Endoscopic Tattoo

Endoscopic tattooing places a permanent submucosal mark adjacent to a colonic lesion so that the site can be reliably identified at later endoscopy or surgery. It is recommended for any lesion of clinical importance that may need future intervention — large polyps left for surgical resection, polyps with high-grade dysplasia or cancer, post-EMR scars marked for surveillance, and lesions in anatomically difficult-to-relocate territory. The right colon and the descending/sigmoid colon are particularly forgiving of recall failure without a tattoo.

Two agents are commonly used: sterile India ink (carbon-particle suspension) is the historical gold standard but requires care because of preparation variability and rare reports of inflammatory reactions. SPOT (a commercially manufactured, sterile, preservative-free carbon suspension) has emerged as the standard agent in the US — it is reliably submucosal, persists for months to years, and has a clean safety profile.

The three-injection technique is the recommended method: place three small (0.5–1 mL) injections at separate quadrants 3–5 cm distal to the lesion. This creates a circumferential marker visible to the surgeon regardless of the colon's intraoperative orientation, and avoids ambiguous "is this proximal or distal" situations. Saline lift first to confirm submucosal plane reduces serosal staining and adhesions.