BackgroundEndometrial ablation by means of photodynamic therapy is currently being evaluated as an outpatient treatment for dysfunctional uterine bleeding. Photodynamic therapy requires the activation of a photosensitizer by laser light. We describe a new device specifically designed to provide light delivery to the uterus for endometrial photodynamic therapy.InstrumentThe intrauterine light probe consists of the three flexible optical fibers converging to one bundle resembling the shape of the uterine cavity. Each of the fibers contains a cylindrical light diffuser.ExperienceThe intrauterine light probe was tested in removed human uteri for its capability to distribute light in a tissue-simulating scattering medium and to deliver sufficient light throughout the endometrium. The light distribution of the intrauterine light probe in the scattering medium is uniform on eight axes tested around the diffusing fibers. The pattern of light distribution in human uteri is similar to that in the medium. At the endomyometrial junction, there is still one third of the light applied to the endometrial surface whereas deeper in the myometrium, the light power drops to less than 10%.ConclusionWe propose a device that will deliver light to the uterine cavity to induce endometrial ablation by means of photodynamic therapy.