Barium Enema Health Article

Definition

A barium enema (or BE), also known as a lower GI (gastrointestinal) series, is a radiographic exam used to view the large intestine. There are two types of barium enemas: the single-contrast technique where just barium sulfate is injected into the rectum to outline the large intestine; and the double-contrast (or "air contrast") technique in which barium and air are injected into the rectum.

Purpose

The purpose of a barium enema is to demonstrate the anatomy and morphology of the large intestine. The large intestine frames the abdomen and is divided into six sections. These include the rectum, sigmoid colon, descending colon, transverse colon, ascending colon, and cecum.

A barium enema may be performed for a variety of reasons, including abdominal pain or a change in bowel habits such as diarrhea or constipation, as well as a change in the caliber (size) of the stools. This exam is also requested when parasites, blood, mucus, or pus are found in the stools. Occult (hidden) blood found in the stools and anemia may be an indication of intestinal bleeding due to ulcers, inflammatory disease, or a cancerous lesion. Doctors may also order this exam as a screening tool for patients with a history of polyps (pre-cancerous growths extending outward from a mucous membrane) or a family history of colorectal cancer.

A barium enema may also be requested when the large intestine was not completely visualized during a

colonoscopy (examination of the large intestine with a fiber-optic tube) or when a sigmoidoscopy is done, which only partially visualizes the colon. Sometimes a barium enema may be used as a treatment for intussusception (telescoping of one section of the bowel into another causing obstruction). This is a rare disorder occuring most often in young children, but when it occurs immediate action must be taken.

A barium enema may also be done to evaluate the remaining colon on colostomy patients. The barium is injected into the stoma (external drainage opening in the abdominal wall) instead of the rectum. A barium enema may be done if obstruction, perforation, or fistula formation is suspected.

Precautions

As with any radiographic procedure there is the risk of radiation. The x-ray technologist must always make sure there is no risk of pregnancy and that the least amount of films as possible are done. No lead shielding can be used since all the abdominal area must be visualized on the films.

Description

All patients must be changed into a hospital gown. All clothing is removed, including shoes and socks, since some leakage of the barium mixture can occur. In some departments disposable slippers are supplied. The x-ray technologist may take one preliminary view of the abdomen to determine how well the patient's bowel has been cleansed. Any retained fecal material can create false filling defects and mucosal abnormalities on the films. A single-contrast enema would usually be done on patients with a poor bowel preparation. After the films are taken and the patient has evacuated as much of the barium as possible air may be introduced into the large intestine and further films taken. This method takes longer and gives more radiation to the patient.

The patient will be instructed to lie on the left side on the x-ray table, and the radiography technologist will insert a lubricated enema tip into the rectum. The enema tips contain a small balloon which may be inflated to help the patient retain the barium. The patient may remain on their left side or turned prone (face-down) depending on the procedure and routine of the radiologist.

For a single-contrast barium enema, the barium sulphate solution is a thinner consistency but a larger amount is needed to completely fill the large intestine. High kilovoltage (100-125kvp) is used to get a good penetration of the barium filled colon, and it is important to take the films as quickly as possible since the patients are very uncomfortable when the bowel is completely distended. Routine films for a single contrast study include a supine and prone abdomen film as well as both obliques to see the hepatic and spenic flexures of the large bowel. The patient will completely evacuate the bowel and one more film, the post-evacuation film (PE) usually done AP (anteroposterior, or front–to–back) supine, will be taken.

In a double-contrast barium enema, a fine coating of thick barium is needed to outline the mucosal lining of the bowel. The patient will be placed prone so that gravity can assist the air in distributing the liquid around the large bowel. The patient is asked to turn over 360 degrees a few times during the exam to aid in the coating of the bowel. The patient is then placed upright, and more air is injected into the bowel so gravity again can assist in visualizing the large intestine. Patients may develop spasms of the bowel during this exam, so the radiologist may give the patient a glucagon injection to relax the large bowel. This injection should not be given to patients with a history of glaucoma and can cause temporary double-vision in these patients.

The radiologist will take spot-films under fluoroscopy of each segment of the bowel but most of the films will be made following the procedure by the x-ray technologist. Since less barium is used along with some air, less kilovoltage (90-100kvp) is needed to achieve a high contrast x-ray of the large intestine. The usual AP and PA (posteroanterior) abdomen films will be done as well as the two oblique views of the abdomen. An upright film may be done as well depending on the routine of the radiologist. The most important films for the double-contrast exam are the two lateral decubitus films. The patient is placed on a large cushion or sponge and turned completely onto one side. A stationary grid is placed next to the patient and the x-ray tube is turned 90 degees. This film allows the air to rise to the upper surface of the abdomen so that the air along with the thin coating of barium creates a detailed visualization of the intestinal lining. This is extremely important when looking for small polyps, cancers, and ulcerations of the bowel. Films of both sides are always taken.