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Is lumbar epidural analgesia an alternative in patients who have incomplete colonoscopy with standard premedication?
0016-5107/82/2804-0240$02.00/0 GASTROINTESTINAL ENDOSCOPY Copyright © 1982 by the American Society for Gastrointestinal Endoscopy
Is lumbar epidural analgesia an alternative in patients who have incomplete colonoscopy with standard premedication? H. Bleiberg, MD T. Deloof, MD P. Ewalenko, MD A. Vandesteene, MD M. Beyens, RN A. Tremblez, RN Brussels, Belgium
Total colonoscopy is unsuccessful in about 10% of attempts. In three fourths of the cases, failure is due to the patient's inability to tolerate the procedure and difficulty in negotiating the sigmoid colon. Lumbar epidural analgesia has been used in a series of 29 patients referred for total colonoscopy which had been unsuccessful using intravenous analgesia. The cecum was reached in 27 of 29 examinations. Mean time required to perform total colonoscopy was 10 min and took less than 5 min in one third of the cases. Complete visceral analgesia was responsible for one case of perforation.
Colonoscopy permits polyps of the cecum and ascending colon to be detected and excised in 80 to 90% of attempts.' Failure in 75% of the cases is due to inability to pass the instrument to the ascending colon or the patient's inability to tolerate the procedure. 2 . 3 Epidural analgesia has been shown to be useful for anorectal surgerl' 5 and relief of pain following upper abdominal operations. 6 A study was undertaken to determine if lumbar epidural analgesia would allow a complete colonoscopic examination with safety in patients who could not be successfully examined with standard premedication.
MATERIALS AND METHODS From August 1979 to December 1980, 29 patients were submitted to total colonoscopy with epidural analgesia. Twenty-three patients were suspected of having polyps and two were suspected of having cancers; four had long standing ulcerative colitis. Three had previously undergone abdominal surgery, and one man with Hodgkin's disease had had abdominal surgery and irradiation. Epidural analgesia was proposed because in most of the cases total colonoscopy using intravenous analgesic agents had been unsuccessful. Patients had experienced pain and refused the proceFrom the Departments of Internal Medicine, Gastroenterology, Anesthesiology, and Surgery, the Jules Bordet Institute, Universite Libre de Bruxelles, Brussels, Belgium. Reprint requests: Dr. Harry Bleiberg, Institute Jules Bordet, 1, rue Heger Bordet, Bl000 Brussels, Belgium.
240
dure following the same method of analgesia. In one case a diagnostic colonoscopy was performed before rectal surgery. Patients were admitted to the hospital the day before and received a thorough medical evaluation before the procedure. This included chest x-ray and ECG, as well as appropriate laboratory studies. Spine x-rays were carried out in patients over 50 years of age. The patients had been on a low residue diet for 48 hours. Colonic preparation was started on the morning of admission with an enema of 2 liters of isotonic saline and this was repeated in the evening. One to 2 hours before the examination enemas were repeated until the return was clear. No laxative was given. In three patients preparation consisted of drinking mannitol (100 g in 1 liter of water) in 1 hour, 4 to 5 hours before colonoscopy. One-half hour before the examination the patients received premedication of intravenous 5 to 10 mg of diazepam and 0.25 to 0.5 mg of atropine. Epidural needle puncture with a 17 gauge Thuoy needle was performed with the patient in the sitting position, via a midline approach at the second-third or third-fourth lumbar interspace. After a test dose of 2 ml, all the patients received a dose of 13 to 18 ml of a standard solution of 2% lidocaine according to age and weight to obtain somatic analgesia up to the 8th thoracic segment. 7 ,8 Lidocaine was injected at a rate of approximately 1 ml/sec through a catheter (epidural cannula 16 G, Portex, S.A.) connected to an antibacGASTROINTESTINAL ENDOSCOPY
terial filter (Millex G.S., Millipore SA). The patients were then placed in the supine position. Twenty to 30 min after the injection, analgesic levels were determined by absence of pain in response to pinprick. If analgesia was insufficient, a complementary dose of 5 to 10 ml of 2% lidocaine was injected through the catheter. Pulse, blood, pressure, and ECG were monitored during the entire procedure. All the examinations were performed in the operating room on a table allowing fluoroscopic control. The procedure began with the patient in the left lateral decubitus position using a 16O-cm Olympus TCF-2l colonoscope. The instrument was inserted into the rectum and advanced under direct vision. Colon examination, polypectomy, and biopsies were undertaken during withdrawal of the colonoscope. After colonoscopy the patient was kept in bed overnight and left the hospital the next morning.
Table 2. Analgesic level obtained with lumbar epidural injection of 15 to 20 ml of 2% lidocaine by age. Analgesic level Age (years)
No. of patients
15-40 41-60 61-80 Total
Above T8
Under T8
Undetermined
3 13 13
2 4 11
1 6 2
3
29
17
9
3
Table 3. Need of complementary lumbar epidural injection of 2% lidocaine by analgesic level. No. of patients
No. of complementary injections
T6 T7-T8 Below T8 Undetermined
6 11 9
0 6 5
Total
29
Analgesic level
RESULTS Among the 29 patients submitted to the procedure, 18 were men and 11 were women. Their mean age was 57 years (range, 17 to 78). Total colonoscopy was successful in 27 patients. The cecum was reached within 10 min in 12 cases, in less than 5 min in nine cases, and in more than 20 min in two cases (Table 1). Fluoroscopy was necessary in four of 30 examinations. The mean dose of 2% lidocaine injected was 20 ml for patients under 40 years of age or less, 17.7 ml for patients between 41 and 60, and 18.2 ml for patients more than 60. An analgesic level above T8 was obtained in two of three patients under 40, in four of 10 patients between 40 and 60, and in 11 of 13 patients over 60 (Table 2). Tolerance was good in almost all successful colonoscopies. However, a complementary injection of 5 to 10 ml 2% lidocaine was necessary in six of 11 patients who had an analgesic level at T7-T8 and in five of 9 with an analgesic level under T8 (Table 3). Among the two failures of total colonoscopy, one patient had had multiple abdominal operations but the other had had no previous surgery. In both cases, we were unable to pass the hepatic flexure. Colonic contractions were not suppressed by lumbar epidural analgesia, and 20 mg of butylscopolamine was administered intravenously in nine of the 30 cases. Complications were observed in three patients. In two of them a drop in blood pressure was corrected by infusion of a plasma substitute (Haemacel). In one
Table 1. Time required to reach the cecum in total colonoscopy with lumbar epidural analgesia. Time (min)
No. of cases
1-5 6-10 11-20 21-40
9 12 4 2
Total
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VOLUME 28, NO. 4, 1982
3 11
patient with Hodgkin's disease and previous abdominal surgery and irradiation, perforation of the colon was apparent shortly after colonoscopy and suture of a sigmoid perforation had to be performed.
DISCUSSION Both the sympathetic and parasympathetic systems provide innervation to the colon. The afferent fibers concerned with the mediation of visceral pain are conducted to the spinal cord only via the sympathetic system by way of the splanchnic nerves originating from T6 down to 13. Rectal and colonic afferent fibers take their origin from T9 to 13. A splanchnic blockade up to T6 will thus produce complete visceral analgesia, whereas a blockade up to T8 would be satisfactory for rectal and colonic analgesia. Since there is anatomical correlation in the spinal cord between somatic and autonomic nerves, one can estimate the level of analgesia produced by pinprick. 7 - 9 With a comparable dose of 2% lidocaine, an analgesic level up to T8 and above was obtained in 11 of 13 patients over 60 and in only six of 16 patients under 60 (Table 2). This confirms that dose requirements of epidurally administered analgesic agents per spinal segment are inversely proportional to the patient's age. lO Good visceral analgesia was obtained during colonoscopy in most of the patients who did not tolerate the procedure with intravenous analgesic agents. In spite of an apparently adequate level of cutaneous analgesia up to T8, satisfactory colonic analgesia was not obtained in all cases after the first injection, and six of 11 patients needed complementary epidural injection of 2% lidocaine. When cutaneous analgesia 241
up to T6 was obtained, visceral analgesia was complete in all cases and no further injection of analgesic agent was needed (Table 3). In fact, the notion of a clear-cut spinal segment is valid mainly for somatic innervation. The anatomical distribution of sympathetic innervation is far less precise, and some degree of overlapping is observed from one spinal segment to another. 9 Patient tolerance of colonoscopy depends on many factors including psychological status, mesenteric anatomy, and colonic attachment and may vary from one patient to another. This is obvious from the fact that four of nine patients with a cutaneous level of analgesia under T8 had no complaints. Increased colonic motility has been observed in most of our patients and required the intravenous administration of butylscopolamine. Splanchnic blockade, as well as sympatholytic drugs, is known to have a stimulating effect in gastrointestinal motility." The relative increase in parasympathetic nervous system activity is probably responsible for that phenomenon. 12 Although the number of patients is small, our results suggest that total colonoscopy has been facilitated by lumbar epidural analgesia. The mean time required to perform total colonoscopy was 10 min and took less than 5 min in one third of the cases (Table 1). This is significantly less than the time of 20 min usually reported when using systemic analgesic agents. 13 Whether this facilitation is due to analgesia alone or to other factors remains unanswered. Perforation is the most serious and common complication of diagnostic colonoscopy and occurs in 0.2% of the procedures. 14 • 15 The possibility that undetected minor perforations may be induced has also been raised. 16 The risk of perforation is increased in patients with colonic disease which distorts colonic architecture or impairs motility. This is the case in patients with postoperative adhesions and fixation of the colon. Irradiated intestines are also vulnerable because of serositis and adhesions, with associated friability of the mucosa and transmural vasculitis. 17 Because all these risk factors were apparent in one of our patients, he should not have been submitted to colonoscopy. By blocking abdominal pain, which is the most prominent symptom of perforation, lumbar epidural analgesia dramatically increases the risk of perforation. This study indicates that lumbar epidural analgesia
242
can be an alternative in failures of total colonoscopy with intravenous analgesia, provided that an analgesic level up to T6 is reached. The procedure is well tolerated and easy to perform but, considering the increased risk of peforation related to visceral analgesia, patients should be cautiously selected. Patients previously submitted to abdominal surgery or irradiation and those with inflammatory or diverticular bowel disease should be definitely excluded.
ACKNOWLEDGMENT The authors thank Mrs. Collette for typing the manuscript. REFERENCES 1. GILBERTSEN VA, WILLIAMS SE, SCHUMAN L, McHUGH R: Colonoscopy in the detection of carcinoma of the intestine. Surg Gynecol Obstet 149:877, 1979 2. BESS MA, SPENCER R]: Colonoscopic polypectomies. Mayo Clin Proc 54:32, 1979 3. WINAWER SI. SHERLOCK P, SCHOHENFElD D, MILLER DG: Screening for colon cancer. Gastroenterology 70:783, 1976 4. HAKAMI M, RAHIMI M, BONYANIAN A: Sacral epidural analgesia for operations on the rectum. Am / Patho/127:39, 1976 5. PENHI OM: Bupivacaine in caudal anaesthesia for anal surgery. Reg Anaesth 1:74, 1978 6. BUCKLEY P, SIMPSON R: Relief of pain following upper abdominal operations by thoracic epidural block with Etidocaine. Acta Anaesthesiol Scand [Suppl] 60:76, 1975 7. BROMAGE PR: Epidural Analgesia, Ed. 2. Philadelphia, WB Saunders, 1978, p. 454 8. DELMAS A: Voies et Centres Nerveux, Ed. 9. Paris, Masson et Cie, 1970, p. 48 9. HANSEN K, SCHLIACK H: Segmentale Innervation, Ed. 1. Stuttgart, Thieme Verlag, 1962, p. 97 10. BROMAGE PR: Ageing and epidural dose requirements. Br / Anaesth 4:1016, 1969 11. NEELY I. CATCHPOLE B: Ileus: the restoration of alimentary tract motility by pharmacological means. Br / Surg 58:21, 1971 12. GElMAN S, FETGENBERG Z, DINTZMAN M, LEVY E: Electroenterography after cholecystectomy. Arch Surg 112:580, 1977 13. GAISFORD WD: Fiberoptic colonoscopy. Total colonoscopy. An office procedure. Dis Colon Rectum 19:388, 1976 14. ROGERS BHG, SILVIS SE, NEBEL OT, ET AL: Complications of flexible fiberoptic colonoscopy and polypectomy. Gastrointest Endosc 22:73.19';;'5 15. SMITH, LE: Fiberoptic colonoscopy, complications of colonoscopy and polypectomy. Dis Colon Rectum 19:407, 1976 16. OVERHOLT BF, HARGROVE Rt, FARRIS RK, WllSo'N NM: Colonoscopic polypectomy: silent perforation. Gastroenterology 70:112, 1976 17. SCHWESINGER WH, LEVINE BA: Complications in colonoscopy. Surg Gynecol Obstet 148:270, 1977
GASTROINTESTINAL ENDOSCOPY
Is lumbar epidural analgesia an alternative in patients who have incomplete colonoscopy with standard premedication? H. Bleiberg, MD T. Deloof, MD P. Ewalenko, MD A. Vandesteene, MD M. Beyens, RN A. Tremblez, RN Brussels, Belgium
Total colonoscopy is unsuccessful in about 10% of attempts. In three fourths of the cases, failure is due to the patient's inability to tolerate the procedure and difficulty in negotiating the sigmoid colon. Lumbar epidural analgesia has been used in a series of 29 patients referred for total colonoscopy which had been unsuccessful using intravenous analgesia. The cecum was reached in 27 of 29 examinations. Mean time required to perform total colonoscopy was 10 min and took less than 5 min in one third of the cases. Complete visceral analgesia was responsible for one case of perforation.
Colonoscopy permits polyps of the cecum and ascending colon to be detected and excised in 80 to 90% of attempts.' Failure in 75% of the cases is due to inability to pass the instrument to the ascending colon or the patient's inability to tolerate the procedure. 2 . 3 Epidural analgesia has been shown to be useful for anorectal surgerl' 5 and relief of pain following upper abdominal operations. 6 A study was undertaken to determine if lumbar epidural analgesia would allow a complete colonoscopic examination with safety in patients who could not be successfully examined with standard premedication.
MATERIALS AND METHODS From August 1979 to December 1980, 29 patients were submitted to total colonoscopy with epidural analgesia. Twenty-three patients were suspected of having polyps and two were suspected of having cancers; four had long standing ulcerative colitis. Three had previously undergone abdominal surgery, and one man with Hodgkin's disease had had abdominal surgery and irradiation. Epidural analgesia was proposed because in most of the cases total colonoscopy using intravenous analgesic agents had been unsuccessful. Patients had experienced pain and refused the proceFrom the Departments of Internal Medicine, Gastroenterology, Anesthesiology, and Surgery, the Jules Bordet Institute, Universite Libre de Bruxelles, Brussels, Belgium. Reprint requests: Dr. Harry Bleiberg, Institute Jules Bordet, 1, rue Heger Bordet, Bl000 Brussels, Belgium.
240
dure following the same method of analgesia. In one case a diagnostic colonoscopy was performed before rectal surgery. Patients were admitted to the hospital the day before and received a thorough medical evaluation before the procedure. This included chest x-ray and ECG, as well as appropriate laboratory studies. Spine x-rays were carried out in patients over 50 years of age. The patients had been on a low residue diet for 48 hours. Colonic preparation was started on the morning of admission with an enema of 2 liters of isotonic saline and this was repeated in the evening. One to 2 hours before the examination enemas were repeated until the return was clear. No laxative was given. In three patients preparation consisted of drinking mannitol (100 g in 1 liter of water) in 1 hour, 4 to 5 hours before colonoscopy. One-half hour before the examination the patients received premedication of intravenous 5 to 10 mg of diazepam and 0.25 to 0.5 mg of atropine. Epidural needle puncture with a 17 gauge Thuoy needle was performed with the patient in the sitting position, via a midline approach at the second-third or third-fourth lumbar interspace. After a test dose of 2 ml, all the patients received a dose of 13 to 18 ml of a standard solution of 2% lidocaine according to age and weight to obtain somatic analgesia up to the 8th thoracic segment. 7 ,8 Lidocaine was injected at a rate of approximately 1 ml/sec through a catheter (epidural cannula 16 G, Portex, S.A.) connected to an antibacGASTROINTESTINAL ENDOSCOPY
terial filter (Millex G.S., Millipore SA). The patients were then placed in the supine position. Twenty to 30 min after the injection, analgesic levels were determined by absence of pain in response to pinprick. If analgesia was insufficient, a complementary dose of 5 to 10 ml of 2% lidocaine was injected through the catheter. Pulse, blood, pressure, and ECG were monitored during the entire procedure. All the examinations were performed in the operating room on a table allowing fluoroscopic control. The procedure began with the patient in the left lateral decubitus position using a 16O-cm Olympus TCF-2l colonoscope. The instrument was inserted into the rectum and advanced under direct vision. Colon examination, polypectomy, and biopsies were undertaken during withdrawal of the colonoscope. After colonoscopy the patient was kept in bed overnight and left the hospital the next morning.
Table 2. Analgesic level obtained with lumbar epidural injection of 15 to 20 ml of 2% lidocaine by age. Analgesic level Age (years)
No. of patients
15-40 41-60 61-80 Total
Above T8
Under T8
Undetermined
3 13 13
2 4 11
1 6 2
3
29
17
9
3
Table 3. Need of complementary lumbar epidural injection of 2% lidocaine by analgesic level. No. of patients
No. of complementary injections
T6 T7-T8 Below T8 Undetermined
6 11 9
0 6 5
Total
29
Analgesic level
RESULTS Among the 29 patients submitted to the procedure, 18 were men and 11 were women. Their mean age was 57 years (range, 17 to 78). Total colonoscopy was successful in 27 patients. The cecum was reached within 10 min in 12 cases, in less than 5 min in nine cases, and in more than 20 min in two cases (Table 1). Fluoroscopy was necessary in four of 30 examinations. The mean dose of 2% lidocaine injected was 20 ml for patients under 40 years of age or less, 17.7 ml for patients between 41 and 60, and 18.2 ml for patients more than 60. An analgesic level above T8 was obtained in two of three patients under 40, in four of 10 patients between 40 and 60, and in 11 of 13 patients over 60 (Table 2). Tolerance was good in almost all successful colonoscopies. However, a complementary injection of 5 to 10 ml 2% lidocaine was necessary in six of 11 patients who had an analgesic level at T7-T8 and in five of 9 with an analgesic level under T8 (Table 3). Among the two failures of total colonoscopy, one patient had had multiple abdominal operations but the other had had no previous surgery. In both cases, we were unable to pass the hepatic flexure. Colonic contractions were not suppressed by lumbar epidural analgesia, and 20 mg of butylscopolamine was administered intravenously in nine of the 30 cases. Complications were observed in three patients. In two of them a drop in blood pressure was corrected by infusion of a plasma substitute (Haemacel). In one
Table 1. Time required to reach the cecum in total colonoscopy with lumbar epidural analgesia. Time (min)
No. of cases
1-5 6-10 11-20 21-40
9 12 4 2
Total
27
VOLUME 28, NO. 4, 1982
3 11
patient with Hodgkin's disease and previous abdominal surgery and irradiation, perforation of the colon was apparent shortly after colonoscopy and suture of a sigmoid perforation had to be performed.
DISCUSSION Both the sympathetic and parasympathetic systems provide innervation to the colon. The afferent fibers concerned with the mediation of visceral pain are conducted to the spinal cord only via the sympathetic system by way of the splanchnic nerves originating from T6 down to 13. Rectal and colonic afferent fibers take their origin from T9 to 13. A splanchnic blockade up to T6 will thus produce complete visceral analgesia, whereas a blockade up to T8 would be satisfactory for rectal and colonic analgesia. Since there is anatomical correlation in the spinal cord between somatic and autonomic nerves, one can estimate the level of analgesia produced by pinprick. 7 - 9 With a comparable dose of 2% lidocaine, an analgesic level up to T8 and above was obtained in 11 of 13 patients over 60 and in only six of 16 patients under 60 (Table 2). This confirms that dose requirements of epidurally administered analgesic agents per spinal segment are inversely proportional to the patient's age. lO Good visceral analgesia was obtained during colonoscopy in most of the patients who did not tolerate the procedure with intravenous analgesic agents. In spite of an apparently adequate level of cutaneous analgesia up to T8, satisfactory colonic analgesia was not obtained in all cases after the first injection, and six of 11 patients needed complementary epidural injection of 2% lidocaine. When cutaneous analgesia 241
up to T6 was obtained, visceral analgesia was complete in all cases and no further injection of analgesic agent was needed (Table 3). In fact, the notion of a clear-cut spinal segment is valid mainly for somatic innervation. The anatomical distribution of sympathetic innervation is far less precise, and some degree of overlapping is observed from one spinal segment to another. 9 Patient tolerance of colonoscopy depends on many factors including psychological status, mesenteric anatomy, and colonic attachment and may vary from one patient to another. This is obvious from the fact that four of nine patients with a cutaneous level of analgesia under T8 had no complaints. Increased colonic motility has been observed in most of our patients and required the intravenous administration of butylscopolamine. Splanchnic blockade, as well as sympatholytic drugs, is known to have a stimulating effect in gastrointestinal motility." The relative increase in parasympathetic nervous system activity is probably responsible for that phenomenon. 12 Although the number of patients is small, our results suggest that total colonoscopy has been facilitated by lumbar epidural analgesia. The mean time required to perform total colonoscopy was 10 min and took less than 5 min in one third of the cases (Table 1). This is significantly less than the time of 20 min usually reported when using systemic analgesic agents. 13 Whether this facilitation is due to analgesia alone or to other factors remains unanswered. Perforation is the most serious and common complication of diagnostic colonoscopy and occurs in 0.2% of the procedures. 14 • 15 The possibility that undetected minor perforations may be induced has also been raised. 16 The risk of perforation is increased in patients with colonic disease which distorts colonic architecture or impairs motility. This is the case in patients with postoperative adhesions and fixation of the colon. Irradiated intestines are also vulnerable because of serositis and adhesions, with associated friability of the mucosa and transmural vasculitis. 17 Because all these risk factors were apparent in one of our patients, he should not have been submitted to colonoscopy. By blocking abdominal pain, which is the most prominent symptom of perforation, lumbar epidural analgesia dramatically increases the risk of perforation. This study indicates that lumbar epidural analgesia
242
can be an alternative in failures of total colonoscopy with intravenous analgesia, provided that an analgesic level up to T6 is reached. The procedure is well tolerated and easy to perform but, considering the increased risk of peforation related to visceral analgesia, patients should be cautiously selected. Patients previously submitted to abdominal surgery or irradiation and those with inflammatory or diverticular bowel disease should be definitely excluded.
ACKNOWLEDGMENT The authors thank Mrs. Collette for typing the manuscript. REFERENCES 1. GILBERTSEN VA, WILLIAMS SE, SCHUMAN L, McHUGH R: Colonoscopy in the detection of carcinoma of the intestine. Surg Gynecol Obstet 149:877, 1979 2. BESS MA, SPENCER R]: Colonoscopic polypectomies. Mayo Clin Proc 54:32, 1979 3. WINAWER SI. SHERLOCK P, SCHOHENFElD D, MILLER DG: Screening for colon cancer. Gastroenterology 70:783, 1976 4. HAKAMI M, RAHIMI M, BONYANIAN A: Sacral epidural analgesia for operations on the rectum. Am / Patho/127:39, 1976 5. PENHI OM: Bupivacaine in caudal anaesthesia for anal surgery. Reg Anaesth 1:74, 1978 6. BUCKLEY P, SIMPSON R: Relief of pain following upper abdominal operations by thoracic epidural block with Etidocaine. Acta Anaesthesiol Scand [Suppl] 60:76, 1975 7. BROMAGE PR: Epidural Analgesia, Ed. 2. Philadelphia, WB Saunders, 1978, p. 454 8. DELMAS A: Voies et Centres Nerveux, Ed. 9. Paris, Masson et Cie, 1970, p. 48 9. HANSEN K, SCHLIACK H: Segmentale Innervation, Ed. 1. Stuttgart, Thieme Verlag, 1962, p. 97 10. BROMAGE PR: Ageing and epidural dose requirements. Br / Anaesth 4:1016, 1969 11. NEELY I. CATCHPOLE B: Ileus: the restoration of alimentary tract motility by pharmacological means. Br / Surg 58:21, 1971 12. GElMAN S, FETGENBERG Z, DINTZMAN M, LEVY E: Electroenterography after cholecystectomy. Arch Surg 112:580, 1977 13. GAISFORD WD: Fiberoptic colonoscopy. Total colonoscopy. An office procedure. Dis Colon Rectum 19:388, 1976 14. ROGERS BHG, SILVIS SE, NEBEL OT, ET AL: Complications of flexible fiberoptic colonoscopy and polypectomy. Gastrointest Endosc 22:73.19';;'5 15. SMITH, LE: Fiberoptic colonoscopy, complications of colonoscopy and polypectomy. Dis Colon Rectum 19:407, 1976 16. OVERHOLT BF, HARGROVE Rt, FARRIS RK, WllSo'N NM: Colonoscopic polypectomy: silent perforation. Gastroenterology 70:112, 1976 17. SCHWESINGER WH, LEVINE BA: Complications in colonoscopy. Surg Gynecol Obstet 148:270, 1977
GASTROINTESTINAL ENDOSCOPY