A barium enema is a rectal injection of barium contrast. This coats the lining of the colon and rectum and X-ray films are obtained under fluoroscopic control. Air introduced into the large bowel may be used to give a double-contrast technique. Barium enemas are performed less often than in the past because of the increasing use of colonoscopy and CT colonography.
A small bowel barium enema refers to the use of a specially designed tube passed nasally and into the duodenojejunal flexure under fluoroscopic control, after which dilute barium is infused via the tube until it reaches the terminal ileum in continuous flow. It is used to investigate suspected small bowel disease (eg, Crohn's disease, lymphoma) and malabsorption (eg, coeliac disease). It is an unpleasant procedure for the patient and is often now replaced by CT or ultrasound where possible.
This rest of this article refers to barium enema as used in the large bowel.
- To assess the anatomy of the large bowel and occasionally the terminal ileum. Abnormalities detected include tumours (benign or malignant), ulcers, diverticulae and thickening of the lining of the colon or rectum.
- A barium enema is not reliable for the diagnosis of rectal pathology.
Indications for barium enema as advised by the Royal College of Radiologists
- Change of bowel habit to looser stools with or without rectal bleeding persistent for six weeks; suspected or possible colorectal neoplasia. (Colonoscopy is the first-line investigation but barium enema is an alternative. Barium enema has a 22% rate of new or missed colorectal tumours over three years following the procedure, compared with 2-6% with colonoscopy.Smaller tumours, particularly those without circumferential involvement, are those most likely to be missed by barium enema.)
- Chronic or recurrent lower gastrointestinal blood loss; only if endoscopy (initial investigation of choice) is not possible.
- Long-term follow-up of inflammatory bowel disease of colon; barium enema has a limited role after complex surgery and in the evaluation of fistulae. Colonoscopy is more reliable in identifying complications - eg, dysplasia, stricture and carcinoma.
- Acute large bowel obstruction; water-soluble studies with contrast enema can confirm diagnosis and level of obstruction, and may indicate the likely cause.
- Conservative treatment with barium, air or saline enema is often effective in children who present with intussusception, unless diagnosis and treatment are delayed.
- Barium enema may be effective in reducing large bowel volvulus in children but resection of the involved segment and primary anastomosis is the definitive treatment.
- Refractory bleeding colonic diverticulae: high-dose barium enema is as effective as endoscopic haemostasis for the prevention of recurrent diverticular bleeding.
Cautions and possible complications
- Barium enema is uncomfortable for the patient and requires good patient mobility and co-operation. More patients find the procedure embarrassing than do patients having colonoscopy or CT colonography. It should not be requested for frail elderly patients unless there is a clear indication.
- A rectal examination or sigmoidoscopy is essential to avoid missing abnormalities.
- Radiation exposure is relatively low.
- The barium enema is a relatively safe procedure. Rare complications include:
- Bowel perforation:
- Occurs in between 2-4/10,000 patients, usually related to iatrogenic trauma from catheter placement.
- Pre-existing diseased bowel is more likely to perforate than normal healthy bowel.
- The mortality rate associated with intraperitoneal perforation is high due to the combination of barium and bacterial load which causes acute peritonitis and shock.
- Barium impaction - causes large bowel obstruction.
- Water intoxication.
- Allergic reactions.
- Cardiac arrhythmias.
Prevention of endocarditis
Currently, antibacterial prophylaxis is not recommended for the prevention of endocarditis in those undergoing radiological procedures involving their lower gastrointestinal tract. Any infection in patients at risk of endocarditis should be investigated and treated promptly to reduce the risk of endocarditis. Patients at risk of endocarditis should be educated as to the signs of infective endocarditis and told to seek expert advice if these occur.
- Allergy to the latex balloon on the tip of enema tube (rare).
- Severe rectal inflammation or recent rectal biopsy (delay for seven days after a full-thickness biopsy). Patients with active colitis should not have a barium enema.
- Acute gastrointestinal bleeding (precludes the use of angiography).
- Pregnancy: X-rays of the abdomen and pelvis should be avoided.
Preparation and procedure
- Low-residue diet for three days prior to the procedure and laxatives 24 hours before.
- Nil by mouth after midnight.
- Bowel washout immediately prior to procedure.
- Antispasmodic (eg, hyoscine butylbromide) may be given to minimise spasm.
- The patient lies on their side and an enema tube is inserted into the rectum.
- Barium is run into the colon under gravity and radiographs are taken. Air is also then introduced into the rectum for a double-contrast barium enema.
Further reading and references
; Royal College of Radiologists
; Rates of new or missed colorectal cancer after barium enema and their risk Am J Gastroenterol. 2008 Dec103(12):3142-8. Epub 2008 Oct 1.
; Effectiveness of high-dose barium enema filling for colonic diverticular bleeding. Colorectal Dis. 2011 Aug13(8):896-8. doi: 10.1111/j.1463-1318.2010.02350.x. Epub 2010 Jun 10.
; Patient experiences of colonoscopy, barium enema and CT colonography: a Br J Radiol. 2009 Jan82(973):13-9. Epub 2008 Sep 29.
; Rectal perforations after barium enema: a review. Dis Colon Rectum. 2006 Feb49(2):261-71.
; Colonic perforation during barium enema in a patient without known colonic Cases J. 2009 Aug 142:6716.
; NICE Clinical Guideline (March 2008)