A Possible New Treatment for Ectopic Pregnancy
By Leon Speroff, MD, Editor, Professor of Obstetrics and Gynecology, Oregon Health and Science University, Portland, is Editor for OB/GYN Clinical Alert.
Synopsis: Photoablation has potential to treat ectopic pregnancies.
Source: Glinert LS, e al. Photodynamic ablation of a selected rat embryo: A model for the treatment of extrauterine pregnancy. Hum Reprod 2008;23:1491-1498.
Glinert and colleagues from Israel report the use of photodynamic therapy to successfully ablate single feto-placental implantations in rats. A photosensitizer drug was injected directly into the placenta, followed 2 minutes later by delivery of a specific wavelength of light to the site. More than three-fourths (78.6%) of the selected embryos were photo-ablated leaving the remaining litter unharmed. Subsequently, the treated animals were able to achieve pregnancy and have normal parturition. Histopathologic examinations of the uteri detected no lesions.
There seldom is a rat study reviewed in these pages, and that is good. But the potential of this new treatment is so tantalizing, I thought it was worthwhile to tuck it into the backs of our minds.
Photodynamic treatment uses a non-toxic photosensitizer drug that combines at the treatment site with focused light that has a wavelength known to induce cellular damage. There are several drugs already approved by the FDA for this purpose. The light can be delivered via optic fibers to a specific location, where it elicits the generation of cytotoxic oxygen molecules. These molecules have such a short half-life, that the damaging effect is limited to the illuminated area. The method has been developed to treat tumors and macular degeneration of the retina. The new generation of photosensitizer drugs acts immediately after injection and allows deep light penetration. The vasculature of tumors is most affected, leading to hypoxia and necrosis within days.
It is not hard to imagine delivering a photosensitizer drug transvaginally under visualization via an endoscope directly into an ectopic pregnancy. The endoscope would also contain an optic fiber system for delivery of light from a laser source. If the photosensitizer drug is inadvertently delivered into the maternal bloodstream, according to the rat study, the dose is about 50 times less than that used for tumor destruction. The method could also be used to treat endometriosis and uterine fibroids. Forgive me for the rat study, but the potential intrigued me. If you are interested, check out the review by Allison et al.1
- Allison R, et al. PD/PDT for gynecological disease: A clinical review. Photodiag Photodyn Therapy 2005;2:51-63.