Bowel preparation before colonoscopy

premalignant lesions, cancer, and inflammatory bowel disease. Clinical investigative trials are sorely needed. The A/ S/G/E has seen the necessity to develop controlled prospective trials in endoscopy. The Research Committee of A/S/G/E has been available to assist any endoscopist in the proper development of clinical trials, although A/S/G/E is not able to fund these investigations. Several clinical problems need to be critically evaluated. At the present time, there is no doubt that development of colonoscopic polypectomy has resulted in a much more cost-effective procedure than surgical removal of these same polyps. However, we know little about the type of follow-up necessary, and data are lacking on the proper approach to the endoscopically resected malignant polyp. Other areas of interest are endoscopic retrograde cholangiopancreatography in the surgical planning of patients with chronic pancreatitis, the uses of the flexible sigmoidoscope, and the risk/benefit of endoscopy versus upper gastrointestinal radiology in diseases of the upper intestinal tract. Some research activities currently being performed are without a unified directional thrust. The validity of manometry of the papilla of Vater is compromised by the lack of uniformity of equipment. Endoscopic sclerosis of varices has caught the imagination of several investigators, but different sclerotic mixture, different injecting needles, and varied injection schedules defy comparability of results. Although the National Institutes of Health has funded (with yearly renewable contracts) investigations for specific devices to control upper gastrointestinal bleeding, under these contract stipulations any new idea or a more promising or more innovative direction cannot be pursued, stifling developmental research. Instrument manufacturers have by default taken almost sale responsibility for development of endoscopic instrumentation. However, the assessment of new technology by instrument makers is decidedly self serving. To grasp the problem, one should look at the saga of the flexible sigmoidoscope, which has become the most commonly sold endoscope to date, surpassing both upper intestinal endoscopes and colonoscopes in sales. The length of the flexible sigmoidoscope was determined as 60 cm because that was most convenient for the manufacturer to produce, not because of clinical trials or established need. Only recently have attempts been made to critically study the flexible sigmoidoscope, although hundreds have already been sold and utilized by gastroenterologists, general surgeons, and internists. Endoscopic centers should share the responsibility of critical assessment of instruments offered, but adequate technical support must be available to do this properly, justly, and rapidly. Jerome D. Waye, MD New York, New York

Bowel preparation before colonoscopy In the excellent book Practical Gastrointestinal Endoscopy by P. B. Cotton and C. B. Williams 1 it is stated VOLUME 28, NO. 1, 1982

in the discussion on bowel preparation for colonoscopy of colitis patients, "Relapses of inflammatory bowel disease are said occasionally to occur after overvigorous bowel preparation. There is a widespread prejudice, on no good evidence, against the use of castor oil but magnesium citrate, senna preparations or saline lavage regimes are well tolerated." That chapter ends with the statement, "If the patient is fit for total colonoscopy he is fit for full bowel preparation." In this issue of Gastrointestinal Endoscopy, Gould and Williams 2 present their data to justify this last statement. They report that in 340 total colonoscopies performed for colitis follow-up they were aware of only three minor relapses of the disease, which responded rapidly to increased medication. They comment, however, that this small incidence may represent the fact that these patients were seen only once or twice a year, and it seemed possible that they were unaware of the true incidence of ill-effects of the preparation. In their prospective study 23 patients were given 30 ml of castor oil 24 hours before the colonoscopy, followed by a liquid diet and at least two tapwater washout enemata or "till clear returns" before the procedure. A second group of 23 patients received five double strength senna tablets (Senokot®, equivalent to 75 mg of total sennosides) instead of castor oil. The state of the patient's colitis during the 2 weeks preceding the colonoscopy was recorded and reevaluated 2 weeks after the procedure. This assessment was made without the knowledge of which laxative the patient received. The authors concluded that this study failed to incriminate castor oil as a more likely cause of exacerbation of colitis than an equally effective dose of senna. However, both types of preparation resulted in minor bowel disturbances in 14 patients (30%), and three (7%) required a short period of oral corticosteroids. One may wonder whether this standard full preparation is really required. We prefer to individualize the preparation and proceed as follows: patients who average more than three soft bowel movements in 24 hours are given 150 ml of citrate of magnesia in the early afternoon on the day preceding the colonoscopy. This is followed by a minimum of two 8-ounce glasses of fluids (water, tea, or soft drinks as desired) and fluids only for the rest of the day. Next morning the patient drinks 30 ml of sorbitol 70% solution in one 8-ounce glass of water every half hour until diarrhea appears. This usually takes about 2 hours which corresponds to four doses. At times, a fifth dose is ingested, giving a total of 150 ml of sorbitol. The patient is also encouraged to drink more fluids between these doses, e.g., coffee or tea, which may bring the total quantity of fluids up to 2 or 2.5 liters. The effluent becomes clear in most patients and colonoscopy can be carried out at 3 or 4 hours after starting this preparation. It may be done later if the patient lives at a greater distance. We use CO 2 as with the pneumotome light source made by ACMI. If the patient has more than three soft stools daily, one may forego the citrate of magnesia. 39

Patients who have only one formed stool a day may tolerate the full amount of citrate of magnesia (300 ml) the day before the colonoscopy with larger amounts of fluids. The same amounts of sorbitol are adequate for the final lavage. This obviates the need for water enemata. This type of preparation is essentially the same as routine preparation for total colonoscopy for other indications; we have used this for over 3 years to our greatest satisfaction, and it appears to be safe for polypectomy under the above conditions. New solutions for peroral colonic lavage are under investigation. The most attractive is the one proposed by Davis et al. 3 with polyethylene glycol replacing the mannitol in an osmotically equivalent amount. Although Goldman and Reichelderfer4 have concluded that this technique is rapid, effective, and well tolerated without altering fluid and electrolyte balance and is therefore a safe alternative to the standard approach, I am not yet willing to change our routine. After studying their article in great detail, I had the impression that these conclusions are somewhat premature and that the procedure is more cumbersome than our present technique, adjusted to individual indications and requirements. Henry Colcher, MD University of Alabama Birmingham, Alabama

REFERENCES 1. COTTON PB, WilLIAMS CB: Practical Gastrointestinal Endoscopy. Edinburgh, Blackwell Scientific Publications, 1980, p. 90 2. GOULD SR, WilLIAMS CB: Caster oil or senna preparation before colonoscopy for inactive chronic ulcerative colitis. Gastrointest

Endosc 28:6, 1982 3. DAVIS GR, SANTA ANA CA, MORAWSKI SG, FORDTRAN IS: Development of a lavage solution associated with minimal water and electrolyte absorption or secretion. Gastroenterology 78:991,

1980 4. GOLDMAN L REICHELDERfER M: Evaluation of rapid colonoscopy preparation using a new gut lavage solution. Gastrointest Endosc

28:9, 1982

Barium enema versus colonoscopy Proctosigmoidoscopy and the barium enema have historically been extremely valuable diagnostic tools in the study of colon disease. Since the barium enema provided an examination far beyond the capability of proctosigmoidoscopy, which could be used to directly examine the more difficult areas of radiologic evaluation, the two techniques were obviously complementary. Current evidence shows that colonoscopy and the double-contrast barium enema are also complementary. Each technique has its distinct advantages and disadvantages. The modern clinician must be fully aware of the relative merits of each method in order to utilize these tools effectively. Colonoscopy has limitations.'-3 The colonoscopist is unable to negotiate extremely acute bends, and lesions may not be reached. Blind areas encountered most frequently are in the rectosigmoid colon, in the splenic and hepatic flexures, and near the ileocecal valve. Fixation and constriction of the colon from 40

adhesions, inflammation, neoplasms, and diverticula limit colonoscopy. Although success rates vary with the skill of the examiner, the entire colon is not examined in about 43% of colonoscopies 3 - 6 However, the examination of the entire colon is mandatory to detect synchronous carcinomas (4 to 7%) or other coexistent lesions. 6 - s The barium enema is often superior for localizing a lesion prior to surgery. Measurements from the colonoscope cannot be transferred to the patient at laparotomy because of "bOWing" and "telescoping" of the colon on the colonoscope. The advantages of colonoscopy relate to detecting mucosal change, polyps, and vascular lesions too subtle for barium enema study and to providing biopsy material. Williams et al. 2 reported that only 18% of colonoscopically diagnosed polyps of less than 1 cm were seen by conventional single-contrast barium enemas, although 78% of such polyps were seen by air-contrast examinations. Similarly Miller9 confirmed that 40% more colon polyps were seen by air-contrast enemas than by conventional single-contrast enemas. Williams et al. 2 also reported that the air-contrast barium enema identified a very respectable 98% of colonoscopically diagnosed polyps greater than 1 cm. Recently, Gilbertsen et al. lO showed that the singlecontrast barium enema misses 35% of all colon carcinomas and 42% of early (Dukes' A and B) potentially curable carcinomas. Recently, Thorpe et al.' 1 concluded that the air-contrast enema detected 96% of Dukes' C and D lesions and 91% of Dukes' A and B lesions in proven carcinoma of the colon. H. G Wells said that it takes 50 to 100 years from the time the perception occurs that something ought to be done until a serious attempt is made to do it. In the detection of curable colon cancer, we clearly do not have and cannot afford that time. In the majority of cases, if the colonoscopist does not have a good air-contrast barium enema for guidance before colonoscopy, it is the endoscopist's own fault. Colonoscopy has a distinct advantage in the diagnosis of small polyps and a small, although important, advantage in the detection of larger polyps. Occasionally, the air-contrast enema will not only detect large missed polyps but even a 4-cm malignant neoplasm of the cecum that had been missed at endoscopy.'2-14 For this reason, colonoscopy and air-contrast barium are complementary examinations. There were 94 cases of polypoid colonic lesions from our own experience where endoscopy failed to identify any of these polyps, even though the endoscope was at or beyond the site of the lesion. Twenty-five of the lesions were carcinomas. Most undetected lesions ranged from 0.5 to 1.5 cm. Histologic proof of each lesion was obtained by repeat endoscopy with biopsy, polypectomy, or surgery. An incomplete examination obviously accounts for the failure to identify colonic lesions by colonoscopy in many cases. Also, the operator may miss a lesion just as the radiologist fails to see a lesion at fluoroscopy or on film. The problem is that if the endoscopist reaches or passes the area in question and does not see a lesion, an endoscopy report of "normal" cannot GASTROINTESTINAL ENDOSCOPY