Design and instrumentation of new devices for performing appendectomy at colonoscopy (with video).

Background: There is increasing interest in natural orifice surgery (NOS). Because the lumen of the appendix is connected to the cecum, a minimally invasive method for removing the appendix by colonoscopy may be feasible.

Objectives: Our purpose was to design, develop, and test new devices for inverting and removing the appendix by colonoscopy.

Design: Prospective prototype development program.

Setting: University-based study in 25 colons from adult human cadavers.

Interventions And Methods: Various prototypes were evaluated by inserting them into the appendiceal orifice to its luminal tip, with the intent to invert the appendix in a controlled fashion into the lumen of the cecum. The advantage of using a tubular structure as a counterforce to aid inversion of the appendix was evaluated. When inversion was incomplete, the growing tissue strain was relieved by endoluminal incision of the mesenteric side of the appendix. Closure methods with endoloops or ligating loops were studied. Appendiceal resection was completed by snare diathermy, leaving an inverted intraluminal stump.

Main Outcome Measurement: Ability to invert the appendix into the cecum.

Results: The mean appendix length and luminal diameter were 84 +/- 23 mm and 4.9 +/- 1.2 mm, respectively. It was possible to advance various types of inversion devices to the tip of the appendiceal lumen. Partial inversion of the appendix was successful in 22 of 25 tests. Mesenteric tissue tension, tissue volume, and device slippage were the main reasons for incomplete inversion. The complete inversion was achieved with a combination of vacuum, tip grip, counterforce at the appendix base, and eventually endoluminal incision.

Conclusions: The inversion of the human appendix by colonoscopy seems feasible and may be an alternative approach to conventional appendectomy.