Objective: To determine whether systemic 5-aminolevulinic acid (ALA) could produce photosensitization and photodynamic ablation of early pregnancy in the rat.
Setting: A conventional laboratory setting.
Patients: Female Sprague-Dawley rats, weighing 220 to 275 g at the time of breeding.
Interventions: Rats at 10 days of gestation were injected IV with saline, 20 or 200 mg/kg ALA. Three hours later, the abdominal cavity was opened to record the number of fetuses in both uterine horns. One or both uterine horns were exposed to photoactivating light at 630 nm for 0, 5, 15, or 30 minutes.
Main outcome measures: Mean fetal survival rate was determined 7 days after treatment.
Results: The mean +/- SEM fetal survival rates in groups (n = 6) treated with saline, 20 or 200 mg/kg ALA followed by 30-minute light exposure were 90.8% +/- 2.8%, 16.0% +/- 4.9%, and 0%, respectively. The mean +/- SEM fetal survival rates in groups (n = 6) treated with 200 mg/kg ALA followed by 0-, 5-, 15-, or 30-minute light exposure were 71.3% +/- 11.8%, 8.9% +/- 6.2%, 0.9% +/- 1.3%, and 0%, respectively.
Conclusions: We conclude that systemic ALA followed by transmural exposure to photoactivating light (630 nm) results in resorption of early pregnancies in the rat. This approach could potentially be developed as a new treatment for human ectopic pregnancy.