Selective photosensitizer localization in the human endometrium after intrauterine application of 5-aminolevulinic acid.

Objective: Our purpose was twofold: to determine the distribution of the endogenous photosensitizer protoporphyrin IX in the uterus and to ascertain the time interval leading to maximal endometrial fluorescence after intrauterine instillation of 5-aminolevulinic acid.

Study Design: One milliliter of a 400 mg/ml 5-aminolevulinic acid-Hyskon solution was instilled into the uterine cavity of 27 women before hysterectomy. On frozen sections of uterine samples 5-aminolevulinic acid-induced fluorescence was measured with fluorescence microscopy.

Results: 5-Aminolevulinic acid-induced fluorescence could first be detected in the superficial endometrial glands 75 minutes after drug injection. In the endometrial gland stumps fluorescence intensity peaked 4 to 8 hours after 5-aminolevulinic acid instillation and was > 48 times higher than in the underlying myometrium.

Conclusions: Fluorescence in the endometrial glands suggests that selective photodynamic destruction of the endometrium may be possible 4 to 8 hours after intrauterine 5-aminolevulinic acid instillation.