Investigations

The following are standard tests in suspected ascites:

• ultrasound
• diagnostic paracentesis in which 30 to 50 ml of fluid is withdrawn. This will enable identification of:
  • protein content: albumin and total protein
  • malignant cells
  • bacteria
  • white blood cells
  • glucose

If there is a very high white cell count, i.e. greater than 250/mm cubed, which is predominantly polymorphs, then this is suggestive spontaneous bacterial peritonitis. Often such an infection is due to coliforms.

A sample of fluid that contains more than one type of organism suggests possible bowel perforation or a contaminated sample. Other tests on the ascitic fluid may be considered:

• amylase - helps detect pancreatic ascites and gut perforation in the peritoneal cavity
• tuberculous smear and culture