ABSTRACT Background and objectives: recently, Olympus developed a new prototype (XCF-Q180AY2L) with responsive insertion tech- nology (RIT), which besides the still known variable stiffness tech- nology, included a passive bending section and a new high force insertion tube. Our objective was to investigate whether the use of this prototype could ease colonoscope insertion, increasing the cecal intubation rate, and/or shortening the cecal intubation time. Material and methods: the study was designed as a prospective observational study in 305 consecutive patients from a colo-rectal cancer screening program. We compared colonoscopies performed with conventional colonoscopes (CFH180AL/CFQ160L) with those performed with the prototype XCF-Q180AY2L. End points were mean cecal and terminal ileal intubation times, cecum intubation rate, and need for specific maneuvers. All colonoscopies were per- formed under sedation with intravenous propofol. Finally, 288 patients were included. Results: no complications were observed. Complete cecal intu- bation rate was 100 % in both groups. The ileum could be reached in 98.95 % of cases. Mean time required to reach the cecum was shorter in the prototype endoscope group (4.31 min, SD 2.63 min) than in the conventional endoscope group (4.66 min, SD 2.52 min) (p < 0.05). Compared with the standard colonoscope group, we observed in the prototype group less subjective sensation of difficulty in the passage of the sigma (p < 0.01), fewer maneuvers when it proved necessary to straighten the scope (p < 0.01), and less frequent need to modify the stiffness of the endoscope (p < 0.05). Conclusion: we concluded that the prototype endoscope (XCF- Q180AY2L) facilitated colonoscope insertion, requiring slightly less time to reach the cecum than a standard colonoscope. Key words: Colonoscope. Prototype. Cecal intubation rate. Cecal intubation time. INTRODUCTION Colonoscopy is currently the method of choice for col- orectal cancer screening, for patients older than 50 years, and for people of any age who are at high risk (1). However, for screening programs to be effective, it is essential that endoscopic procedures meet certain minimum quality cri- teria. One of the most important is that the complete colonoscopy rate should exceed 90 % in all cases, or 95 % of healthy adult screening cases(1). Complete colonoscopy, reaching the cecum, not only depends on the skill of the endoscopist and the sedation depth (2), but also on the tech- nical features of the endoscope (3). With respect to the latter, over the last twenty years, the technical features of endo- scopes have greatly improved. Higher image resolution, a wider angle of vision, narrower endoscope shafts, and vari- able shaft stiffness are some of the many improvements (3). In 2005, Olympus developed a prototype endoscope (XCF-Q160AW) with a passive bending section (PB), locat- ed between the insertion tube and the conventional bending section of the endoscope, to facilitate intubation. A ran- domized study showed that its use decreased the discomfort of the procedure in on-demand sedation patients (4). These results were reinforced by another study with further advanced colonoscopes in which graded flaccidity of the passive bending section (PB) was introduced (5). Recently, the same company has developed a new pro- totype (XCF-Q180AY2L), which, besides the passive bend- ing section (PB), incorporates a new insertion tube that bet- ter transmits the pushing force. There are no published data about the impact of using this new insertion tube in real practice, and therefore, neither published studies about the Comparative study of a responsive insertion technology (RIT) colonoscope versus a variable-stiffness colonoscope César Prieto-de-Frías, Miguel Muñoz-Navas, Cristina Carretero, Juan Carrascosa, M.ª Teresa Betés, Susana de-la-Riva, M.ª Teresa Herraiz and José Carlos Subtil Service of Digestive Diseases. Clínica Universidad de Navarra. Pamplona, Navarra. Spain 1130-0108/2013/105/4/208-214 REVISTA ESPAÑOLA DE ENFERMEDADES DIGESTIVAS Copyright © 2013 ARÁN EDICIONES, S. L. REV ESP ENFERM DIG (Madrid) Vol. 105. N.° 4, pp. 208-214, 2013 Received: 01-10-2012 Accepted: 28-02-2013 Correspondence: César Prieto de Frías. Service of Digestive Diseases. Clínica Universidad de Navarra. Avda. Pío XII, 36. 31008 Pamplona, Navarra. Spain e-mail: cprieto@unav.es ORIGINAL PAPERS Prieto-de-Frías C, Muñoz-Navas M, Carretero C, Carrascosa J, Betés MT, De-la-Riva S, Herraiz MT, Subtil JC. Comparative study of a responsive insertion technology (RIT) colonoscope versus a varia- ble-stiffness colonoscope. Rev Esp Enferm Dig 2013;105:208-214.