Reliability of barium enema in detecting colonic neoplasia

Iatrogenic perforation at colonic imaging

AIM

Adequate colonic imaging is generally an invasive procedure with attendant risks, particularly perforation. Endoscopy, barium enema and computed tomographic colonography (CTC) are the main techniques for investigating patients with symptoms of, or screening for, colorectal cancer. The potential complications of these investigations have to be weighed against the benefits. This article reviews the literature on the incidence, presentation and management of iatrogenic colonic perforation at colonic imaging.

METHOD

A literature review of relevant studies was undertaken using PubMed, Cochrane library and personal archives of references. Manual cross-referencing was performed, and relevant references from selected articles were reviewed. Studies reporting complications of endoscopy, barium enema and CT colonography were included in this review.

RESULTS

Twenty-four studies were identified comprising 640,433 colonoscopies, with iatrogenic perforation recorded in 585 patients (0.06%). The reported perforation rate with double-contrast barium enema was between 0.02 and 0.24%. Serious complications with CTC were infrequent, though nine perforations were reported in a case series of 24,365 patients (0.036%) undergoing CTC.

CONCLUSION

Perforation remains an infrequent and almost certainly under-reported, complication of all colonic imaging modalities. Risk awareness, early diagnosis and active management of iatrogenic perforation minimizes an adverse outcome.

Critical analysis of the performance of double-contrast barium enema for detecting colorectal polyps > or = 6 mm in the era of CT colonography

OBJECTIVE

The purpose of our study was to perform a meta-analysis comparing the performance of double-contrast barium enema (DCBE) with CT colonography (CTC) for the detection of colorectal polyps > or = 6 mm using endoscopy as the gold standard.

MATERIALS AND METHODS

Prospective DCBE and CTC studies were identified. Percentages of polyps and of patients with polyps > or = 10 mm and 6-9 mm were abstracted. The performance of DCBE versus CTC was determined by separately evaluating each technique's performance versus that of endoscopy, and contrasting the techniques. The I-squared statistic and Fisher's exact test were used for heterogeneity, the Cochran-Mantel-Haenszel and the Kruskal-Wallis tests for correlation, and the A(z) test for comparing pooled weighted estimates of performance.

RESULTS

Eleven studies of DCBE (5,995 patients, 1,548 polyps) and 30 studies of CTC (6,573 patients, 2,348 polyps) fulfilled inclusion criteria. For polyps > or = 10 mm, a 0.121-per-patient sensitivity difference favored CTC (p < 0.0001; DCBE, 0.702 [95% CI, 0.687-0.715]; CTC, 0.823 [0.809-0.836]). For polyps > or = 10 mm, a 0.031-per-polyp sensitivity difference favored CTC (p < 0.0001; DCBE, 0.715 [0.703-0.726]; CTC, 0.746 [0.735-0.757]). For polyps > or = 10 mm, a specificity difference of 0.104 favored CTC (p = 0.001; DCBE, 0.850 [0.847-0.855]; CTC, 0.954 [0.952-0.955]). DCBE was also significantly less sensitive for 6- to 9-mm polyps (p < 0.001).

CONCLUSION

DCBE has statistically lower sensitivity and specificity than CTC for detecting colorectal polyps > or = 6 mm.

Screening for colon cancer

Colorectal cancer screening reduces mortality in individuals 50 years and older. Each of the screening tests currently available has advantages and limitations, and there is no consensus as to which test or combination of tests is best. What is clear, however, is that the rates of colorectal cancer screening remain low. This review summarizes the clinical evidence supporting colorectal cancer screening in the average risk population and in high risk groups, discusses the advantages and disadvantages of the available screening tests, outlines the currently recommended guidelines for screening based on risk category, and discusses new and emerging technologies for colorectal cancer screening.

Screening for colorectal cancer: the cost to find an advanced adenoma

OBJECTIVE

Cancer Care Ontario has recommended a program to screen for colorectal cancer using fecal occult blood testing (FOBT). Patients who test positive on FOBT will require further investigation. We examined the cost of finding an advanced adenoma in these patients using four different strategies.

METHODS

Using decision analysis software (DATA 3.5, TreeAge Software, Boston, MA), we considered four strategies for evaluating patients referred for a positive FOBT: 1) flexible sigmoidoscopy to the splenic flexure, 2) flexible sigmoidoscopy with air contrast barium enema (ACBE), 3) virtual colonoscopy, and 4) colonoscopy. If an adenoma was found in any of the first three methods, colonoscopy and polypectomy were performed. An advanced adenoma was defined as a villous adenoma, tubular adenoma > or = 10 mm, high grade dysplasia, or cancer. Values for probabilities, test characteristics and costs ($CDN) were estimated from a MEDLINE literature review, local costs, and OHIP fee codes. Patients with adenomas identified as well as direct medical costs from a third party payer perspective were calculated.

RESULTS

Assuming a probability of adenoma of 16.9%, the cost for each strategy (compared to no investigation) was as follows: flexible sigmoidoscopy to the splenic flexure, $226; flexible sigmoidoscopy with ACBE, $424; virtual colonoscopy, $597; and colonoscopy, $387. The cost to clear a patient of adenoma(s) was $1,930, $2,840, $3,681, and $2,290, respectively. Despite being most cost-effective, the sigmoidoscopy strategy was predicted to detect 69% of cases of advanced adenomas. The radiological strategies would be less expensive if ACBE cost less than $115 or virtual colonoscopy cost less than $291. The colonoscopy strategy was more cost-effective if the probability of an adenoma was > or = 33.5%. When the incremental costs were considered to investigate 1000 patients, virtual colonoscopy and sigmoidoscopy with ACBE were both more costly then colonoscopy, and neither detected as many cases of advanced adenomas.

CONCLUSION

Improved access to colonoscopy seems to be the preferred approach to deal with increased referrals.

The double contrast barium enema: a retrospective single centre audit of the detection of colorectal carcinomas

AIM

To determine retrospectively the sensitivity and specificity of the double contrast barium enema (DCBE) as performed in one institution for the detection of colorectal carcinoma.

SUBJECTS AND METHODS

Eight hundred and eighty barium enema reports were reviewed of consecutive adult patients who underwent DCBE and also had hospital case notes with a minimum follow up of two years, a later diagnostic colonoscopy, or operative and histological findings.

RESULTS

Seventy-four true positive cases of colorectal carcinoma diagnosed at DCBE were confirmed at surgery and histological examination. There were four false positive diagnoses of carcinoma at DCBE. Eight false negative cases at DCBE were demonstrated within a two-year follow-up period. The sensitivity of the DCBE for detecting colorectal carcinoma was therefore 90.2% and the specificity was 99.5%.

CONCLUSION

DCBE is a sensitive and highly specific investigation for the detection of colorectal carcinoma.

Cost-effectiveness of colorectal cancer screening

PURPOSE

To determine the most cost-effective colorectal cancer screening strategy costing less than $100,000 per life-year saved and to determine how available strategies compare with each other.

MATERIALS AND METHODS

Standardized methods were used to calculate incremental cost-effectiveness ratios (ICERs) from published estimates of cost and effectiveness of colorectal cancer screening strategies, and the direction and magnitude of any effect on the ratio from parameter estimate adjustments based on literature values were estimated.

RESULTS

Strategies in which double-contrast barium enema examination was performed emerged as optimal from all studies included. In average-risk individuals, screening with double-contrast barium enema examination every 3 years, or every 5 years with annual fecal occult blood testing, had an ICER of less than $55,600 per life-year saved. However, double-contrast barium enema examination screening every 3 years plus annual fecal occult blood testing had an ICER of more than $100,000 per life-year saved. Colonoscopic screening had an ICER of more than $100,000 per life-year saved, was dominated by other screening strategies, and offered less benefit than did double-contrast barium enema examination screening.

CONCLUSION

Double-contrast barium enema examination can be a cost-effective component of colorectal cancer screening, but further modeling efforts are necessary.

Screening for colorectal cancer

Colorectal cancer is the third most commonly diagnosed cancer and the second leading cause of cancer deaths in the United States. Fortunately, both the incidence and mortality associated with the disease have declined during the past 2 decades. This is likely due, at least in part, to improved efforts at screening and more aggressive removal of adenomatous polyps. However, colorectal cancer screening is still generally underutilized. This article reviews the current status and future outlook for colorectal cancer screening, including a discussion of risk factors for the disease, its anatomic distribution, proposed mechanisms of development from adenomatous polyps, rationale for screening, and screening options. Published literature concerning the cost-effectiveness of colorectal cancer screening is also summarized. The article concludes with a discussion of the emerging consensus regarding the importance of and approaches to screening.

The role of the barium enema in the diagnosis of colorectal neoplasia

The recent interest in guidelines for colorectal cancer diagnosis, management and in screening has important implications for radiologists. The present article reviews the role of the barium enema in colorectal neoplasia diagnosis in symptomatic patients, and in the context of screening programmes.

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.

Importance of total colonoscopy in the diagnosis of colonic disorders

The need for colonoscopic examination of the whole colon was determined by evaluating the accuracy of a barium enema X-ray report with particular reference to the right colon. Long colonoscopies were performed on 108 patients. The reports of the barium enema X-ray examination in these patients were compared with the colonoscopy reports. Over all, the barium enema X-ray report was accurate in 47% of cases. The rate of false negative reports was 10% and that of false positive reports 43%. For lesions of the right colon, the barium enema X-ray report was accurate in only 32% of cases, with 68% false positive and 15% false negative reports. False positive reports of carcinoma or polyps result mainly from imperfect preparation. Of the eight right colonic lesions missed in the barium enema X-ray examination, five were polyps and one was carcinoma. Long colonoscopy, rather than short colonoscopy, or flexible sigmoidoscopy and barium enema X-ray examination, would be accompanied by the greatest diagnostic accuracy. Air-contrast barium enema X-ray examination and long colonoscopy together offer the best methods of diagnosis of occult lesions in the right colon.