170 degrees wide-angle colonoscope: effect on efficiency and miss rates

BACKGROUND: Small polyps are routinely missed during colonoscopy even with careful examination. AIM: To determine and compare endoscopic efficiency and polyp miss rate between a prototype 170 degrees wide-angle (WA) colonoscope and a standard (S) colonoscope. METHODS: Two consecutive same-day colonoscopies were performed in 50 patients with intact colons. The patients were randomized to undergo the first colonoscopy with either the prototype WA 170 degrees angle of view colonoscope or an S adult 140 degrees angle of view colonoscope. RESULTS: The mean time for insertion was 2.09 (1.09) min versus 2.53 (1.47) min (p= 0.002) for the WA colonoscope and the S colonoscope, respectively. Similarly, the mean time for examination during withdrawal was shorter with the WA colonoscope (4.98 (0.94) vs 5.74 (1.12) min; p < 0.0001). The mean insertion time for the second examination was shorter than the insertion time for the first examination, irrespective of the colonoscope (p= 0.006). However, the withdrawal times were not significantly different between the first and second examinations (p= 0.11). The miss rate for all polyps with the WA colonoscope (19%) was similar to the miss rate with the S colonoscope (27%; p= 0.19). The miss rates for adenomas with the WA (10/33; 30.3%) and the S scope (15/50; 30%) were similar (p= 0.98). CONCLUSIONS: The use of the WA colonoscope was associated with a reduction in insertion time to the cecum, as well as examination time during withdrawal. No evidence was found that the accuracy of the two colonoscopes differs.     

The Miss Rate for Colorectal Adenoma Determined by Quality-Adjusted, Back-to-Back Colonoscopies

Background/Aims

Colonoscopy is considered to be the gold standard for detecting adenomatous polyps. Polyps are missed during colonoscopic examination at a rate that varies from 6% to 27%. The adenoma miss rate affects colonoscopic surveillance intervals and procedural quality. We aimed to assess the adenoma miss rate and the variables affecting the rate using same-day, quality-adjusted, back-to-back colonoscopies.

Methods

This prospective study was performed at a single institution and included 149 patients. Two consecutive same-day colonoscopies were performed by two experienced endoscopists. The adenoma miss rates and variables affecting the missed adenomas, including polyp characteristics and procedure times, were evaluated.

Results

The miss rates of polyps, adenomas, and advanced adenomas were 16.8%, 17%, and 5.4%, respectively. The smaller polyps and increased number of polyps detected during the first colonoscopy were more likely to be missed. A longer insertion time during the colonoscopy was correlated with an increased adenoma detection rate.

Conclusions

There was a significant miss rate in the detection of colonic adenomas even in quality-adjusted, back-to-back colonoscopies. The adenoma miss rate can be reduced with a sufficient observation time during colonoscopic insertion. The development of specific technological methods to reduce the adenoma miss rate is necessary.     

Impact of proximal colon retroflexion on adenoma miss rates

BACKGROUND: Small adenomas are commonly missed during routine colonoscopy. The aim of this study was to determine whether routine retroflexion in the proximal colon would improve adenoma detection rates. METHODS: One hundred patients underwent colonoscopy from the cecum to the splenic flexure by a gastroenterology fellow, with the removal of all visualized polyps. The cecum was then reintubated and patients were randomized to a second exam of the proximal colon by an experienced staff physician in either the forward view or a retroflexed view. RESULTS: Two patients were excluded due to a difficult initial cecal intubation. Forty-eight patients were randomized to forward view and 50 patients were randomized to a retroflexed view. Retroflexion was successful in the cecum in 60%, the ascending colon 100%, and the transverse colon 98%. The success in retroflexion was determined in part by the type of colonoscope used. If any portion of the retroflexed examination could not be performed, that reexamination was performed in the forward view. The calculated miss rates for all polyps and adenomas among patients randomized to second examination in the forward view was 36.8% and 33.3%, respectively. The calculated miss rate for all polyps and for adenomas among patients randomized to a second examination in the retroflexed view was 38.1% and 23.7%, respectively. There was no difference in miss rates for all polyps or for adenomas (p= 0.31) when the second examination was performed in the forward view versus retroflexed view. CONCLUSIONS: A second examination by retroflexion in the proximal colon did not increase the calculated miss rate relative to that performed by a forward view examination. These results do not support the addition of routine right colon retroflexion to colonoscopy.     

ASSESSMENT OF MISS AND INCIDENCE RATES OF NEOPLASTIC POLYPS AT COLONOSCOPY

Background: The incidence rate after a colonoscopic polypectomy includes the true incidence rate of new polyp formation and miss rate of polyps at the initial colonoscopy. It is therefore important to assess accurate incidence rates of polyps as well as those of missing polyps with colocoscopy. Methods: Six hundred and eighty‐eight patients who underwent total colonoscopy twice within 30 days were investigated to determine the miss rates of neoplastic polyps under colonoscopy. The cumulative incidence rates of neoplasm were evaluated by the Kaplan‐Meier method in another series of investigations on 864 patients who underwent surveillance total colonoscopy over 31 days. Results: In 157 (22.8%) patients out of 688, 200 neoplastic lesions (all adenomas) were missed during the first examination. The miss rate was 16% for adenomas ≤ 5 mm and 2% for adenomas > 10 mm. The miss rates of patients with 0, 1, 2, or > 2 neoplastic polyps on the first examination was 5.3%, 19.6%, 23.5% and 35.5%, respectively. One year cumulative incidence rates of patients with 1, 2, or > 2 neoplastic polyps on the first examination were 18.4%, 21.1% and 34.2%, respectively. Conclusion: Detection of multiple neoplasms on index colonoscopy predicts a high miss rate and cumulative incidence rate on surveillance colonoscopy. A substantial proportion of neoplasms detected at nearly 1‐year postpolypectomy surveillance colonoscopy were missed at the initial total colonoscopy.     

Does autofluorescence imaging videoendoscopy system improve the colonoscopic polyp detection rate?--a pilot study

OBJECTIVES: Colonoscopy is considered the gold standard for the detection of colorectal polyps; however, polyps can be missed with conventional white light (WL) colonoscopy. The aim of this pilot study was to evaluate whether a newly developed autofluorescence imaging (AFI) system can detect more colorectal polyps than WL.
METHODS: A modified back-to-back colonoscopy using AFI and WL was conducted for 167 patients in the right-sided colon including cecum, ascending and transverse colon by a single experienced colonoscopist. The patient was randomized to undergo the first colonoscopy with either AFI or WL (group A: AFI-WL, group B: WL-AFI). The time needed for both insertion and examination for withdrawal and all lesions detected in the right-sided colon were recorded.
RESULTS: Eighty-three patients were randomized to group A and 84 to group B. The total number of polyps detected by AFI and WL colonoscopy was 100 and 73, respectively. The miss rate for all polyps with AFI (30%) was significantly less than that with WL (49%) ( P = 0.01).
CONCLUSIONS: AFI detects more polyps in the right-sided colon compared to WL colonoscopy.     

Risk factors associated with missed colorectal flat adenoma: A multicenter retrospective tandem colonoscopy study

AIM: To determine the miss rate for colorectal flat adenomas during colonoscopy and the risk factors. METHODS: Flat adenomas are frequently missed during colonoscopy. However, the risk factors that influence their miss rates are unclear. This was a multicenter, retrospective study in which patients diagnosed with colorectal adenomas at a diagnostic colonoscopy and followed within 3 mo by a second therapeutic colonoscopy were pooled out from the established database. The “per-patient” and “per-adenoma” adenoma miss rates (AMR) for overall adenomas and flat adenomas, and patient-, adenoma-, and procedure-related risk factors potentially associated with the “per-adenoma” AMR for flat adenomas were determined. RESULTS: Chromoscopy and high-definition colonoscopy were not taken under consideration in the study. Among 2093 patients with colorectal adenomas, 691 (33.0%) were diagnosed with flat adenomas, 514 with concomitant protruding adenomas and 177 without. The “per-patient” AMR for flat adenomas was 43.3% (299/691); the rates were 54.3% and 11.3%, respectively, for those with protruding adenomas and those without (OR = 9.320, 95%CI: 5.672-15.314, χ² = 99.084, P < 0.001). The “per-adenoma” AMR for flat adenomas was 44.3% (406/916). In multivariate analysis, older age, presence of concomitant protruding adenomas, poor bowel preparation, smaller adenoma size, location at the right colon, insufficient experience of the colonoscopist, and withdrawal time < 6 min were associated with an increased “per-adenoma” AMR for flat adenomas. The AMR for flat adenomas was moderately correlated with that for overall adenomas (r = 0.516, P < 0.0001). The AMR for flat adenomas during colonoscopy was high. CONCLUSION: Patient’s age, concomitant protruding adenomas, bowel preparation, size and location of adenomas, proficiency of the colonoscopist, and withdrawal time are factors affecting the “per-adenoma” AMR for flat adenomas.     

Findings on optical colonoscopy after positive CT colonography exam

BACKGROUND & AIMS:  The aim of this study is to evaluate the findings on optical colonoscopy (OC) after a positive CT colonography (CTC) exam and characterize the type of polyps seen on OC but not reported by CTC.
METHODS:  Over an 18-month period a total of 159 asymptomatic adults had polyps seen on computed tomography colonography examination and subsequently underwent planned therapeutic optical colonoscopy. The colonoscopists were aware of the findings on CT colonography prior to further evaluation of the colon. Characteristics of polyps and adenomas seen on subsequent optical colonoscopy but not seen or reported on CT colonography were examined.
RESULTS:  The adenoma miss rate for CT colonography overall was 18.9% (25/132) including 6.2% (4/65) for polyps >9 mm and 18.2% (8/44) for polyps 6–9 mm. Three of the adenomas >9 mm not seen on CTC were sessile, and two were found in patients with technically difficult CT colonography studies due to poor colonic distention. No adenomas with advanced pathology <6 mm were found on optical colonoscopy but not reported on CT colonography. False-positive CTC referral where no polyp was seen on colonoscopy was 5.0%.
CONCLUSIONS:  CT colonography has adenoma miss rates similar to miss rates historically found with optical colonoscopy, with most missed adenomas being <10 mm and sessile in shape.     

Clinical usefulness of single-balloon endoscopy in patients with previously incomplete colonoscopy

AIM: To evaluate the clinical usefulness of single-balloon endoscopy (SBE) in patients in whom a colonoscope was technically difficult to insert previously.METHODS: The study group comprised 15 patients (8 men and 7 women) who underwent SBE for colonoscopy (30 sessions). The number of SBE sessions was 1 in 7 patients, 2 in 5 patients, 3 in 1 patient, 4 in 1 patient, and 6 in 1 patient. In all patients, total colonoscopy was previously unsuccessful. The reasons for difficulty in scope passage were an elongated colon in 6 patients, severe intestinal adhesions after open surgery in 4, an elongated colon and severe intestinal adhesions in 2, a left inguinal hernia in 2, and multiple diverticulosis of the sigmoid colon in 1. Three endoscopists were responsible for SBE. The technique for inserting SBE in the colon was basically similar to that in the small intestine. The effectiveness of SBE was assessed on the basis of the success rate of total colonoscopy and the presence or absence of complications. We also evaluated the diagnostic and treatment outcomes of colonoscopic examinations with SBE.RESULTS: Total colonoscopy was successfully accomplished in all sessions. The mean insertion time to the cecum was 22.9 ± 8.9 min (range 9 to 40). Abnormalities were found during 21 sessions of SBE. The most common abnormality was colorectal polyps (20 sessions), followed by radiation colitis (3 sessions) and diverticular disease of the colon (3 sessions). Colorectal polyps were resected endoscopically in 15 sessions. A total of 42 polyps were resected endoscopically, using snare polypectomy in 32 lesions, hot biopsy in 7 lesions, and endoscopic mucosal resection in 3 lesions. Fifty-six colorectal polyps were newly diagnosed on colonoscopic examination with SBE. Histopathologically, these lesions included 2 intramucosal cancers, 42 tubular adenomas, and 2 tubulovillous adenomas. The mean examination time was 48.2 ± 20.0 min (range 25 to 90). Colonoscopic examination or endoscopic treatment with SBE was not associated with any serious complications.CONCLUSION: SBE is a useful and safe procedure in patients in whom a colonoscope is technically difficult to insert.     

Retrospective analysis of missed advanced adenomas on surveillance colonoscopy

OBJECTIVE: Miss rates of large polyp/cancer during colonoscopy are reported from tertiary centers where experts do the colonoscopies. This information is important for determining surveillance intervals for repeat colonoscopy, patient safety, and malpractice issues. We evaluated retrospectively the miss rates of advanced adenomas in the setting of a GI fellowship training where most colonoscopies are done by closely supervised fellows. METHODS: We reviewed the 235 patients who had at least one repeat colonoscopy after initial polypectomy, between 1992 and 1999, at the Dayton Veterans Affairs Medical Center. Advanced adenomas were defined as polyps 10 mm or greater in size with or without a villous component or high-grade dysplasia. Data of missed advanced adenomas on 122 patients who had complete colonoscopy with satisfactory preparation and the excluded patients are reported. RESULTS: Four advanced adenomas (one had intramucosal cancer) on second colonoscopy and two advanced adenomas on third colonoscopy were missed. The miss rate of advanced adenoma for 232 patients was 1.7%, and the miss rate for the 122 patients with complete colonoscopy and satisfactory colon preparation was 2.5% and 3.3% on second and third repeat colonoscopy, respectively. No cancer was missed. CONCLUSIONS: The present study shows an advanced polyp miss rate that is comparable with other studies even in a fellowship training setting. Prospective studies with tandem surveillance colonoscopy are needed to confirm our findings.     

Polyp miss rate determined by tandem colonoscopy: a systematic review

BACKGROUND AND AIMS: Colonoscopy is the best available method to detect and remove colonic polyps and therefore serves as the gold standard for less invasive tests such as virtual colonoscopy. Although gastroenterologists agree that colonoscopy is not infallible, there is no clarity on the numbers and rates of missed polyps. The purpose of this systematic review was to obtain summary estimates of the polyp miss rate as determined by tandem colonoscopy. METHODS: An extensive search was performed within PUBMED, EMBASE, and the Cochrane Library databases to identify studies in which patients had undergone two same-day colonoscopies with polypectomy. Random effects models based on the binomial distribution were used to calculate pooled estimates of miss rates. RESULTS: Six studies with a total of 465 patients could be included. The pooled miss rate for polyps of any size was 22% (95% CI: 19-26%; 370/1,650 polyps). Adenoma miss rate by size was, respectively, 2.1% (95% CI: 0.3-7.3%; 2/96 adenomas > or =10 mm), 13% (95% CI: 8.0-18%; 16/124 adenomas 5-10 mm), and 26% (95% CI: 27-35%; 151/587 adenomas 1-5 mm). Three studies reported data on nonadenomatous polyps: zero of eight nonadenomatous polyps > or =10 mm were missed (0%; 95% CI: 0-36.9%) and 83 of 384 nonadenomatous polyps <10 mm were missed (22%; 95% CI: 18-26%). CONCLUSIONS: Colonoscopy rarely misses polyps > or =10 mm, but the miss rate increases significantly in smaller sized polyps. The available evidence is based on a small number of studies with heterogeneous study designs and inclusion criteria.     

Colonoscopy surveillance after polypectomy

The goal of surveillance examinations after polypectomy is to detect new adenomas and missed synchronous adenomas, as well as preventing adenomas from becoming invasive or cancerous. The first colonoscopy surveillance program reported was the National Polyp Study from the United States in 1997, with an update in 2003. First screening colonoscopy and polypectomy have been shown to produce the greatest effects in reducing the incidence of colorectal cancer in patients with adenomatous polyps. However, a large number of adenomas are being discovered as a result of the increased use of colorectal cancer screening, particularly with the dramatic increase in screening colonoscopy and surveillance. Increased efficiency of surveillance colonoscopy practices is therefore needed to decrease the cost, risk, and overuse of medical resources. In developing surveillance programs, studying miss rates and incidences and performing separate evaluations are important, along with accurately assessing incidence. This is because the recurrence rate or apparent incidence after colonoscopic polypectomy includes the true incidence of new polyp formation plus the incidence of missed polyps from the initial colonoscopy. Many studies have indicated the number of adenomas on initial examination as the most significant predictor for missed adenoma and incidence of adenoma on surveillance colonoscopy. In Japan, many facets of colonoscopic examination differ from those in Western countries. Further studies are recommended to establish an appropriate and original Japanese colonoscopy surveillance program for use after polypectomy, based on guidelines from the United States.     

A novel retrograde-viewing auxiliary imaging device (Third Eye Retroscope) improves the detection of simulated polyps in anatomic models of the colon

BACKGROUND: Colonoscopy is the "gold standard" for colorectal polyp and cancer detection, but important lesions may be missed on the proximal aspect of haustral folds, rectal valves, or flexures. OBJECTIVE: Our purpose was to evaluate a prototype auxiliary imaging device that extends beyond the colonoscope's tip, providing a continuous retrograde view to detect lesions missed by the forward-viewing colonoscope. DESIGN: Three anatomic models of the colon were prepared with simulated polyps, 32% in obvious locations and 68% on the proximal aspect of folds. Six endoscopists examined each model with two methods. Method A used a standard video colonoscope. Method B involved an identical colonoscope with a retrograde-viewing auxiliary device positioned within its instrument channel. Order of testing was randomized and blinded. SETTING: Laboratory bench. MAIN OUTCOME MEASUREMENTS: Detection rates for simulated polyps. RESULTS: Of 78 "obvious" polyps, 69 (88%) and 70 (90%) were detected by methods A and B, respectively (P > .9). In contrast, of 162 polyps on proximal aspects of folds, 20 (12%) and 131 (81%) were detected by methods A and B, respectively (P < .00001). LIMITATIONS: Limitations resulted from (1) use of commercially available anatomic models in which haustral folds are less prominent and more rigid than in humans and (2) evaluation of a prototype device that had larger size and narrower angle of view than the planned production model and that was fixed in relation to the colonoscope. CONCLUSIONS: In simulated testing, a retrograde-viewing auxiliary imaging device used with a standard video colonoscope significantly improves detection rates of simulated polyps and promises to enhance the diagnostic yield of colonoscopy in humans.     

MR-colonography in hospitalized patients: feasibility and sensitivity

INTRODUCTION: Besides conventional colonoscopy, CT and MR colonography offer alternate virtual imaging modalities of the colon. The sensitivity of CT colonography, which is associated with radiation exposure, has been published in prior, large studies. Regarding MR colonography, in particular dark lumen MR colonography with the rectal administration of a water enema as a contrast agent, only limited published data exist. The goal of this study was to compare MR colonography with conventional colonoscopy in the detection of colorectal polyps. In addition the feasibility and image quality in unselected hospitalised patients were assessed. PATIENTS/METHODS: Included were 103 hospitalised patients who had to undergo colonoscopy for various indications. Immediately prior to conventional colonoscopy, MR colonography with rectal water enema and additional intravenous administration of contrast material was performed. Detection rates for polyps and adenomas were documented with both imaging modalities. Image quality and completion rates (practicability) and other (incidental) findings were also recorded. RESULTS: In 15 of 103 patients the MR examination could not be done or was only partially completed. The detection rate of MR colonography for polyps (adenomas) was 2% (4%) for polyps (adenomas) up to 5 mm in diameter, 38% (56%) for polyps (adenomas) 6-10 mm in diameter and 89% (89%) for polyps (adenomas) up to 11 mm in diameter. One flat carcinoma seen with conventional coloscopy was missed on MR colonography. CONCLUSIONS: MR colonography offers the possibility of imaging the colon without exposure to radiation. Polyps and adenomas are detected, similar to the detection rate of CT colonography, with adequate sensitivity only if they are larger than 10 mm in diameter. Therefore this imaging technique is not (yet) suitable as a screening test. Additional limitations are the necessary cooperation of the patient which can reduce the practicability and image quality in selected patients. Further studies like the just started German multicentre trial are needed to assess the position of MR colonography.     

Bowel preparations as quality indicators for colonoscopy

Colonoscopy is the principal investigative procedure for colorectal neoplasms because it can detect and remove most precancerous lesions.The effectiveness of colonoscopy depends on the quality of the examination.Bowel preparation is an essential part of high-quality colonoscopies because only an optimal colonic cleansing allows the colonoscopist to clearly view the entire colonic mucosa and to identify any polyps or other lesions.Suboptimal bowel preparation not only prolongs the overall procedure time,decreases the cecal intubation rate,and increases the costs associated with colonoscopy but also increases the risk of missing polyps or adenomas during the colonoscopy.Therefore,a repeat examination or a shorter colonoscopy follow-up interval may be suitable strategies for a patient with suboptimal bowel preparation.     

Surface visualization at CT colonography simulated colonoscopy: effect of varying field of view and retrograde view

OBJECTIVES: Colonoscopy is the gold standard for diagnosis of mucosal disease, but has a recognized "miss rate" for polyps probably because some lesions lie in areas of the colonic surface that do not enter the field of view. Using CT colonography (CTC) simulation this pilot study aimed to determine how much colonic surface is visualized with a standard, modern optical colonoscope (field of view 140 degrees ) with or without the addition of a retrograde viewing auxiliary imaging device (RVAID; 135 degrees ) and of a wide-angle (170 degrees ) colonoscope. METHODS: Supine CTC datasets for 20 patients were reviewed with customized CTC software that calculated the percentage of colonic surface seen and number and area of nonvisualized "missed" areas at a unidirectional three-dimensional (3D) endoluminal flythrough, approximating the view obtained at optical colonoscopy. The field of view could be varied from 0-180 degrees . The combination of a colonoscope with RVAID was simulated by an additional flythrough facing the rectum. RESULTS: Mean colonic surface area was 2,743 +/- 759 cm2. Percentage colonic surface visualized at simulated optical colonoscopy with a 90 degrees , 140 degrees , and 170 degrees field of view was 68.0 +/- 5.2%, 86.6 +/- 3.3%, and 92.2 +/- 3.3%, respectively, P < 0.001. Simulation of a 140 degrees colonoscope with an RVAID resulted in almost complete surface visualization, 98.7 +/- 0.5%, with total missed area reduced 10-fold compared with a 170 degrees colonoscope, P < 0.001. CONCLUSION: CTC simulated 140 degrees optical colonoscopy visualizes over 85% of the colonic surface. 170 degrees colonoscopy provides a modest reduction in missed surface and the simulated addition of RVAIDs appears beneficial.     

Colonoscopic polypectomy in retroflexion

BACKGROUND: Little has been written about the value of retroflexion in the removal of large sessile colon polyps. OBJECTIVE: The objective of the study was to evaluate the utility of retroflexion for removal of large sessile colon polyps. DESIGN: This was a retrospective evaluation of consecutive cases. SETTING: This study was conducted at an academic-hospital-based tertiary-referral colonoscopy practice. PATIENTS: The study comprised consecutive patients with sessile polyps > or = 2 cm who were undergoing endoscopic resection. INTERVENTIONS: The intervention was endoscopic resection of 59 consecutive sessile colon polyps 2 cm or larger in size and located proximal to the rectum by using prototype colonoscopes with short bending sections. MAIN OUTCOME MEASURES: The main outcome measurement was successful endoscopic resection. RESULTS: Fourteen of the polyps were removed either entirely (n = 4) or partially (n = 10) in retroflexion. Patients with polyps that were removed in retroflexion were more likely to have been referred by another colonoscopist than those patients with polyps removed entirely in the forward view (p = 0.05). There were no perforations and no complications related to retroflexion. LIMITATIONS: The study is retrospective, and the practice is a tertiary referral colonoscopy practice. The colonoscopes used are not widely available at this time. CONCLUSIONS: Retroflexion is a useful adjunctive procedure for the removal of some colon polyps proximal to the rectum that are difficult to access endoscopically. The use of retroflexion can increase the fraction of proximal sessile colon polyps amenable to endoscopic resection.     

CLINICAL SIGNIFICANCE OF THE USE OF MAGNETIC ENDOSCOPE IMAGING FOR COLONOSCOPY

Background: A new endoscopic system using low‐density alternating magnetic ?elds to visualize loop formation during insertion has been developed and has recently been made available. The present study was designed to assess the usefulness of this new endoscopic system, which is known as magnetic endoscope imaging (MEI), compared with the use of a variable stiffness colonoscope without MEI in the performance of routine colonoscopy. Methods: Ten less‐experienced and 11 experienced colonoscopists performed colonoscopy either with or without the assistance of MEI. After each procedure, the colonoscopist assessed the usefulness of MEI, and the patient also assessed the degree of pain experienced while undergoing the procedure with a pain scale. Success rates in reaching the cecum, insertion time, and the rate of manual abdominal counter‐pressure were recorded by endoscopic assistants. Results: There were no signi?cant differences in the time and cecal insertion rate taken to complete insertion between colonoscopy with and without MEI. However, the level of pain experienced during insertion from the anus to the cecum was signi?cantly lower with MEI than without it when less‐experienced colonoscopists performed the colonoscopy. The rates of manual abdominal counter‐pressure used during colonoscopy were higher in groups where MEI was used. Moreover, manual abdominal counter‐pressure was quite easily undertaken with the assistance of MEI. Conclusion: In summary, MEI is useful for decreasing the level of patient pain in the less‐experienced colonoscopist group.     

Colonoscopic miss rates determined by direct comparison of colonoscopy with colon resection specimens

OBJECTIVES: Colonoscopy is an effective method for discovery of adenomas and for colon cancer screening and prevention. Studies evaluating back-to-back colonoscopies have estimated significant miss rates but are limited by the lack of a definitive gold standard. Our study evaluated the sensitivity of colonoscopy compared with examination of surgically resected colon as a gold standard. METHODS: This was a retrospective analysis of patients who had a portion of colon surgically removed and had lower endoscopy within 5 months. The focus of the review was not for the particular lesion for which the surgery was indicated but, rather, for the synchronous lesions in the portions of bowel that were removed. Sensitivity was determined by counting the number of lesions detected at colonoscopy compared with those found in the surgically resected segment. RESULTS: A total of 73 synchronous lesions were present in the resected segments of 156 patients. Colonoscopy detected 56 of 73 the lesions (sensitivity 76.7%: 95% CI = 67-86). Of the 17 missed lesions, 14 of 17 (82%, 95% CI = 64-100) were < 1-cm polyps. Endoscopy overlooked one 1-cm adenoma in the ascending colon. Two cancers were missed, both in the same patient in whom endoscopy detected a sigmoid cancer but missed synchronous lesions in the cecal and ascending colon. CONCLUSIONS: Colonoscopy is an effective method of finding cancers and polyps, but it is associated with significant miss rates for polyps <1 cm. The entire bowel should be carefully evaluated to exclude synchronous tumors in patients with known colorectal cancer. Further improvement of colonoscopic techniques and technologies is warranted.     

Colonoscopy: Its role in cancer of the colon and rectum

In order to determine the feasibility, yield, and impact of routine total colonoscopy on the management of large-bowel cancer 157 cancer patients underwent 175 colonoscopic procedures; 13.6 per cent of the cancers had been missed on double-contrast barium enema examination. Among 92 patients undergoing perioperative colonoscopy, the lesion was reached in 89 per cent and the cecum in 60 per cent; 7.6 per cent demonstrated synchronous cancers, all curable, and all missed on barium-enema examination. Seventy-eight patients underwent colonoscopy at an average of 3.7 years after treatment of the index cancer; 7.7 per cent demonstrated metachronous cancers, all curable, two-thirds of which were missed on barium-enema examination. Benign polyps were noted in 62 per cent of the patients studied; 77 per cent of those polyps, 1 cm or greater in size, were missed on barium-enema examination. Polyps were found proximal to the cancer in 60 per cent of the patients with polyps. Approximately 85 per cent of those with multiple cancers demonstrated benign polyps. Preoperative total colonoscopy with periodic postoperative colonoscopy at an interval of three to five years are essential in the reliable detection of synchronous cancers and for the detection of metachronous cancers at an earlier, more favorable stage. Read at the Meeting of the American Society of Colon and Rectal Surgeons, Atlanta, Georgia, June 10 to 14, 1979. This article received the Purdue Frederick Award for best paper authored by a resident.     

Colonic polyps diagnosis by conventional video colonoscopes and chromoscopy with indigo carmine dye solution

BACKGROUND: Magnification colonoscopy and contrast chromoscopy with indigo carmine dye solution have been used to differentiate neoplastic polyps (adenomas and adenocarcinomas) from non-neoplastic (hyperplastic, inflammatory, juvenile) in an attempt to obviate endoscopic polypectomy. On the other hand, little published information exists concerning conventional video colonoscopes and chromoscopy for polyp histology prediction. Aim - To assess usefullness of conventional video colonoscopes and contrast chromoscopy with indigo carmine solution for differential diagnosis of colon polyps. METHODS: In a routine colonoscopy series, we performed chromoscopy with conventional video colonoscopes before endoscopic excision of detected polyps. If a sulcus pattern was observed on the surface of the lesion, it was classified as neoplastic. Polyps were classified as non-neoplastic if no sulcus was detected on its surface. These observations were then compared with histology. RESULTS: In the study period (18 months), we detected 133 polyps in 53 patients. We were able to compare results of histology and chromoscopy in 126 lesions. The sensitivity, specificity, diagnostic accuracy, negative predictive value, and positive predictive value were 56,4%, 79,2%, 65,1%, 52,8%, and 81,5%, respectively. CONCLUSION: On the base of the presented data, we concluded that conventional video colonoscopes and contrast chromoscopy with indigo carmine solution is not a good technique for differential diagnosis of colon polyps.