Embryo transfer is a simple procedure that follows in vitro fertilization (IVF) and is often considered the simplest and final step of the in vitro fertilization process. The objective of embryo transfer is to facilitate conception following fertilization from the in vitro fertilization procedure.
Embryos are generally transferred to the woman’s uterus at the 2-8 cell stage. Embryos may be transferred anytime between day 1 through day 6 after the retrieval of the egg, although it is usually between days 2-4. Some clinics are now allowing the embryo to reach blastocysts stage before transferring, which occurs around day 5.
The patient returns to the clinic to have the embryos transferred. Anesthesia is often not necessary, although a sedative may be used. An ultrasound may be used to help guide the physician as he transfers the embryos. A predetermined number of embryos are loaded into a fine transfer catheter that passes through the vagina and cervix, into the uterus. The embryos are deposited from the catheter into the uterus. Following this procedure, the patient usually remains in a recovery room resting on her back and is discharged 4-6 hours after the procedure. The couple will then wait and optimistically watch for early pregnancy symptoms.
There are minimal risks associated with the embryo transfer procedure. They include the loss of the embryos during transfer or implanting the embryos in the wrong place such as the fallopian tubes. Although some women experience mild cramps, the procedure is usually painless.
The number of embryos that should be transferred during any single IVF cycle is subject to debate. Medical experts and writers seem to agree that transferring no more than four embryos per IVF cycle will yield optimal results. Transferring more than four is believed to result in excess numbers of multiple pregnancies leading to the increase of other complications. Transferring four embryos instead of only one or two increases the probability of pregnancy but with the risk that all four embryos could implant. After implantation, the next step is watching for the signs and symptoms of pregnancy.