FLUORESCENCE AND PHOTOSENSITIZATION OF EXPERIMENTAL ENDOMETRIOSIS IN THE RAT AFTER SYSTEMIC 5-AMINOLEVULINIC ACID ADMINISTRATION - A POTENTIAL NEW APPROACH TO THE DIAGNOSIS AND TREATMENT OF ENDOMETRIOSIS

OBJECTIVE: Our purpose was to evaluate and compare the conversion of 5 -aminolevulinic acid into the endogenous photosensitizer protoporphyri n IX in experimentally induced endometriosis and in other normal tissu es in a rat model. STUDY DESIGN: Fluorescence of experimental endometr iotic lesions, uterus, peritoneum, bowel mesentery, bladder, eye, skin , and skeletal muscle was assessed 3 hours after either intravenous, o ral, or intrauterine administration of 5-aminolevulinic acid with use of spectrophotofluorometry. In another experiment the fluorescence of surgically induced endometriosis and adjacent normal peritoneum was ev aluated every 15 minutes after 5-aminolevulinic acid administration to assess the time course of protoporphyrin IX production. RESULTS: In t he rat endometriosis model intralesional and systemic 5-aminolevulinic acid produced fluorescence within implants showing viable endometrial cells. Treatment with 5-aminolevulinic acid produced low-intensity fl uorescence in peritoneum, bower mesentery, and eye. Relatively intense fluorescence was seen in skin, bladder, and uterus. No fluorescence w as observed in skeletal muscle. The intensity of fluorescence varied w ith the dosage and route of administration of 5-aminolevulinic acid. F luorescence intensity of protoporphyrin IX was significantly greater i n implants than in adjacent normal peritoneum between 2 and 4 hours af ter treatment. CONCLUSIONS: Protoporphyrin IX fluorescence in experime ntally induced endometriosis lesions after intravenous and oral delive ry of 5-aminolevulinic acid was significantly greater than the fluores cence detected in adjacent normal peritoneum.