What is a frozen embryo replacement cycle?
Following an IVF treatment cycle there may be surplus good quality embryos which can be frozen (cryopreserved). These frozen embryos can then be thawed and replaced in a subsequent treatment cycle known as a frozen embryo transfer, or a frozen embryo replacement cycle.
What are the benefits of embryo replacement cycle?
A frozen embryo replacement cycle utilises good quality embryos which might otherwise have been discarded. The treatment cycle is much simpler than a full IVF treatment cycle.
Frozen embryo replacements can be managed either as a natural cycle or in a controlled cycle. In a natural cycle no drugs are given. Ultrasound scans are carried out to monitor the cycle in order to pinpoint the best time for embryo replacement, i.e. when ovulation has occurred and when the endometrium (lining of the womb) is suitably thickened.
In a controlled cycle a mild form of stimulation is given. Ultrasound is used to monitor the cycle and an injection is given to induce ovulation – this is done when a leading follicle is considered the right size and the endometrium is the right thickness. Alternatively a cycle of hormone replacement therapy (HRT) may be prescribed in tablet form to help thicken the endometrium.
The timing of the transfer is important. The embryos are thawed in conjunction with the cycle and are replaced three to five days after ovulation. Not all embryos survive the freeze-thaw process and occasionally we find that no embryos have survived the thawing process.
For more information or if you have any queries, speak to your consultant.
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