Robotic, self-propelled, self-steerable, and disposable colonoscopes: Reality or pipe dream? A state of the art review

Table 1 The features of the ideal robotic colonoscope

No.	Ideal robotic colonoscope features
1	Affordable
2	Acceptable to patients and endoscopists
3	More comfortable than conventional colonoscopy
4	Lower risk than conventional colonoscopy
5	Improved caecal intubation rate compared to conventional colonoscopy
6	Offer at least comparable mucosal visibility with the option of image enhancement (virtual chromoendoscopy)
7	Capable of taking biopsies and therapeutics such as polypectomy
8	Offer integration with artificial intelligence for polyp detection and characterisation
9	Ideally have autonomous features, such as self-navigation
10	Reduce the training time to achieve competence compared to conventional colonoscopy
11	Procedure times should be less than, but must not be significantly longer than, conventional colonoscopy
12	Have sustainability in mind in the manufacturing, reprocessing or disposal of the device

Table 2 Advantages and limitations of conventional colonoscopy alternatives

Procedure	Advantages	Limitations
Conventional colonoscopy	Extensive knowledge base and expertise already available, diagnostic and therapeutic capabilities. Gold standard	Bowel cleansing required, painful for some (sedative and analgesics often required), prolonged training period required, risk of perforation due to forces required
CT colonography[39,41,101]	Lower intensity bowel cleansing, shorter procedure, less discomfort (no sedation or analgesia needed), other intraabdominal pathology can be detected, lower risk of perforation, better patient tolerance	Low dose radiation used, lower sensitivity for small and flat polyps, no therapeutic capability, no direct mucosal visualisation, limited evidence of a benefit in CRC incidence or mortality
Wireless capsule colonoscopy	Minimally invasive, painless, better patient tolerability, low perforation risk	Aggressive bowel cleansing required, lower sensitivity than CC for polyps, no control of the capsule, no therapeutic capability, risk of capsule retention, limited battery life can cut out before complete colon visualisation

CRC: Colorectal cancer; CC: Conventional colonoscopy; CT: Computed tomography.

Table 3 Technology readiness levels as applicable to robotic colonoscopy[57,102,103]

TRL	Definition	Supporting information relevant to robotic colonoscopy
1	Basic principles observed and reported	Published research on the core principals of the technology
2	Technology concept and/or application formulated	Moving from principals to applied research with potential applications speculated
3	Analytical and experimental proof of concept	Active research and development proving the concept within a laboratory setting. Benchtop testing
4	Component validation in laboratory environment	Proof of concept and safety in an ex-vivo animal colon
5	Component/system validation in a relevant environment	In-vivo animal testing with an aim at providing relevant evidence for human testing or FDA approval
6	High fidelity alpha protype demonstration in a relevant environment	Clinical trials assessing feasibility and safety in small number of humans
7	Beta prototype demonstrated in a relevant environment	Clinical safety and effectiveness trials. Determination of risks and adverse events. Final design validation
8	Completed system and qualified to relevant requirement/standards through testing and demonstration	FDA or equivalent approval
9	Actual system proven through successful operation	Device being marked with post-market studies proving real world operational capability

Adopted from United States Department of Defense Technology Readiness Assessment (TRA) Guidance document, and the supporting evidence required from the United States Department of Defense Technology Readiness Assessment (TRA) Desk book. TRL: Technology readiness level; FDA: Food and Drug Administration.

Table 4 Active flexible colonoscopy platforms with technology readiness level

Device name (manufacturer)	Latest study	Outcomes	TRL
Aer-O-Scope-GI View Ltd., Ramat Gan, Israel[21,59-61,63,64]	2016: Human tandem study, 58 CRC screening patients. CIR: 98.2%. CIT: 11 min. 87.5% of polyps detected. No PREMs	CE marked and FDA approved. Balloon propulsion model no longer manufactured	8
ColonoSight-Stryker GI Ltd., Haifa, Israel[65,66]	2008: Human study on 178 participants. CIR 90%. CIT: 11.2 min. No PREMs	FDA approved. No longer manufactured	8
Consis medical-Beer’Sheva, Israel[21,67]	None available	No regulatory approvals	3
Endoculus-Department of Mechanical Engineering & Division of Gastroenterology, University of Colorado, United States[20]	2020: In-vivo and ex-vivo porcine colon in one. Unable to traverse an in-vivo colon, but capable of negotiating an ex-vivo porcine colon	No regulatory approvals	4
ENDOO robotic colonoscope-Endoo Project, Pisa, Italy[87-89]	2020: Ex-vivo porcine colon human simulator study	No regulatory approvals	4
Endotics-ERA Endoscopy SRL, Peccioli, Italy[69-74]	2020: Learning curve study of 57 participants. CIR and CIT improved to 100% and 22 min following a learning block. PREMs: Mild or no discomfort in most	CE marked and FDA approved. Commercially available in Europe and Japan	8
Invendoscope-Invendo Medical GmbH, Weinheim, Germany (acquired by Ambu A/S, Copenhagen, Denmark in 2017)[21,77-79]	2018: Human study on 40 participants using the SC210 model. CIR 95%. CIT 14.2 min. No PREMs on this study, but previous studies reported lower pain scores than CC	CE marked and FDA approved. No longer manufactured	8
Magnetic Flexible Endoscope-STORM lab, Leeds, United Kingdom & Nashville, TN, United States[4,53,85,86,104]	2020: In-vivo porcine study. Clinical trial due 2022	No regulatory approvals	5

TRL: Technology readiness level; CIR: Caecal intubation rate; CIT: Caecal intubation time; FDA: Food and Drug Administration; CRC: Colorectal cancer; CC: Conventional colonoscopy; CE: Capsule endoscopy.