The present status of the radiologic examination of the colon

Colorectal carcinoma: radiological diagnosis and staging

Colorectal carcinomas are the most common gastrointestinal tract tumors. 50-60% of the colorectal carcinomas originate in rectum and sigmoid colon. The new developments in imaging modalities have brought improvements in therapeutic aspects. The survival rates in these patients depend on the tumor penetration and the presence of regional lymph node or distant metastasis. The recurrence rates have decreased with the new operation techniques and preoperative radiotherapy, thus increasing the importance of accurate tumor staging. Double contrast barium enema studies enable the diagnosis while staging and follow-up is best done by topographic imaging techniques.

Gastrointestinal radiology: current indications and referral patterns

To determine the current indications and referral patterns for routine gastrointestinal radiology examinations, 1000 consecutive patients were prospectively analyzed. The following specialties were the largest sources of referral: general internal medicine (38%), gastroenterology (21%), and general and colorectal surgery (17%). Referrals from gastroenterologists were weighted toward areas not well evaluated by endoscopy, such as suspected small bowel disease. The major indications for upper gastrointestinal (GI) examinations were dysphagia and swallowing disorders (32%), hiatus hernia/reflux (14%), and ulcer (14%). Small bowel series were predominantly performed for inflammatory bowel disease (37%), obstruction (25%), and occult blood loss (18%). The majority of combined upper GI/small bowel studies were performed for indications primarily relating to the small bowel. Forty percent of barium enemas were performed for detection of neoplasms and polyps, with pain/irritable colon (14%) and exclusion of leak (14%) the next most common indications. Traditional indications, such as peptic ulcer disease and neoplastic disease, continue to be sources of referral for gastrointestinal radiology. However, more specialized applications, particularly in areas not well suited to endoscopy, such as swallowing disorders, inflammatory disease of the small bowel, and evaluation of surgical anastomoses, are also being commonly used. The changing indications, along with the previously documented decreased volume of gastrointestinal radiologic procedures, should be kept in mind when planning a radiology resident educational curriculum.

Colorectal cancer. Principles of postoperative follow-up

Monitoring patients after primary large bowel surgery for malignancy is predicated on the concept that early detection of recurrence may provide salvage treatment for cure. Knowledge of the pathologic site and stage provides important information as to the probability of recurrence and the patterns of failure that are likely to occur. Available methods to detect recurrence include clinical, roentgenographic, and serum tests that are done more frequently during the first 2 years after surgery. Monitoring plasma carcinoembryonic antigen levels can lead to identification of asymptomatic recurrences, but there is controversy about the curability of recurrences outside the liver. Newer techniques (such as computed tomographic portography, intraoperative ultrasonography, and radioimmunoguided surgery) provide greater diagnostic accuracy and lead to more appropriate procedures during "second-look" operations. For example, hepatic resection in properly selected patients offers up to a 30% chance of cure and should be pursued aggressively. A search for metachronous cancers by endoscopy also should be done. Knowledge of the potential and patterns of failure can provide a useful guide during the postoperative follow-up care of the patient with large bowel cancer.

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.

Colonoscopic diagnosis and treatment of lower gastrointestinal bleeding

Methods of diagnosis and treatment of lower gastrointestinal bleeding depend on the rate of bleeding and the amount of blood lost. If bleeding is occult, colonoscopy is the single best way to determine the source, if bleeding is gross but mild, causing melena or small amounts of hematochezia, colonoscopy or a combination of flexible sigmoidoscopy and double-contrast barium enema should be used to evaluate the colon. In most patients with melena, the upper tract must be examined endoscopically. Acute lower gastrointestinal bleeding stops spontaneously in 75 to 90 per cent of patients, permitting preparation of the colon before colonoscopy. If bleeding is continuing, diagnostic options include colonoscopy with no preparation of the colon, relying on the cathartic effect of blood, or a red cell radionuclide scan followed by angiography if the scan is positive. A bleeding lesion seen on angiography is usually treated by infusion of vasopressin. Colonoscopic treatment of a bleeding site uses the BICAP probe, heater probe, or argon laser. Patients who bleed severely and those who do not respond to treatment or rebleed after treatment are candidates for operation. Segmental resection is preferred if the bleeding site is known. If not, total colectomy with ileorectal anastomosis may be necessary. A mortality rate of 10 to 15 per cent in patients with severe bleeding reflects the advanced age of many of these patients and the difficulty of managing gastrointestinal bleeding in the presence of associated medical conditions.