Is there a need for diagnostic upper gastrointestinal endoscopy before cholecystectomy?

Cholecystectomy is recommended for symptomatic gallstone disease, however atypical abdominal symptoms may be incorrectly attributed to gallstones found by chance at ultrasound. High rates of post-cholecystectomy symptoms confirm that surgery is often performed inappropriately in patients whose complaints do not derive from the biliary tract. We therefore performed esophagogastroduodenoscopy (EGD) in 56 symptomatic patients with gallstones to determine if there was an alternative explanation for patient symptoms. A surgeon then assessed the patient in the light of these findings and decided whether to operate. Of 41 patients who were questioned 12.4 +/- 7.3 months after entry, 1 of 22 patients who underwent surgery, and 5 of 19 patients treated conservatively, were symptomatic (P < 0.05). In the surgical group, one of seven patients with an endoscopic finding remained symptomatic, and in the nonsurgical group one of nine patients remained symptomatic (NS). However, in patients without endoscopic findings, none of the 15 surgical patients but 4 of 10 nonsurgical patients (40.0%) remained symptomatic (P < 0.01). We conclude that patients with gallstone disease and negative EGD who undergo cholecystectomy are less likely to remain symptomatic than those treated conservatively. Thus, endoscopy of the upper gastrointestinal tract in patients with gallstones may provide important information for the surgeon, prior to the making of therapeutic decisions.

Epidemiology of Crohn's disease in southern Israel

OBJECTIVES

Crohn's disease in Israel was described in the past as being of low incidence, more common in Europe-America-born Jews than other Jews, and of uncharacteristically low morbidity. However, recent experience has suggested that these premises are no longer correct.

METHODS

The records of all hospital and outpatient cases of Crohn's disease in southern Israel for the period 1968-1992 were reviewed. Private family practitioners and specialists were contacted to assure complete case ascertainment.

RESULTS

The prevalence rate of Crohn's disease among Jews on December 31, 1992, was 50.6/10(5) (Asia-Africa-born Jews 55.0/10(5), Europe-America-born Jews 58.7/10(5), and the rate was 8.2/10(5) among Bedouin Arabs. The annual incidence rate (1987-1992) was calculated as 4.2/10(5)/yr in Jews (Asia-Africa-born 4.6/10(5)/yr, Europe-America-born 3.9/10(5)/yr). The age of presentation declined progressively over the study period, was lower in Israel-born patients than immigrants, and was lower in ileocolonic versus other sites of disease.

CONCLUSIONS

The data show that Crohn's disease has become more common in Jews in Israel, losing ethnic differences of frequency, and that it occurs at a younger age than before. In Arabs, the disease is more rare.

Adenocarcinoma in the rectal segment in familial polyposis coli is not prevented by sulindac therapy

Sulindac, a nonsteroidal anti-inflammatory drug, causes regression of polyps in familial polyposis coli and may prevent new lesions. However, it is not clear whether the effect of sulindac in preventing polyps also applies to carcinoma. This case report describes a patient with familial polyposis coli who developed a carcinoma in a rectal segment after subtotal colectomy and ileorectal anastomosis. She had been treated with 450 mg sulindac daily for 28 months and was free of polyps during the latter 12 months of this period. However, despite intensive endoscopic follow-up, she developed an adenocarcinoma of the rectum. This finding may have important implications for our understanding of the development of colon cancer in familial polyposis coli and the use of sulindac to prevent it. Development of de novo carcinoma in microadenomatous tissue of the rectal mucosa, which bypasses the polyp-cancer sequence, must be considered as a possibility in these patients.

Effect of panel composition on appropriateness ratings

Cholecystectomy is performed frequently and for relatively few indications. An all surgical panel agreed on more indications and fewer contra-indications for cholecystectomy than a mixed specialty panel but did not approve indications for patients with higher comorbidity. In mixed panels subspecialists (gastroenterologists) were more conservative than generalists and surgeons. Similar findings have been shown for carotid endarterectomy. Comparing the results of British and Israeli panels showed variations in rating appropriateness that indicate differences in approach between countries. We conclude that the composition of panels will influence the assessment of appropriateness.

Increasing serum creatinine and age reduce the response to hepatitis B vaccine in renal failure patients

The relationship between diminished response to hepatitis B vaccine in renal failure patients and serum creatinine level, age and other factors is unknown. The immune response of patients with renal failure of varying severity to hepatitis B vaccine was determined in this study. Sixty-eight patients with renal failure of varying severity who were negative for hepatitis B markers received four doses of hepatitis B vaccine, and anti-HBs titers were determined at 0, 1, 2, 3, 6, 8 and 12 months. Maximum anti-HBs titers were seen at 8 months. At this time 86% of patients with creatinine < or = 4 mg/dl but only 37% with creatinine > 4.0 mg/dl had a protective titer of > or = 10 mIU/ml (p < 0.002). Age was inversely related to anti-HBs titer (p = 0.045) and was independent of serum creatinine in predicting antibody response. We conclude that all patients with chronic renal failure should be immunized against hepatitis B as early as possible in the development of their disease, to ensure maximum response, and to minimize the effects of elevated serum creatinine and increasing age.

Hyperplastic polyp and colonic neoplasia. Is there an association?

Hyperplastic polyps are regarded as non-neoplastic lesions with no malignant potential. However, several case reports and a clustering phenomenon suggest that they may arise in abnormal colonic that is predisposed to develop neoplastic lesions. The hyperplastic polyp also displays markers associated with colorectal cancer. In addition, several recent articles have addressed the question of hyperplastic polyp in the distal colon as a marker of more proximal adenomatous polyp. Many endoscopists discovering a distal hyperplastic polyp will wish to ensure the absence of a proximal neoplastic lesion.

Validation of a centrally maintained computerized hospital database: comparison with operating room logbooks

Substantial interest exists in variations in the use of surgical procedures by specific populations. Studies of this issue are often based on routinely collected data that are maintained in central computer systems. In this study a method is presented for examining the validity of such a database, which is maintained by Kupat Holim, in terms of sensitivity and positive predictive value by comparing its data to data from other information sources, such as operating room log books and in-patient medical records. The validation process was performed in Israel for three surgical procedures: cholecystectomy and prostatectomy each in four hospitals and hysterectomy in two hospitals. The sensitivity of the computerized database ranged from 90% to 98% and the positive predictive value from 96% to 99%. We conclude that the centrally maintained computerized database is a reliable source of information, however, when extremely accurate information is needed the use of complementary sources of information, e.g., operating room logbooks, is recommended.

Indications for cholecystectomy: the results of a consensus panel approach

A consensus panel approach was used in Israel to develop a list of clinical indications for which there was agreement that cholecystectomy should be performed. Nine physicians from different disciplines were asked to score a list of 266 clinical indications for cholecystectomy. Each indication was scored on a scale of 1 (inappropriate, i.e. health risks exceed health benefits) to 9 (appropriate, i.e. benefits exceed risks). Each indication also included one of four comorbidity levels (none to high). Agreement and disagreement were defined and panelists met to discuss, modify and rescore the list. The composition of the panel and definitions of agreement had a considerable impact on the preparation of a list of agreed, appropriate indications for cholecystectomy. Gastroenterologists in the panel were less likely to recommend surgery than either surgeons or general internists both before and after the panel discussion. Following the discussion the level of agreement (defined as after discarding the highest and lowest score all of the remaining seven panelists were in a 3-point range) increased from 39% to 46% (p < 0.08) and disagreement decreased from 27% to 18% (p < 0.01). Fifty-nine of the 266 indications were considered appropriate with agreement.

The agreed indications and contra-indications for cholecystectomy

Indications as to which patients should undergo cholecystectomy remain, at least in part, a matter of controversy. In 1987, a panel of nine Israeli physicians from different specialties established a list of indications for the performance of cholecystectomy based on the literature available at the time. The panel agreed that cholecystectomy was appropriate for 59 indications and that it was inappropriate for 58. The major indications for surgery were biliary colic and acute cholecystitis. Patients who were asymptomatic or had vague symptoms were not recommended to undergo surgery unless they had stones in the common bile duct and were less than 71 years of age. Patients with pancreatitis were recommended for surgery if they had stones in the common bile duct and did not have a history of alcohol abuse. Performing a cholecystectomy at the same time as abdominal surgery was being performed for other reasons was indicated only if the patient was symptomatic from his gall-stones.

[Screening for colorectal cancer and polyps]

Screening programs for the early detection of colorectal neoplasms may prevent cancer or improve its prognosis. We screened 1101 individuals (89% of whom were asymptomatic) using 3 methods. The fecal occult blood test, done in 96% of those screened, was positive in only 1.9% and was low in both sensitivity (2.1%) and positive predictive value (6.7%). However, flexible sigmoidoscopy, performed in 48%, gave positive results in 7.8% of those screened, revealing 41 cases of polyps and 1 of cancer. Colonoscopy was performed in 8% and 37 cases of polyps and 1 of cancer were detected. Of the 3 screening methods tested, sigmoidoscopy appeared to be the best because of its high diagnostic yield. The risk of colorectal neoplasm was shown for the first time to be equal in Jews of oriental and occidental origin.

Inflammatory bowel disease in the Bedouin Arabs of southern Israel: rarity of diagnosis and clinical features

A prospective epidemiological and clinical study of ulcerative colitis and Crohn's disease was undertaken in the Bedouin Arabs of southern Israel between 1981 and 1990. There were six patients with ulcerative colitis and the prevalence rate in 1990 was calculated to be 9.8/10(5) (95% confidence intervals 3.6-17.4) in the total population, or 6.2/10(5) (0.8-22.5) in men and 13.7/10(5) (3.7-35.0) in women. Two cases of Crohn's disease occurred, both in women; the prevalence rate was 3.2/10(5) (0.4-11.8) in the entire population, and 6.8/10(5) (0.8-17.5) in women. The prevalence rates (age adjusted) in Arabs were significantly lower (p less than 0.01) than the corresponding rates in the local Jewish populations. The Bedouin patients were aged mean (SD) 34.0 (16.4) years at time of diagnosis. The clinical features of both diseases resembled those in the Jewish and other reported populations. It is suggested that the exposure of the Bedouin Arabs to the environmental causative factors of ulcerative colitis and Crohn's disease has hitherto been limited and thereby accounts for the rarity of these diseases in this population.

Theta, a new class of glutathione transferases purified from rat and man

Glutathione transferases (GSTs) of a novel class, which it is proposed to term Theta, were purified from rat and human liver. Two, named GST 5-5 and GST 12-12, were obtained from the rat, and one, named GST theta, was from the human. Unlike other mammalian GSTs they lack activity towards 1-chloro-2,4-dinitrobenzene and are not retained by GSH affinity matrices. Only GST 5-5 retains full activity during purification, and its activities towards the substrates 1,2-epoxy-3-(p-nitrophenoxy)propane, p-nitrobenzyl chloride, p-nitrophenethyl bromide, cumene hydroperoxide, dichloromethane and DNA hydroperoxide are 185, 86, 67, 42, 11 and 0.03 mumol/min per mg of protein respectively. Earlier preparations of GST 5-5 or GST E were probably a mixture of GST 5-5 and GST 12-12, which was largely inactive, and may also have been contaminated by less than 1% with another GSH peroxidase of far greater activity. Partial analysis of primary structure shows that subunits 5, 12 and theta are related to each other, particularly at the N-terminus, where 25 of 27 residues are identical, but have little relationship to the Alpha, Mu and Pi classes of mammalian GSTs. They do, however, show some relatedness to subunit I of Drosophila melanogaster [Toung, Hsieh & Tu (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 31-35] and the dichloromethane dehalogenase of Methylobacterium DM4 [La Roche & Leisinger (1990) J. Bacteriol, 172, 164-171].

Effect of cimetidine on hepatic vitamin D metabolism in humans

Cimetidine inhibits the action of vitamin D-hydroxylase (a hepatic mixed-function oxidase) in the rat. Therefore, the hypothesis was tested that this H2 receptor antagonist would affect vitamin D metabolism in humans. Nine adult patients were treated with 400 mg cimetidine orally twice daily during a period from winter to summer, when days were becoming longer. Serum levels of 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D and 1,25-dihydroxyvitamin D were monitored before treatment, after 4 weeks of treatment, and 1 month after cessation of treatment. No seasonal increase in the level of 25-hydroxyvitamin D was observed during the period of treatment, but the level rose significantly after withdrawal of the drug. The other hydroxylates of vitamin D were not affected. Levels of albumin, total calcium, phosphorus and alkaline phosphatase remained normal. The data suggest that short-term treatment with cimetidine could potentially perturb vitamin D metabolism in man.

Differential distribution of protein kinases along the crypt-to-lumen regions of rat colonic epithelium

The activity of cAMP-dependent and cAMP-independent protein kinases, a class of enzymes involved in the regulation of cell proliferation was measured in rat colonic epithelium. Sequential cell populations harvested by a stepwise scraping technique from colonic crypt regions were identified by histology and incorporation of [3H]-thymidine into DNA. cAMP-independent phosphorylation of casein, in the presence of [gamma-32P]ATP, was markedly suppressed by quercetin, a bioflavonoid known to inhibit G-type casein kinase, protein kinase-C and tyrosine protein kinase. Conversely, the cyclic nucleotide regulatable form requiring histone as substrate was responsive to the action of the heat stable protein kinase inhibitor. The protein kinase species were characterised and partially purified by DEAE-cellulose chromatography. The activity of cAMP-dependent protein kinase in colonic cytosols (pmol 32P/min/mg protein, means (SE)) increased from 129.4 (15.9) in superficial cell populations to 238.5 (31.4) in lower crypt cell fractions (p less than 0.01). Colonic cAMP-independent protein kinase activity increased from 87.3 (15.6) in surface cell preparations to 178.1 (30.0) in lower crypt cell populations (p less than 0.02). A comparable activity gradient was observed in membrane fractions. The activity gradient persisted when the results were expressed as a function of cellular DNA. These findings indicate that protein kinases display a defined topological segregation along the colonic crypt regions and that during migration to the lumen colonic cells attenuate enzyme signals supposedly related to tissue growth.

Modifications to the gas-enhanced small bowel barium follow-through using gastrografin and compression

The transit time of barium through the small bowel has been assessed in two groups of patients. In 52 patients who were given 300 ml 50% w/v baritop and effervescent tablets, the mean transit time was 78.4 min. In 61 patients who were given 300 ml 100% w/v baritop to which 10 ml of Gastrografin had been added, and who were also given effervescent tablets, the mean transit time was 60.2 min. This difference is highly significant (P less than 0.001). It is suggested that small quantities of Gastrografin act as an accelerator of barium transit by causing the release of serotonin (5-hydroxytryptamine) from the small intestinal mucosa. We believe that the distension of the small bowel lumen achieved by the administration of effervescent tablets improves the quality of the small bowel follow-through examination and also improves its accuracy particularly in the diagnosis of Crohn's disease and small bowel adhesions. The importance of performing the whole examination under fluoroscopic control and the value of compression films is stressed.

Hepatitis B infections in a chronic hemodialysis unit in a country where hepatitis B is endemic: a prospective study

Hepatitis B markers were determined in patients with chronic renal failure and in staff members prior to entry into the hemodialysis unit of a hospital in southern Israel, an area in which hepatitis B is endemic. Patients and staff who were negative for hepatitis B markers were followed for a mean of 26.7 and 29.2 months, respectively, between November 1975 and May 1984. New infections occurred in 25.9% of the patients and 17.3% of the staff; the difference was not statistically significant. Hepatitis B markers were found in 26% of the staff and 41% of the patients (p less than 0.05) prior to their entry into the hemodialysis unit. Furthermore, in the patients, a relatively high rate of carriers was detected (7% compared with 2% in the general population), while no carriers were detected among the staff members. Within the staff group, nurses were at particularly high risk for new infections, accounting for seven of the nine (78%) events recorded. The high risk for the nursing staff is probably due to greater exposure to blood among nurses compared with other staff members.

Cerebral infarction secondary to unsuspected intracranial fibromuscular dysplasia following bypass of aortic coarctation

Fibromuscular dysplasia (FMD) is an uncommon finding in the cerebral circulation. We present a case of unsuspected intracranial FMD in a patient dying from a large cerebral infarct following a bypass operation for coarctation of the aorta. The need for recognizing the possible co-existence of these two lesions is emphasized.

The small bowel barium follow-through enhanced with an oral effervescent agent

A method is described for consistently improving the quality of the small bowel barium follow-through by enhancement with an oral effervescent agent. With this method, although satisfactory double-contrast views of the whole small bowel were obtained in less than half the patients, satisfactory distension of the small-bowel loops was achieved in 96% of examinations.

The double-contrast barium meal: a correlation with endoscopy

The radiological and endoscopic findings are described in 214 patients with 252 lesions in whom endoscopy had been requested by a radiologist either to confirm or clarify a radiological opinion. There was radiological and endoscopic agreement about the presence or absence of oesophagitis in 73% of patients, but there was agreement about the presence or absence of duodenitis in only 48%. There were only two cases of early gastric cancer, and no early gastric cancers were found in a group of 43 patients on whom endoscopy had been specifically requested because of an abnormal gastric mucosal pattern. Endoscopy failed to detect 13% of gastric ulcers at the initial endoscopic examination.

Extrinsic compression of the third part of the duodenum

The clinical findings in 12 patients who exhibited marked to-and-fro peristalsis in the duodenum with extrinsic compression of the third part and proximal dilatation at barium meal examination are described. In nine cases the compression was thought to be due to the superior mesenteric artery and its mesentery. In two of these cases there was associated duodenal ulceration and in another patient there was evidence of chronic idiopathic intestinal pseudo-obstruction. In the remaining three cases, the duodenal compression was caused either by tumour or malignant glands in the root of the mesentery. It is emphasised that vigorous to-and-fro peristalsis in the proximal duodenum seen at fluoroscopy is an abnormal radiological feature which is associated in most cases with significant pathology.

Grey-scale ultrasonography and percutaneous transhepatic cholangiography in biliary tract disease

Fifty-one patients with suspected obstructive jaundice and 14 without jaundice in whom disease of the biliary tract was suspected but infusion cholangiography had been unhelpful were examined by grey-scale ultrasonography and percutaneous transhepatic cholangiography and the findings analysed retrospectively. Grey-scale ultrasonography distinguished between obstructive and hepatocellular jaundice in 35 out of 46 patients (76%) and indicated the site of the obstruction in 27 (58%) and the cause of the obstruction in 13 (28%). Percutaneous transhepatic cholangiography distinguished between obstructive and hepatocellular jaundice in 42 of the patients (91%) and indicated the site of the obstruction in 42 (91%) and the cause in 29 (63%). In the 14 patients without jaundice percutaneous transhepatic cholangiography showed bile-duct stones in one an ampullary stenosis in three. It is concluded that grey-scale ultrasonography and percutaneous transhepatic cholangiography are complementary examinations and that ultrasonography should always be undertaken first as it is a non-invasive procedure that may provide the surgeon with all the diagnostic information he requires. Percutaneous transhepatic cholangiography should be performed when grey-scale ultrasonography has shown dilated bile ducts but failed to provide adequate diagnostic information. Cholangiography is also required when preoperative percutaneous drainage of the bile duct is contemplated. In those patients in whom grey-scale ultrasonography shows non-dilated ducts endoscopic retrograde cholangiopancreatography is probably the contract examination of choice.

Industrial accidents and their prevention

Accident prevention is a task for all sections of the community; it should be part of the industrial process and not separated. It depends primarily on attitudes, communication and industrial relations. Money spent by management on safety is necessary, but it is not the only prerequisite. In the framework of workmen's compensation legislation where payment of lump sums for injury is the philosophy, the disability of the worker is the predominant factor. This is a negative attitude and early rehabilitation with the assessment of the worker's ability to perform is closely allied to accident prevention.

The double contrast barium meal in patients with acute upper gastrointestinal bleeding

One hundred and seven patients admitted to a small general hospital with acute upper gastrointestinal bleeding have been examined by the double contrast barium meal technique. The presumed bleeding site was identified in 75 cases (70%). Twenty-eight patients showed radiological evidence of recent or active bleeding. These were all examined within 24 h of the bleed and 18 (64%) continued to bleed or had a further bleed whereas of 79 patients who did not show radiological signs of recent or active bleeding only 10(13%) continued to bleed or had a further bleed. The radiological features of recent or active bleeding seen on the double contrast barium meal are: 1, Blood clot in an ulcer or adherent to a recently bleeding lesion. 2. An artery in the base of an ulcer. 3. Active bleeding during the course of the examination seen as a dynamic alteration or disturbance in the barium as it flows over the bleeding site.

Percutaneous transhepatic cholangiography with the Chiba Needle

Percutaneous transhepatic cholangiography using the Chiba needle has been performed on 102 patients. There was an overall success rate of 86 out of 102 cases (84%). Dilated bile ducts were successfully demonstrated in 61 out of 65 patients (94%) and non-dilated ducts in 25 out of 37 patients (70%). Gallbladder filling was achieved in 40 out of 70 cases (67%). The hepatic lymphatics were filled in 32 cases but dilated lymphatics were mainly seen in patients with biliary cirrhosis, inflammatory liver disease or lymphoma. It is suggested that an excessive radiation dose may be given to the radiologist's fingers unless the fluoroscopy diaphrams are kept well coned down. Complications requiring active medical intervention occurred in three cases and emergency surgery in one case.

Aneurysms of the coronary arteries in infants and children. A review, and report of six cases

In recent years large numbers of the so-called "mucocutaneous lymph node syndrome" or "Kawasaki's disease" have been described by Japanese workers, but instances of this disorder are only now being reported as isolated cases by European or North American physicians. The disease has, therefore, been considered to be a new entity. One of its most striking features is the development of aneurysms of the coronary arteries in infants or children, which may lead to sudden death. Aneurysms of the coronary arteries in childhood are rare, and hence it was considered relevant to report six such cases, and to examine their possible relationship to Kawasaki's disease. The pathological changes underlying the latter disorder are not well known; they are considered to be indistinguishable from infantile polyarteritis nodosa. A diagnosis of polyarteritis nodosa was also thought to be most likely to apply in the cases presented here, particularly in view of the frequency with which aneurysms of the coronary arteries have been found in this disorder. In the absence of valid pathological distinctions between Kawasaki's disease and infantile polyarteritis nodosa, the question arises whether these entities are, in fact, different, and whether Kawasaki's disease is the new entity it is assumed to be.

Disseminated peritoneal leiomyomatosis

Disseminated peritoneal leiomyomatosis is an unusual condition characterized by the development of numerous nodules in the peritoneal cavity which histologically have the appearance of smooth muscle tumors. The ninth proven case of this ill-understood disorder is presented here, with comments on some of the other published instances. Most reported cases were diagnosed in pregnant women, and there is good reason to believe that endocrine factors are of importance in the development of this condition. Attention is drawn to experimental studies in which an apparently similar condition has been produced in guinea pigs by endocrine manipulation. Clinically, the condition appears to be benign and the correct diagnosis is, therefore, of great importance. In the case presented here histological involution of the leiomyomatous peritoneal nodules could be demonstrated for the first time by two biopsies at an interval of 4 months--in the absence of any therapy apart from the termination of pregnancy.

Radiology and endoscopy in acute upper gastrointestinal bleeding

Of 112 patients admitted with acute upper gastrointestinal bleeding, the presumed bleeding site was detected in 61-5% of cases by radiology and in 57% of cases on endoscopy. Thirty-one patients who had barium-meal examination were operated on and the surgical and radiological findings agreed in 26 (84%). Twenty-three patients who had endoscopy were operated on and the surgical and endoscopic findings agreed in 15 (65%). In 10 cases radiology detected a lesion not identified on endoscopy and in nine endoscopy detected a lesion not seen at radiology. We suggest that when there are two potential sources of bleeding radiology as well as endoscopy can detect the actively bleeding lesion. The supplementary nature of radiology and endoscopy is emphasised and we conclude that both methods should be used if there is any doubt at the initial radiological or endoscopic examination about the source of the bleeding.

The double contrast enema in ulcerative and Crohn's colitis

One hundred double contrast enema examinations using a colonic activator (veripaque in the preliminary cleansing enema and 51 conventional barium enema examinations without a preliminary veripaque enema have been performed on 94 patients with either ulcerative colitis or Crohn's disease of the colon. The severity of the disease at barium enema examinations has been graded and compared with the severity of the disease found at sigmoidoscopy. In the double contrast examination, there was agreement between the radiological and sigmoidoscopic findings in 77% of cases and a disagreement of one grade in the remaining 23% of cases. The double contrast enema demonstrated lesions in the colon proximal to the range of the sigmoidoscope of a greater severity than that seen at sigmoidoscopy in 30% of cases. It was not found possible to use the same grading method with the conventional enema, and unless frank ulceration is present, it is considered that the conventional enema is unreliable in assessing the state of the colonic mucosa. It is concluded that the double contrast enema, using a colonic activator in the preliminary cleansing enema, causes no greater risk of complications than either the conventional enema or sigmoidoscopy.