**4.2 Endoluminal access**

Endoluminal techniques for the treatment of duodenal obstruction based on principles of natural orifice transluminal endoscopic surgery (NOTES) were first introduced for adults in 1980 by Turnbull A. et al. using endoscopic biopsy forceps for membrane resection [58]. The first case of endoluminal surgery for congenital duodenal stenosis in children was reported by Okamatsu T. et al. In 1989, the author presented a successful case of endoscopic membranectomy in a 2-monthold child [59].

This technology involved the introduction of a small diameter occlusion catheter (5 Fr) into the opening of the fenestrated membrane, which, after inflating the balloon, stretches toward the stomach. The membrane spread on the catheter is dissected with a T-shaped incision using an electrode. Several other methods of duodenal web dissection have been reported, including the use of a sphincterotome [60, 61] and laser ablation [34, 62].

Several small case series demonstrated good results of partial CDO treatment using endoluminal balloon dilation [63–65]. The largest number of patients in the series included 6 children in whom balloon dilation was used as the first line of treatment [66]. The largest study of endoscopic membranotomy included 15 patients in whom dissection of the membrane was performed with a sphincterotome. One complication, perforation of the duodenum, was reported in this series [67].

There are several limitations to endoluminal methods in patients with partial CDO. The first one is a combination of duodenal stenosis with a more distal small bowel obstruction. Goring J. et al. described such a patient who subsequently underwent laparotomy and small bowel anastomosis [67]. The second limitation is annular pancreas, which reduces the chances of long-term success after endoluminal treatment [66]. Therefore, an abdominal MRI is recommended to assess the anatomy of the pancreas before transoral procedures [67]. If an annular pancreas is revealed on MRI, the use of endoluminal treatments is contraindicated.
