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Background and study aims: In cases where biopsies remain inconclusive, removal of mediastinal lymph nodes for further analysis requires surgical means. Natural orifice transluminal endoscopic surgery (NOTES) procedures allow incision/closure of the gut wall, which might enable endoscopic excision of pre-marked nodes. The aims of the current study were to investigate the feasibility, safety, and reproducibility of lymph node generation in an animal model to enable endoscopic ultrasound-guided (EUS) lymph node removal (ELR) using transesophageal NOTES access/closure and to compare this procedure with thoracoscopic lymph node removal (TLR) in a randomized long term survival animal study. Patients and methods: Lymph node creation using graphite injection was performed in 12 pigs. After randomization into ELR and TLR groups, lymph nodes were marked with newly developed anchors under EUS guidance and removed using either ELR or TLR. ELR included incision of the esophageal wall and closure after lymph node removal. The main outcome measures were success in lymph node generation, technical success of lymph node removal, complications, and comparability of ELR and TLR. Results: Generation of lymph nodes proved successful in all animals in 46 /48 sites injected (96 %). Anchors were placed through the selected nodes in a mean of 9.4 minutes. TLR and ELR were successful in all cases. One bleeding occurred during esophageal incision in ELR, which was stopped endoscopically. After lymph node removal, endoscopic suturing of the incision took a mean of 18 minutes. Procedure time was longer for ELR than TLR (mean 48 vs. 42 minutes). All animals survived the procedures. Autopsy after 4 weeks showed two thoracic wall abscesses in the TLR group and none in the ELR group. Microscopic analysis revealed well healed esophageal scars. Conclusion: ELR proved to be feasible in this limited sample size and complications were not observed more frequently in this group than in the TLR group.

Introduction: Full thickness biopsy (FTB) of the gut is necessary for the diagnosis of enteric neuromuscular diseases (ENMD). To date FTB is only done by surgery. Endoscopic biopsy methods would enable easier diagnosis of ENMD and facilitate research of other diseases. Aims: To test the ability of a novel prototype FTB-device, to obtain ≈1cm in diameter full-thickness gut tissue to provide appropriate histology for the diagnosis of ENMD; 2) To determine whether the FTB-device would damage adjacent tissue in the peritoneal cavity and whether endoscopic closure of the defect with t-tags is sufficient. Methods: In 12 animals 2 FTB each were taken from the anterior (n=6) and posterior (n=6) gastric walls with the new endoscopic device and retrieved for histology. The defects were closed with endoscopic t-tags. Post intervention a laparoscopy was performed to inspect the resection site for any damage caused. Animals were kept alive for 2 weeks, thereafter autopsy was carried out to evaluate late complications. Results: All FTBs were successfully performed. Retrieval of the specimens was possible in 34/36 samples. Median time to perform FTB was 8.7min (range 5.8–13.3), for defect closure 19.8min (range:8.6–29). T-tag closure was successful in all cases. No major complications were seen. Post-procedure laparoscopy proved a minor defect at the surface of the liver, but no other lesions. The FTB samples were median 7.8mm in diameter with little evidence of serious edge damage. Histology proved the presence of neurons in the submucosal and myenteric plexus. The circular and longitudinal muscle layers were of very good quality for analysis. At autopsy, the scars of the FTB appeared to have healed well. No abscesses or other abnormalities were seen. Conclusion: Using an innovative endoscopic FTB-device we have shown that FTB was possible, successful and provided plenty of material when performed in the anterior/posterior wall of the stomach. Histology proved the tissue to be excellent and appropriate for ENMD diagnosis. It also showed that there was potential for possible damage, when performed at the posterior side. Further studies including other areas of the gut such as the small bowel and colon will be necessary to prove the clinical importance of this new method.