Evaluation of the Barium-enema Examination and Colonoscopy in Diagnosis of Colonic Cancer* OLE KRONBORG, M.D., ASSER ~)STERGAARD, M . D .
From the Department of Surgical Gastroenterology F, Bispebjerg Hospital, Copenhagen, Denmark
Colonoscopy was performed after the barium-enema studies in all cases (in 112 cases, three or more days later). T h e aperient used for bowel preparation was Bisacodylum NIrN, 40 mg, given as tablets the day before, with 10 m g given as an enema a few hours before colonoscopy. Sedation was obtained by intravenous injection of the diazepam, 10-20 mg, in 91 cases, while injection of fentanyl and droperidol was used for analgesia in 26. Six patients had no medication. Fluoroscopy was used for insertion during 92 of the 123 examinations. T h e instrument was the "long" colonoscope, Olympus CIr . LB. T w o experienced examiners performed 112 c o l o n o s c o p i c examinations. T h e y did not attempt to reach the cecum in every patient, but to reach the process demonstrated by the barium-enema. A diagnosis of cancer, questionable cancer, no colonic disease, or other colonic disease was established if the area of the "process" was reached. Laparotomy was performed in 78 of the 123 cases. T h e remaining 45 patients had clinical follow-up studies 6 to 12 months after colonoscopy.
IrALSE-POSITIVE DIAGNOSES Of c a n c e r o f t h e
colon are made on the basis of bariumenema examination in 10 to 20 per cent of cases of patients who have symptoms suggesting cancer.l, 2 These patients are consequently subjected to unnecessary laparotomies. Colonoscopy has been said to eliminate the need for laparotomy in most such cases,6, 7, 9, lo but confirmation of the "definitive" colonoscopic diagnosis by later clinical follow-up has been achieved in only a few studies, a, s T h e purpose of the present study was to investigate the possible diagnostic value of colonoscopy in patients with certain or questionable cancer of the colon as demonstrated by routine barium-enema examination. This could be accomplished by clinical follow-up studies of patients not subjected to laparotomy. Materials and Methods Patients who had certain or questionable diagnoses of cancer of the colon made on the basis of barium-enema examination during the period April 1973 to August 1974 were included in the study. Excluded were those with acute obstruction, perforation, or accompanying severe diseases that did not allow laparotomy to be performed. T h e distribution of the remaining 123 patients is shown in Table 1. T h e n u m b e r of women was twice the n u m b e r of men. An abdominal mass was found in 23 and ascites in nine patients; 46 were thin, 15 obese, and 62 had normal weights (average __+10 per cent in Documenta Geigy).
Results Radiologic Cancer: Cancer was excluded by colonoscopy in the cases of three of the 43 patients diagnosed as having cancer on the basis of radiologic examination (Table 2). T h e barium-enema examination was repeated after colonoscopy, and cancer could no longer be seen in the three patients, who were symptom-free at follow-up studies 12, 11, and 7 months later, respectively.
* Received for publication March 3, 1975. Address reprint requests to Dr. Kronborg, Kajer6dvej 124, 3460 Birker6d, Denmark.
674 Dis. Col. & Rect. Nov.-Dec. 1975
Volume 18 Number 8
BARIUM-ENEMA AND COLONOSCOPY
Volume 18 Number 8
I n the cases of 22 p a t i e n t s the r a d i o l o g i c diagnosis of cancer was confirmed by colonoscopy a n d later l a p a r o t o m y . Stenosis of the sig:noid colon p r e v e n t e d passage of the scope in four patients; consequently, the r a d i o l o g i c diagnosis could n o t be challenged, a n d these four p a t i e n t s were shown to have cancer at l a p a r o t o m y . N o endoscopic diagnosis was o b t a i n e d for 14 p a t i e n t s ( T a b l e s 2 a n d 4 ) . I n c o m p l e t e insertion was n o t r e l a t e d to age, sex, weight, a b d o m i n a l mass a n d ascites, type of anesthesia a n d use of fluoroscopy. C a n c e r was f o u n d in 13 of the 14 p a t i e n t s at l a p a r o t omy, w h i l e one d e n i e d o p e r a t i o n . Exclusion of the last p a t i e n t results in a predictive vahte of a diagnosis of cancer on the basis of b a r i u m - e n e m a e x a m i n a t i o n of 93 p e r cent ( 4 2 - 3 / 4 2 ) . T w o of the 42 p a t i e n t s h a d m o r e t h a n one b a r i u m - e n e m a examin a t i o n before the diagnosis of cancer was made. R a d i o l o g i c Suspicion of Cancer: T h e suspect area was most f r e q u e n t l y the left
675
TABLE l. Distribution According to Age and Radiologic Diagnosis
Age (Years)
Cancer Number of Patients
Cancer ? Number of Patients
30-59 60-69 70-88
8 19 16
19 28 33
43
80
TOTAL
side of the colon w i t h this diagnosis ( T a b l e 3), a n d a c c o m p a n y i n g d i v e r t i c u l a r disease was found by b a r i u m - e n e m a e x a m i n a t i o n in 17 of the 47 p a t i e n t s . T h e b a r i u m - e n e m a studies were unsatisfactory f r o m a technical p o i n t of view in 33 of 80 cases, a n d they were r e p e a t e d in 12, b u t w i t h o u t any c h a n g e i n the r a d i o l o g i c diacnosi~ Cancer was e x c l u d e d by colonoscopy in 30 of the 80 cases; seven of these 30 p a t i e n t s h a d unsatisfactory b a r i u m - e n e m a studies, which were n o t r e p e a t e d . C o n f i r m a t i o n of the endoscopic diagnosis was o b t a i n e d by
TABLE 2. Colonoscopy in Patients with Radiologically Demonstrated Cancer Cancer Number of Patients
Site of Cancer Demonstrated Radiologically Sigmoid and descending colon Transverse colon Cecum and ascending colon Two locations
Diagnosis by Colonoscopy Cancer ? Normal No Diagnosis Number Number Number of Patients of Patients of Patients 4
II
4 6
I
1
2
11 1
3
14
1
I
22
4
TABLE 3. Colonoscopy in Patients with Radiologic Suspicion of Cancer
Site of Cancer Suspected on the Basis of Radiologic Examination Sigmoid and descending colon Transverse colon Cecum and ascending colon
Cancer Number of Patients
Diagnosis by Colonoscopy Other Cancer ? Normal Disease Number Number Number of Patients of Patients of Patients
11 3
16 2
11 5
1
1
7
15
19
23
7
No Diagnosis Number of Patients 2 4 10
7
16
676
KRONBORG AND OSTERGAARD
Causesof Unsuccessful Colonoseopy in Relation to Radiologic Diagnosis
TABLE 4.
Cancer Number of Patients
Cancer ? Number of Patients
Growing or double loop of sigmoid
4
Sharp a n g u l a t i o n between sigmoid a n d descending colon
1
1
Sharp a n g u l a t i o n at left flexure
1
2
4
L o n g transverse colon
6
4
Insufficient bowel p r e p a r a t i o n
2
2
Pain
0
3
14
16
laparotomy in three cases and by follow-up studies in 23. Barium-enema studies were repeated in the cases of six of the last 23 patients after colonoscopy, when cancer was no longer suspected. T h r e e patients had died from causes other than cancer, but one was operated upon because of a sigmoidal cancer, which was missed by a less experienced colonoscopist. In this case radiologic e x a m i n a t i o n s u g g e s t e d a cancer in the ascending colon, but colonoscopy showed a normal colon. Other pathologic conditions shown by colonoscopy (Table 3) were diverticular disease in six patients and a polyp in one patient. T h e predictive value of excluding cancer by colonoscopy in the 30 patients was 97 per cent (29/30). T h e colonoscopic diagnosis of cancer in 15 cases of patients suspected to have cancer on the basis of radiologic examination could be confirmed in only 11; all 15 patients were operated upon, and cancer was found in 11, while one had a polyp with pronounced precancerosis, another a villous adenoma, and the remaining two patients peridiverticulitis of the sigmoid colon. T h e radiologic impression of cancer in 19 cases could not be challenged because of stenosis that could not be passed by the scope. T h r e e of the patients had cancer and one a normal colon at laparotomy. Seven more were operated upon, five having
Dis. Col. & Rect. Nov.-Dec. 1975
perisigmoiditis, one Crohn's disease, and another adhesions around the transverse colon. T h e remaining eight patients had no symptom of cancer at follow up. No endoscopic diagnosis was reached in 16 cases (Tables 3 and 4). Incomplete insertion of the scope was not related to any of the problems encountered in the cases of patients who had radiologic evidence of cancer. Nine of the 16 patients were operated upon, three having cancer and two other diseases, but four having normal colons; the other seven patients had no symptom of cancer at follow-up and repeat barium-enema studies of five showed no disease. No complication was seen after colonoscopy except a lesion of the sigmoid serosal layer (a longitudinal split), which was detected during a laparotomy for cancer. Discussion T h e circumstances that most patients were more than 60 years old and had their bariun>enema studies after bowel preparation at home explain the high number of unsatisfactory examinations. Further evidence is given by the finding of normal colon by a repeat barium-enema studies performed during the hospital stays of 11 patients with questionable diagnoses of cancer based upon the first barium-enema studies and no symptom of cancer at follow-up. A small benefit from colonoscopy was seen in patients with radiologically certain cancer, since three of 4 3 patients avoided laparotomy. One of these had coprostasis, but all three barium-enema studies were considered satisfactory. A larger benefit from colonoscopy was seen in patients suspected to have cancer on the basis of radiologic evidence, since 30 of 80 avoided laparotomy; the one patient with an overlooked cancer h a d a m isleacting barium-enema study and was examined by an inexperienced colonoscopist. T w o of the four patients who had false-positive diag-
Volume I8 Number 8
BARIUM-ENEMA AND COI.ONOSCOPY
noses of cancer by colonoscopy would not have been spared laparotomy by performance of biopsy during colonoscopy, because neither precancerosis nor villous adenoma could be totally removed by use of a biopsy forceps or a sling, tt thus seems reasonable to claim a predictive vahte of cancer diagnosis by colonoscopy in the present series of 95 per cent (22/22 + 13/15). T h e diagnostic value of colonoscopic biopsies was not evaluated. Colonoscopy was not very helpful in cases of patients who had radiologically evident stenosis of the sigmoid colon; othersS have had the same experience. Colonoscopy cannot always be completed. However, the present number of tulstlccessfttl colonoscopies probably can be reduced. Tim use of a plastic tttbe 4 to straighten the sigmoid colon may reduce the number of unsuccessful attempts resulting from the first four causes listed in Table 4. Pains are less frequent if diazepam is combined with pethidine. T h e three patients with prohibitive pain in the present series had only diazepam. T h e lack of fluoroscopy in 31 cases resulted in one unsuccessful colonoscopy; most of these examinations were sigmoid colonoscopies. No fatal complication occurred; lesions of the serosal layer of the sigmoid colon have been reported before, s but it is not known how often they are seen during laparotomy. One lethal perforation of the si~m'noid was seen among 66 patients having colonoscopy for other reasons during the trial period. T h e perforation was detected three days after a complete insertion of the colonoscope.
Summary and Conclusions T h e diagnostic value of colonoscopy was investigated in 123 patients with certain or questionable cancer of the colon as demonstrated by an ordinary barium-enema examination. T h e diagnosis was revised by laparotomy or clinical follow-up studies in
677
cases of patients having no operation. Tim following conclusions were deduced: 1) T h e number of unnecessary laparotomies may be redticed by doing colonoscopy in patients with certain or questionable cancer of the colon as demonstrated by ordinary barium-enema studies. 2) T h e gain in diagnostic value of adding a colonoscopy to a barium-enema examination is more pronounced in patients with questionable than in those with certain cancer as visualized by the barium-enema studies. 3) T h e risk of missing a cancer of the colon during colonoscopy is very small if an experienced examiner looking for cancer performs the colonoscopy. 4) Colonoscopy is of little diagnostic value in cases of patients who have radiologic evidence of stenosis of the sigmoid colon. 5) T h e number of patients selected for colonoscopy on the basis of radiologic evidence suggesting cancer probably can be reduced by refinement of the barium-enema examination.
References 1. Anders A, Peveretos P, Taenzer V: Falschpositive Tumorbefunde des rechten Hemicolon. Chirurg 45: 127, 1974 2. Cooley RN: Evaluation of the barium enema examination in the diagnosis of carcinoma of the colon: A 13-year experience. Congreso Internacional de Radiologia, Abstracts, Madrid, 1973, p. 162 3. Dean AC, Newell JP: Colonoscopy in the differential diagnosis of carcinoma from diverticulitis of the sigmoid colon. Br J Surg 60: 633, 1973 4. Deyhle P: A plastic tube for the maintenance of the straightening of the sigmoid colon during coloscopy. Endoscopy 4: 224, 1972 5. Koyama Y: Fiberscopic examination of colorectal diseases. Am J Proctol 25: 5l, 1974 6. Kuld Hansen L: Colonoscopy: A study of 50 cases. Scand J Gastroenterol 6: 687, 1971 7. Oestergaard A: Colonoscopy: Assessment of 100 consecutive examinations. Ugeskr Laeger 135: 2444, 1973 8. Sugarbaker PH, Vineyard GC, Lewicki AM, et al: Colonoscopy in the management of diseases of the colon and rectum. Surg Gynecol Obstet 139: 341, 1974 9. Teague RH, Salmon PR, Read AE: Fibreoptic examination of the colon: A review of 955 cases. Gut 14: 139, 1973 10. Williams C, Teague R: Progress report: Colonoscopy. Gut 14: 990, 1973
From the Department of Surgical Gastroenterology F, Bispebjerg Hospital, Copenhagen, Denmark
Colonoscopy was performed after the barium-enema studies in all cases (in 112 cases, three or more days later). T h e aperient used for bowel preparation was Bisacodylum NIrN, 40 mg, given as tablets the day before, with 10 m g given as an enema a few hours before colonoscopy. Sedation was obtained by intravenous injection of the diazepam, 10-20 mg, in 91 cases, while injection of fentanyl and droperidol was used for analgesia in 26. Six patients had no medication. Fluoroscopy was used for insertion during 92 of the 123 examinations. T h e instrument was the "long" colonoscope, Olympus CIr . LB. T w o experienced examiners performed 112 c o l o n o s c o p i c examinations. T h e y did not attempt to reach the cecum in every patient, but to reach the process demonstrated by the barium-enema. A diagnosis of cancer, questionable cancer, no colonic disease, or other colonic disease was established if the area of the "process" was reached. Laparotomy was performed in 78 of the 123 cases. T h e remaining 45 patients had clinical follow-up studies 6 to 12 months after colonoscopy.
IrALSE-POSITIVE DIAGNOSES Of c a n c e r o f t h e
colon are made on the basis of bariumenema examination in 10 to 20 per cent of cases of patients who have symptoms suggesting cancer.l, 2 These patients are consequently subjected to unnecessary laparotomies. Colonoscopy has been said to eliminate the need for laparotomy in most such cases,6, 7, 9, lo but confirmation of the "definitive" colonoscopic diagnosis by later clinical follow-up has been achieved in only a few studies, a, s T h e purpose of the present study was to investigate the possible diagnostic value of colonoscopy in patients with certain or questionable cancer of the colon as demonstrated by routine barium-enema examination. This could be accomplished by clinical follow-up studies of patients not subjected to laparotomy. Materials and Methods Patients who had certain or questionable diagnoses of cancer of the colon made on the basis of barium-enema examination during the period April 1973 to August 1974 were included in the study. Excluded were those with acute obstruction, perforation, or accompanying severe diseases that did not allow laparotomy to be performed. T h e distribution of the remaining 123 patients is shown in Table 1. T h e n u m b e r of women was twice the n u m b e r of men. An abdominal mass was found in 23 and ascites in nine patients; 46 were thin, 15 obese, and 62 had normal weights (average __+10 per cent in Documenta Geigy).
Results Radiologic Cancer: Cancer was excluded by colonoscopy in the cases of three of the 43 patients diagnosed as having cancer on the basis of radiologic examination (Table 2). T h e barium-enema examination was repeated after colonoscopy, and cancer could no longer be seen in the three patients, who were symptom-free at follow-up studies 12, 11, and 7 months later, respectively.
* Received for publication March 3, 1975. Address reprint requests to Dr. Kronborg, Kajer6dvej 124, 3460 Birker6d, Denmark.
674 Dis. Col. & Rect. Nov.-Dec. 1975
Volume 18 Number 8
BARIUM-ENEMA AND COLONOSCOPY
Volume 18 Number 8
I n the cases of 22 p a t i e n t s the r a d i o l o g i c diagnosis of cancer was confirmed by colonoscopy a n d later l a p a r o t o m y . Stenosis of the sig:noid colon p r e v e n t e d passage of the scope in four patients; consequently, the r a d i o l o g i c diagnosis could n o t be challenged, a n d these four p a t i e n t s were shown to have cancer at l a p a r o t o m y . N o endoscopic diagnosis was o b t a i n e d for 14 p a t i e n t s ( T a b l e s 2 a n d 4 ) . I n c o m p l e t e insertion was n o t r e l a t e d to age, sex, weight, a b d o m i n a l mass a n d ascites, type of anesthesia a n d use of fluoroscopy. C a n c e r was f o u n d in 13 of the 14 p a t i e n t s at l a p a r o t omy, w h i l e one d e n i e d o p e r a t i o n . Exclusion of the last p a t i e n t results in a predictive vahte of a diagnosis of cancer on the basis of b a r i u m - e n e m a e x a m i n a t i o n of 93 p e r cent ( 4 2 - 3 / 4 2 ) . T w o of the 42 p a t i e n t s h a d m o r e t h a n one b a r i u m - e n e m a examin a t i o n before the diagnosis of cancer was made. R a d i o l o g i c Suspicion of Cancer: T h e suspect area was most f r e q u e n t l y the left
675
TABLE l. Distribution According to Age and Radiologic Diagnosis
Age (Years)
Cancer Number of Patients
Cancer ? Number of Patients
30-59 60-69 70-88
8 19 16
19 28 33
43
80
TOTAL
side of the colon w i t h this diagnosis ( T a b l e 3), a n d a c c o m p a n y i n g d i v e r t i c u l a r disease was found by b a r i u m - e n e m a e x a m i n a t i o n in 17 of the 47 p a t i e n t s . T h e b a r i u m - e n e m a studies were unsatisfactory f r o m a technical p o i n t of view in 33 of 80 cases, a n d they were r e p e a t e d in 12, b u t w i t h o u t any c h a n g e i n the r a d i o l o g i c diacnosi~ Cancer was e x c l u d e d by colonoscopy in 30 of the 80 cases; seven of these 30 p a t i e n t s h a d unsatisfactory b a r i u m - e n e m a studies, which were n o t r e p e a t e d . C o n f i r m a t i o n of the endoscopic diagnosis was o b t a i n e d by
TABLE 2. Colonoscopy in Patients with Radiologically Demonstrated Cancer Cancer Number of Patients
Site of Cancer Demonstrated Radiologically Sigmoid and descending colon Transverse colon Cecum and ascending colon Two locations
Diagnosis by Colonoscopy Cancer ? Normal No Diagnosis Number Number Number of Patients of Patients of Patients 4
II
4 6
I
1
2
11 1
3
14
1
I
22
4
TABLE 3. Colonoscopy in Patients with Radiologic Suspicion of Cancer
Site of Cancer Suspected on the Basis of Radiologic Examination Sigmoid and descending colon Transverse colon Cecum and ascending colon
Cancer Number of Patients
Diagnosis by Colonoscopy Other Cancer ? Normal Disease Number Number Number of Patients of Patients of Patients
11 3
16 2
11 5
1
1
7
15
19
23
7
No Diagnosis Number of Patients 2 4 10
7
16
676
KRONBORG AND OSTERGAARD
Causesof Unsuccessful Colonoseopy in Relation to Radiologic Diagnosis
TABLE 4.
Cancer Number of Patients
Cancer ? Number of Patients
Growing or double loop of sigmoid
4
Sharp a n g u l a t i o n between sigmoid a n d descending colon
1
1
Sharp a n g u l a t i o n at left flexure
1
2
4
L o n g transverse colon
6
4
Insufficient bowel p r e p a r a t i o n
2
2
Pain
0
3
14
16
laparotomy in three cases and by follow-up studies in 23. Barium-enema studies were repeated in the cases of six of the last 23 patients after colonoscopy, when cancer was no longer suspected. T h r e e patients had died from causes other than cancer, but one was operated upon because of a sigmoidal cancer, which was missed by a less experienced colonoscopist. In this case radiologic e x a m i n a t i o n s u g g e s t e d a cancer in the ascending colon, but colonoscopy showed a normal colon. Other pathologic conditions shown by colonoscopy (Table 3) were diverticular disease in six patients and a polyp in one patient. T h e predictive value of excluding cancer by colonoscopy in the 30 patients was 97 per cent (29/30). T h e colonoscopic diagnosis of cancer in 15 cases of patients suspected to have cancer on the basis of radiologic examination could be confirmed in only 11; all 15 patients were operated upon, and cancer was found in 11, while one had a polyp with pronounced precancerosis, another a villous adenoma, and the remaining two patients peridiverticulitis of the sigmoid colon. T h e radiologic impression of cancer in 19 cases could not be challenged because of stenosis that could not be passed by the scope. T h r e e of the patients had cancer and one a normal colon at laparotomy. Seven more were operated upon, five having
Dis. Col. & Rect. Nov.-Dec. 1975
perisigmoiditis, one Crohn's disease, and another adhesions around the transverse colon. T h e remaining eight patients had no symptom of cancer at follow up. No endoscopic diagnosis was reached in 16 cases (Tables 3 and 4). Incomplete insertion of the scope was not related to any of the problems encountered in the cases of patients who had radiologic evidence of cancer. Nine of the 16 patients were operated upon, three having cancer and two other diseases, but four having normal colons; the other seven patients had no symptom of cancer at follow-up and repeat barium-enema studies of five showed no disease. No complication was seen after colonoscopy except a lesion of the sigmoid serosal layer (a longitudinal split), which was detected during a laparotomy for cancer. Discussion T h e circumstances that most patients were more than 60 years old and had their bariun>enema studies after bowel preparation at home explain the high number of unsatisfactory examinations. Further evidence is given by the finding of normal colon by a repeat barium-enema studies performed during the hospital stays of 11 patients with questionable diagnoses of cancer based upon the first barium-enema studies and no symptom of cancer at follow-up. A small benefit from colonoscopy was seen in patients with radiologically certain cancer, since three of 4 3 patients avoided laparotomy. One of these had coprostasis, but all three barium-enema studies were considered satisfactory. A larger benefit from colonoscopy was seen in patients suspected to have cancer on the basis of radiologic evidence, since 30 of 80 avoided laparotomy; the one patient with an overlooked cancer h a d a m isleacting barium-enema study and was examined by an inexperienced colonoscopist. T w o of the four patients who had false-positive diag-
Volume I8 Number 8
BARIUM-ENEMA AND COI.ONOSCOPY
noses of cancer by colonoscopy would not have been spared laparotomy by performance of biopsy during colonoscopy, because neither precancerosis nor villous adenoma could be totally removed by use of a biopsy forceps or a sling, tt thus seems reasonable to claim a predictive vahte of cancer diagnosis by colonoscopy in the present series of 95 per cent (22/22 + 13/15). T h e diagnostic value of colonoscopic biopsies was not evaluated. Colonoscopy was not very helpful in cases of patients who had radiologically evident stenosis of the sigmoid colon; othersS have had the same experience. Colonoscopy cannot always be completed. However, the present number of tulstlccessfttl colonoscopies probably can be reduced. Tim use of a plastic tttbe 4 to straighten the sigmoid colon may reduce the number of unsuccessful attempts resulting from the first four causes listed in Table 4. Pains are less frequent if diazepam is combined with pethidine. T h e three patients with prohibitive pain in the present series had only diazepam. T h e lack of fluoroscopy in 31 cases resulted in one unsuccessful colonoscopy; most of these examinations were sigmoid colonoscopies. No fatal complication occurred; lesions of the serosal layer of the sigmoid colon have been reported before, s but it is not known how often they are seen during laparotomy. One lethal perforation of the si~m'noid was seen among 66 patients having colonoscopy for other reasons during the trial period. T h e perforation was detected three days after a complete insertion of the colonoscope.
Summary and Conclusions T h e diagnostic value of colonoscopy was investigated in 123 patients with certain or questionable cancer of the colon as demonstrated by an ordinary barium-enema examination. T h e diagnosis was revised by laparotomy or clinical follow-up studies in
677
cases of patients having no operation. Tim following conclusions were deduced: 1) T h e number of unnecessary laparotomies may be redticed by doing colonoscopy in patients with certain or questionable cancer of the colon as demonstrated by ordinary barium-enema studies. 2) T h e gain in diagnostic value of adding a colonoscopy to a barium-enema examination is more pronounced in patients with questionable than in those with certain cancer as visualized by the barium-enema studies. 3) T h e risk of missing a cancer of the colon during colonoscopy is very small if an experienced examiner looking for cancer performs the colonoscopy. 4) Colonoscopy is of little diagnostic value in cases of patients who have radiologic evidence of stenosis of the sigmoid colon. 5) T h e number of patients selected for colonoscopy on the basis of radiologic evidence suggesting cancer probably can be reduced by refinement of the barium-enema examination.
References 1. Anders A, Peveretos P, Taenzer V: Falschpositive Tumorbefunde des rechten Hemicolon. Chirurg 45: 127, 1974 2. Cooley RN: Evaluation of the barium enema examination in the diagnosis of carcinoma of the colon: A 13-year experience. Congreso Internacional de Radiologia, Abstracts, Madrid, 1973, p. 162 3. Dean AC, Newell JP: Colonoscopy in the differential diagnosis of carcinoma from diverticulitis of the sigmoid colon. Br J Surg 60: 633, 1973 4. Deyhle P: A plastic tube for the maintenance of the straightening of the sigmoid colon during coloscopy. Endoscopy 4: 224, 1972 5. Koyama Y: Fiberscopic examination of colorectal diseases. Am J Proctol 25: 5l, 1974 6. Kuld Hansen L: Colonoscopy: A study of 50 cases. Scand J Gastroenterol 6: 687, 1971 7. Oestergaard A: Colonoscopy: Assessment of 100 consecutive examinations. Ugeskr Laeger 135: 2444, 1973 8. Sugarbaker PH, Vineyard GC, Lewicki AM, et al: Colonoscopy in the management of diseases of the colon and rectum. Surg Gynecol Obstet 139: 341, 1974 9. Teague RH, Salmon PR, Read AE: Fibreoptic examination of the colon: A review of 955 cases. Gut 14: 139, 1973 10. Williams C, Teague R: Progress report: Colonoscopy. Gut 14: 990, 1973
