Fecal occult blood testing. Problems, pitfalls, and diagnostic concerns

The diagnostic approach to the asymptomatic patient who has tested positive for fecal occult blood varies among clinicians. Colonoscopic evaluation is the procedure of choice in initiating the workup of patients 50 years of age and older. In younger patients, examination by sigmoidoscopy and barium enema using air for contrast (double contrast study) may be considered as an alternative to colonoscopy as the initial test. Evaluation of the upper gastrointestinal tract should be considered if a colonic source is not detected. The challenge in diagnostic test selection lies in choosing the most appropriate and cost-effective procedure for detecting disease, especially neoplastic lesions.     

Colorectal carcinoma: causes, diagnosis, and prevention

Colorectal carcinoma is the second leading cause of cancer death in the U.S. The risk for colon carcinoma increases after the age of 40 years. Because there is a very significant familial incidence of colorectal carcinoma, this is a major group of individuals who should be screened. The vast majority of colorectal carcinomas are associated with adenomatous polyps of the large intestine. Colonoscopy is the best procedure available to evaluate those at risk; the double-contrast barium enema and flexible sigmoidoscopy also play a significant role in diagnosis. Screening for occult blood in the stool is presently the best tool to evaluate groups for potential colorectal lesions. Although there are still significant problems with occult blood testing, it can account for a definite decrease in morbidity and mortality from colorectal carcinoma.     

Colorectal cancer screening

Colorectal cancer causes significant morbidity and mortality in the United States. The incidence of colorectal cancer increases at age 50, approximately. Risk factors that have been identified include a personal history of colorectal cancer or adenomas, a family history of colon cancer or adenomas, inherited colorectal cancer syndromes, and long standing inflammatory bowel disease. Several screening tests have been developed for colorectal cancer prevention. Surveillance strategy is based on an individual's colorectal cancer risk. This article reviews fecal occult blood testing, flexible sigmoidoscopy, colonoscopy, barium enema, and genetic testing.     

Flexible sigmoidoscopy as a screening procedure for asymptomatic colorectal carcinoma in patients with inguinal hernia

In patients about to have hernia repair, preoperative screening studies for early colorectal cancer using the rigid proctosigmoidoscope and barium enema have previously shown minimal cost effectiveness and poor patient acceptance. Flexible sigmoidoscopy may be more acceptable to patients and of greater diagnostic value. Between October 1980 and December 1983, 100 consecutive asymptomatic male surgical patients were examined using the Olympus 60 flexible proctosigmoidoscope. All patients were admitted for elective hernia repair. Age ranged from 21 to 88 years (mean 59.7). All patients with stool positive for occult blood on admission were excluded from this study. In addition, patients with any gastrointestinal symptoms, history of colorectal disease, or family history of colorectal polyps or carcinoma were excluded. Examinations were done under direct supervision of an attending surgeon (W.W. or C.S.C.). Of the 22 patients who had one or more benign polyps, three had villous adenomas. Two additional patients had carcinoma. Results of examination were completely normal in 63, while 13 patients were found to have hemorrhoids or diverticular disease. There were no complications and the procedure was well tolerated by all patients.     

Utility of flexible sigmoidoscopy as an adjunct to double-contrast barium enema examination

Background: There is controversy regarding the most appropriate investigation for suspected colorectal carcinoma. We offered these patients same-day flexible sigmoidoscopy (FS) and double-contrast barium enema (DCBE). Methods: We reviewed the results of 117 consecutive adult patients. All patients underwent FS followed by DCBE on the same day. The radiographs were reviewed by two of the authors who were blinded to the clinical information, flexible sigmoidoscopy reports, and the original DCBE report. Results: One hundred seventeen patients made up the study population. Thirty-four of the 117 patients had polyps and/or carcinoma. Three malignant tumours were detected by DCBE; one of these was also seen on FS, and the other two cancers were out of FS range. Fifty-three polyps were found by FS; nine were removed by biopsy prior to the enema examination. Of the 44 remaining polyps, DCBE failed to detect 87% of the 0–9-mm group and 67% of the >9-mm group. Ten polyps were seen only on DCBE; seven of these 10 were beyond the range of the sigmoidoscope, and the three remaining polyps were less than 5 mm. Conclusion: DCBE is insensitive in the detection of rectosigmoid polyps. FS should continue to be used as a complementary examination to DCBE in the investigation of suspected colorectal carcinoma. Received: 9 September 1996/Accepted: 8 January 1997     

A combined flexible sigmoidoscopy and double-contrast barium enema service: initial experience

Background: A service has been instituted offering a combined single-stage procedure of flexible sigmoidoscopy and double-contrast barium enema (FS/DCBE). The results have been reviewed in the first 80 patients to undergo this examination (45 male:35 female; mean age 61.4 years). Methods: Indications for investigation were abdominal pain or suspected diverticular disease (22 patients), altered bowel habit (19), rectal bleeding (17), iron deficiency anemia (6), and miscellaneous (16). FS was followed immediately by DCBE. Radiographs were reviewed by two radiologists unaware of the FS findings. Results: The extent of FS was to the proximal sigmoid or sigmoid descending junction in 45% of patients, proximal descending colon or splenic flexure in 12.5%, and mid or distal sigmoid in 37.5%. Biopsies were performed at FS in 26 patients (33%). In 67 (84%) of DCBEs the barium coating was assessed as satisfactory or better. FS yielded pathological findings not seen at DCBE in 21 patients (26%). DCBE demonstrated additional abnormalities within the range of the FS examination in 15 patients (19%), almost entirely due to its increased sensitivity for diverticular disease. Conclusion: FS/DCBE is feasible as a one-stage combined procedure. The quality of DCBE following FS is satisfactory, and the extra yield of FS and its potential for biopsy make the combined FS/DCBE a useful technique in the investigation of large bowel disease.     

Colorectal cancer: risk factors and recommendations for early detection.

Spurred by mounting evidence that the detection and treatment of early-stage colorectal cancers and adenomatous polyps can reduce mortality, Medicare and some other payors recently authorized reimbursement for colorectal cancer screening in persons at average risk for this malignancy. A collaborative group of experts convened by the U.S. Agency for Health Care Policy and Research has recommended screening for average-risk persons over the age of 50 years using one of the following techniques: fecal occult blood testing each year, flexible sigmoidoscopy every five years, fecal occult blood testing every year combined with flexible sigmoidoscopy every five years, double-contrast barium enema every five to 10 years or colonoscopy every 10 years. Screening of persons with risk factors should begin at an earlier age, depending on the family history of colorectal cancer or polyps. These recommendations augment the colorectal cancer screening guidelines of the American Academy of Family physicians. Recent advances in genetic research have made it possible to identify persons at high risk for colorectal cancer because of an inherited predisposition to develop this malignancy. These patients require aggressive screening, usually by lower endoscopy performed at an early age. In some patients, genetic testing can guide screening and may be cost-effective.     

Prevention and early detection of colorectal cancer.

Adherence to a low-fat, high-fiber diet and regular screening to detect and identify polyps at an early, more treatable stage may reduce deaths from colorectal cancer. Patients should be told that they can reduce their risk of colorectal cancer by increasing their intake of fruits, vegetables and whole grain cereals and decreasing their intake of fat. Although scientific controversy exists regarding the specific methods and intervals of screening for colorectal cancer, family physicians should adopt a regular approach to screening in their patients. In adults 50 years of age or older, annual fecal occult blood testing is recommended. If positive results are obtained, follow-up examination should be performed with either colonoscopy or flexible sigmoidoscopy plus air-contrast barium enema. Persons between 50 and 75 years of age may also benefit from screening with flexible fiberoptic sigmoidoscopic examination every three to five years.     

Submucous lipoma of the ileocaecal valve presenting as caecal volvulus

Caecal volvulus is a well described but unusual condition. We report here, a case of caecal volvulus in a 53-year-old Caucasian woman associated with intussuscepted submucous lipoma of the ileocaecal region. The imaging and pathology are presented. Submucous lipoma of the ileocaecal region is uncommon but well described. It can be mistaken as carcinoma of the ascending colon on barium enema and on computed tomography scan. The combination with caecal volvulus is a rare occurrence.     

Barium enema utilization within a defined geographic region: A survey

All 118 hospital-based radiology departments in Indiana (USA) responded to a survey of barium enema (BE) utilization. The percentage of community hospitals in Indiana using barium enema, both single contrast (SCBE) and double contrast (DCBE), for various indications was similar to that reported for major medical centers around the world (RF Thoeni and AR Margulis,Radiology, 167:7–12, 1988). The use of SCBE and DCBE did not differ between small and large hospitals, or between hospitals in small vs large communities. There was, however, wide variation among community hospitals in their overall use of either contrast technique. Barium enema was usually performed without antecedent sigmoidoscopy. However, 60% of Indiana hospitals perform BE on the same day as flexible sigmoidoscopy.The results indicate that the use of BE in community hospitals in Indiana is similar to that reported for major medical centers. Also like major medical centers, there is no consensus regarding many issues in the performance of BE.     

Endorectal surface coil MR imaging as a staging technique for rectal carcinoma: a comparison study to rectal endosonography

Background: Preoperative staging of rectal cancer is critical for guiding therapy and prescribing the most appropriate treatment option. The purpose of this investigation was to compare the accuracy of endorectal surface coil magnetic resonance imaging (ERSCMRI) with endosonography (EUS) in staging rectal lesions. Methods: Fourteen patients with rectal carcinoma, initially detected by barium enema or sigmoidoscopy underwent ERSCMRI and EUS. Subsequent resection of the lesions was performed, and the staging accuracies of these two modalities are compared. Results: MR T-staging agreement with pathologic T-staging was similar to that of EUS, but MR enabled more accurate identification of nodal involvement. Conclusion: ERSCMRI produced greater overall accuracy in staging for rectal carcinoma than did EUS. Received: 10 September 1998/Revision accepted: 10 February 1999     

Screening for colorectal cancer. Guidelines for choosing the appropriate test for each patient

The importance of screening for colorectal cancer has been established, but the decision about which test to use for each patient may seem less clear. In this article, Dr Wineman discusses assessment of colorectal cancer risk and the advantages and disadvantages of the fecal occult blood test, flexible sigmoidoscopy, double-contrast barium enema, and colonoscopy. Potential screening methods that could make regular colon examination more acceptable to patients also are presented.     

Recent developments in colorectal cancer screening and prevention

Colorectal cancer is a significant contributor to morbidity and mortality in the United States. Studies published in the early 1990s, showing that screening for colorectal cancer can reduce colorectal cancer-related mortality, led many organizations to recommend screening in asymptomatic, average-risk adults older than 50 years. Since then, however, national screening rates remain low. Several important studies published over the past four years have refined our understanding of existing screening tools and explored novel means of screening and prevention. The most important new developments, which are reviewed in this article, include the following: Additional trial results support the effectiveness of fecal occult blood testing in reducing the incidence of, and mortality from, colorectal cancer. New studies document the sensitivity of fecal occult blood testing, sigmoidoscopy, and double-contrast barium enema compared with colonoscopy. Cost-effectiveness models show that screening by any of several methods is cost-effective compared to no screening. Randomized trials show that calcium is effective but fiber is not effective in preventing reoccurrence of adenomatous polyps. Preliminary data suggest that nonsteroidal anti-inflammatory drugs may prevent adenomatous polyps and that DNA stool tests and virtual colonoscopy may show promise as screening tools. This new information provides further support for efforts to increase the use of colorectal cancer screening and prevention services in adults older than 50 years.     

Fecal occult blood testing. Guidelines for follow-up after positive findings

Fecal occult blood testing should be performed under optimal conditions to minimize false-positive test results. Obvious bleeding from the rectum or other sources during the test period should be investigated and testing should be postponed. When a fecal occult blood test is positive, colonoscopy is recommended as the definitive method of diagnosis and often of treatment. When a complete colonoscopy cannot be performed, sigmoidoscopy with air-contrast barium enema is the next best alternative for direct visualization of the distal bowel and indirect investigation of the proximal colon.     

Screening and surveillance of colorectal cancer

Although colorectal cancer (CRC) is the second leading cause of cancer deaths in the United States, it is preventable. Screening modalities include fecal occult blood testing, flexible sigmoidoscopy, double-contrast barium enema, and colonoscopy. Colonoscopy allows effective detection and removal of precursor adenomatous polyps and is the dominant CRC screening modality. Emerging technologies include CT and MR colonography and fecal DNA tests. Effective and cost-effective surveillance after polypectomy and curative CRC resection requires balancing the protective effect of polypectomy while maximizing intervals between examinations; thus, estimation of the risk of recurrence determines the intensity of surveillance for individual patients.     

INVESTIGATION OF COLONIC SYMPTOMS : THE VALUE OF FLEXIBLE SIGMOIDOSCOPY

SUMMARY Colonic symptoms and large-bowel disease are common in elderly people,¹ but the optimum investigative schema is not well established. Double-contrast barium enema (DCBE) and full colonoscopy share several drawbacks; both require colonic preparation which at best causes stool frequency and urgency, at worse dehydration and hypovolaemia. Many physicians feel that in the elderly this represents such a risk that inpatient preparation is preferred. Both investigations may involve much discomfort and distress.²,³ Rigid sigmoidoscopy is the traditional first colonic examination in patients with colonic symptoms, but will detect fewer than 10% of significant colonic lesions.⁴ Further investigation is almost always needed in elderly patients.     

Preoperative barium contrast enema in patients with inguinal hernia

Whether patients over age 40 should have a barium contrast enema (BCE) examination for possible identification of an unsuspected colon carcinoma before elective inguinal herniorrhaphy remains an unanswered question. We reviewed the medical records of all patients over age 40 who had inguinal herniorrhaphy at our institution between January 1980 and December 1984. Of 80 patients, 46 received a preoperative barium enema. One asymptomatic colon carcinoma (2.1%) was discovered. The reported incidence of asymptomatic colon cancer found by BCE in association with inguinal hernia ranges from 0 to 2.5%. We conclude that if there is a cause and effect relationship between asymptomatic colon cancer and inguinal hernia, the mechanism is as yet unknown.     

多层螺旋CT在大肠癌诊断中的作用

目的 评价多层螺旋CT检查及后处理技术在大肠癌诊断中的作用。方法 85例经手术病理证实的大肠癌患者行大肠充气MSCT容积扫描和图像重建(包括MPR、MIP、SSD、Raysum和CTVE)，并与钡灌肠(80例)、结肠镜(60例)及手术结果进行比较。结果 所有病人的诊断符合率为100％，其三维重建与钡灌肠、CTVE与结肠镜的发现完全符合。结论 大肠充气MSCT检查及后处理技术能更好地反映大肠癌的病变和范围，明显优于单独应用X线钡灌肠或结肠镜检查。     

How good is screening for colorectal cancer?

Colorectal cancer is potentially preventable. Use of fecal occult blood testing, flexible sigmoidoscopy, and a combination of air-contrast barium enema examination and colonoscopy has proved to be a safe, relatively inexpensive approach to detecting colon cancer in its early stages, decreasing morbidity and increasing survival. Future work in secondary prevention of colon cancer should be aimed at standardized trials of fecal occult blood agents, thus optimizing the yield of localized lesions and decreasing the cost so that mass screening becomes possible. Major efforts should be aimed at educating physicians and the public alike. Primary prevention will deserve greater emphasis when specific risk factors pathogenetic of colon cancer are discovered.     

Diagnosis and management of colorectal cancer

Colorectal cancer is an important disease with high mortality. Clinical features are usually nonspecific and vary with the location of the tumor. Diagnosis depends on colonic investigations initiated by a high index of clinical suspicion. Rectal examination, sigmoidoscopy, air-contrast barium enema, and colonoscopy are the crucial diagnostic tools. Clinical judgment dictates the extent of work-up in individual symptomatic patients. Screening of asymptomatic middle-aged and elderly persons is widely advised but less widely practiced. More evidence is needed to clarify the value of screening, especially by occult blood testing. CEA testing is unsuitable for screening and of only limited value for monitoring patients with known colorectal cancer. Surgical resection is the mainstay of treatment. Radiotherapy is useful for palliation of rectal cancer and may delay postoperative tumor recurrence. Chemotherapy for disseminated disease generally gives disappointing results, since only a minority of tumors respond and survival benefit is marginal. Periodic colonic surveillance is important after tumor resection, primarily to detect premalignant new growths.