Biomedical subjects
Publications and source records attributed to Christopher B Williams.
The authors hope that the combination of ScopeGuide imager (to make sense of colon looping) and the new-generation Colonoscopy Simulator (allowing structured teaching and repetitive practice) will make it possible to accelerate colonoscopy training and perhaps also will provide an acceptable way of re-honing the skills of existing endoscopists.
BACKGROUND & AIMS: The value of colonoscopic surveillance for neoplasia in long-standing extensive ulcerative colitis remains controversial. This study reports on prospectively collected data from a surveillance program over a 30-year period. METHODS: Data were obtained from the prospective surveillance database, medical records, colonoscopy, and histology reports. The primary end point was defined as death, colectomy, withdrawal from surveillance, or census date (January 1, 2001). Follow-up information was obtained for patients who left the program. RESULTS: Six hundred patients underwent 2627 colonoscopies during 5932 patient-years of follow-up. The cecal intubation rate was 98.7%, with no significant complications. Seventy-four patients (12.3%) developed neoplasia, including 30 colorectal cancers (CRCs). There was no difference in median age at onset of colitis for those with or without CRC (P = .8, Mann-Whitney). The cumulative incidence of CRC by colitis duration was 2.5% at 20 years, 7.6% at 30 years, and 10.8% at 40 years. The 5-year survival rate was 73.3%. Sixteen of 30 cancers were interval cancers. CRC incidence decreased over time (r = -.40, P = .04; linear regression). CONCLUSIONS: Colonoscopic surveillance is safe and allows the vast majority of patients to retain their colon. Although two thirds of patients with potentially life-threatening neoplasia benefited from surveillance, the program was not wholly effective in cancer prevention. The cancer incidence, however, was considerably lower than in the majority of other studies, and was constant for up to 40 years of colitis duration, suggesting there is no need to intensify surveillance over time.
Colonoscopy traditionally has been taught using the apprenticeship approach. Assessment of competence has been, at best, informal and based largely on the number of procedures trainees have performed. The advent of colorectal cancer screening has demanded formalization of training and assessment using structured teaching and state-of-the-art training tools, such as computer simulation. New-generation approaches and technology have the ability to raise the standard of coloscopy provided by competent practitioners.
BACKGROUND: Patients with long-standing extensive ulcerative colitis are at increased risk for colorectal carcinoma. Because most dysplasia is believed to be macroscopically invisible, recommended surveillance protocols include multiple non-targeted colonic biopsies. It was hypothesized by us that most dysplasia is actually colonoscopically visible. This study assessed the proportion of dysplasia that has been detected macroscopically in patients who underwent colonoscopy surveillance at our center. METHODS: A retrospective review was conducted of colonoscopically detected neoplasia (dysplasia or cancer) in patients with ulcerative colitis who underwent surveillance from 1988 through 2002. An established surveillance protocol was used in all cases that included random segmental biopsies every 10 cm throughout the length of the colon, in addition to targeted biopsies of macroscopic lesions. Neoplasia detection was categorized as resulting from either targeted or non-targeted ("random") biopsies. Follow-up information was obtained to the study end. RESULTS: A total of 525 patients underwent 2204 surveillance colonoscopies. A total of 110 neoplastic areas were detected in 56 patients: 85 (77.3%) were macroscopically visible at colonoscopy, and 25 (22.7%) were macroscopically invisible. Fifty patients (89.3%) had macroscopically detectable neoplasia, and 6 (10.7%) had macroscopically invisible lesions. The frequency of cancer in patients who had endoscopic resection of neoplasia did not differ from that for the surveillance population as a whole (1/40 vs. 18/525; p=1.0, Fisher exact test), irrespective of whether the lesion was thought to be an adenoma or a dysplasia-associated lesion/mass. Conversely, a high proportion of unresectable lesions harbored cancer. CONCLUSIONS: Most dysplastic lesions in ulcerative colitis are visible at colonoscopy. From a clinical perspective, the endoscopic resectability of a lesion is more important than whether it is thought to be a sporadic adenoma or a dysplasia-associated lesion/mass.
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OBJECTIVE: To study the long-term outcomes of patients who have had endoscopic balloon dilation of Crohn's strictures. DESIGN: Retrospective case-note review over a 16-year period. PATIENTS: Patients with a Crohn's stricture causing obstructive symptoms and who had at least 6 months' follow-up data or a surgical outcome following dilation were sought; 59 patients (124 dilations) were identified. INTERVENTION: Patients all underwent endoscopic balloon dilation. RESULTS: Strictures were anastomotic in 53 patients (111 dilations) and de novo in six patients (13 dilations). The median stricture length was 3.0 cm. Median follow-up time was 29.4 months. Out of the total group, 41% of patients achieved long-term clinical benefit following dilation and in 17% after only a single dilation. The median number of dilations per patient was one. A total of 35 (59%) patients required surgery for their stricture during follow-up. There were two (1.6%) perforations as a result of dilation, one in an anastomotic stricture (managed conservatively) and one in a de-novo stricture (requiring surgery). There were no deaths. CONCLUSIONS: Colonoscopic balloon dilation of Crohn's strictures can achieve long-term clinical benefit in many patients. Repeat dilations are justified in initial non-responders. In this series, the procedure appears safe with low morbidity.
BACKGROUND: Small adenomas may be missed during colonoscopy, but chromoscopy has been reported to enhance detection. The aim of this randomized-controlled trial was to determine the effect of total colonic dye spray on adenoma detection during routine colonoscopy. METHODS: Consecutive outpatients undergoing routine colonoscopy were randomized to a dye-spray group (0.1% indigo carmine used to coat the entire colon during withdrawal from the cecum) or control group (no dye). RESULTS: Two hundred fifty-nine patients were randomized, 124 to the dye-spray and 135 to the control group; demographics, indication for colonoscopy, and quality of the preparation were similar between the groups. Extubation from the cecum took a median of 9:05 minutes (range: 2:48-24:44 min) in the dye-spray group versus 4:52 minutes (range: 1:42-15:21 min) in the control group (p < 0.0001). The proportion of patients with at least 1 adenoma and the total number of adenomas were not different between groups. However, in the dye-spray group significantly more diminutive adenomas (<5 mm) were detected proximal to the sigmoid colon (p = 0.026) and more patients were identified with 3 or more adenomas (p = 0.002). More non-neoplastic polyps were detected throughout the colon in the dye-spray group (p = 0.003). There were no complications. CONCLUSIONS: Dye-spray increases the detection of small adenomas in the proximal colon and patients with multiple adenomas, but long-term outcomes should be studied to determine the clinical value of these findings.
BACKGROUND: Variable-stiffness colonoscopes combine the flexibility of pediatric instruments for negotiation of the sigmoid colon with the ability to stiffen the insertion tube to prevent or control looping after straightening. Previous studies have found wide variation in the efficacy of the stiffening mechanism. Thus, two studies were conducted to assess the potential benefit of the stiffening device and its optimal use. METHODS: In study 1, the effect of routinely stiffening the straightened variable-stiffness colonoscopes in the mid-descending colon was determined in 82 patients. Two insertions were performed (mid-descending colon to cecum) in each patient with and without application of the stiffening device (randomized). The time to negotiate the proximal colon (mid-descending to cecum), time to pass the variable-stiffness colonoscopes across the splenic flexure into the transverse colon, time to pass the right colon, and ancillary maneuvers used were recorded for each insertion. In study 2, consecutive patients, excluding any with previous colonic resection, were examined by using standard adult variable-stiffness colonoscopes. Real-time views of the procedure with magnetic endoscope imaging were recorded for all examinations, but procedures were randomized to be done either with (n = 88), or without (n = 87) the endoscopist viewing the magnetic endoscope imaging display. Whenever stiffening was applied, the anatomic location of the colonoscope tip and stiffness efficacy were recorded. RESULTS: In study 1, time taken to negotiate the proximal colon (p = 0.0041) and time to negotiate the splenic flexure (p = 0.006) were significantly shorter and ancillary maneuvers performed were fewer (p = 0.0014) with the stiffening device activated. In study 2, stiffening was used with similar frequency in patients examined with and without the magnetic endoscope imaging view, most commonly for passing the splenic flexure (71%), but also in the transverse colon (12%), right colon (9%), and sigmoid/descending colon (8%). Stiffening was significantly more effective when used in combination with magnetic endoscope imaging (69% with imager vs. 45% without imager; p = 0.0102). CONCLUSIONS: Overall, the variable-stiffness device used was effective in controlling looping 57% of the time. Activating maximum stiffness appears to be effective once the sigmoid colon has been negotiated and the colonoscope straightened with the tip in the proximal colon, reducing the number of ancillary maneuvers and shortening the insertion time through the proximal colon. Routine magnetic endoscope imaging further enhances the efficacy of the variable-stiffness colonoscopes by helping to identify the optimal time for stiffening.
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BACKGROUND: Recurrence is frequent after piecemeal snare resection of large sessile colorectal polyps. The aim of this study was to evaluate the safety and efficacy of argon plasma coagulation (APC) in preventing recurrence when applied to the edge and base of the polypectomy site after apparently complete piecemeal resection. METHODS: Patients with large (>1.5 cm) sessile polyps removed by piecemeal snare cautery were placed into 2 groups. The first consisted of patients with polyps believed by the endoscopist to be completely excised. These patients were randomized to either no further therapy (control) or to APC of the rim and any residual mucosal or submucosal tissue in the base of the polypectomy site. The second group comprised patients in whom polyps, as judged by the endoscopist, were incompletely excised by snare polypectomy; APC was routinely applied without randomization to all visible remaining adenomatous tissue. Follow-up colonoscopy was performed within 3 months and 1 year; biopsy specimens were taken routinely from the resection site and further polypectomy was performed as indicated. RESULTS: There were fewer recurrences after APC in the randomized group (1/10 APC, 7/11 no APC; p = 0.02). In the group with initial incomplete snare polypectomy, recurrence was detected at 3 months in 6 of 13 despite APC. One patient was hospitalized with abdominal pain and minor rectal bleeding but required no intervention. There were no other episodes of significant late bleeding caused by piecemeal polypectomy. One patient was referred for surgery after unsuccessful endoscopic management. CONCLUSIONS: In patients with apparent complete endoscopic snare resection of large adenomas, postpolypectomy application of APC reduces adenomatous recurrence.
BACKGROUND: Pain during colonoscopy is primarily related to mesenteric stretching from looping of the colonoscope insertion tube. Prompt recognition and removal of loops reduces patient discomfort and may lessen sedation requirements. Magnetic endoscope imaging allows real-time visualization of the colonoscope during insertion. The effect of magnetic endoscope imaging on patient pain and sedation requirements was assessed in a prospective randomized controlled trial. METHODS: A total of 122 consecutive patients undergoing routine colonoscopy by a single experienced endoscopist were randomized to have the procedure performed either with the endoscopist viewing the imager display (n = 62), or without the imager view (n = 60). Procedures began with administration of hyoscine-N-butylbromide alone, and sedative medications (midazolam and meperidine) were self-administered by the patient with a patient-controlled analgesia pump. Cardiorespiratory parameters were recorded and patient pain was assessed with a 100-mm visual analogue scale. RESULTS: The number of attempts at straightening the colonoscope was fewer (median 8 [0-66] vs. 15 [0-87], p = 0.0076) and the duration of looping less (median 4.5 min [0-27.3 min] vs. 6.4 min [0-29.4 min]), when the endoscopist was able to see the imager view. The total number of patient demands (by patient-controlled analgesia) for medication (median 1 vs. 2.5) and total doses of midazolam (median 0.44 mg vs. 0.88 mg) and meperidine (median 16.75 mg vs. 32.5 mg) administered did not significantly differ between patients examined with or without the imager. Patient pain scores were also similar. CONCLUSIONS: Magnetic endoscope imaging allows accurate assessment and straightening of loops during colonoscopy, but without a significant reduction in patient requirements for sedative medication or improvement in patient tolerance. However, the dosages of sedation drugs used were small.
BACKGROUND: Counting the number of procedures performed provides at best a crude measure of technical competence in colonoscopy. The aim of this study was to develop and validate a qualitative and a quantitative score for measuring technical competency in colonoscopy using videotape evaluation. METHODS: Eighteen endoscopists with varying levels of experience were prospectively videotaped during colonoscope insertion. The following were recorded simultaneously: a closed circuit television view showing instrument handling, the endoscopic luminal view, and a continuous display of the colonoscope configuration (magnetic endoscope imaging). Videotapes were reviewed blindly and in random order by 3 experts. Performance in 3 categories was evaluated: (1) manipulation of instrument controls (0-10), (2) manipulation of the insertion tube (0-6) and (3) depth of insertion (0-4). A global assessment of competence was given for each endoscopist. RESULTS: Comparing the total scores as assessed by the 3 blinded experts, for each individual endoscopist, there were significant differences. However, there was good interobserver agreement and correlation between the individual scores and global assessment ratings of competence (p < 0.0001). CONCLUSIONS: The video assessment tool described appears to measure technical competence at colonoscopy, although in its present form it lacks reliability. Refinement of the score may improve reliability and deserves further evaluation.