Objective

Our purpose was to determine the optical dose required for irreversible endometrial destruction and prevention of implantation by photodynamic therapy with topical 5-aminolevulinic acid.

Study design

Three hours after drug application 74 female Sprague-Dawley rats received varying doses of 630 nm of light delivered by an intrauterine cylindric diffusing fiber.

Results

A 64 J/cm2 in situ optical dose resulted in long-term irreversible endometrial destruction; 43 J/cm2 damaged endometrial stroma and myometrium but not glandular epithelium 1 day after photodynamic therapy. At this lower light dose endometrium regenerated to full thickness within 3 weeks; however, implantation sacs were significantly reduced.

Conclusions

Photodynamic destruction of glandular epithelium accompanies irreversible endometrial ablation, whereas isolated stromal damage leads to reproductive impairment only. The optical dose required for endometrial ablation is approximately 1.5-fold higher than for reproductive impairment (functional damage) because of differential cell photosensitivity.