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179 Solid-state colonic manometry 8 Catheter placement Solid state catheters were placed by three different techniques; two types of retrograde placement and one type of antegrade placement. The decision which technique to use was dependent upon available access routes to the colon and availability of resources (e.g. OR scheduling time, availability of interventional radiology). 1) Retrograde placement : colonic manometry catheters were placed via the anus with the aid of colonoscopy or with a guidewire under fluoroscopy by an interventional radiologist, both placement techniques have been discussed previously. 13,19 In all retrograde placements, the tip of the catheter was placed between the cecum and the splenic flexure, depending on the length of the child’s colon; the catheter was placed so that recording sites spanned at least from the splenic flexure to the rectum. a. Colonoscopy: a suture loop connected to the tip of the catheter was grabbed using a hemostatic clip passed through the biopsy channel of the colonoscopy to help carry the catheter through the colon during colonoscopy. 13 Once the catheter tip was located in the cecum or all sensors had passed through the anus, the loop on the catheter tip was clipped to the mucosa with the hemostatic clip to secure its position (Boston Scientific, USA). b. Interventional radiology: If placed by an interventional radiologist, the catheter was advanced with the aid of a guidewire and positioned under fluoroscopic guidance. 19 Clipping of the catheter was not possible if the catheter was placed by interventional radiology. 2) Antegrade placement : if a cecostomy or appendicostomy was already in place, the catheter could be placed through this artificial opening with the aid of interventional radiology. The in-dwelling device (e.g., Chait cecostomy button) was removed and the manometry catheter could then be advanced with a guide wire under fluoroscopic guidance as described above. For both antegrade and retrograde catheter placements the manometry catheters were placed under sedation or anesthesia. The position of the catheter was verified by abdominal radiography at the time of placement by the radiologist or visually if placed by colonoscopy. An abdominal radiography was obtained in all patients at the end of the post-prandial observation period, before administration of the stimulant laxative, to verify the positioning of the catheter tip, since there is a potential for it to migrate distally.