Thawing and embryo transfer

Frozen-thawed (FT) embryo transfer is a procedure used for the storage and transfer of excess embryos obtained during in vitro fertilization (IVF)–intracytoplasmic sperm injection (ICSI) cycles. In recent years, improvements in laboratory conditions and limitations on the number of embryos to be transferred have led to a progressive increase in FT embryo transfer cycles. Another preferred practice to prevent multiple pregnancies in IVF cycles is to transfer a single embryo and freeze all surplus embryos.

Frozen-thawed embryo transfer prevents embryo waste and increases the probability of pregnancy in a single stimulated cycle. Protocols applied in FT cycles aim for endometrial preparation only and are therefore simpler than complicated protocols that aim to develop many follicles.