gastrointestinal disorders
X Ray and Other Imaging Contrast Studies of the Gastrointestinal Tract
X Ray Contrast Studies of the Abdomen
X-ray and other imaging contrast studies visualize the entire gastrointestinal tract from pharynx to rectum and are most useful for detecting mass lesions and structural abnormalities (eg, tumors, strictures). Single-contrast studies fill the lumen with radiopaque material, outlining the structure. Better, more detailed images are obtained from double-contrast studies, in which a small amount of high-density barium coats the mucosal surface and gas distends the organ and enhances contrast. The gas is injected by the operator in double-contrast barium enema, whereas in other studies, intrinsic gastrointestinal tract gas is adequate. In all cases, patients turn themselves to properly distribute the gas and barium. Fluoroscopy can be used to monitor the progress of the contrast material. Either video or plain films can be taken for documentation, but video is particularly useful when assessing motor disorders (eg, cricopharyngeal spasm, Achalasia ). The main contraindication to x-ray contrast studies is Suspected perforation Acute Perforation of the Gastrointestinal Tract is a contraindication because free barium is highly irritating to the mediastinum and peritoneum; water-soluble contrast is less irritating and may be used if perforation is possible. Older patients may have difficulty turning themselves to properly distribute the barium and intraluminal gas. Patients having upper gastrointestinal x-ray contrast studies must have nothing by mouth (npo) after midnight. Patients having barium enema follow a clear liquid diet the day before, take an oral sodium phosphate laxative in the afternoon, and take abisacodylsuppository in the evening. Other laxative regimens are effective. Complications of abdominal x-ray contrast studies are rare. Perforation can occur if barium enema is done in a patient with Toxic colitis . Barium impaction may be prevented by postprocedure oral fluids and sometimes laxatives. A barium enema can be done as a single- or double-contrast study. Single-contrast barium enemas are used for potential Intestinal Obstruction , A small-bowel meal is done by using fluoroscopy and provides a more detailed evaluation of the small bowel. Shortly before the examination, the patient is givenmetoclopramide20 mg orally to hasten transit of the contrast material. An upper gastrointestinal examination is best done as a biphasic study beginning with a double-contrast examination of the esophagus, stomach, and duodenum, followed by a single-contrast study using low-density barium. Glucagon0.5 mg IV can facilitate the examination by causing gastric hypotonia. , which functions as a double-contrast agent that enhances visualization of the small-bowel mucosa. Enteroclysis has largely been replaced by CT enterography and MR enterography . 