Cycle monitoring in IVF and frozen embryo transfer

Cycle monitoring

  • Careful monitoring helps control and optimise ovarian response during hormone stimulation in preparation for egg collection.
  • Careful monitoring helps control and optimise endometrial development during hormone therapy in preparation for frozen embryo transfer.
  • Careful monitoring helps assess the change during the menstrual cycle in preparation for frozen embryo transfer in a natural cycle.
  • Monitoring includes repeated transvaginal ultrasound scans to track follicle number and size, endometrial development, and can also include blood tests to check the hormone levels.
  • Monitoring during controlled ovarian stimulation (COS) helps in achieving the best possible outcome for you while avoiding potential complications and cycle cancellation. The main reasons for monitoring include:
    • To determine the best timing for egg retrieval.
    • To assess the risk of hyper-response (over-response puts patients at higher risk of ovarian hyperstimulation syndrome, known as OHSS).
    • To make necessary mid-course adjustments to your treatment protocol by increasing or decreasing dosage of medications or adding new ones.

What happens during the transvaginal ultrasound?

What are the blood tests done for?

How much monitoring is needed?

Cycle monitoring for the frozen embryo transfer (FET) cycle

  • FET can be done in a natural cycle or in a hormonal replacement treatment (HRT) cycle.
  • Natural cycle preparation occurs with no supplementation of hormones and ovulation occurs spontaneously, although in some cases it can be triggered when the follicle reaches 18-20mm, to better time the embryo transfer procedure.
    • Cycle is monitored by ultrasound scan to time ovulation.
    • Endometrial thickness is measured.
    • FET of a blastocyst is generally done 7 days after ovulation.
  • In the HRT cycle the endometrial lining is prepared using oestrogen and progesterone treatment.
    • Oestrogen is started on day 2 or 3 of the period.
    • After 7-10 days of treatment a transvaginal ultrasound scan is done to measure the lining of the uterus.
    • Oestrogen treatment and monitoring continues until the endometrial thickness is greater than 7 mm.
    • Progesterone is added, and the embryo transfer is carried out 4-6 days later according to the fertility consultant’s practice and the centre’s protocol.

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If you are ready to start your journey, book a consultation with one of our experienced fertility consultants.

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