Overview
Spontaneous bacterial peritonitis (SBP) describes the development of a bacterial infection in the ascitic fluid in patients with ascites and carries a high mortality rate if left untreated. It is thought to be due to the spread of bacteria via the blood into the ascitic fluid.
The usual causes are enteric organisms, with the most common cause being Escherichia coli.
Risk Factor
- Any cause of ascites (usually liver cirrhosis)
- Gastrointestinal bleeding
- Invasive procedures
Presentation
- Patients usually have ascites with abdominal pain and signs of infection, such as fever. Other features include:
- Worsening ascites
- Nausea and vomiting
- Features of hepatic encephalopathy
- Signs of sepsis, such as tachycardia and hypotension
Differential Diagnoses
Budd-Chiari syndrome
- Classic triad of ascites, abdominal pain, and hepatomegaly is present
- Signs of infection, such as fever, are not present
Investigations
- FBC:
- May show leukocytosis in infection
- May show anaemia in gastrointestinal bleeds
- LFTs:
- May be deranged in liver disease
- U&Es:
- May be deranged if hepatorenal syndrome is present
- Paracentesis and ascitic fluid analysis:
- May appear cloudy or bloody
- Neutrophil count > >250 cells/mm³ is diagnostic
- Ascitic fluid cultures identify the causative organism
Management
Acute management
- 1st-line: IV broad-spectrum antibiotics (usually cefotaxime)
- Large-volume paracentesis and albumin cover may be considered
Prophylaxis
- Prophylactic ciprofloxacin or norfloxacin is offered for the following:
- Any patient who has had an episode of SBP
- Any patient with ascites with ascitic protein levels <15 g/L until the ascites resolves
Low ascitic protein is associated with reduced immunoglobulins and opsonic factors in the ascitic fluid, increasing the risk of infection.
Prognosis
- If renal dysfunction develops, the prognosis is poor
