Cryopreservation of in vitro-fertilized human embryos: histologic and cytogenetic analysis of an ectopic conceptus.

In this study, 39 embryos from 17 patients were cryopreserved in a Planer R204 cell freezer using the protocol of Mohr et al. (J Vitro Fert Embryo Transfer 2:1-10, 1985). The procedure was modified by supplementing the cryoprotectant with 10% heat-inactivated and filtered (0.22 micron) maternal serum instead of fetal calf serum, and embryos were frozen in 500-microliter plastic straws instead of glass ampoules. After 12-25 weeks of storage in liquid nitrogen, 12 embryos from six patients were thawed at 8.0 degrees C min to room temperature, incubated in 75% maternal serum with Ham's F-10, and replaced in utero. One pregnancy occurred. The patient was a 34-year-old nulligravida with occluded fallopian tubes. A year prior, she conceived triplets from three embryos during an in vitro fertilization (IVF) cycle, but she delivered at 21 weeks and the infants did not survive. The second IVF attempt produced four embryos. Two were replaced during the IVF cycle, but they did not implant. Two were cryopreserved and replaced 25 weeks later. On day 28 after replacement, beta human chorionic gonadotropin (beta-hCG) was 4126 IU, but there was no gestational sac in utero on ultrasonographic examination. Laparoscopy disclosed a right tubal pregnancy which was removed with the fallopian tube. Histological examination demonstrated normal chorionic villi. The chromosomal pattern was 46 XX by direct analysis and cell culture.