A barium enema is often used to investigate your bowel symptoms. It can be used to pick up conditions that cause bleeding or change in bowel habit such as cancer, colon polyps, diverticular disease and inflammatory bowel disease.
A barium Xray procedure is sometimes used as an alternative to a colonoscopy in the investigation of your bowel symptoms particularly when a colonoscopy is not technically possible or contraindicated for health reasons.

A milky dye or barium is passed, via an enema, through your anus or 'back passage' into the rectum and colonl. This shows up the inner lining of your colon and can highlight colon polyps, cancers and narrowing’s or ‘strictures’ in your bowel such as those caused by diverticular disease. It does this by coating over these areas as it passes through to your cecum or the start of your large bowel.
To perform your barium enema procedure, your bowel will need to be emptied with laxatives and sometimes an enema or suppository as well.
This is called 'bowel prep' and the type of medication you receive is usually determined by your local hospitals policy.

On the day of your barium test, you will be asked to go to the radiology or X-ray department. A needle will be inserted in to your hand or arm through which medication can be given (normally Buscopan or Hyoscine Butylbromide). A tube is passed into your back passage through which ‘dye’ is passed. Sometimes air is also passed into the bowel to inflate it. This is called a double contrast barium. You will then be placed in to different positions or angles to aid the passage of ‘dye’ through your colon and x-ray pictures are then taken to be assessed by a qualified X-ray doctor or Radiologist.
Yes, occasionally problems can arise when having a barium enema, but thankfully they are rare. The test can be uncomfortable (of particular note, IBS patients often get more pain when air is passed into the bowel) and you should be prepared for this. The dye usually contains Iodine and some people are allergic to this. It is important to let the X-ray department know this beforehand if you are already aware of this already. Very rarely, perforation can occur. If this happens you are likely to require an operation, but thankfully this is very rare (I haven't seen this happen in all the years I have been practising medicine).
The answer to this is definitely NO. It should only be done when there is a good clinical need for the investigation. If you are pregnant or have a latex allergy then this test should be avoided (the enema tube usually has a latex balloon on the end! Also, if you have had a recent biopsy from the rectum or anus then the test should be delayed as there is an increased risk of perforation (putting a hole in the bowel).
In conclusion, a barium enema is a good bowel investigation for patients with colon cancer warning signs, in highlighting colon polyps and strictures such as those seen in diverticular disease. It won't however diagnose IBS, but will help to exclude other potential causes of your bowel symptoms.
IBS symptoms › Colonoscopy Procedure › Barium Enema