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Excerpt
Contrasted radiographic techniques may yield important information about several of the diagnostic issues that arise in the patient with suspected intestinal obstruction. One use is to clarify whether or not obstruction is present when the abdominal films and clinical evaluation are equivocal. Another is to clarify whether intestinal obstruction is partial or complete since this will have important implications in management. A third use is to identify the possible cause of obstruction. Finally, these techniques give additional information that may clarify whether or not ischemic changes are occurring.
The role of contrast radiographic techniques in identifying obstruction in patients with an equivocal clinical presentation is well established. 1,2 Computed tomography with contrast and small bowel radiography with either barium or oral water soluble contrast can differentiate obstruction from ileus.
Contrast radiography is also fairly accurate in determining partial versus complete intestinal obstruction. 1,2 Computed tomography with contrast will identify a transition point with decompressed distal bowel. Small bowel follow-through will likewise demonstrate a point of partial obstruction with movement of contrast beyond the point of narrowing if the obstruction is partial. Depending on the level of obstruction, contrast studies using barium may give more mucosal detail and more clearly delineate the anatomy. The relative importance of potential complications with these agents (e.g. aspiration of water-soluble contrast and barium peritonitis) is not clear.
These techniques can also provide additional information about whether or not ischemic changes are developing in the bowel. Computed tomography is particularly valuable in this regard, as it may show earlier signs of ischemia than other contrast techniques or plain abdominal x-rays. The presence of pneumoperitoneum, bowel wall changes, mesenteric inflammation, and intraabdominal fluid collections can be ascertained.
A final benefit of these techniques in diagnosis would be identifying a potential cause for the obstruction or ileus. Computed tomography may show other evidence of disease, such as in the adjacent mesentery, or other organs, such as the liver or pancreas. Furthermore, CT will give additional information about the colon, such as thickening suggestive of inflammatory bowel disease, even if contrast does not reach this level.
In clinical studies, CT with contrast has proven the most versatile in assisting in these diagnostic aspects of intestinal obstruction. Peck et al. 2 studied 55 patients having both computed tomography and small bowel follow-through studies to evaluate possible small bowel obstruction. They found that CT was significantly more sensitive (90% versus 50%) and had similar specificity (57% versus 57%) compared with small bowel follow-through. Computed tomography was particularly accurate in identifying high-grade partial obstruction and complete bowel obstruction. When CT was inconclusive, the small bowel follow through clarified a low-grade partial obstruction in 6 additional patients, which improved the accuracy from 81% to 93%. Thus, CT is the initial procedure of choice and is superior for detecting the cause of obstruction and the presence of strangulation. Furthermore, it can be obtained fairly quickly and does not need the constant attention of a radiologist.
A more controversial role for radiographic materials has been a therapeutic one.
