Impact of bending section length on insertion and retroflexion properties of pediatric and adult colonoscopes

BACKGROUND: Colonoscopes with short bending sections facilitate retroflexion but their effect on other aspects of colonoscope insertion are unknown. We sought to determine the impact of short bending on cecal insertion, terminal ileal intubation, and proximal colon retroflexion. METHODS: Two studies were performed. In study 1, we randomized 104 adult patients with intact colons to undergo colonoscopy with a standard pediatric colonoscope (Olympus PCF-160), a prototype pediatric colonoscope with short bending in four directions (PCF-AYL), or a prototype pediatric colonoscope with short bending in two directions, and normal bending in two directions (PCF-AY3L). In study 2, we randomized 70 patients with intact colons to undergo colonoscopy with a prototype 170 degrees wide angle colonoscope (CFQ160-WL) with a standard bending section length or to a prototype 170 degrees colonoscope with a short bending section (CFQ160-W2L). RESULTS: In study 1, the cecum was reached in all patients. Using the AYL, the cecal intubation time (4.08 min) was significantly longer when compared to both the PCF-160 (2.62 min; p=0.0001) and the AY3L (3.25 min; p=0.02). The AYL required the application of abdominal pressure (79%) and activation of the variable stiffness device (70%) more frequently when compared to both the PCF-160 (32%; p=0.0001 and 41%; p=0.02, respectively) and the AY3L (34%; p=0.0003 and 41%; p=0.02, respectively). Successful cecal retroflexion was possible less often with the PCF-160 (57%) when compared to either the AYL (94%; p=0.005) or AY3L (91%; p=0.001). The ability to intubate the terminal ileum was similar in all three groups (PCF-160 and AY3L 100%; AYL 94%) as was the time needed to intubate (p=0.73). Depth of ti intubation was deeper for the PCF-160 when compared to the AYL (p=0.0002) or AY3L (p=0.02). There was a trend toward deeper ileal intubation with the AY3L compared to AYL (p=0.09). In study 2, no difference was noted in cecal intubation time (p=0.1) or in frequency of application of abdominal pressure (p=0.28), position change (p=0.15), or activation of the stiffening device (p=0.46). Cecal retroflexion was successful more often when using the W2L when compared to the WL (p=0.00001). CONCLUSION: Short bending sections facilitate proximal colon retroflexion for both pediatric and adult colonoscopes, but can negatively impact cecal insertion and terminal ileal intubation in pediatric colonoscopes. A pediatric colonoscope with short bending in only two directions had good function for both cecal insertion and proximal colon retroflexion.     

Tapered colonoscope performs better than the pediatric colonoscope in female patients: a direct comparison through tandem colonoscopy

BACKGROUND: The pediatric variable-stiffness colonoscope (PVSC) is used by many endoscopists to negotiate the colon that requires a flexible colonoscope; it has a smaller diameter, but may lead to excessive looping. A prototype colonoscope tapers from an adult width to a pediatric diameter at approximately 25 cm. The tapered colonoscope (TC), while retaining the flexibility of the PVSC, has the column strength of the adult colonoscope to help negotiate the proximal colon. OBJECTIVE: Our hypothesis is that use of the TC in female patients would be associated with less looping than the PVSC during the procedure, fewer required maneuvers, and thus a quicker examination. DESIGN: Direct comparison through tandem colonoscopies. SETTING: University endoscopy suite. PATIENTS: Forty unselected female patients. INTERVENTIONS: Tandem colonoscopies with PVSC and TC. MAIN OUTCOME MEASUREMENTS: Time to the cecum and the ability to retroflex in the cecum. RESULTS: Compared with the PVSC, the TC had faster times to achieve cecal intubation (mean [standard deviation], 8.83+/-4.68 minutes versus 6.88+/-4.08 minutes; P=.013) and a higher rate of retroflexion in the cecum (31/40 patients vs 39/40 patients; P<.01). Use of the TC was associated with a decreased need for abdominal pressure (P<.001). CONCLUSIONS: The TC achieved faster cecal intubation rates and had a higher success of cecal retroflexion than a PVSC. This performance likely was because of diminished looping and thus a decreased need for maneuvers. The TC may be preferable to the PVSC for female patients.     

Colonoscopy: go small for success?

Colonoscopy using standard adult colonoscopes can be difficult in patients with fixed, angulated sigmoid colons. An earlier study from the same center suggested that in women who have had hysterectomy, successful colonoscopy occurred with greater frequency when initiated with a pediatric colonoscope versus an adult colonoscope. This follow-up study was a nonblinded clinical trial comparing the use of a pediatric colonoscope with an adult colonoscope for routine colonoscopy in women with previous hysterectomy. A total of 100 female patients presenting for an outpatient colonoscopy were randomized to use the pediatric (Olympus PCF-100) or adult (Olympus CF-100L or CF-Q140L) colonoscope.
The primary outcome was the comparative rate of cecal intubation. Secondary outcomes included total procedure time, cecal insertion time, sedative administration, procedural difficulty, and patients' experience. Endoscopists encountering difficult insertion had the opportunity to use the alternate scope. The cecum was reached in 49 of 51 (96.1%) women when using the pediatric colonoscope versus 35 of 49 (71.4%) women when using the adult colonoscope. Of the 14 incomplete examinations initiated with an adult colonoscope, the pediatric colonoscope was used 12 times, and the cecum was reached in nine, adjusting the rate of successful colonoscopy to 44 of 49 (89.8%). There was no statistical difference in total procedure time, cecal insertion time, sedative drug dosages, procedural difficulty, or patient comfort using either scope.
When performing routine colonoscopy in women with previous hysterectomy, the authors recommend either starting with a pediatric colonoscope or having one available in the advent of a fixed, angulated sigmoid colon.     

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.     

Usefulness of a pediatric colonoscope for colonoscopy in adults

BACKGROUND: There are few published data on how different types of colonoscopes affect success in reaching the cecum and patient comfort. We examined the feasibility of using a pediatric colonoscope for routine colonoscopy in adults and investigated whether there were subgroups of patients in whom use of this instrument was preferable. METHODS: One-hundred fifty adults undergoing outpatient colonoscopy were randomized to colonoscopy with a standard colonoscope (Olympus CF-100L) or with a pediatric colonoscope (Olympus PCF-100). All procedures were performed by a faculty endoscopist and timed by an independent observer. After examinations, the endoscopist graded procedure difficulty and patients were given a questionnaire that assessed their experience. RESULTS: The adult (n = 77) and pediatric (n = 73) colonoscope groups were comparable in all outcomes measured, including success in reaching the cecum (91% vs. 93%, p = 0.61), mean time to reach the cecum (11.4 vs. 9.7 min, p = 0.07), mean total procedure time (21.8 vs. 21.9 min, p = 0.95), mean meperidine dose (55 vs. 52 mg, p = 0.17); median midazolam dose (2.0 mg in both groups, p = 0.10), the endoscopists' perception of procedure difficulty, and patient comfort scales. Of the 7 patients in whom colonoscopy with the adult colonoscope was unsuccessful, the cecum was reached in 4 by switching to a pediatric colonoscope (all women, 3 of whom had prior hysterectomy). In the 5 patients in whom colonoscopy with the pediatric colonoscope was unsuccessful, the cecum was reached in 1 by switching to an adult colonoscope. Including the cases in which the cecum was reached by switching to the alternative colonoscope, the overall frequency of cecal intubation was 143 of 150 (95%). Subgroup analysis disclosed no difference between the 2 groups in outcomes when gender, presence of diverticulosis, and patient size were considered. Colonoscopy with the pediatric colonoscope was more successful than with the adult instrument in reaching the cecum in women with prior hysterectomy (11 of 12 [92%] vs. 15 of 21 [71%]); however, the numbers in each group were relatively small and the difference was not significant (p = 0.22). CONCLUSIONS: The pediatric colonoscope is suitable for routine colonoscopy in adults. It is also useful in patients in whom colonoscopy with the adult colonoscope is unsuccessful in reaching the cecum (particularly in women). Additional study is needed to see if the pediatric colonoscope is actually superior to the adult colonoscopy for routine colonoscopy in women with prior hysterectomy.     

Usefulness of a pediatric colonoscope for routine colonoscopy in women who have undergone hysterectomy

BACKGROUND: Colonoscopy can be difficult in some women who have undergone hysterectomy, which can be associated with a fixed, angulated sigmoid colon caused by postoperative pelvic adhesions. Our goal was to determine whether colonoscopy is easier and more comfortable for women after hysterectomy when performed with a pediatric colonoscope, which is thinner in diameter and more flexible than a standard "adult" colonoscope. METHODS: One hundred women with a history of hysterectomy undergoing outpatient colonoscopy were randomized in unblinded fashion to colonoscopy with a standard colonoscope (CF-100L or CF-Q140L, Olympus) or with a pediatric colonoscope (PCF-100, Olympus). All procedures were performed by a faculty endoscopist and timed. After examination, the endoscopist graded procedure difficulty, and patients were given a questionnaire that assessed their experience. RESULTS: The cecum was intubated more frequently in the pediatric colonoscope group than in the standard colonoscope group (96.1% vs. 71.4%, p < 0.001). Success increased in the standard colonoscope group to 89.8% when the pediatric colonoscope was used to complete the examination. There were no differences in the two groups in terms of mean total procedure times (21.4 minutes vs. 22.6 minutes), mean doses of meperidine administered (57 mg both groups), mean doses of midazolam administered (1.5 mg vs. 1.7 mg), scales of procedure difficulty as graded by the endoscopists, and comfort scales as graded by patients. For the cases in which the cecum was intubated, the mean time to reach the cecum (11.7 minutes for the pediatric colonoscope group vs. 12.7 minutes for the adult) was similar. CONCLUSIONS: The pediatric colonoscope is a reasonable choice for colonoscopy in women who have had a hysterectomy. Alternatively, if the endoscopist elects to start the procedure with a standard colonoscope, it is helpful to have a pediatric colonoscope available for use should a fixed, angulated sigmoid colon be encountered that cannot be easily or safely traversed with the standard colonoscope.     

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.     

Ultrathin colonoscope with a diameter of 9.8 mm for total colonoscopy

BACKGROUND: The pediatric colonoscope is superior to the standard colonoscope in some patients with a fixed, angulated colon. A colonoscope thinner than the pediatric one is thought to outperform even the pediatric colonoscope in such cases. This study was conducted to assess the efficacy of an ultrathin colonoscope, 9.8 mm in diameter, comparing it with pediatric and standard colonoscopes. METHODS: Three types of colonoscopes were used: ultrathin, pediatric, and standard. A total of 287 consecutive patients were assigned to three groups: ultrathin (n=94), pediatric (n=98), and standard (n=95). First assessment was the ratio of cecal intubation and the reasons for unsuccessful colonoscopy. The second was the time to cecal intubation. RESULTS: Cecal intubation rates were not different among three groups (96% in each). The main reasons for failed colonoscopy were looping in the ultrathin group, and angulation or stricture in the pediatric and standard groups. Mean time to the cecum was slightly longer in the ultrathin group (6.5 minutes) than the pediatric group (5.6 minutes) and standard group (6.1 minutes), but there were no significant differences among three groups. CONCLUSION: Colonoscopy with the ultrathin colonoscope was as successful as with the pediatric and standard colonoscopes. The advantage of the ultrathin colonoscope might be notable in cases with stricture or severe angulation.     

A prospective trial of variable stiffness pediatric vs. standard instrument colonoscopy

BACKGROUND: The pediatric variable stiffness colonoscope is believed to have theoretical advantages over the standard colonoscope, however a systematic evaluation of this instrument in routine clinical practice involving adult patients is lacking. METHODS: Consecutive patients (blinded) undergoing colonoscopy in an outpatient endoscopy center by one of 4 experienced colonoscopists had the procedure performed with a standard colonoscope (n=384) or pediatric variable stiffness colonoscope (n=413). Failure to negotiate the sigmoid colon within 10 minutes was regarded as a failure and, if suitable, the patient was crossed over to colonoscopy with the alternative instrument. RESULTS: Median (95% CI) time to the cecum was significantly faster in the pediatric variable stiffness colonoscope group (odds ratio 5.0: 95% CI[4.7,5.3] minutes) compared with the standard colonoscope group (odds ratio 5.5: 95% CI[5.2,5.8] minutes, p=0.01). There were 22 failures overall (2.8%), 14 in the standard colonoscope group (3.6%) and 8 in the pediatric variable stiffness colonoscope group (1.9%; p=0.1). With regard to the 14 failures in the standard colonoscope group, colonoscopy was attempted with the pediatric variable stiffness colonoscope in 13 and completed successfully in 12 (92%). The pediatric variable stiffness colonoscope was superior in cases of severe stenosing diverticular disease; two of 27 examinations with the pediatric variable stiffness colonoscope were rated as failed vs. 12 of 18 with the standard colonoscope (p<0.001). CONCLUSIONS: Intubation time was faster with the pediatric variable stiffness colonoscope, but use of this instrument was not associated with a superior cecal intubation rate compared with the standard colonoscope. However, in patients with severe stenosing diverticular disease, the intubation rate with the pediatric variable stiffness colonoscope was superior.     

Use of a pediatric colonoscope improves the success of total colonoscopy in selected adult patients

Background: Colonoscopy using a standard adult colonoscope can be difficult or impossible when there is a fixed, angulated sigmoid colon or stricture. It is sometimes possible to traverse such segments using a smaller-diameter, more flexible pediatric colonoscope. Methods: For this prospective study, one endoscopist started 645 consecutive, elective colonoscopies with a standard adult Olympus CF-100L colonoscope (52% women, 48% men). There were 36 examinations (5.6%) in which the adult colonoscope could not be passed through a fixed, angulated sigmoid colon (n = 34) or a sigmoid colonic stricture (n = 2). In such instances (33 women and 3 men), the endoscopist switched to a pediatric colonoscope. Results: The pediatric colonoscope successfully reached the cecum in 21 of the 36 cases (58.3%). The figure was 38.5% for the older Olympus CF-P20L fiberoptic colonoscope (n = 13) and 69.6% for the newer Olympus PCF-100 videocolonoscope (n = 23). Concomitant conditions in the 34 patients in whom the pediatric colonoscope was used because of a fixed, angulated sigmoid included previous pelvic surgery in 22, pelvic radiation therapy in 2, pelvic endometriosis in 3, and two with previous sigmoid diverticulitis. Conclusions: The pediatric colonoscope, and particularly the newer Olympus PCF-100 colonoscope, is very useful in adult patients in whom it is not possible to traverse a fixed, angulated sigmoid colon or stricture using the standard adult colonoscope. This is predominantly a problem of female patients. Previous pelvic surgery may be an important causative factor in this regard. (Gastrointest Endosc 1996;44:675-8.)     

Retroflexion in the colon: a useful and safe technique in the evaluation and resection of sessile polyps during colonoscopy

OBJECTIVE: Endoscopic polypectomy has become the standard management approach for colon polyps. Three factors can make endoscopic resection of colonic polyps difficult: size, configuration, and location. We describe the use of retroflexion in the colon as a useful and routine technique using a standard colonoscope for the resection of difficult sessile polyps. METHODS: Fifteen patients in whom the retroflexion technique was used for polyp removal were prospectively identified. Each polyp was visualized and resected using both a forward and retroflexed view. RESULTS: Nine women and six men were identified between the ages of 49 and 81 years. The 15 polyps were located in the cecum (3), ascending colon (3), hepatic flexure (3), splenic flexure (2), descending colon (2), and sigmoid colon (2). All the polyps were sessile and their largest diameter ranged from 20 mm to 50 mm. Retroflexion combined with forward viewing allowed for a better assessment of the size and extent of all the polyps compared with forward viewing alone. All polyps, except two, were completely resected during the first session, using both the prograde and retroflexion approaches. No complications from retroflexion of the colonoscope, including perforation or bleeding, occurred. CONCLUSION: Retroflexion complements the conventional prograde inspection of sessile polyps that are only partially visualized on prograde view alone. Retroflexion allows a complete assessment of the lesions' size and extent and aid in their complete removal.     

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.     

Short turn radius colonoscope in an anatomical model: Retroflexed withdrawal and detection of hidden polyps

AIM: To evaluate the new Retro View~(TM) colonoscope and compare its ability to detect simulated polyps "hidden" behind colonic folds with that of a conventional colonoscope, utilizing anatomic colon models.METHODS: Three anatomic colon models were prepared,with twelve simulated polyps "hidden" behind haustral folds and five placed in easily viewed locations in each model. Five blinded endoscopists examined two colon models in random order with the conventional or Retro View~(TM) colonoscope, utilizing standard withdrawal technique. The third colon model was then examined with the Retro View~(TM) colonoscope withdrawn initially in retroflexion and then in standard withdrawal. Polyp detection rates during standard and retroflexed withdrawal of the conventional and Retro View~(TM) colonoscopes were determined. Polyp detection rates for combined standard and retroflexed withdrawal(combination withdrawal) with the Retro View~(TM) colonoscope were also determined.RESULTS: For hidden polyps, retroflexed withdrawal using the Retro View~(TM) colonoscope detected more polyps than the conventional colonoscope in standard withdrawal(85% vs 12%, P = 0.0001). For hidden polyps, combination withdrawal with the Retro View~(TM) colonoscope detected more polyps than the conventional colonoscope in standard withdrawal(93% vs 12%, P ≤ 0.0001). The Retro View~(TM) colonoscope in "combination withdrawal" was superior to other methods in detecting all(hidden + easily visible) polyps, with successful detection of 80 of 85 polyps(94%) compared to 28(32%) polyps detected by the conventional colonoscope in standard withdrawal(P 0.0001) and 67(79%) polyps detected by the Retro View~(TM) colonoscope in retroflexed withdrawal alone(P 0.01). Continuous withdrawal of the colonoscope through the colon model while retroflexed was achieved by all endoscopists. In a post-test survey, four out of five colonoscopists reported that manipulation of the colonoscope was easy or very easy.CONCLUSION: In simulated testing, the Retro View~(TM) colonoscope increased detection of hidden polyps. Combining standard withdrawal with retroflexed withdrawal may become the new paradigm for "complete screening colonoscopy".     

Usefulness of a small-caliber, variable-stiffness colonoscope as a backup in patients with difficult or incomplete colonoscopy

OBJECTIVES: Although variable-stiffness colonoscopes have been developed, difficult or incomplete colonoscopies occasionally occur. The aim of this study was to evaluate the usefulness of a small-caliber, variable-stiffness colonoscope (scVSC) as a backup in patients with difficult or incomplete colonoscopies. METHODS: First, we retrospectively reviewed the cecal intubation rate of colonoscopies in which an adult standard colonoscope (AC) was immediately switched to an scVSC in all patients in whom a colonoscopy with an AC was incomplete. Second, 374 consecutive patients were randomized to undergo colonoscopy with a pediatric variable-stiffness colonoscope (PVSC, n = 123), AC (n = 125), or scVSC (n = 126). The scVSC was used by the same endoscopist to reattempt colonoscopy immediately after colonoscopy with a PVSC or an AC had been assessed as difficult or incomplete. The cecal intubation rate and time and the ancillary maneuvers used were evaluated. RESULTS: Fifty-two (2.5%) of the 2,056 attempted colonoscopies with an AC did not reach the cecum. Fifty-one of the 52 patients (98.1%) had complete colonoscopies after the switch from the AC to the scVSC. The initial intubation rate and time were not statistically different among the groups: PVSC, 95% and 6.8 min; AC, 91% and 7.5 min; and scVSC, 98% and 8.2 min. Cecal intubation was achieved in all five patients (100%) and in 10 out of 11 (91%) patients, respectively, after the PVSC or AC was switched to the scVSC. CONCLUSIONS: The completion rate markedly improved after switching from an AC or PVSC to an scVSC in difficult or incomplete colonoscopies, although the scVSC does not appear to offer any distinct advantage over the AC or PVSC for routine colonoscopies.     

The variable stiffness colonoscope: assessment of efficacy by magnetic endoscope imaging

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.     

Usefulness of pediatric colonoscopes in adult colonoscopy

Use of small diameter, extraflexible pediatric colonoscopes has proved to be valuable in adult endoscopy practice, not only for passing strictures and stomas but also where either fixation due to diverticular disease or postoperative adhesions, or unavoidably painful looping made passage of adult colonoscopes impossible. In 70 of 78 (92%) of the cases where the adult colonoscope could not be passed through the sigmoid colon by an expert endoscopist, the pediatric colonoscope passed through, often very easily. Fifteen of these patients were considered to have been saved surgery by successful passage. The "failure" rate for all colonoscopy examinations was only 2%; this low failure rate was attributable to the use of pediatric instruments whenever passage through the sigmoid colon proved to be impossible with standard colonoscopes. In our opinion every unit performing frequent colonoscopies should have a pediatric colonoscope available for selected adult patients as well as for use in children.     

Endoscopic innovations to increase the adenoma detection rate during colonoscopy

Up to a quarter of polyps and adenomas are missed during colonoscopy due to poor visualization behind folds and the inner curves of flexures, and the presence of flat lesions that are difficult to detect. These numbers may however be conservative because they mainly come from back-to-back studies performed with standard colonoscopes, which are unable to visualize the entire mucosal surface. In the past several years, new endoscopic techniques have been introduced to improve the detection of polyps and adenomas. The introduction of high definition colonoscopes and visual image enhancement technologies have been suggested to lead to better recognition of flat and small lesions, but the absolute increase in diagnostic yield seems limited. Cap assisted colonoscopy and water-exchange colonoscopy are methods to facilitate cecal intubation and increase patients comfort, but show only a marginal or no benefit on polyp and adenoma detection. Retroflexion is routinely used in the rectum for the inspection of the dentate line, but withdrawal in retroflexion in the colon is in general not recommended due to the risk of perforation. In contrast, colonoscopy with the Third-Eye Retroscope^® may result in considerable lower miss rates compared to standard colonoscopy, but this technique is not practical in case of polypectomy and is more time consuming. The recently introduced Full Spectrum Endoscopy™ colonoscopes maintains the technical capabilities of standard colonoscopes and provides a much wider view of 330 degrees compared to the 170 degrees with standard colonoscopes. Remarkable lower adenoma miss rates with this new technique were recently demonstrated in the first randomized study. Nonetheless, more studies are required to determine the exact additional diagnostic yield in clinical practice. Optimizing the efficacy of colorectal cancer screening and surveillance requires high definition colonoscopes with improved virtual chromoendoscopy technology that visualize the whole colon mucosa while maintaining optimal washing, suction and therapeutic capabilities, and keeping the procedural time as low and patient discomfort as optimal as possible.     

How to manage difficulties with colonoscope insertion

Unsuccessful insertion of a colonoscope is usually as a result of bending or looping of the scope. Looping of the colonoscope increases when too much air is insufflated or the scope is inserted with undue force, resulting in increased pain and risk of perforation. Successful insertion therefore requires careful handling of the scope to keep it straight, careful regulation of air levels, shortening of the colon length by gathering of the colon folds and rapid correction of any looping that should occur. This can be complicated in cases with an unusually long colon or with adhesion. The use of a colonoscope with variable rigidity or a small‐caliber colonoscope is recommended to increase the rate of successful insertion to relieve pain and to prevent accidents.     

A randomized controlled trial in a training institution comparing a pediatric variable stiffness colonoscope, a pediatric colonoscope, and an adult colonoscope

BACKGROUND: There are few comparative data on the efficacy of different colonoscopes. This study compared the efficacy of a new pediatric variable stiffness colonoscope with that of standard pediatric and adult colonoscopes in the performance of routine colonoscopy. METHODS: Three hundred sixty-three consecutive patients were randomized to undergo colonoscopy with a pediatric variable stiffness (n = 122), pediatric (n = 114), or adult colonoscope (n = 127). Primary outcomes recorded were minutes to the cecum and completeness of the examination. Secondary outcomes included patient tolerance, use of abdominal compression, and endoscopists' assessment of the difficulty of the procedure. RESULTS: Cecal intubation rates were not statistically different between the groups: variable stiffness (94.3%), pediatric (96.5%), and adult (89.8%) (p = 0.099). There was no significant difference in mean insertion time, patient tolerance, use of abdominal compression, or endoscopists' global assessment or examination difficulty between groups. Overall, the initial completion rate of 93% increased to 97% on switching to a different colonoscope. Colonoscopy was unsuccessful more often and was more time consuming in women who had undergone hysterectomy. CONCLUSION: The variable stiffness colonoscope performs well, but does not appear to offer any distinct advantage over standard pediatric or adult colonoscopes for routine colonoscopy. Further study may identify subgroups of patients that benefit from this new technology.     

Accuracy of assessment of the extent of examination by experienced colonoscopists.

One hundred colonoscopies were done. The colonoscopist noted whether the cecum had been intubated as well as the markers used to make this determination. With the colonoscope in position at maximum penetration, a radiologist independently determined its position using fluoroscopy, with a contrast agent delivered through the colonoscope. The cecum was entered in 86 of 100 cases. The tip of the colonoscope was at the level of the ileocecal valve in nine additional cases; the colonoscopist judged that the cecum was well seen in five of these nine. In one case, the colonoscopist overestimated the extent of the examination when transillumination in the right lower quadrant was the only confirming marker. When the more reliable markers (ileocecal valve, appendiceal orifice, converging indentations of the taenia coli in the cecal pole) were seen, no errors were made. Experienced colonoscopists are accurate in assessing the extent of colonoscopy and fluoroscopic confirmation is not routinely needed. When reliable markers are not seen during the examination, a barium enema, preferably with air contrast, should be done.