Analysis of and mathematical model insight into loop formation in colonoscopy

Impact of looping on premalignant polyp detection during colonoscopy

BACKGROUND

The presence of premalignant polyps on colonoscopy is an indicator of metachronous colorectal cancer. Looping during colonoscopy is associated with old age, female sex, and colonoscopy insertion time. However, the clinical significance of looping is not fully understood. We aimed to clarify the effect of looping on colorectal premalignant polyp detection.

AIM

To assess the effects of looping on premalignant polyp detection using logistic regression analyses.

METHODS

We retrospectively investigated patients who underwent colonoscopy at Toyoshima Endoscopy Clinic between May, 2017 and October, 2020. From the clinic’s endoscopy database, we extracted data on patient age, sex, endoscopist-assessed looping, colonoscopy duration, endoscopist experience, detection rate, and number of premalignant polyps.

RESULTS

We assessed 12259 patients (mean age, 53.6 years; men, 50.7%). Looping occurred in 54.3% of the patients. Mild and severe looping were noted in 4399 and 2253 patients, respectively. The detection rates of adenomas, advanced adenomas, high-risk adenomas, clinically significant serrated polyps (CSSPs), and sessile serrated lesions (SSLs) were 44.7%, 2.0%, 9.9%, 8.9% and 3.5%, respectively. The mean numbers of adenomas and SSLs were 0.82 and 0.04, respectively. The detection rates of adenomas, high-risk adenomas, and CSSPs increased with looping severity (all P < 0.001). The number of adenomas increased with looping severity (P < 0.001). Multivariate analyses found that detection of adenomas, high-risk adenomas, and CSSPs was associated with severe looping (P < 0.001, P < 0.001, and P = 0.007, respectively) regardless of age, sex, time required for colonoscope insertion and withdrawal, and endoscopist experience.

CONCLUSION

Looping severity was independently associated with high detection rates of premalignant polyps. Therefore, looping may predict the risk of metachronous colorectal cancer. Endoscopists should carefully examine the colorectum of patients with looping.

Outcomes of use of electromagnetic guidance with responsive insertion technology (RIT) during colonoscopy: a prospective randomized controlled trial

Background and study aims  Colonoscopy can be technically challenging and cause discomfort in patients. The integrated Scope Guide assist is built in to show that with its use outcomes are improved during colonoscopy. We aimed to test the usefulness of the Magnetic Scope Guide Assist (ScopeGuide ) with respect to cecal intubation time, and other procedural quality outcomes. Patients and methods  We conducted a prospective study of outpatients undergoing elective colonoscopy at the endoscopic units of the University of Alabama at Birmingham (UAB) from March 2016 to July 2016. Patients were randomly assigned in a 1:1 block design to groups that either had standard colonoscopy or Scope-guided colonoscopy. The primary outcome measure was cecal intubation time (CIT). Secondary outcome measures included use of manual pressure, position changes for cecal intubation and sedation requirements. Results  Three hundred patients were randomized to either group; standard (n = 150) vs. Scope-guided (n = 150). The mean CIT was not statistically different for the standard and the Scope-guided groups (4.6 vs. 4.3 minutes; P  = 0.46). There were also no statistical differences in frequency of manual pressure applied (16.7 % for Scope-guided vs. 19.1 % for standard; P  = 0.65) or position changes (11.4 % for scope guided vs. 8.8 % standard; P  = 0.56). Sedation requirements showed lesser use of midazolam (3.9 mg vs. 4.7 mg, P  = 0.003) in the Scope-guide group, while there was no significant difference in use of fentanyl (fentanyl - 62.1 mg vs. 68.9 mg, P  = 0.09 similar between groups, for Scope-guided vs. standard groups, respectively). Adverse events were similar in both groups. Conclusions  In patients undergoing routine elective colonoscopy, use of ScopeGuide by experienced colonoscopists did not improve CIT or affect the frequency of ancillary maneuvers. The benefit of this device during training of endoscopists could be considered for further studies.

Use of an abdominal obstetric binder in colonoscopy: A randomized, prospective trial

BACKGROUND AND AIMS

Various methods have been reported as aids to cecal intubation. This study aimed to prospectively investigate whether an abdominal obstetric binder (AOB) used during pregnancy and attached to the patients' abdomen during colonoscopy could facilitate effective colonoscopic insertion.

METHODS

This was a prospective study of 451 consecutive outpatient colonoscopies performed by a single experienced endoscopist. The recruited patients were randomly separated into two groups that received colonoscopy either with (Group A) or without an AOB attached (Group B). The cecal intubation time, cecal intubation length of the colonoscope, use of manual pressure, position change of each patient, and the number of patients with abdominal distension were collected for comparison.

RESULTS

A total of 451 patients (224 in Group A and 227 in Group B) were ultimately included in this study. In Group A, cecal intubation time and cecal intubation length of colonoscope (CIL) were significantly reduced (P < 0.001). The patients had significantly fewer position changes and manual pressure in Group A (P < 0.001). Significantly less abdominal distension was reported by patients in Group A (P < 0.001).

CONCLUSIONS

During colonoscopy, the application of an AOB provided a significantly faster and more effective colonoscope insertion.

Detection of endoscopic looping during colonoscopy procedure by using embedded bending sensors

Background

Looping of the colonoscope shaft during procedure is one of the most common obstacles encountered by colonoscopists. It occurs in 91% of cases with the N-sigmoid loop being the most common, occurring in 79% of cases.

Purpose

Herein, a novel system is developed that will give a complete three-dimensional (3D) vector image of the shaft as it passes through the colon, to aid the colonoscopist in detecting loops before they form.

Patients and methods

A series of connected links spans the middle 50% of the shaft, where loops are likely to form. Two potentiometers are attached at each joint to measure angular deflection in two directions to allow for 3D positioning. This 3D positioning is converted into a 3D vector image using computer software. MATLAB software has been used to display the image on a computer monitor. For the different configuration of the colon model, the system determined the looping status.

Results

Different configurations (N loop, reverse gamma loop, and reverse splenic flexure) of the loops were well defined using 3D vector image.

Conclusion

The novel sensory system can accurately define the various configuration of the colon during the colonoscopy procedure.

Use of an Abdominal Compression Device in Colonoscopy: A Randomized, Sham-Controlled Trial

BACKGROUND & AIMS

Looping is a common problem during colonoscopy that prolongs procedure time. We aimed to determine the efficacy and safety of ColoWrap, an external abdominal compression device, with respect to insertion time and other procedural outcomes.

METHODS

We performed a prospective study of outpatients undergoing elective colonoscopy (40-80 years old; mean age, 60.5 years) at endoscopy facilities in the University of North Carolina Hospitals from April 2013 through March 2014. Subjects were randomly assigned to groups that received either ColoWrap (n = 175) or a sham device (control, n = 175) during colonoscopy. Colonoscopists and staff were blinded to the application. The primary outcome was cecal intubation time (CIT). Secondary outcomes included use of manual pressure and position change.

RESULTS

The mean CIT was similar for the control and ColoWrap groups (6.69 vs 6.67 minutes; P = .98). There were no statistical differences in the frequency of manual pressure (45% for controls vs 37% for ColoWrap group, P = .13) or position changes (4% for controls vs 2% for ColoWrap group, P = .36). Among patients with body mass index between 30 and 40 kg/m(2) (n = 78), CIT was significantly lower for patients in the ColoWrap group (4.69 minutes) than controls (6.10 minutes) (P = .03). Adverse events were similar between groups.

CONCLUSIONS

In patients undergoing elective colonoscopy, application of an external abdominal compression device did not improve CIT or affect the frequency of ancillary maneuvers. A possible benefit was observed in patients with body mass index between 30 and 40 kg/m(2), but further studies are needed. ClinicalTrials.gov number: NCT02025504.

PREDICATION FOR RELATIVE MOTION OF THE COLONOSCOPE IN COLONOSCOPY

Colonoscopy is common procedure frequently carried out. It is not without its problems, which include looping formation. Looping formation prevents the tip of the colonoscope itself from advancing, thus further probing induces a risk of perforation, significant patient discomfort, and failure of colonoscopy. During colonoscopy, the manipulated colonoscope for intubation in the colon goes through the friction between the colonoscope and the colon. Due to major frictional force, the sigmoidal colon forms looping with the scope during intubation. The interactive frictional force between the colon and the colonoscope is highly complex because of frictional contact between two deformable objects. In this paper, contact force computation was formulated into a linear complementarity problem (LCP) by linearizing Signorini's problem, which was adapted into non-interpenetration with unilateral constraints. Frictional force was computed by the mechanical compliance of finite element method (FEM) models with the consideration of dynamic friction between the colonoscope and the intestinal wall. Furthermore, we presented a mathematical model of the elongation of the colon that predicts the motion of scope relative to the intestinal wall in colonoscopy.

Modeling and in vitro experimental validation for kinetics of the colonoscope in colonoscopy

Colonoscopy is the most sensitive and specific means for detection of colon cancers and polyps. To make colonoscopy more effective several problems must be overcome including: pain associated with the procedure, the risk of perforation, and incomplete intubation colonoscopy. Technically, these problems are the result of loop formation during colonoscopy. Although, several solutions such as modifying the stiffness of the colonoscope, using an overtube and developing image-guided instruments have been introduced to resolve the looping problem, the results of these systems are not completely satisfactory. A new paradigm to overcome loop formation is proposed that is doctor-assistive colonoscopy. In this approach, the endoscopists performance is enhanced by providing using a kinetic model that provides information such as the shape of the scope, direction of the colon and forces exerted within certain sections. It is expected that with the help of this model, the endoscopist would be able to adjust the manipulation to avoid loop formation. In the present studies, the kinetic model is developed and validated using an ex vivo colonoscopy test-bed with a comprehensive kinematic and kinetic data collection. The model utilizes an established colon model based on animal tissue with position tracking sensors, contact force sensors for the intraluminal portion of the scope and a Colonoscopy Force Monitor for the external insertion tube.