Please advise on the coding of the following polyp removal with full thickness resection device. Is an unlisted appropriate in this scenario?

A 12 mm polyp was found in the recto-sigmoid colon at 15 cm from the anal verge. Polyp has associated scar from prior
treatment and adjacent SPOT tattoo. The polyp was sessile. Preparation for full thickeness resection was made. The
margin of the lesion was marked with the cautery marking device. The colonoscope was exchanged for a new colonoscope
with the attached Full Thickness Resection Device. The Device was driven to the lesion. The lesion was grasped with the
grasping forceps into the cap, care taken not to use suction. The closure device was then deployed and the lesion
ensnared in the indwelling snare. Full thickness resection was then performed. Edges trimmed with dual knife and snare.
After scope and specimen removal the site was again evaluated showing appropriate clip placement with no perforation,
bleeding or residual lesion seen.
External hemorrhoids were found during

Any help is greatly appreciated.

Thank you