Introduction

High quality diagnostic colonoscopy requires adequate mucosal visualisation and thorough examination of all segments of the colon. Mucosal visualisation may be impeded by inadequate colonic distension. We hypothesised that different segments of the colon require different endoluminal pressure to achieve adequate mucosal exposure. Although studies have previously examined endoluminal pressures in the upper gastrointestinal tract in humans and in the colon in animal models^1,2, no study has previously reported in vivo measurement of endoluminal pressure for patients during colonoscopy.

Aims & Methods

The primary aim of this study was to compare endoluminal pressure in different segments of the colorectum during diagnostic colonoscopy. Secondary aims were to determine whether certain patient, endoscopist or procedure characteristics are associated with variation in endoluminal pressure. This was a prospective, observational, single-centre study. Ethical approval was obtained from the institutional review board. Patients undergoing diagnostic colonoscopy were recruited and consented. Each procedure was performed by one of five consultant gastroenterologists, using carbon dioxide. Endoluminal pressure was measured throughout withdrawal, using a digital manometer attached to the endoscope instrument channel. The manometer was in turn attached to a digital recorder, which output the measurements digitally at 0.1 second intervals. Designation of the colonic segment was by agreement between the endoscopist and the study researcher, confirmed by a magnetic imager (ScopeGuide, Olympus Medical Systems). The position of the patient at each timepoint and the start and finish time of any intervention were recorded. Patients were excluded for Boston Bowel Prep Score < 8 or depressurisation of the measurement circuit.

Results

Thirty patients had complete pressure recordings. The indications for colonoscopy were screening following positive faecal immunochemical test (73%) or symptomatic (27%). Median age was 62.5 years (range 51-75 years). The median (IQR) pressure required for examination of each segment of the colon during withdrawal was; ascending colon 6.81mmHg (3.94 – 11.13), transverse colon 7.34mmHg (4.46 – 11.78), descending colon 9.69mmHg (6.16 – 15.31) and sigmoid colon 9.43mmHg (5.24 – 15.84). When right colon (caecum to splenic flexure) was compared to left colon (splenic flexure to rectosigmoid junction) across all cases, median pressure required in left colon was noted to be significantly higher 9.54mmHg vs 7.08mmHg (p<0.001). Casewise paired analysis showed left colon pressure was higher in the left colon by 3.60 mmHg (p<0.001). Pressure was higher when the patient was in the left lateral than in the supine position, in both left colon 13.35mmHg (8.12 - 18.45) vs 8.78mmHg (4.98 - 14.14) (p<0.001) and the right colon 6.68mmHg (3.28 - 11.13) vs 6.42mmHg (4.07 - 9.17), p=0.018. No significant difference was observed in left colon or right colon pressure according to sex or age of patient, procedure indication or endoscopist.

Conclusion

This is the first reported human in vivo measurement of endoluminal pressure during colonoscopy. Examination of the descending colon and sigmoid colon requires higher endoluminal pressure to be achieved, compared to other colonic segments. Difficulty in achieving adequate endoluminal pressure in these segments may contribute to missed lesions. Further study is required to determine what other factors affect endoluminal pressure and how this can be modified to ensure consistent mucosal visualisation with an expected impact on polyp detection.

References

1. Ushimaru Y, Nakajima K, Hirota M, Miyazaki Y, Yamashita K, Saito T, Tanaka K, Makino T, Takahashi T, Kurokawa Y, Yamasaki M. The endoluminal pressures during flexible gastrointestinal endoscopy. Scientific reports. 2020 Oct 23;10(1):18169.
2. Hirota M, Miyazaki Y, Takahashi T, Yamasaki M, Takiguchi S, Mori M, Doki Y, Nakajima K. Dynamic Article: Steady Pressure CO: 2: Colonoscopy: Its Feasibility and Underlying Mechanism. Diseases of the colon & rectum. 2014 Sep 1;57(9):1120-8.

Disclosure

JOD and LF work for Palliare, a medical device company specialising in advanced insufflation.
The other authors have no disclosures.