Maximizing detection of adenomas and cancers during colonoscopy

Some patients who undergo colonoscopy that appeared to have cleared the colorectum of neoplasia return within a short interval (1-3 yr) with colorectal cancer. Although several a priori mechanisms could account for this occurrence, wide variation in detection rates of adenomas and cancer at colonoscopy suggests that suboptimal colonoscopic technique is a significant contributor. Optimal technique with white-light colonoscopy involves taking adequate time for inspection during withdrawal (an average of at least 6 min in normal colons), interrogating the proximal sides of folds, flexures, and valves, clearing fluid and debris, and distending adequately. Some adjunctive techniques are directed toward exposing more colonic mucosa during colonoscopy. Wide-angle colonoscopy appears to improve efficiency but does not eliminate miss rates. Colonoscopy in retroflexion was unsuccessful in reducing miss rates in one study, whereas cap-fitted colonoscopy was successful in reducing miss rates in one small study. Techniques to improve detection of flat lesions include pancolonic chromoendoscopy (CE). In two randomized controlled trials, CE improved adenoma detection, but CE does not appear to provide substantially greater yields than those obtained by the more sensitive white-light colonoscopists. Narrow band imaging and autofluorescence are being assessed for improved detection of flat lesions. Adenoma detection rates are an important measure of the quality of colonoscopy and should be reported to endoscopists in quality improvement programs in 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.     

Wide angle colonoscopy with a prototype instrument: impact on miss rates and efficiency as determined by back-to-back colonoscopies

OBJECTIVE: Polyps are missed during conventional colonoscopy, even with meticulous technique. The aim of this study was to investigate whether a prototype wide angle colonoscope is associated with a reduced miss rate for polyps. METHODS: Two studies were performed. In study 1, a total of 50 patients underwent back-to-back, same-day colonoscopy by a single examiner with the prototype wide angle colonoscope and with a standard colonoscope, with the order of scopes randomized. In study 1, an attempt was made to keep examination time with the two colonoscopes equal. In study 2, a total of 20 patients were examined, 10 by the same colonoscopist who performed study 1 and 10 by a second colonoscopist. In study 2, examiners tried to perform the examinations as quickly as accuracy would allow. RESULTS: In study 1, the miss rate for all polyps was lower with the wide angle colonoscope (20% vs 31%; p = 0.046), although the mean examination time with the wide angle instrument was shorter (6.75 min vs 7.64 min; p = 0.0005). There was no significant difference in detection of adenomas. Polyps, including adenomas, were missed in the peripheral endoscopic field more frequently with the standard colonoscope. In study 2, wide angle colonoscopy was associated with reductions in examination time of 25% and 30% for the two examiners, respectively. Miss rates were the same for one colonoscopist but were higher for the other colonoscopist when the wide angle instrument was used. CONCLUSION: A prototype wide angle colonoscope did not eliminate polyp miss rates. Wide angle colonoscopy has the potential to reduce examination time and improve visualization of the periphery of the endoscopic field of view, but improvements in resolution are needed.     

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.     

Detection of colonic polyps according to insertion/withdrawal phases of colonoscopy

Background and aims  Issues on colonoscopy quality are crucial to reduce the advanced neoplasia miss rate of colonoscopy. Recently, a >6-min withdrawal time has been recommended. However, the relative prevalence of polyp detected during insertion and withdrawal phases of colonoscopy is unknown. Therefore, we designed this prospective, endoscopic study. Materials and methods  Three hundred and sixty-eight patients with 396 adenomas were selected from a consecutive colonoscopic series of 1,205 cases. Detection rates of adenomas, advanced adenomas, and cancer according to withdrawal and insertion phases of colonoscopy, also subgrouping polyps for size and location, were compared. Results  Thirty-two (74%) advanced adenomas and 21 (95%) cancers were detected during the insertion, being only 11 (26%) and one (5%) identified during withdrawal, respectively. This was mainly due to a higher detection of >10 mm polyps during insertion than during withdrawal (75% versus 25%). Conclusions  Most advanced neoplasia are detected during the insertion. Although withdrawal time has been shown to be important, the scope insertion phase related to polyp detection should be specifically addressed.     

CO2 insufflation for potentially difficult colonoscopies:Efficacy when used by less experienced colonoscopists

AIM: To clarify the effectiveness of CO_2 insufflation in potentially difficult colonoscopy cases, particularly in relation to the experience level of colonoscopists. METHODS: One hundred twenty potentially difficult cases were included in this study, which involved females with a low body mass index and patients with earlier abdominal and/or pelvic open surgery or previously diagnosed left-side colon diverticulosis. Patients receiving colonoscopy examinations without sedation using a pediatric variable-stiffness colonoscope were divided into two groups based on either CO_2 or standard air insufflation. Both insufflation procedures were also evaluated according to the experience level of the respective colonoscopists who were divided into an experienced colonoscopist (EC) group and a less experienced colonoscopist (LEC) group. Study measurements included a 100-mm visual analogue scale (VAS) for patient pain during and after colonoscopy examinations, in addition to insertion to the cecum and withdrawal times. RESULTS: Examination times did not differ, however, VAS scores in the CO_2 group were significantly better than in the air group (P < 0.001, two-way ANOVA) from immediately after the procedure and up to 2 h later. There were no significant differences between either insufflation method in the EC group (P = 0.29), however, VAS scores for CO_2 insufflation were significantly better than air insufflation in the LEC group (P = 0.023) immediately after colonoscopies and up to 4 h afterwards. CONCLUSION: CO_2 insufflation reduced patient pain after colonoscopy in potentially difficult cases when performed by LECs.     

CO2 insuffiation for potentially difficult colonoscopies： Efficacy when used by less experienced colonoscopists

AIM: To clarify the effectiveness of CO_2 insufflation in potentially difficult colonoscopy cases, particularly in relation to the experience level of colonoscopists. METHODS: One hundred twenty potentially difficult cases were included in this study, which involved females with a low body mass index and patients with earlier abdominal and/or pelvic open surgery or previously diagnosed left-side colon diverticulosis. Patients receiving colonoscopy examinations without sedation using a pediatric variable-stiffness colonoscope were divided into two groups based on either CO_2 or standard air insufflation. Both insufflation procedures were also evaluated according to the experience level of the respective colonoscopists who were divided into an experienced colonoscopist (EC) group and a less experienced colonoscopist (LEC) group. Study measurements included a 100-mm visual analogue scale (VAS) for patient pain during and after colonoscopy examinations, in addition to insertion to the cecum and withdrawal times. RESULTS: Examination times did not differ, however, VAS scores in the CO_2 group were significantly better than in the air group (P < 0.001, two-way ANOVA) from immediately after the procedure and up to 2 h later. There were no significant differences between either insufflation method in the EC group (P = 0.29), however, VAS scores for CO_2 insufflation were significantly better than air insufflation in the LEC group (P = 0.023) immediately after colonoscopies and up to 4 h afterwards. CONCLUSION: CO_2 insufflation reduced patient pain after colonoscopy in potentially difficult cases when performed by LECs.     

The use of indigocarmine spray increases the colonoscopic detection rate of adenomas

Purpose  It remains controversial whether chromocolonoscopy using indigocarmine increases the detection of colorectal polyps. We aimed to assess the impact of indigocarmine dye spray on the detection rate of adenomas and the feasibility of learning the technique in a Western practice. Methods  400 patients were prospectively allocated into 2 groups; A (n = 200): indigocarmine chromocolonoscopy was performed by a Japanese colonoscopist with expertise in chromoscopy; B (n = 200): initial 100 patients (B-1), a Western colonoscopist with no previous experience of chromoscopy performed conventional colonoscopy, but with at least 10 min observation during colonoscopy withdrawal. In the next 100 patients (B-2), he performed chromocolonoscopy. All polyps found were resected. Regression analysis was used to compare the numbers of polyps detected in groups A, B-1 and B-2, whilst controlling for gender, age, indication and history of colorectal cancer. Results  There were significant differences in the numbers of neoplastic polyps and flat adenomas between groups A and B-1 as well as between B-1 and B-2, but not between A and B-2. There was no significant difference in numbers of advanced lesions. Chromocolonoscopy (A and B-2) detected more neoplastic polyps of ≤5 mm. Conclusion  Chromocolonoscopy increases the detection of neoplastic polyps and flat adenomas, particularly diminutive polyps, but does not increase the detection of advanced lesions.     

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.     

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.     

Adenoma Detection Rate: The Real Indicator of Quality in Colonoscopy

Purpose  Completion rate is the most commonly used index of quality in colonoscopy, and yet a complete examination is not necessarily a good examination. The ability to detect and treat adenomas is an important component of endoscopic skill, because many colonoscopies are performed for this express purpose. Adenoma detection rate is rarely reported, although it seems to depend on the time taken for withdrawal. The literature suggests that adenomas should be detected in approximately 25 percent of men and 15 percent of women older than age 50 years. We have reviewed the adenoma detection rates of six colorectal surgeons to provide insight into the range of adenoma detection rates and the factors that influence them. Methods  A prospective departmental colonoscopy database was queried. Colonoscopy completion rates, adenoma detection rates, and times of insertion and withdrawal were noted and stratified by the six staff colonoscopists. Adenoma detection rates were tabulated for the four common indications for colonoscopy. Results  Each staff endoscopist performed >250 examinations per year and had performed >1,000 total examinations. Although completion rates are fairly uniform (mean, 96.5 (range, 94.8–97.9) percent), there is a wide range of ADR, especially when adenomas are common (polyp or cancer surveillance; range, 14.2–27.4 percent). With the exclusion of one outlier staff, regression of withdrawal time against adenoma detection rate produced an r² of 0.975 (P = 0.0016). Conclusions  Adenoma detection rate is independent of completion rate as a colonoscopy quality indicator. There is a wide range of adenoma detection rates among experienced colorectal surgeons. Colonoscopists need to be aware of their adenoma detection rate. Read at the meeting of The American Society of Colon and Rectal Surgeons, Seattle, Washington, June 3 to 7, 2006. Reprints are not available.     

Link between a preference for women colonoscopists and social status in Korean women

BACKGROUND: Although the sex preference in women patients for their colonoscopist has been reported, the characteristics of these women have not been evaluated yet. OBJECTIVE: The aim of this study was to investigate the characteristics of women who have a specific preference for a man or a woman colonoscopist. DESIGN: Single-center prospective study. SETTING: Academic medical center, from October to November 2005. SUBJECTS: A total of 465 women who visited the Digestive Disease Center. METHODS: Subjects were asked to complete a self-administered questionnaire on the sex preference of the colonoscopist, employment status, and clinical symptoms. MAIN OUTCOME MEASUREMENTS: Factors related with sex preference for the colonoscopist. RESULTS: Only 358 subjects (77.0%) completed the questionnaire. Of these, 195 women (54.5%) had no preference, whereas 115 women (32.1%) preferred a woman colonoscopist and 48 women (13.4%) preferred a man colonoscopist. Subjects who preferred women colonoscopists were generally younger (P< .0001), more educated (P< .0001), single (P< .0001), and employed (P< .0001) than the other population. Neither the symptoms of functional dyspepsia nor irritable bowel syndrome were related with the sex preference of the colonoscopist. LIMITATIONS: A self-administered questionnaire study did not investigate specific physician interpersonal or communication styles. CONCLUSIONS: More than half of the women had no sex preference for their colonoscopist, and the sex preference for a specific sex was related to employment status, education level, age, and marital status. Such a sex-based preference in employed, highly educated young women predicts an increasing demand for women colonoscopists in the near future, particularly given the increasing social participation of women in these times of rapid industrialization.     

Point-of-care, peer-comparator colonoscopy practice audit: The Canadian Association of Gastroenterology Quality Program--Endoscopy

BACKGROUND

Point-of-care practice audits allow documentation of procedural outcomes to support quality improvement in endoscopic practice.

OBJECTIVE

To evaluate a colonoscopists’ practice audit tool that provides point-of-care data collection and peer-comparator feedback.

METHODS

A prospective, observational colonoscopy practice audit was conducted in academic and community endoscopy units for unselected patients undergoing colonoscopy. Anonymized colonoscopist, patient and practice data were collected using touchscreen smart-phones with automated data upload for data analysis and review by participants. The main outcome measures were the following colonoscopy quality indicators: colonoscope insertion and withdrawal times, bowel preparation quality, sedation, immediate complications and polypectomy, and biopsy rates.

RESULTS

Over a span of 16 months, 62 endoscopists reported on 1279 colonoscopy procedures. The mean cecal intubation rate was 94.9% (10th centile 84.2%). The mean withdrawal time was 8.8 min and, for nonpolypectomy colonoscopies, 41.9% of colonoscopists reported a mean withdrawal time of less than 6 min. Polypectomy was performed in 37% of colonoscopies. Independent predictors of polypectomy included the following: endoscopy unit type, patient age, interval since previous colonoscopy, bowel preparation quality, stable inflammatory bowel disease, previous colon polyps and withdrawal time. Withdrawal times of less than 6 min were associated with lower polyp removal rates (mean difference −11.3% [95% CI −2.8% to −19.9%]; P=0.01).

DISCUSSION

Cecal intubation rates exceeded 90% and polypectomy rates exceeded 30%, but withdrawal times were frequently shorter than recommended. There are marked practice variations consistent with previous observations.

CONCLUSION

Real-time, point-of-care practice audits with prompt, confidential access to outcome data provide a basis for targeted educational programs to improve quality in colonoscopy practice.     

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.     

Flat colonic adenomas in Malaysia: Fact or fancy?

BACKGROUND: Some two-thirds of colorectal carcinomas arise from adenomatous polyps, and as such, screening by colonoscopy and polyp removal should significantly reduce colorectal cancer. This has not been the case, as evidenced by recent studies, which revealed that endoscopy failed to prevent up to 50% of all subsequent carcinomas. Flat or depressed adenomas, frequently reported from Japan but rarely elsewhere, might explain the 'missed carcinomas.' Detection of flat adenomas has not been previously reported from Malaysia. METHODS: In the present prospective study, 426 consecutive patients underwent colonoscopic examination between March 1997 and January 2000, for a variety of bowel symptoms. The examinations were performed by an experienced endoscopist using a standard colonoscope and methylene blue dye spraying technique. Macroscopically, flat adenomas were defined using the criteria proposed by Sawada. RESULTS: Twenty-nine adenomas were identified in 12 patients, of which 15 were polypoid and 14 were flat, with no depressed lesions. Eight polypoidal lesions and all the flat adenomas contained mild or moderate areas of epithelial dysplasia. Seven severely dysplastic polyps were identified. One Duke's A polypoidal cancer and two advanced carcinomas were also found. All the severely dysplastic lesions and Duke's A carcinomas were found in polyps greater than 10 mm in mean size. The flat adenomas were all less than 5 mm in size. CONCLUSIONS: A significant proportion of colonic adenomas in Malaysian patients appear as small flat lesions, which could easily be missed during endoscopy. Increased recognition and treatment of flat adenomas among colonoscopists is warranted.     

The application of artificial intelligence in improving colonoscopic adenoma detection rate: Where are we and where are we going

Colorectal cancer (CRC) is one of the common malignant tumors in the world. Colonoscopy is the crucial examination technique in CRC screening programs for the early detection of precursor lesions, and treatment of early colorectal cancer, which can reduce the morbidity and mortality of CRC significantly. However, pooled polyp miss rates during colonoscopic examination are as high as 22%. Artificial intelligence (AI) provides a promising way to improve the colonoscopic adenoma detection rate (ADR). It might assist endoscopists in avoiding missing polyps and offer an accurate optical diagnosis of suspected lesions. Herein, we described some of the milestone studies in using AI for colonoscopy, and the future application directions of AI in improving colonoscopic ADR.     

A simple method to improve adenoma detection rate during colonoscopy: Altering patient position

BACKGROUND:

Colonoscopy is currently considered to be the gold standard method for detecting and removing adenomatous polyps. However, tandem colonoscopy studies reveal a pooled polyp miss rate of 22%.

OBJECTIVE:

A prospective randomized trial was conducted to assess whether alteration of patient position during colonoscopy withdrawal increases the adenoma detection rate (ADR).

METHOD:

The study group included 120 patients who presented for elective colonoscopic examination. After reaching the cecum, patients were randomly assigned in a 1:1 ratio to examination in either the left lateral position or other positions (left lateral position for the cecum, ascending colon and hepatic flexure; supine for transverse colon; and supine and right lateral position for splenic flexure, descending and sigmoid colon) first. Examination of the colon was performed segment by segment. The size, morphology and location of all polyps were recorded. Polyps were removed immediately after examination of a colon segment when all positions were completed. ADR and polyp detection rates (PDR) were calculated.

RESULTS:

A total of 102 patients completed the study. Examination in the left lateral position revealed 66 polyps in 31 patients (PDR 30.3%) and 42 adenomas in 24 patients (ADR 23.5%). PDR increased to 43.1% (81 polyps in 44 patients) and the ADR to 33.3% (53 adenomas in 34 patients) after the colon was examined in the additional positions (P<0.001 and P=0.002, respectively). The increase in the number of adenomas detected was statistically significant in the transverse and sigmoid colon. The addition of position changes led to a 9.8% increase in the ADR in the transverse colon, splenic flexure, and descending and sigmoid colon. The frequency of surveillance interval was shortened in nine (8.8%) patients after examination of the colon in dynamic positions.

CONCLUSION:

Alteration of patient position during colonoscopy withdrawal is a simple and effective method to improve ADR.     

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.     

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.