Methylene blue mucosal staining improves polyp margin identification during TAMIS. A Validation Study

Aljandro Moreira Grecco, MD, Fernando Dip, MD, Gonzalo Zapata, MD, Maria Eugenia De Faveri, MD, Luis Sarotto, MD, PhD. Hospital de Clinicas Buenos Aires

INTRODUCTION   Local resection for rectal polyps and early rectal cancer has progressed to become the standard of care in most institutions. This technique retrieves no fragmented specimen with a high percentage of negative histological limits. In some cases identification of the appropiate resection marging becomes challenging. We propose the use of methylene blue for mucosal staining to improve intraoperative lesion identification.  

Material y methods. We present a prospective serie of patients with indication for local resection of rectal a denomas. Preoperative work up was performed after rectal examination, colonoscopy with biopsy and high resolution MRI. All patients were submitted to surgery using the  trans anal minimally invasive surgery (TAMIS) platform. The procedures were performed under general anesthesia and in lithotomy position. After insertion of a gel point path (applied medical) set and neumorectum was created. The rectal mucosa over the lesion was stained with 1% methylene blue for pathological mucosa delineation. Polyp resection was performed. Rectal wall defect was closed with interrupted sutures in all cases. For objective surgical technique validation, a series of videos depicting lesion before and after the methylene blue staining during tamis was presented to colorectal surgeons, general surgeon, surgical residents and gastroenterologist. After watching the videos they answered a liker scale survey.  

Results Between February 2013 and April 2015, 8 patients with rectal adenomas were operated.. Mean age was 63 years (+- 18), mean lesion to anal margin distance was 6.5 cm (+- 2), 28% at the rectal circumference (+-10) was compromised by the polyp. The entire polyp was resected as non-fragmented specimens and with negative lateral and deep histological margins. Median follow up was of 7.5 month (3-18). The survey was performed to 57 faculties, including 6 colorectal surgeons, 28 general surgeons, 12 surgical residents, and 11 gastroenterologists. Sixty one percent could of the faculties did not identified the margins of the lesions properly with the white light only. When the dye was used the accuracy of margin detection increased to 100 %.

Conclusion Methylene blue mucosal vital staining during TAMIS is feasible, easy to perform and improves lesion border identification.

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