Endometrial Ablation by DHE Photoradiation Therapy in Estrogen-Treated Ovariectomized Rats

Photodynamic therapy (PDT) by means of gold vapor laser was applied to uterine horns of ovariectomized rats. In 9 of 10 estrogen-primed rats treated with PDT, 3 hours after dihematoporphyrin ether (DHE) intravenous injection, selective necrosis of the endometrium and the inner part of the circular (internal) muscle layer occurred, whereas the contralateral horn (without photoradiation) remained intact. More extensive necrosis resulted in 8 of 10 horns of rats pretreated with estrogen, affecting also the inner part of the longitudinal (external) muscle layer. PDT applied 24 and 48 hours after DHE injection resulted in complete uterine necrosis in 4 estrogen primed and 4 nonprimed uterine horns. We conclude that proper timing of PDT and estrogen priming are important factors in achieving selective uterine layer necrosis in rats.