cause
Portal vein (∼ 20%)
Hepatic artery (∼ 15%)
Contiguous area (< 5%)
- Pyogenic liver abscess (80% of liver abscesses)
- Non-pyogenic liver abscess
- Classic triad of pyogenic liver abscess
- Anorexia and weight loss
- Nausea and vomiting
- Symptoms of diaphragmatic irritation
- Physical examination
- Complete blood count: neutrophilic leukocytosis, normocytic normochromic anemia
- Liver function tests: and enzymes: ↑ alkaline phosphatase (90%), ↑ AST and ALT; , hypoalbuminemia, hyperbilirubinemia
- Inflammatory markers: ↑ ESR and CRP
- Blood culture: positive in ∼ 50% of cases
- Abdominal imaging is a confirmatory test for pyogenic liver abscess
- Abdominal ultrasound (US): Seen as solitary/multiple, poorly demarcated, fluid-filled, round hypoechoic lesion(s) within the hepatic parenchyma with surrounding edema and hyperemia .
- Abdominal CT scan: : Findings are similar to those on abdominal ultrasound; a peripheral rim enhancement is seen on IV contrast administration.
- Chest x-ray: Elevated right hemidiaphragm; right lower lobar atelectasis with/without right pleural effusion
Percutaneous aspiration and culture of the aspirate
- Both diagnostic and therapeutic (see “Treatment” section below)
- Performed under US or CT guidance
- Aspirated material is cultured to determine the organism and its antibiotic-susceptibility profile.
- Indicated in all cases
- Broad-spectrum IV antibiotics: ampicillin + sulbactam; piperacillin + tazobactam; 3rd generation cephalosporin + metronidazole (until antibiotic susceptibility is available)
Drainage of the abscess cavity
- Indicated in nearly all cases of pyogenic liver abscess IV antibiotics alone may cause complete resolution of an abscess < 3 cm in a patient with no signs of sepsis.
- Indication for percutaneous drainage/needle aspiration: solitary abscess
- Indications for surgical drainage (open/laparoscopic)
- Contraindications: coagulopathy (e.g., (INR) > 1.5; thrombocytopenia due to sepsis)
- Untreated pyogenic liver abscess: 100%
- With treatment: ∼12 %
- Poor prognostic factors