Non-radiological technique for three-dimensional imaging of endoscopes

JAG consensus statements for training and certification in colonoscopy

Introduction

In the UK, endoscopy certification is awarded when trainees attain minimum competency standards for independent practice. A national evidence-based review was undertaken to update and develop standards and recommendations for colonoscopy training and certification.

Methods

Under the oversight of the Joint Advisory Group (JAG), a modified Delphi process was conducted between 2019 and 2020 with multisociety expert representation. Following literature review and Grading of Recommendations, Assessment, Development and Evaluations appraisal, recommendation statements on colonoscopy training and certification were formulated and subjected to anonymous voting to obtain consensus. Accepted statements were peer reviewed by JAG and relevant stakeholders for incorporation into the updated colonoscopy certification pathway.

Results

In total, 45 recommendation statements were generated under the domains of: definition of competence (13), acquisition of competence (20), assessment of competence (8) and postcertification support (4). The consensus process led to revised criteria for colonoscopy certification, comprising: (1) achieving key performance indicators defined within British Society of Gastroenterology standards (ie, unassisted caecal intubation rate >90%, rectal retroversion >90%, polyp detection rate >15%+, polyp retrieval rate >90%, patient comfort <10% with moderate–severe discomfort); (2) minimum procedure count 280+; (3) performing 15+ procedures over the preceding 3 months; (4) attendance of the JAG Basic Skills in Colonoscopy course; (5) terminal ileal intubation rates of 60%+ in inflammatory bowel disease; (6) satisfying requirements for formative direct observation of procedure skills (DOPS) and direct observation of polypectomy skills (Size, Morphology, Site, Access (SMSA) level 2); (7) evidence of reflective practice as documented on the JAG Endoscopy Training System reflection tool; (8) successful performance in summative DOPS.

Conclusion

The UK standards for training and certification in colonoscopy have been updated, culminating in a single-stage certification process with emphasis on polypectomy competency (SMSA Level 2+). These standards are intended to support training, improve standards of colonoscopy and polypectomy, and provide support to the newly independent practitioner.

Longer observation time increases adenoma detection in the proximal colon - a prospective study

BACKGROUND AND STUDY AIMS

Longer observation times are associated with increased adenoma detection rates (ADR) in the entire colon. However, adenomas in the proximal colon are at risk of being missed during colonoscopy. The aim of this study was to investigate the impact of observation time on detection of adenomatous polyps in the proximal colon.

PATIENTS AND METHODS

This was a prospective study at a university hospital in Germany. Colonoscopies were conducted using magnetic endoscope imaging (MEI) in order to determine the exact position of the scope. Exact observation times spent for the detection of polyps in the proximal and distal colon segments were assessed. The primary outcome was adenoma detection in the proximal colon. ROC curves were generated in order to test the correlation between observation time and adenoma detection. Logistic regression analysis was used to check for interfering factors.

RESULTS

 A total 480 procedures with 538 polyps were available for analysis. The overall adenoma detection rate was 38.5 %. ADR in the proximal colon was 28.0 %. There was a significant association between observation time in the proximal colon and the detection of proximal adenomas ( P  < 0.001). The impact of the time factor on ADR was stronger in the proximal compared to the distal colon ( P  = 0.030). A net period of 4 min 7 sec was found to be the minimum time span for sufficient adenoma detection in the proximal colon.

CONCLUSION

Observation time is significant in terms of adenoma detection in the proximal colon. The impact of observation time on ADR is stronger in the proximal compared to the distal colon. In the proximal colon a minimum time span of 4 minutes should be spent in order to ensure adequate adenoma detection.

Magnetic endoscope imaging in single-balloon enteroscopy

BACKGROUND AND AIM

Magnetic endoscope imaging (MEI) provides continuous viewing of the position of the endoscope on a monitor without using X-ray and has already been established for colonoscopy. The aim of the present study was to evaluate a new MEI probe for enteroscopy.

METHODS

In this prospective feasibility study, consecutive patients received single-balloon enteroscopy guided by the new MEI probe. Fluoroscopy was also used in all examinations. MEI images were compared to fluoroscopy images with respect to concordance of loop configuration by two independent observers after the examinations. Main outcome measurement was the rate of concordant MEI and fluoroscopy images with respect to loop configuration.

RESULTS

In all 10 patients, single-balloon enteroscopy with MEI was carried out without any adverse events or technical difficulties. Concordance of MEI and fluoroscopy images was seen in 36/38 images (95%; 95% CI, 82-99%) by both observers. Overall agreement between the two observers was 95% (κ = 0.47, 95% CI, -0.04-1).

CONCLUSION

The use of MEI in single-balloon enteroscopy is safe and feasible. Detection and control of loops can be accurately achieved.

Magnetic endoscopic imaging vs standard colonoscopy: Meta-analysis of randomized controlled trials

AIM: To assess the theoretical advantages of magnetic endoscope imaging (MEI) over standard colonoscopies (SCs) and to compare their efficacies.

METHODS: Electronic databases, including PubMed, EMBASE, the Cochrane library and the Science Citation Index, were searched to retrieve relevant trials. In addition, abstracts from papers presented at professional meetings and the reference lists of retrieved articles were reviewed to identify additional studies. The meta-analyses were performed using RevMan 5.1. A random effect model with the Mantel-Haenszel method was used for pooling dichotomous and continuous data. A sensitivity analysis was performed by excluding the trials with a small number of patients and by excluding the trials performed by inexperienced providers.

RESULTS: Eight randomized controlled trials (RCTs), including 2967 patients, were included in the meta-analysis to compare cecal intubation rates and times, sedation dose, abdominal pain scores and the use of ancillary maneuvers between MEI and SC. The overall OR was 1.92 (95%CI: 1.13-3.27, eight RCTs), as indicated by the cecal intubation rate of MEI compared with SC, but MEI did not have any distinct advantage over SC for cecal intubation time (MD = -0.07, 95%CI: -0.16-0.02; three RCTs). MEI did not generally result in lower pain scores. Outcomes were also analyzed for the two subgroups based on the endoscopists’ experience level to evaluate cecal intubation rates. MEI presented better outcomes for non-experienced colonoscopists than experienced colonoscopists.

CONCLUSION: The real-time magnetic imaging system is of benefit in training and educating inexperienced endoscopists and improves the cecal intubation rate for experienced and inexperienced endoscopists.

Training and teaching innovations in colonoscopy

Optimization of training and teaching methods in colonoscopy at all levels of experience is critical to ensure consistent high-quality procedures in practice. Competency in colonoscopy may not be achieved until more than 250 colonoscopies are performed by trainees. Such tools as computer-based endoscopic simulators can aid in accelerating the early phases of training in colonoscopy, and magnetic endoscopic imaging technology can guide the position of the colonoscope and aid with loop reduction. Periodic feedback and retraining experienced endoscopists can improve the detection of colonic lesions.

Newly developed electromagnetic tracked flexible neuroendoscope

Flexible endoscopes can be used in areas that are difficult to approach using rigid endoscopes. No current real-time navigation systems identify the tip of the flexible neuroendoscope. We have developed a flexible neuroendoscope mounted with a magnetic field sensor tip position-tracking system and evaluated the accuracy of this magnetic field neuronavigation system. Based on an existing flexible neuroendoscope, we created a prototype with a built-in magnetic field sensor in the tip. A magnetic field measurement device provides a magnetic field with a working volume of 500 × 500 × 500 mm in front of the device. The device consists of a flat field generator that creates a pulsed magnetic field, connected to a system control unit that interfaces with a computer. The magnetic field sensor (1.8 × 9 mm) was sealed in a site 0.9 mm from the endoscope tip. Accuracy of neuroendoscope tracking was measured using a three-dimensional coordinate-measuring machine that measures the position of objects along 3 axes, with an error of about 3 µm. The accuracy for this neuroendoscope with built-in magnetic field sensor was root mean square error of 1.2 mm and standard deviation of 0.5 mm. This magnetic field neuronavigation system enables real-time tracking of the tip of the flexible neuroendoscope. Application of this flexible neuroendoscope to intraoperative navigation appears promising, and may provide new advantages for minimally invasive endoscopic surgery.

3D preoperative planning in the ER with OsiriX®: when there is no time for neuronavigation

The evaluation of patients in the emergency room department (ER) through more accurate imaging methods such as computed tomography (CT) has revolutionized their assistance in the early 80s. However, despite technical improvements seen during the last decade, surgical planning in the ER has not followed the development of image acquisition methods. The authors present their experience with DICOM image processing as a navigation method in the ER. The authors present 18 patients treated in the Emergency Department of the Hospital das Clínicas of the University of Sao Paulo. All patients were submitted to volumetric CT. We present patients with epidural hematomas, acute/subacute subdural hematomas and contusional hematomas. Using a specific program to analyze images in DICOM format (OsiriX^®), the authors performed the appropriate surgical planning. The use of 3D surgical planning made it possible to perform procedures more accurately and less invasively, enabling better postoperative outcomes. All sorts of neurosurgical emergency pathologies can be treated appropriately with no waste of time. The three-dimensional processing of images in the preoperative evaluation is easy and possible even within the emergency care. It should be used as a tool to reduce the surgical trauma and it may dispense methods of navigation in many cases.

Advanced 3-Dimensional Planning in Neurosurgery

During the past decades, medical applications of virtual reality technology have been developing rapidly, ranging from a research curiosity to a commercially and clinically important area of medical informatics and technology. With the aid of new technologies, the user is able to process large amounts of data sets to create accurate and almost realistic reconstructions of anatomic structures and related pathologies. As a result, a 3-diensional (3-D) representation is obtained, and surgeons can explore the brain for planning or training. Further improvement such as a feedback system increases the interaction between users and models by creating a virtual environment. Its use for advanced 3-D planning in neurosurgery is described. Different systems of medical image volume rendering have been used and analyzed for advanced 3-D planning: 1 is a commercial “ready-to-go” system (Dextroscope, Bracco, Volume Interaction, Singapore), whereas the others are open-source-based software (3-D Slicer, FSL, and FreesSurfer). Different neurosurgeons at our institution experienced how advanced 3-D planning before surgery allowed them to facilitate and increase their understanding of the complex anatomic and pathological relationships of the lesion. They all agreed that the preoperative experience of virtually planning the approach was helpful during the operative procedure. Virtual reality for advanced 3-D planning in neurosurgery has achieved considerable realism as a result of the available processing power of modern computers. Although it has been found useful to facilitate the understanding of complex anatomic relationships, further effort is needed to increase the quality of the interaction between the user and the model.

Magnetic endoscopic imaging saves abdominal compression and patient pain in routine colonoscopies

OBJECTIVE

Magnetic endoscope imaging (MEI) is a technique for the direct visualisation of endoscope configuration within the colon. This method may prevent loop formation by giving visual feedback of endoscope movement. This study aimed to evaluate the efficacy of MEI in improving colonoscopy performance.

METHODS

Overall 1000 consecutive patients who underwent a complete routine colonoscopy were randomized into two groups: in group A with MEI, while in group B without MEI. Sedation was performed according to local standards. In both groups time to reach the cecum, the number of positioning maneuvers and involvement of a second assistant nurse were recorded. Abdominal compression was graded from 1 to 4 according to the duration and intensity of compression was quantified using a scale from 1-3 according to compression form and patient reaction.

RESULTS

Patients were randomized (group A with MEI, n = 490; group B without MEI, n = 510) and a total colonoscopy was performed. Time to cecal intubation did not differ between the groups (507 s vs 538 s; NS). The duration of abdominal compression was significantly shorter in MEI guided colonoscopy. The intensity of abdominal compression was lower in group A and fewer turn maneuvers needed per patient. A trend towards a reduced need for assistance in MEI group was seen.

CONCLUSION

Although MEI does not generally accelerate colonoscope advancement, it significantly reduces the force and the duration of abdominal compression by assistant personnel, thus minimizing patient discomfort and decreasing the need for additional staff.

Evaluation of magnetic scope navigation in screening endoscopic examination of colorectal cancer

Background

Colorectal cancer is the most common cancer in Europe. Early diagnosis and treatment gives the patient a chance for complete recovery. Screening colonoscopies in the symptom-free patients are currently performed on a wide scale. The examinations are performed under local anesthesia which does not eliminate all discomfort and pain related to the examination. The aim of this study was to evaluate magnetic scope navigation in screening endoscopic examinations performed to detect early-stage colorectal cancer.

Methods

The study group consisted of 200 patients, aged 40–65 years, who were free from colon cancer symptoms. All patients underwent complete colonoscopy under local anesthesia. The equipment could be fitted with the scope that allows three-dimensional observation of instrument localization in the bowel. The examination was performed by three experienced endoscopists, each of whom performed over 5,000 colonoscopies. The patients were randomized to two groups: those whose equipment did not have 3D navigation (group I) and those whose equipment did have 3D navigation (group II). Each group consisted of 100 cases matched by gender, age, and BMI. The authors compared the duration of introducing instrument to cecum, the pulse rate before the examination and at the time the instrument reached the cecum, and subjective pain evaluation by the patient on the visual analog scale.

Results

Group I consisted of 54 women and 46 men with a mean age of 54.6 years and mean BMI of 27.8 kg/m², and group II had 58 women and 42 men, mean age of 55.1 years and mean BMI of 26.4 kg/m². The average time it took for the instrument to reach the cecum was 216s in group I and 181s in group II (P < 0.05). Pain measured on the 10-point VAS scale was 2.44 in group I and 1.85 in group II (P < 0.05). The results showed a significantly shorter time for the instrument to reach the cecum in group II and significantly lower pain intensity during the examination was reported by the group II patients. No significant differences were found in the pulse measurements between the groups (P = 0.5).

Conclusions

3D navigation during colonoscopy decreases the time for the instrument to reach the cecum and lowers pain intensity subjectively reported by the patients. The use of 3D and the possibility to observe instrument localization and maneuvers brings more comfort to the patients.

Determining scope position during colonoscopy without use of ionizing radiation or magnetic imaging: the enhanced mapping ability of the NeoGuide Endoscopy System

BACKGROUND

Knowledge of the position and shape of the endoscope could overcome many challenges of performing colonoscopy, e.g., loop formation. A novel computer-assisted colonoscope (NeoGuide Endoscopy System) delivers a real-time, three-dimensional map of the tip position and insertion tube shape in addition to the video image of the colon lumen. The aim of this study is to evaluate the mapping capabilities of the NeoGuide Endoscopy System in terms of colonic looping, insertion depth, tip position, and tip angle formation.

METHODS

Ten endoscopists with various levels of experience were each shown 70 map images generated by the NeoGuide endoscopy system in a benchtop anatomical colon model. First endoscopists were asked to determine the tip angle based on the map image and the system's corresponding tip positioning aid (20 images). In the second part they had to identify the scope-tip position in the colon model (40 images). In the third part ten images were presented for identification of colonic loops.

RESULTS

The tip angle was correctly identified in 99% (198/200) of images. Using only the map images the scope position was accurately determined in 87.5% (350/400). Identification of colonic looping of the scope was appropriate in 99% (99/100). Overall accuracy was 92.4%, and overall positive predictive value was 94.9%.

CONCLUSION

Three-dimensional map images generated by the NeoGuide endoscopy system provide accurate information regarding tip position, insertion tube position, and colonic looping.

Use of an electromagnetic colonoscope to assess maneuvers associated with cecal intubation

Background

Safe and effective colonoscopy is aided by the use of endoscopic techniques and maneuvers (ETM) during the examination including patient repositioning, stiffening of the endoscope and abdominal pressure.

Aim

To better understand the use and value of ETM during colonoscopy by using a device that allows real-time imaging of the colonoscope insertion shaft.

Methods

The use of ETM during colonoscopy and their success was recorded. Experienced colonoscopists and endoscopy assistants used a commercially available electromagnetic (EM) transmitter and a special adult variable stiffness instrument with 12 embedded sensors to examine 46 patients. In 5 of these a special EM probe passed through the instrument channel of a standard pediatric variable stiffness colonoscope was used instead of the EM colonoscope.

Results

Thirty-nine men and 7 women with a mean age of 64 years (range 33–90) were studied. The cecum was intubated in 93.5% (43/46). The mean time to reach the cecum was 10.6 minutes (range 3–25). ETM were used a total of 174 times in 41 of the patients to assist with cecal intubation. When ETM were required to reach the cecum, and the cecum was intubated, an average of 3.82 ETM/patient was used. While ETM were used most often when the tip of the colonoscope was in the left side of the colon (rectum 5.0%, sigmoid colon 20.7%, descending colon 5.0%, and splenic flexure 11.6%), when the instrument was in the transverse colon (14.8%), hepatic flexure (20.7%) and ascending colon (19.8%) the use of ETM was also required. When the colonoscope tip was in the transverse colon, hepatic flexure and ascending colon, ETM success rates were less (61.1%, 52.0%, and 41.7% respectively) compared to the left colon success rates (rectum 83.3%, sigmoid colon 84.0%, descending colon 100%, and splenic flexure 85.7%).

Conclusion

The EM colonoscope allows imaging of the insertion shaft without fluoroscopy and is a useful device for evaluating the efficacy of ETM. ETM are important tools of the colonoscopist and are used most often in the left colon where they are most effective.

The usefulness of a magnetic endoscope locating device in colonoscopy in daily practice: a prospective case-controlled study

BACKGROUND

This study aimed to investigate the effects of magnetic endoscope imaging (MEI) regarding examination time, caecal intubation rate, and sedation and analgesic requirements during routine colonoscopy compared with earlier used X-ray imaging.

METHODS

Consecutive outpatients undergoing colonoscopy were prospectively studied for two periods. In the first period X-ray was used to establish the correct position of the endoscope. In the second period MEI was used. Outcome measures were examination time, caecal intubation rate, median dose of analgesic and sedative administered, and median X-ray dose used.

RESULTS

The two groups studied were comparable with regards to age, sex, and number of therapeutic examinations. The examination time was significantly shorter with use of MEI (median 29 min versus 43 min). No significant differences in the use of analgesic and sedative were found (median 50 microg phentanyle and 2 mg midazolam in both groups). Median X-ray dose was 150 cGy in the group using X-ray imaging.

CONCLUSION

MEI is the imaging methodology of choice and should always be available in colonoscopy, especially for precise locating of colonic lesions.

Recording forces exerted on the bowel wall during colonoscopy: in vitro evaluation

A novel system for distributed force measurement between the bowel wall and the shaft of a colonoscope is presented. The system, based on the piezoresistive method, involves the integration of soft miniature transducers to a colonoscope to enable a wide range of forces to be sensed. The attached sensing sheath does not restrict the propulsion of the colonoscope nor notably alter its flexibility. The addition of the sensor sheath increases the colonoscope diameter by 15-20% depending on the type of the colonoscope (adult or paediatric). The transducer's accuracy is +/-20 grammes if it is not subjected to extensive static forces. Under large static force conditions the errors may increase to +/-50 grammes. The tactile force measuring sensors have provided preliminary results from experiments on a model of the large bowel. The force measurements confirm the predictions on the location and magnitude of the forces and that most of the forces are exerted whilst the instrument is looping.

Emergency endoscopy in children

Endoscopy in children has developed along with pediatric gastroenterology over the last four decades. Introduction of endoscopic techniques in adults precedes application in children, and pediatric endoscopists do fewer procedures than their adult counterparts whether routine or as an emergency. Training for pediatric endoscopists therefore needs to be thorough. This article in particular highlights developments in pediatric gastroenterology of importance to emergency procedures.

Computer-assisted colonoscopy (the NeoGuide Endoscopy System): results of the first human clinical trial ("PACE study")

OBJECTIVES

Unsedated colonoscopy is an uncomfortable procedure for most patients. Discomfort during colonoscopy is largely related to looping of the colonoscope, which displaces the colon from its native configuration and stretches attachments to the mesentery. A novel computer-assisted colonoscope utilizes a fully articulated, computer-controlled insertion tube. On manual insertion of the colonoscope, the position and angle of the scope's tip are encoded into a computer algorithm. As the colonoscope is advanced, the computer directs each successive segment to take the same shape that the tip had at a given insertion depth. The insertion tube thus changes its shape at different insertion depths in a "follow-the-leader" manner.

METHODS

This initial clinical trial with this novel colonoscopy system was designed as a prospective, nonrandomized, unblinded, feasibility study. Three physicians of varying levels of experience participated in the study.

RESULTS

Eleven consecutive patients (seven men, four women, age range 19-80) meeting inclusion criteria for screening or diagnostic colonoscopy were enrolled in the study. The cecum was reached in 10 consecutive patients (100%). Findings included diverticular disease in two cases and multiple colonic polyps in two cases. Postprocedure assessment at discharge, 48 h, and 30 days revealed no complications or adverse effects. Physician satisfaction and patient acceptance of this new technique were high.

CONCLUSIONS

In this limited, first of its kind feasibility study, the computer-assisted colonoscope was shown to perform colonoscopy safely and effectively. The colonoscope's unique design limited loop formation during colonoscopy. Large-scale clinical trials are indicated.

Aids to insertion: magnetic imaging, variable stiffness, and overtubes

Inserting the colonoscope quickly and safely without undue patient discomfort is the primary aim of the colonoscopist. The inherently mobile, flexible and unpredictable nature of the colon means that looping occurs frequently during insertion and the colonoscopist must constantly strive to keep the instrument straight whilst at the same time advancing the tip towards the caecum. Colonoscopists have struggled with insertion for many years but recent developments described in this chapter have the potential to make insertion easier and more predictable.

Advances in colonic imaging: technical improvements in colonoscopy

Colonoscopy has been available since the early 1970s and has become critical to the diagnosis and management of colorectal disorders. Features of the modern colonoscope and its variants are discussed, including the role of paediatric and variable stiffness colonoscopes for difficult insertion. The place of magnetic endoscope imaging systems and simulators in routine colonoscopy and training are examined. Finally, several recent innovations are used to illustrate how colonoscopy may evolve in the future, including new takes on the current instrument as well as potentially revolutionary pain-free, technically-easy, robotic devices for examination of the bowel.

Determination of large bowel length and loop complexity in patients with acromegaly undergoing screening colonoscopy

BACKGROUND

Patients with acromegaly are at moderately increased risk of developing colorectal cancer and may be considered for screening colonoscopy. In turn, large bowel dimensions may be increased in these patients, factors that predict for increased risk of serious complications such as perforation.

OBJECTIVE

To evaluate this risk potential, we measured large bowel length and loop complexity using magnetic endoscopic imaging (MEI).

DESIGN

Case-control study in 25 unselected patients with acromegaly (mean age 56 years) vs. 41 nonacromegalic controls (mean age 60 years) undergoing screening colonoscopy.

MEASUREMENTS

MEI parameters were determined and age- and sex-adjusted mean differences calculated. The dependency of total large bowel length on various demographic and disease-related factors (e.g. GH exposure, IGF-I and IGFBP-3 concentrations) was assessed using regression techniques.

RESULTS

Total large bowel length was increased by 20%[95% confidence interval (CI) 9-31%] in patients with acromegaly compared with controls (unadjusted and adjusted; P-values < 0.001). Acromegaly was also associated with increased time taken to reach the caecum (P = 0.01) and increased pelvic loop complexities (5/25 vs. 1/41, Fisher's exact test: P = 0.03). Total large bowel length was predicted by age at colonoscopy (P = 0.003) and patient height (P = 0.03), but not by surrogate biochemical markers of disease activity.

CONCLUSIONS

Acromegaly is associated with increased large bowel length and loop complexity making colonoscopy technically challenging, and theoretically increasing the risk of serious complications. Patients need to be counselled accordingly, and appropriate resources with experienced staff allocated.

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.

Effect of magnetic endoscope imaging on patient tolerance and sedation requirements during colonoscopy: a randomized controlled trial

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.

Inadequacy of colonoscopy revealed by three-dimensional electromagnetic imaging

INTRODUCTION

It is generally accepted that clinicians performing colonoscopy should reach the cecum in at least 90 percent of examinations. However, little attention has been paid to whether the endoscopist correctly estimates the amount of colon actually seen.

METHODS

During colonoscopy, endoscopists were asked to state how far they had reached. This was compared with the amount of colon actually seen, as assessed by a novel electromagnetic imaging device that recorded a three-dimensional position of the scope within a magnetic field pervading the patient's abdomen. If electromagnetic imaging showed that the cecum had not been reached, the endoscopist was asked to use the electromagnetic imaging system to determine whether it helped advance the colonoscope further.

RESULTS

In 119 patients undergoing colonoscopy, clinical assessment of position reached was correct in only 92 (77.3 percent). When the endoscopists stated that cecal landmarks had been seen (n = 85), the scope was distal to the cecum in seven cases (8.2 percent). When cecal landmarks had not been seen (n = 34), the endoscopist's assessment of the position of the scope was accurate in only 14 (41.2 percent). The use of electromagnetic imaging in this latter group assisted passage to the cecum in 26 cases (76.5 percent).

CONCLUSION

Despite assumed visualization of the cecum, inadequate colonoscopy highlights the potential for missing significant pathology in the right colon.

Effect of magnetic endoscope imaging on colonoscopy performance: a randomised controlled trial

BACKGROUND

Colonoscopy can be technically challenging because of unpredictable colonoscope looping. Without imaging, straightening the colonoscope is sometimes difficult since the endoscopist has to guess where the tip is. Magnetic endoscope imaging (MEI), a new non-radiographical technique for picturing the colonoscope shaft in real time, could facilitate loop straightening and thus improve performance.

METHODS

We assessed trainees and endoscopists with much experience of routine outpatient colonoscopy. In group 1, trainees examined 113 consecutive patients. MEI views were recorded in all examinations, but procedures were randomised to be done by two trainees, either with the endoscopist and endoscopy assistants viewing the imager display (n=58), or without the imager view (n=55). In group 2, two skilled endoscopists were randomised (as with group 1) to undertake consecutive examinations (n=183) either with (n=92) or without (n=91) the MEI view. MEI views of all procedures were analysed retrospectively.

FINDINGS

In both groups, intubation times were shorter (median 11.8 min [4.3-31.5] vs 15.3 min [4-67] [group 1]; 8.0 min [2.6-40.8] vs 9.3 min [2.5-52.6] [group 2]) and number of attempts at straightening the colonoscope fewer (median 5 [0-20] vs 12 [0-57] [group 1]; 7 [0-55] vs 10 [0-80] [group 2]), when the endoscopist was able to see the imager view. In group 1, colonoscopy completion rates were also higher (100% [58] vs 89% [49]) and duration of looping was reduced (median 3 min [0-18.8] vs 5.4 min [0-44.5]) when the imager could be seen. Abdominal hand pressure was more effective when the endoscopist and endoscopy assistant could see the imager view.

INTERPRETATION

MEI significantly improves performance of colonoscopy, particularly when used by trainees, or by experts in technically difficult cases; loops were straightened or controlled effectively, resulting in quick intubation times and high completion rates.

The measurement of forces exerted during colonoscopy

BACKGROUND

The widely varying forces used at colonoscopy have not been measured. An electronic device was designed to measure the forces exerted by the clinician on the endoscope during colonoscopy.

METHODS

The device featured a handle designed in the shape of a hinged split cylinder that could be locked around the endoscope but readily moved up and down the insertion tube as the colonoscopy proceeded. This cylinder contained strain-gauges arranged so that the forces transmitted could be accurately measured. The device recorded the torque forces in addition to the push and pull forces exerted during diagnostic colonoscopy.

RESULTS

In a series of 21 colonoscopies in 20 patients: peak pushing force = 4.4 kg, pulling force = -1.8 kg, anti-clockwise torque = 1.0 Newton meters, clockwise torque = 0.8 Newton meters. Percentage time force greater than 1 kg = 5%. Peak anal insertion force = 1.8 kg.

CONCLUSIONS

These measurements represent the first accurate measurements of the forces exerted during colonoscopy. Reducing the force during colonoscopy is likely to diminish pain and reduce the risk of perforation. A knowledge of these forces may also help with the design of new instruments and models for teaching or research.

Magnetic imaging of colonoscopy: an audit of looping, accuracy and ancillary maneuvers

BACKGROUND

Colonoscopy is one of the most frequently performed outpatient examinations. However, the procedure is still technically challenging, largely due to unpredictable looping during insertion. The aims of this study were (1) to assess the frequency of loop formation and types of loop during colonoscopy, (2) to determine the accuracy of the endoscopist's assessment of the anatomic location of the endoscope tip and of the presence and type of endoscope loop formation, and (3) to determine the efficacy of abdominal compression and change in patient position in promoting colonoscope advancement.

METHODS

Consecutive patients undergoing routine, day-case colonoscopy were studied using real-time, three-dimensional magnetic endoscope imaging. All examinations were performed by expert colonoscopists, blinded to the imager view. The endoscopist estimated the position of the colonoscope tip, assessed when and what type of loop had formed, and the efficacy of ancillary maneuvers such as hand pressure or patient position change. The magnetic imager view of each procedure was recorded and retrospectively analyzed.

RESULTS

One hundred complete colonoscopies were performed. Looping occurred in 91% with N-sigmoid (79%) and deep transverse (34%) being most common. Most loops (69%) were incorrectly diagnosed by the endoscopist. Atypical loops were more common in women than men (p = 0.025). The endoscopist's assessment of tip location was correct 85% of the time overall, but 100% in the cecum. Abdominal pressure was less effective (54 of 145 times, 37%) than patient position change (95 of 144 times, 66%) in promoting endoscope tip advancement.

CONCLUSIONS

Looping occurs frequently during routine colonoscopy. Although the endoscopist's assessment of tip location is fairly accurate, the majority of colonoscope loops are incorrectly appreciated. Although used frequently, ancillary maneuvers (abdominal compression and patient position change) are effective in only 52% of attempts.

How accurate is the endoscopist's assessment of visualization of the left colon seen at flexible sigmoidoscopy?

OBJECTIVE

There are concerns that the left colon may be incompletely examined by the standard 60-cm flexible sigmoidoscope. Our objective was to compare the endoscopist's assessment of the length of colon seen with the actual length visualized.

PATIENTS AND METHODS

During flexible sigmoidoscopy, endoscopists were asked to state how far they had reached. This was compared with the length of colon actually seen, assessed by a novel electromagnetic imaging (EMI) device that records the three-dimensional position of the scope within a magnetic field pervading the patient's abdomen. If EMI showed that the splenic flexure had not been reached, the endoscopist was asked to use the imager to see if it helped advance the scope further.

RESULTS

In 94 patients, the endoscopist's assessment of position reached was correct in only 47 cases (50%), with an overestimate of length of colon visualized in 24 (25.5%) and an underestimate in 23 (24.5%). EMI showed the splenic flexure had not been reached in 56 patients (59.6%). Using information from the EMI system, further progress was subsequently made in 45/56 (80.4%).

CONCLUSION

Caution is required in the diagnosis of rectal bleeding using flexible sigmoidoscopy alone. This has implications for the use of the 60-cm flexible sigmoidoscope as a screening tool.

Colonoscopy aided by magnetic 3D imaging: is the technique sufficiently sensitive to detect differences between men and women?

Colonoscopy tends to be more difficult to perform in women. Women also experience more pain during flexible sigmoidoscopy, and the mean insertion distance of the instrument is less than in men. The 'Bladen system', first described in 1993, is a non-radiological method of continuously visualising the path of the endoscope using magnetic drive coils under the patient and a chain of sensors up the biopsy channel of the instrument. In 1998, results were published that used a novel computer graphics system (the 'RMR system'), in which a much more realistic endoscope could be produced using the stored positional data from the Bladen system. The RMR computer graphics system has been further refined to enable measurement of the anatomical lengths of different parts of the large intestine to an accuracy of greater than 5 mm. The system is used to analyse the results obtained in 232 patients undergoing a total colonoscopy. In women, the colonoscope tends to form loops in the sigmoid colon more readily than in men (p < 0.05). When the first 50 cm of the endoscope are inserted for the first time, the tip passes either up to or beyond the splenic flexure in 40/116, or 34.5%, of males, compared with 24/117, or 20.5%, of females (p = 0.0137). It is demonstrated that women have longer transverse colons than men, and the differences are especially apparent when a stiffening tube is used to splint the left side of the colon (p < 0.0001). The possible relevance of these observations to biomedical engineers and those manufacturing and assessing prototype endoscopes is discussed.

Colonoscopy aided by magnetic 3D imaging: assessing the routine use of a stiffening sigmoid overtube to speed up the procedure

There are not enough trained colonoscopists to cope with the present recommended number of examinations required for diagnostic and surveillance purposes. If colorectal cancer screening is to be introduced, endoscopic examination of the large bowel needs to be easier to learn and significantly quicker to carry out. The 'Bladen system', first described in 1993, is a non-radiological method of visualising the path of the endoscope, using magnetic drive coils under the patient and a chain of sensors along the biopsy channel of the instrument. In 1998, results were published using a novel computer graphics system (the RMR system), in which a much more realistic image of the endoscope could be produced using the stored positional data from the Bladen system. The RMR system has been further refined to allow, for the first time ever, accurate measurement of the effect of the passage of a colonoscope along the bowel on the lengths of different segments of the large intestine. The results obtained in 232 patients undergoing colonoscopy are analysed. In 77 of the patients, a stiffening overtube is used to splint the sigmoid colon once the endoscope is at or beyond the splenic flexure. The mean time taken to pass the colonoscope across the transverse colon is significantly shorter (p < 0.001) when an overtube is used, despite it resulting in significant lengthening of the transverse colon. The routine use of a stiffening overtube can be expected to reduce the total procedure time by between 10 and 20%.

Non-radiological technique for 3D imaging of intestinal endoscopes: computerised graphical 3D representation of endoscope and skeleton

Colorectal cancer is a common malignancy but as yet there is no agreement regarding the optimal method for screening. Colonoscopy is theoretically the investigation of choice. The examination can, however, be difficult to perform and the average trainee requires at least 200 supervised examinations to become proficient. Colonoscopy takes on average about half an hour per patient and sedation is normally required because of painful instrument looping. The authors previously developed a non-radiological method of visualising the path of the endoscope using magnetic drive coils under the patient and a chain of sensors in the biopsy channel of the instrument. The computer-generated grey-scale images produced in real time were deemed unsatisfactory and the anatomical markers confusing. A new computer graphics system is described in which a much more realistic endoscope and, if necessary, skeleton can be produced. The wire-frame octagonal representation should help in the detailed analysis of colonoscopy using existing endoscopes and aid in future computer design and testing of novel instruments incorporating worm or snake-like properties.

Device for measuring the forces exerted on the shaft of an endoscope during colonoscopy

Colonoscopy involves advancing a flexible endoscope into and along the entire length of the colon. The procedure can be painful and carries the risk of perforating the organ, yet very little is known of the forces involved. A device to measure the forces exerted on the endoscope during colonoscopy is described. The device features a handle designed in the shape of a hinged split cylinder that locks around the endoscope, gripping it tightly. The handle has two parts, an inner part that grips the endoscope, and an outer part that is gripped by the endoscopist. The two parts are joined together by members that transmit the forces through to the endoscope. One of the members incorporates strain gauges that measure the torque applied to the endoscope, as well as the push and pull forces. The handle can easily be unlocked and moved along the endoscope as the colonoscopy proceeds. The device is used to measure the forces applied to the endoscope during 11 routine colonoscopies, and summary results are presented. These are believed to be the first accurate measurements of the forces exerted during colonoscopy.

Why is colonoscopy more difficult in women?

BACKGROUND

In our experience colonoscopy in women is more difficult than in men. A retrospective review of 2194 colonoscopies performed by a single experienced endoscopist (CBW) showed that 31% of examinations in women were considered technically difficult compared with 16% in men.

METHODS

To investigate a possible anatomic basis for this finding, normal barium enema series from 183 female and 162 male patients were identified. From these barium enemas, measurements of colonic length and mobility were independently taken by two physicians who were unaware of each patient's gender.

RESULTS

Total colonic length was greater in women (median, 155 cm) compared to men (median, 145 cm), p = 0.005, despite women's smaller stature (p < 0.0001). Although there were no significant differences in rectum plus sigmoid, descending, or ascending plus cecum segmental lengths, women had longer transverse colons (female median length, 48 cm; male median length, 40 cm), p < 0.0001. There were no differences in mobility of the descending colon and transverse colon between the sexes, but the transverse colon reached the true pelvis more often in women (62%) than in men (26%), p < 0.001.

CONCLUSIONS

Colonoscopy appears to be a technically more difficult procedure in women. The reason for this may be due in part to an inherently longer colon.

First clinical results with a real time, electronic imager as an aid to colonoscopy

The early clinical results are described of a real time, electromagnetic imaging system as an aid to colonoscopy. After gaining experience with the use of the system, one experienced endoscopist was randomised to perform consecutive colonoscopies either with (n = 29) or without (n = 26) the imager view. All procedures were recorded on computer disk and replayed for retrospective analysis. Total colonoscopy was achieved in all patients except one (imager view not available). Comparing intubation time and duration of loop formation per patient, there was no significant difference between the two study groups. The number of attempts taken to straighten the colonoscope pre patient, however, was less when the endoscopist was able to see the imager view, p = 0.03. Hand pressure was also more effective when the endoscopist and endoscopy assistant could see the imager display, p = 0.02. Preliminary experience suggests that real time, electronic imaging of colonoscopy is safe, effective, and will improve the accuracy of the procedure.

Can barium enema indicate when colonoscopy will be difficult?

The barium enemas of 48 consecutive patients, who were technically difficult to intubate at colonoscopy, were compared to those of 46 patients who were not. Measurements were taken of colonic length and mobility, and an assessment made of diverticular disease. Rectosigmoid length (mean difficult group = 61 cm, mean control = 54 cm, P = 0.01) and total colonic length (mean difficult group = 157 cm, mean control = 140 cm, P < 0.0001) were greater in the difficult colonoscopy group as were transverse colon mobility (mean difficult group = 10 cm, mean control = 7 cm, P = 0.003) or redundancy (transverse colon reaching the true pelvis on the erect film); 65% difficult group vs 17% control group, P < 0.0001. The presence of moderate or severe diverticular disease was also greater in the difficult (23%) compared to the control (4%) group, P = 0.02. When available, assessment of a previous barium enema is a useful guide to probable technical difficulty of colonscopy. It may allow appropriate allocation of potentially difficult cases to specialist endoscopy lists.

A peroperative comparison of Western and Oriental colonic anatomy and mesenteric attachments

It has been suggested that the Oriental colon is easier to colonoscope than its Western counterpart. The aim of this study was to investigate possible differences in colonic anatomy between Western and Oriental patients that might explain this observation. Measurements of colonic length and mesenteric attachments were taken according to a set protocol from 115 Western (Caucasian) and 114 Oriental patients at laparotomy. Sigmoid adhesions were found more frequently in Western (17%) compared to Oriental (8%) patients, P = 0.047. A descending mesocolon of > or = 10 cm occurred in 10 (8%) Western patients but only 1 (0.9%) Oriental patient, P = 0.01. The splenic flexure was more frequently mobile in Western patients (20%) compared to Oriental (9%) patients, P = 0.016. In 29% - of Western patients the mid-transverse colon reached the symphysis pubis, or lower when pulled downwards in contrast to 10% of Oriental patients, P < 0.001. There was no significant difference in total colonic length comparing Western (median = 114 cm, range 68-159 cm) to Oriental (median = 111 cm, range 78-161 cm) patients. Western patients have a higher incidence of sigmoid colon adhesions and increased colonic mobility when compared to Orientals. These findings support the observation that colonoscopy is a more difficult procedure in Western patients.