Concurrent IVF and spontaneous conception resulting in a quadruplet pregnancy.

Blastocyst transfer of just one or two embryos has been used to help limit the number of high-order gestations. In this case report we describe the occurrence of a quadruplet pregnancy after the transfer of only two blastocysts during IVF. Sonographic examination showed four fetuses and what appeared to be quadriamniotic/quadrichorionic sacs, suggesting that a concomitant spontaneous conception had occurred. Definite confirmation of zygosity was obtained by genetic testing using DNA microsatellite polymorphism determinations after the birth of one boy and three girls at 32 weeks gestation. Although this event has not been reported previously, the possibility of its occurrence should be kept in mind. IVF patients with patent Fallopian tubes should be cautioned against intercourse late in their controlled ovarian stimulation, especially if they would decline multifetal reduction.