Effects of various laser wavelengths and energy levels on pig rectal submucosal tissue.

This phase I animal study attempts to develop a nonexcisional method of treating hemorrhoidal varicosities submucosally using interstitial laser beam. Three laser wavelengths at four energy levels were applied interstitially to pig rectal submucosa to evaluate the effects on the vasculature, mucosa, and the muscle. As expected YAG laser caused a "cooking" of the tissue with necrosis and abscess formation. KTP laser was intermediate in its effect, causing less mucosal injury and muscle necrosis. Pulse dye laser had more specific effects on the vessels with little damage to the mucosa or muscle layers. Further studies using pulse laser are warranted as a possible nonexcisional interstitial treatment for hemorrhoids.