Monozygotic twin birth after the transfer of a cleavage stage embryo resulting from a single pronucleated oocyte

To present a case involving the transfer of a single pronucleated oocyte resulting in a monozygotic twin pregnancy. A descriptive case report of a single patient. The patient conceived and was found to have a monochorionic diamnionic pregnancy which resulted in the birth of normal identical twin boys at 32 weeks of gestation. The case report addresses an issue that has not received proper attention in the literature. It illustrates that observing a single PN in an oocyte at fertilization check should not be an absolute deterrent to transferring the resulting embryo even in an older patient with a high FSH level. This report also suggests that single observations, especially at the assessment of fertilization, in the IVF laboratory are limited when evaluating embryo potential and normalcy.