Lower gastro-intestinal tract series
Single or double contrast enema
What is a barium enema?
The aim of this investigation is to visualise the large bowel or colon with the use of X-rays and a contrast medium called barium sulphate. The contrast medium is instilled into the colon after the placement of a rectal tube or catheter. The contrast medium coats the lining of the large bowel, which enables visualisation of the bowel on radiographs. This investigation is done for similar reasons as a colonoscopy and in most clinical situations, the two investigations can be complementary. The bowel detail that can be seen in this investigation makes it an extremely useful aid in diagnosing simple and complicated diseases affecting the large bowel.
Patients complaining of changing bowel habits, blood or mucus in the stools, constipation, abdominal pain, unexplained weight loss or abdominal distention could have large bowel disease. These patients can be evaluated with the aid of a barium enema.
It is used to diagnose large bowel polyps, diverticula, cancers, narrowing causing obstruction and inflammation of the large bowel.
How should I prepare?
It is essential that the large bowel is cleared from stool or faecal material before the study is performed. This is achieved by undergoing bowel preparation. This would entail drinking a liquid solution that acts as a laxative and clears the large bowel. This is done from the day before the investigation. Instructions on how this is to be done will be given to the patient by the radiology department, together with the solution that needs to be taken. This can be done at home and the patient need not be hospitalised for this. The patient should be starved from the night before the examination and not eat or drink anything on the day of the investigation.
Bowel content present in the large bowel will influence the investigation and can lead to difficulties in visualisation of the normal lining of the colon and even lead to confusion of possible disease in a normal colon. No sedation or anaesthetic is used during the investigation, so the patient can drive themselves to and from the hospital and presume their normal daily activities.
How is the procedure performed?
The investigation is performed in the radiology unit by a radiologist and radiographer. The entire procedure will be explained by the radiologist on the day of the investigation. Before the start of the test, an injection can be given to the patient intra-muscularly. The reason for this would be to slow down the normal bowel movement. This will allow better visualisation of the bowel walls. The patient will then be laid on an X-ray bed after which a rectal catheter with a small balloon will be inserted. The catheter will be used to install the barium into the large bowel. This is not painful to the patient. A full sensation of the stomach might be experienced by the patient, which might be slightly uncomfortable.
As the contrast medium is installed slowly into the large bowel, the patient will be asked to change position. The X-ray bed will also move. This will allow the contrast medium to travel throughout the entire length of the large bowel. During this, X-rays will be taken of the large bowel filled with the contrast medium.
Some air can also be inflated through the rectal catheter with the contrast medium. This will distend the collapsed segments of the large bowel, making sure that all segments of the bowel are very well seen. Diseased segments of the bowel can therefore not be missed.
At the end of the examination, the contrast medium and air is allowed to run out through the catheter. The X-rays taken during the study are then evaluated for any abnormalities to the large bowel lining.
A small risk of rupturing the bowel exists if the study is not performed under careful supervision, or if the bowel is extremely diseased.
Pregnant females should inform the radiologist or radiographer of their pregnancy and should not undergo this study. X-rays do pose a potential risk to the foetus.
X-rays do have a potential risk of inducing certain cancers, but the chances of this is significantly reduced by controlling the amount of X-ray exposure to the patient, high quality equipment and various protective/shielding methods used.
Limitations of the procedure
If the bowel preparation is not adequate, the results from the study can be influenced or even make it impossible to continue with the study. The study does not allow visualisation of the small bowel or diseases outside the bowel wall.