How is diverticular disease diagnosed?

Seeing your doctor

The doctor will take a history, enquiring about your bowel habit, abdominal pain, bleeding, diet and medications. Normally a physical examination is performed, involving an examination of your abdomen and a digital rectal exam. This requires the doctor to insert a gloved, lubricated finger into your back passage to feel for pain or a blockage and to check the stool for blood. Normally the examination is normal, although the doctor may be able to feel a thickened bowel loop in the lower left quadrant.

Occasionally, the doctor may pass a tube (rigid sigmoidoscope) approximately 15 to 20 centimetres into your back passage to have a look at the lining of your bowel and to check for internal tears or piles. The doctor may also arrange for you to have a blood test looking for anaemia or infection, and send a stool sample to test for infection. This initial history and examination are important because diverticular disease can mimic many other conditions, so other investigations are usually necessary to exclude them.

Endoscopy

An easy way of diagnosing diverticular disease is to use a camera test (endoscopy) of the large bowel. This is done by passing a tube (endoscope) with a camera on the end through your back passage and inside the large bowel. The diverticula will be seen as little pockets in the bowel wall. They are typically best seen during insertion rather than on the way out. They can make for a more challenging procedure. The camera test that your doctor may have organised will be either a ‘flexible sigmoidoscopy’, which looks only at the left side of the bowel up to approximately 60 centimetres or a ‘colonoscopy’, which will look at the whole large bowel.

CT (computed tomography) colonoscopy

Another option is a two- or three-dimensional scan of your large bowel. Pumping air into the rectum via a tube distends the bowel and X-rays are then taken of the large bowel in different positions. The examination may also confirm the presence of complications such as abscesses. Occasionally, a dye (contrast) may be given into the vein if felt necessary. The preparation for this test is very similar to that of a colonoscopy.

Barium enema

This test is done infrequently these days and shouldn’t be done if there are signs of acute diverticulitis. A liquid dye containing barium is inserted via a tube into your back passage, which coats the inner lining of the bowel wall. Several S-rays are then taken in different positions to check for the presence of diverticula.

Ultrasound scan

This is a useful investigation that can assess bowel wall thickness and the complications of diverticulitis; it can be used by the radiologist to guide a needle to drain any abscess.

The procedures can be uncomfortable and may pose a risk but the decision to undergo a test and the choice of investigation will be made with your doctor after discussing the pros and cons. It is important that invasive investigations such as colonoscopy are deferred for about six weeks after an episode of diverticulitis so as to avoid exacerbating any microperforation, which could lead to further problems.

What preparation is needed for the investigations?

Good bowel preparation is crucial to obtain good views of the colon.

Flexible sigmoidoscopy

You will be require an enema to cleanse your bowel, usually given by the nursing staff just before the procedure. There are no dietary restrictions.

Barium enema/Colonoscopy/CT colonoscopy

Preparation requires dietary restrictions in the two days leading up to the procedure (a low residue diet) and a potent laxative to cleanse the bowel. The laxative is strong so ensure that you have a toilet within easy reach. Each hospital has its own laxative and dietary regimen, which will be explained to you in advance of the procedure. Some medications such as iron tablets and anti-diarrhoea medications need to be stopped before the test. Some patients who have kidney problems or heart failure may require a different type of bowel preparation. Please check with your doctor before taking the laxative.