Peritonitis can often be diagnosed after a physical examination and tests.

Physical examination

Your GP will ask you about your symptoms and recent medical history, and will carry out a detailed physical examination.

If you have peritonitis, parts of the body such as the abdominal (tummy) wall often become tender to the touch. A physical examination will help rule out other conditions that can cause similar symptoms, such as a hernia.

The risk of complications from peritonitis is high, so you'll be admitted to hospital if your GP suspects you have it.

Tests

You may need blood tests and urine tests to check for infection. If you have a build-up of fluid in your abdomen (tummy), a small sample may be removed using a thin needle so it can be checked for infection.

Doctors may also recommend:

• an X-ray – where radiation is used to produce an image to look for evidence of air leakage from the bowel
• an ultrasound scan – where sound waves are used to build a picture of the inside of your peritoneum
• a computerised tomography (CT) scan – a series of X-rays are taken to build up a more detailed three-dimensional picture of your peritoneum

These types of scans can often detect whether there is internal damage inside your abdomen, such as a burst appendix, a ruptured stomach ulcer, or extensive inflammation of the colon.