How is an FET cycle done? Before starting an FET cycle, the physician needs to assess the uterine cavity using one of three tests: Hysterosalpingogram (HSG) – In which x-ray dye is injected into the uterus and the cavity is viewed with x-rays; Sonohysterogram (SonoHSG) – In which saline is injected into the uterus and the cavity is viewed with ultrasound; Hysteroscopy – In which a fiberoptic scope is introduced into the uterus and the cavity viewed directly. If any abnormalities are detected, they should be corrected surgically before going forward with a frozen embryo transfer. There are two protocols used for FET cycles. Both of these protocols use hormones to prepare the uterus for embryo implantation. The first FET protocol involves pituitary gland suppression using subcutaneous injections of Lupron for approximately two weeks to decrease the chance of ovulation occurring unexpectedly. Estrogen medications are also given to increase uterine lining thickness, preparing it for implantation. When the uterine lining has achieved a targeted thickness, the Lupron is discontinued and progesterone is given. Embryo transfer is usually done on either the 4th or 6th day of progesterone, depending on which day following fertilization the embryo had been frozen. The second FET protocol does not include Lupron but simply involves the use of estrogen for up to 3 weeks. When the endometrium reaches a targeted thickness and ovulation has not occurred, progesterone is begun, followed by embryo transfer on either the 4th or 6th day of progesterone as in the first protocol. There is no data that any one protocol works better than another and the protocol chosen is based upon your specific needs. Best Fertility Care Centre, Advanced Fertility Care Centre , Ashwini Hospital & Fertility Centre Moondrumavadi Madurai -07 , Maternal and Child Health Care Centre .