Periprocedural adverse events after endoscopic resection of T1 colorectal carcinomas

Cellular mechanisms in basic and clinical gastroenterology and hepatolog

Optimizing colonoscopy outcomes in daily clinical practice

In the current era of a rapidly aging general population, an increasing colorectal cancer (CRC) incidence and the initiation of population-based screening programs for CRC, the main challenges for endoscopists in the coming years lie in increasing the quantity as well as optimizing the quality of colonoscopies. In this thesis, studies are described that aim to improve allocation of a patient with a correct indication to the appropriate examination at the right time, and to quantify colonoscopy quality. In a diverse range of studies, several issues regarding colonoscopy capacity and quality are addressed. In a prospective questionnaire study it is shown that patients referred for a change in bowel habits or rectal blood loss are at an increased risk of having CRC and should have priority on the waiting list to undergo colonoscopy. From a retrospective study in a large secondary care hospital it is found that symptomatic patients over 50 years should undergo colonoscopy rather than flexible sigmoidoscopy, because of the high prevalence of polyps and CRC in this patient population. Furthermore, in patients with abdominal pain as only symptom, colonoscopy and flexible sigmoidoscopy are unlikely to yield CRC or another relevant cause for their symptoms. In a review of the available literature on quality indicators for colonoscopy, it shown that of the currently available quality indicators for colonoscopy, only adenoma detection rate has been shown to be directly associated with the ideal outcome measure: post-colonoscopy CRC, i.e. CRC occurring within a few years after a colonoscopy. Furthermore, the additional value of CT-colonography performed in case of incomplete colonoscopy is investigated in this thesis: it is shown that CT-colonography can effectively be used to visualize the remainder of the colon in case of incomplete colonoscopy. It yields relevant additional information in over 19% of patients. In two large, nationwide population-based studies with data from PALGA, the Dutch Pathology Registry, it is shown that the rate of early or missed CRCs in the 3 years following a colonoscopy with polypectomy has not decreased over a 10-year period. Location in the right side of the colon was an independent risk factor for missed or early CRCs. Furthermore, CRC due to incomplete adenoma resection within a few years after polypectomy is shown to occur in one in four hundred resected adenomas. Finally, in a prospective randomized pilot study, a new colonoscopy platform with robotic steering and automated lumen centralization is proven feasible. It seems to be more intuitive and to allow faster cecal intubation compared to conventional colonoscopy, at least when performed by endoscopy naive novices. The results of this thesis may help in correctly prioritizing patients for colonoscopy in a time where supply does not meet demand. Furthermore, several quality issues that need to be improved are identified. The results of this thesis provide several interesting starting points for further studies, aiming at increasing colonoscopy capacity, optimizing patient allocation, increasing overall colonoscopy quality and reducing the number of post-colonoscopy CRCs

Feasibility of automated target centralization in colonoscopy

Purpose:\ud Early detection of colorectal cancer is key to full recovery. This urged governments to start population screening programs for colorectal cancer, often using flexible endoscopes. Flexible endoscopy is difficult to learn and time-consuming. Automation of flexible endoscopes may increase the capacity for the screening programs. The goal of this pilot study is to investigate the clinical and technical feasibility of an assisting automated navigation algorithm for a colonoscopy procedure.\ud \ud Methods:\ud Automated navigation (lumen centralization) was implemented in a robotized system designed for conventional flexible endoscopes. Ten novice and eight expert users were asked to perform a diagnostic colonoscopy on a colon model twice: once using the conventional and once using the robotic system. Feasibility was evaluated using time and location data as measures of the system’s added value.\ud \ud Results:\ud Automated target centralization (ATC) was turned on by the novices for a median of 4.2 % of the time during insertion and 0.3 % during retraction. Experts turned ATC on for 4.0 % of the time during insertion and 11.6 % during retraction. Novices and experts showed comparable times to reach the cecum with the conventional or the robotic setup with ATC.\ud \ud Conclusion:\ud The ATC algorithm combined with the robotized endoscope setup works in an experimental setup that closely resembles the clinical environment and is considered feasible, although ATC use was lower than expected. For novices, it was unclear whether the low usage was due to unfamiliarity with the system or because they did not need ATC. Experts used ATC also during the retraction phase of the procedure. This was an unexpected finding and may indicate an added value of the system