Misoprostol associated refractile material in fetal and placental tissues after medical termination of pregnancy.

Misoprostol is a synthetic prostaglandin analog administered vaginally to induce labor for intrauterine death or termination of pregnancy for congenital abnormalities. We encountered a case of misoprostol induction of labor at 14 weeks of gestation for fetal acrania associated with amniotic bands. Histology demonstrated abundant deposits of refractile material appearing to be of vegetable fiber origin on the maternal surface of the fetal membranes. Misoprostol tablet scrapings had a similar microscopic appearance. Ten additional placentas from cases of misoprostol induction of labor between 16 and 18 weeks of gestation were examined and half were found to contain such deposits. No deposits were seen in cases between 15 and 18 weeks of gestation where misoprostol was not used. We attribute the refractile material to a nonmedicinal ingredient, microcrystalline cellulose, in the misoprostol tablet preparation. This study demonstrates that vaginal administration of misoprostol tablets can be detected microscopically in at least half of cases and may have a florid appearance simulating a potential causative factor of fetal malformation. Despite the large amounts of microcrystalline cellulose and its apparent embedding in placental tissue, the misoprostol in our index case was unlikely to have caused the amniotic bands and the resulting cranial abnormality.