ANATOMICAL FEATURES OF THE ILEOCAECAL JUNCTION AND THEIR IMPLICATIONS FOR PROOF OF COLONOSCOPY COMPLETION

Introduction A completion rate for colonoscopy in excess of 90% is a Joint Advisory Group quality assurance standard; although images of the appendix orifice, tri-radiate fold and ileo-caecal junction (ICJ) are conventional markers for this, numerous studies have shown a lack of specificity confounded by variations in human anatomy. Terminal ileal intubation, with images of villiform mucosa, provides irrefutable evidence of completion but cannot always be achieved. We aimed to study the anatomy of the ICJ to determine the factors that may be relevant to documentation of proof of completion. Methods The features of 69 embalmed cadaveric ICJ specimens were assessed, including gross morphology and the ileocaecal angle. In addition, 100 consecutive colonoscopy videos performed by a single Bowel Cancer Screening colonoscopist showing ileal intubation were reviewed to determine ICJ morphology, time taken for ileal intubation and difficulties encountered. Results The morphology of all cadaveric ICJs was categorised, with all except 2 being labial or papillary in type. The average angle of ileal entry into the caecum was 106 degrees (range 59–180). Both major ICJ types had on average a greater distance from the posterior caecal wall to the tip of the top lip compared to the distance to the lower lip, giving the ICJ an inferior tilt. In nearly half of the labial-type valves, the top lip overhung the bottom lip. On average, labial-type valves had thinner lips and a narrower vertical opening than papillary-type valves. These features could render a labial-type valve more difficult to visualise and intubate at colonoscopy. In the colonoscopy videos, over a third of ICJs could not be fully visualised or categorised, with these having a lower rate of initial successful intubation than categorised valves. The median time taken for intubation was shorter for papillary compared to labial-type valves. Ileal intubation was faster in categorised valves when the appendix was visualised. It was also achieved more quickly in patients who were given buscopan pre-procedure. Conclusions Appreciating the anatomical features of the ICJ should assist endoscopists to approach ICJs which can be difficult to navigate. Administering buscopan as pre-medication and visualising the appendix prior to attempting ileal intubation have both been shown to decrease the time taken for successful intubation.