The double-contrast enema: myths and misconceptions

Radiologic imaging modalities in the diagnosis and management of colorectal cancer

Colorectal carcinoma poses a serious public health threat. Detection in its early stages in the best predictor for long-term survival, which is the impetus for population-based screening programs. We believe that full-colon imaging by either DCBE or colonoscopy is necessary for colon cancer screening because flexible sigmoidoscopy, even if perfect, only detects 50% to 60% of colon cancers, a rate far worse than even the worst rate reported for single-contrast barium enema. Screening for colon cancer with flexible sigmoidoscopy is equivalent to performing a "left" mammogram for the detection of breast cancer. The role of CT colonography is still to be determined. When confronted with a symptomatic patient, barium enema is applied in conjunction with CT to detect primary colorectal carcinoma, to differentiate it from other benign and malignant processes involving the colon, and to assess for disease extent before surgery in selected high-risk patient populations. Pelvic MRI may be useful in the preoperative assessment of patients with rectal carcinoma as a means for assisting surgical planning. CT, MRI, and barium enema are used in postoperative follow-up for detecting local recurrence and distant spread. In response to known difficulty in discriminating between normal postoperative changes and tumor recurrence and in determining the nature of certain liver lesions, FDG-PET has been approved for the detection and localization of recurrent colorectal cancer in patients with rising CEA levels and indeterminate findings on standard imaging studies. Given its current promise of offering high sensitivity, specificity, and accuracy, the indications for PET may well expand in the future, but its final role in still to be determined.

Double-contrast barium enema examination technique

This review article presents the principles for performing a safe, comfortable, and accurate double-contrast barium enema examination. The procedure is a flexible examination in which the fluoroscopist interacts with the patient, the controls of the fluoroscope, and the image on the television monitor. During a double-contrast examination, images of the colon are created by manipulating the patient, the barium pool, and the amount of air insufflated into the rectum. Fluoroscopy is essential for guiding the radiologist to obtain spot images with adequate technical factors. The fluoroscopist analyzes the luminal contour, the barium-coated mucosal surface en face, and the barium pool to detect abnormalities in the colon. With careful technique, a high-quality examination can be performed in most patients.

Hydrosonography in the evaluation of colorectal polyps

Prewarmed saline enemas and transabdominal ultrasound (hydrosonography) were used to evaluate 17 consecutive children with rectal bleeding before colonoscopy. Twelve patients with polyps were identified (10 by ultrasound, 10 by endoscopy): these included multiple hyperplastic polyps (1), multiple polyps (1), solitary polyps (9), and pseudopolyps (1). Ultrasound identified 11 polyps in 10 patients, missing two patients with small polyps less than 0.5 cm in diameter. The polyps were hyperechoic ovoid masses fixed to the colonic wall, with a stalk (7), submucosal infolding (5), and intraluminal floating (5). There was one false positive. Colonoscopy was refused by one patient and failed to reach beyond the distal sigmoid in another following previous surgery for malrotation. Colonoscopy was superior in identifying finer mucosal detail (colitis, ulcers, proctitis, anal fissure) and in detecting smaller polyps (sessile polyps, hyperplastic polyps). Hydrosonography of the colon is a simple, relatively non-invasive procedure that provides an alternative, radiation-free examination of the whole colon before colonoscopy. It is complementary to colonoscopy in the management of rectal bleeding in children.

False-negative barium enema in patients with sigmoid cancer and coexistent diverticula

The false-negative rate of barium enema examinations for the recognition of polypoid sigmoid cancer was evaluated in 167 patients with histologically proven carcinoma. The cases were classified according to the coexistence of sigmoid diverticula. In patients with less than 15 diverticula, 3.1% of lesions were missed, while in those with more than 15 diverticula, 20.4% of tumors were undetected. The overall error rate was 7.2%. Extensive diverticulosis is an important factor limiting the sensitivity of barium enema examinations for the evaluation of sigmoid masses.

Manometrically guided colon insufflation during double-contrast barium enemas

The double-contrast enema's potential for high accuracy depends in part on consistently good inflation of the colon. However, optimal inflation is often not obtained because of deflation during filming, underinflation because of fear of perforating the colon, or patient discomfort. To help meet the dual requirements of ensuring consistently good bowel inflation while avoiding over-inflation, we have designed a modified insufflator which incorporates a manometer and allows accurate readings of intraluminal large-bowel pressures during or following insufflation. In more than 3000 examinations using this method we have experienced no complications.

Radiologic manifestations of the syndrome of neurocrest and colonic tumors

This report describes the radiologic findings in the recently described syndrome of multiple colonic polyps and malignant tumors of neurocrest origin. One patient had multiple endocrine neoplasia syndrome type 11B with malignant medullary thyroid carcinoma, another had malignant pheochromocytoma, and the third had malignant carcinoid tumor. All patients had multiple colonic tubular or tubulovillous adenomas. In 2 patients, there were 8 sessile or pedunculated polyps distributed throughout the colon. In the patient with multiple endocrine neoplasia syndrome type 11B, the colon was carpeted with small polyps, 2-6 mm in size.

Combined use of double- and single-contrast barium enema in the evaluation of suspected colonic disease

Although controversy has surrounded the use of single- and double-contrast barium enemas for many years, a growing opinion exists that these studies are complementary, each possessing advantages in different clinical settings. We have found that when interpretation of double-contrast studies is difficult because suspected abnormalities are subtle or because technical quality of examinations is less than ideal, single-contrast enemas can be helpful. We have been able to obtain high-quality single-contrast studies using low-viscosity, low-density barium suspensions administered immediately following evacuation after initial air contrast evaluation.

Radiologic spectrum of rectal carcinoid tumors

Radiographs of 12 carcinoid tumors of the rectum were reviewed and compared with pathologic findings. There was a good correlation between the radiologic and pathologic findings with respect to tumor invasion and extent. Nine tumors that radiologically presented a smooth round defect less than 2.0 cm in diameter did not invade the muscular layer and did not metastasize. Three tumors that presented a deep crater with an irregular edge greater than 2.0 cm were found to have invaded the muscular layer and metastasized to the lymph nodes or the liver. The double-contrast enema showed an excellent detection rate; no lesion was missed by it.

Predictive value of a diagnosis of colonic polyp on the double-contrast barium enema

The positive predictive value of a diagnosis of colonic polyp on the double-contrast barium enema was determined by analyzing 160 polypoid lesions reported in 105 patients. Of the 160 polyps, 139 were confirmed by endoscopy, surgery, or repeat barium enema for a positive predictive value of 87%. Twenty-one lesions were not confirmed despite repeat endoscopy, repeat barium enema, review of the original study, or surgery, giving a false positive rate of 13%. The individual false positive error rates of 5 radiologists ranged from 8% to 26%. False positive errors were due to stool, diverticula, air bubbles, misinterpretation of the ileocecal valve, and haustration. Many of the false positive errors appeared to have been avoidable if the original examination had been more meticulously interpreted.

Colon cleansing regimens. A clinical study in 1200 patients

The purgative effect of bisacodyl, anthraquinone glycosides (Cascara), and sodium picosulfate, alone or in combination with a saline purge and a tap water enema, was studied in 1200 patients. The cleansing effect was scored with regard to retained fecal residue evident on double-contrast studies of the colon. The combination of a contact laxative and a saline purge produced good cleansing effect in 52%-80% of the patients. With an additional tap water enema given 1 hour before the colon examination, however, 96% of the colons were clean. The taste and the effects of the cleansing systems were tolerated favorably by more than 90% of the patients. However, 17% reported restriction in work capacity on the day of bowel cleansing.

Reliability of barium enema in detecting colonic neoplasia

Three hundred and seven unselected patients were examined by double contrast barium enemas. Twenty-four patients (7.8%) had carcinomas; 11 patients (3.6%) had polyps; six patients (2%) had possible polyps, not confirmed by colonoscopy; and in four patients (1.3%) the radiological findings were misleading or wrong. No carcinoma was missed by barium enema X-ray examination, to be diagnosed by other means. Two patients had radiological lesions, not demonstrable endoscopically, but confirmed surgically. Extensive follow-up of 286 patients (93.2%) revealed only one subsequent case of carcinoma. The shortcomings of colonoscopy are briefly discussed. It is recommended that barium enema examination precede colonoscopy in the investigation of suspected large bowel neoplasia, and that both be used alternately to screen high-risk patients.

Gallium-67-citrate scintigraphy in ulcerative colitis

Gallium-67-citrate scanning was performed in 9 patients with ulcerative colitis. In all patients there was good correlation between the regional uptake of gallium and the extent and activity of disease. In 2 patients the scans were positive during an acute exacerbation and reverted to normal or near normal during clinical remission. In one patient in whom the colon was resected because of toxic dilatation, good correlation was found between pathologic and scintigraphic examinations. During the acute attack of ulcerative colitis, when colonoscopy or barium enema may be contraindicated, gallium scanning may be a noninvasive means of assessing the extent of colonic involvement. It may also be an alternative means of following the clinical course of the disease.

Causes of error in gastrointestinal radiology. II. Barium enema examination

A study of causes of error on barium enema examinations is reported. There were 144 patients with 189 inflammatory and neoplastic lesions of the large bowel examined endoscopically and with a preceding barium enema. Twelve lesions were not reported radiologically, a false negative error rate of 6.3%. Radiographic errors included 11 polyps and 1 sigmoid carcinoma. Causes for these errors were analyzed and classified into perceptive, technical, or combined categories. Ten lesions were visible in retrospect. Five lesions, clearly visible but not noted, were due to perceptive error. Five other lesions, poorly visible due to faulty studies, represented combined error. Two lesions could not be identified and represented purely technical failure. All unreported lesions were distal to the splenic flexure with the majority located in the sigmoid colon.

Extent of inflammatory lesions in ulcerative colitis assessed by radiology, colonoscopy, and endoscopic biopsies

Radiography of the colon with double-contrast technique was performed directly after total colonoscopy with multiple biopsies in 50 patients with ulcerative colitis. In two-thirds of the series the inflammatory lesions were found to be more widespread at colonoscopy than on radiography. Signs of colitis in an even larger part of the bowel were found on examination of the biopsies in half of the cases. The distribution of characteristic inflammatory changes seen at colonoscopy was also studied. The frequency of the lesions was found to be relatively low in the rectum and highest in the descending and sigmoid parts of the colon.

The extent of successful colonscopy: its implication for the radiologist

Records of 230 colonoscopies were reviewed to determine the success in viewing the entire colon and the extent of the colon viewed when colonoscopy was incomplete. It was found that colonoscopy was complete to the cecum or ileum in 57% of studies, and that an average 63.8% of the colon was viewed during incomplete studies. Overall, 84.4% of the combined length of all colons examined was successfully viewed. The significant numbers of incomplete colonoscopies suggest that colonoscopy and the barium enema examination must remain complementary for maximum detection of colon lesions.

Double-contrast artifacts

With the increasing use of double-contrast technique in radiological evaluation of the gastrointestinal tract, certain artifacts peculiar to this mode of examination need to be identified. These artifacts arise because of: (a) the characteristics of the barium suspensions used for double-contrast studies; (b) the see-through effect obtained on double-contrast studies whereby opacities lying in front of or behind the organ being examined may simulate pathologic lesions; (c) infolding of the mucosa which may simulate pathology; (d) extraneous or foreign material which is frequently detected and must be differentiated from intrinsic disease; (e) certain anatomical structures such as the cardia, pylorus, and retrogastric structures which are seen with unusual clarity and detail and which, in some cases, may simulate pathology. In general, these artifacts may simulate diffuse superficial ulceration, discrete ulceration, or polypoid lesions. Familiarity with the double-contrast technique and an understanding of these artifacts will help to avoid diagnostic errors.

Costs of gastrointestinal examinations: a comparative study

The costs of performing four major gastrointestinal examinations were studied and compared: single-contrast and double-contrast upper gastrointestinal series, and single-contrast and double contrast barium enema. A total of 1,725 examination records were reviewed for the number of films expended, room occupancy time, and physician involvement time, and the costs of the studies determined. The data indicated a large and significantly increased time and expense required for the double-contrast barium enema over the single-contrast barium enema. A relatively small increment was found in the cost performing the double-contrast upper gastrointestinal series over the single-contrast study.

Aphthoid ulcers in Crohn's colitis

Aphthoid ulceration is a strong indication and the earliest radiographic sign of Crohn's colitis. These small discrete ulcers were found by double contrast barium enema examination in 40 out of 91 patients with Crohn's colitis. Seen en face each ulcer appears as a central fleck of barium surrounded by a translucent halo set amidst a patch of normal mucosa. Their detection gives a more accurate assessment of the extent of disease. This information is required in order to plan medical or surgical treatment and can only be provided by meticulous double contrast examination or colonoscopy. Aphthoid ulceration has been demonstrated prior to the onset of bowel symptoms, and several years before the advent of severe colonic disease. The appearance of aphthoid ulcers in established quiescent disease has been observed to herald a relapse. The radiographic demonstration of the evolution of ulceration, which is illustrated, closely reflects what is seen on macroscopic examination of excised specimens and explains the characteristic patchiness and discontinuity of disease.