Diagnosis

To diagnose peritonitis, your doctor will talk with you about your medical history and perform a physical exam. When peritonitis is associated with peritoneal dialysis, your signs and symptoms, particularly cloudy dialysis fluid, may be enough for your doctor to diagnose the condition.

In cases of peritonitis in which the infection may be a result of other medical conditions (secondary peritonitis) or in which the infection arises from fluid buildup in your abdominal cavity (spontaneous bacterial peritonitis), your doctor may recommend the following tests to confirm a diagnosis:

• Blood tests. A sample of your blood may be drawn and sent to a lab to check for a high white blood cell count. A blood culture also may be performed to determine if there are bacteria in your blood.
• Imaging tests. Your doctor may want to use an X-ray to check for holes or other perforations in your gastrointestinal tract. Ultrasound also may be used. In some cases, your doctor may use a computerized tomography (CT) scan instead of an X-ray.
• Peritoneal fluid analysis. Using a thin needle, your doctor may take a sample of the fluid in your peritoneum (paracentesis), especially if you receive peritoneal dialysis or have fluid in your abdomen from liver disease. If you have peritonitis, examination of this fluid may show an increased white blood cell count, which typically indicates an infection or inflammation. A culture of the fluid may also reveal the presence of bacteria.

The above tests may also be necessary if you're receiving peritoneal dialysis and a diagnosis of peritonitis is uncertain after a physical exam and an examination of the dialysis fluid.