Background and aims: Peritoneoscopy by natural orifice transluminal endoscopic surgery (NOTES) could replace laparoscopic staging peritoneoscopy (LAP) if the yield were comparable to that from LAP. In previously performed porcine experiments, transgastric peritoneoscopy seemed inferior to LAP due to limited visualization of the liver. The aim of the present study was to improve liver visualization by using a colonic approach and to compare transcolonic peritoneoscopy (TCP) with the previously set LAP standard. Methods: Small beads were stapled into porcine peritoneal cavities to simulate metastases. Previously in the same model LAP had detected 95% of beads (95% CI 87%-98%). Using a non inferiority design, a sample size of 33 beads was determined; these were distributed among six animals with randomization for numbers and location. TCP was performed using either standard endoscopic accessories (TCP-s) or a specially designed toolkit (TCP-t) in randomized order by one of two blinded endoscopists. Primary outcome was number of beads found and touched during peritoneoscopy. Results: Locations of beads included abdominal peritoneum (6 beads), diaphragm (8), liver (18), and miscellaneous sites (1). TCP-s found 25 beads (yield 76%, 95% CI 59%-87%). TCP-t found 19 beads (yield 58%, 95% CI 41%-71%). The majority of missed beads were located at the inferior liver surface: TCP-s detected 8/15 (53%) and TCP-t 5/15 (33%) of these simulated metastases. Conclusions: In this prospective, experimental trial, transcolonic NOTES peritoneoscopy was inferior in comparison with the diagnostic laparoscopy done previously in the same model.
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