Trichorionic Triamniotic Triplets After Single Embryo Transfer: A Case Series and Literature Review

Abstract

Objectives: Monozygotic triplet pregnancy very rarely occurs in assisted reproductive technology (ART) treatment. The present study reported two cases of trichorionic triplet pregnancies after single embryo transfer (SET) and reviewed the literature in this regard. Case Presentation: In the first case, a 29-year-old female underwent the long protocol using gonadotropin-releasing hormone analogue and one full blastocyst was transferred in a fresh cycle. At 6 gestational weeks, three gestational sacs were clearly observed, while only one fetus with fetal heart beat was found after one week. In the second case, a 39-year-old female underwent intracytoplasmic sperm injection treatment and seven embryos were frozen accordingly. After assisted hatching, one completely expanded blastocyst was transferred during a hormone replacement cycle. Three gestational sacs with three yolk sacs were observed at 6 gestational weeks. Finally, two fetuses with fetal heart beat were found after one week. Conclusions: Overall, although the developmental mechanisms of monozygotic triplets are unknown, clinicians should be aware of the possibility of multiple pregnancies under SET.