Diverticular disease can be difficult to diagnose from the symptoms, alone because there are other conditions that cause similar symptoms, such as irritable bowel syndrome (IBS).
As a first step, your GP may recommend blood tests to rule out other conditions such as coeliac disease (a condition caused by an abnormal immune response to gluten) or bowel cancer.
In some cases, you may be offered treatment for IBS and diverticular disease at the same time.
To make sure there is not a more serious cause of your symptoms, your GP may refer you for a colonoscopy, where a thin tube with a camera at the end (a colonoscope) is inserted into your rectum and guided into your colon. Before the procedure begins, you will be given a laxative to clear out your bowels.
A colonoscopy is not usually painful, but it can feel uncomfortable. You may be offered painkilling medication and a sedative beforehand to make you feel more relaxed and help reduce any discomfort.
CT pneumocolon or colonography
Another technique for confirming the presence of diverticula is a computerised tomography (CT scan). A CT scan uses X-rays and a computer to create detailed images of the inside of the body.
As with a colonoscopy, you will be given a laxative to clear out your bowels before you have the CT scan.
Unlike a regular CT scan, the colonography scan involves a tube being inserted into your rectum, which is used to pump some air up into your rectum. The CT scan is then taken with you lying on your front, and again lying on your back.
You may need to have an injection of contrast dye before the scan, but this is not always necessary.
If you have had a previous history of diverticular disease, your GP will usually be able to diagnose diverticulitis from your symptoms and a physical examination. A blood test may be taken, because a high number of white blood cells indicates infection. If your symptoms are mild, your GP will treat it at home and you should recover within four days.
Further tests will be needed if you have no previous history of diverticular disease.
If you are unwell, your GP may refer you to hospital for blood tests and investigations. This is to look for complications of diverticulitis and to rule out other possible conditions, such as gallstones or a hernia.
An ultrasound scan may be used, as well as a CT scan.
A CT scan may also be used if your symptoms are particularly severe. This is to check whether a complication, such as a perforation or an abscess, has occurred.