You’ve done the heavy lifting with egg retrieval and egg freezing. This page explains how to use frozen eggs – from secure storage (cryopreservation) and thawing to ICSI fertilization, blastocyst culture, optional preimplantation genetic testing, and embryo transfer-so you can plan the next steps with confidence.
Within just a few hours of your egg retrieval, your eggs are preserved by vitrification, an advanced method of cryopreservation of eggs that rapidly cools them to prevent ice-crystal formation. During vitrification, eggs are moved through solutions that remove intracellular water and add cryoprotectants that permeate the cell membrane to safeguard the cells.
Next, eggs are placed on specialized vitrification devices-usually 2–3 eggs per device-in a minimal volume of media. When the device is submerged in liquid nitrogen, the eggs are rapidly cooled to –196 °C, and the surrounding media solidifies into a glass-like state.
Each vitrification device is individually labeled and loaded into a labeled cane dedicated to your eggs only. Canes are stored in long-term cryogenic containers called dewars that are pre-filled with liquid nitrogen and equipped with a 24/7 alarm system to alert embryologists to any temperature fluctuation. Your eggs can be stored there indefinitely until you choose to start your family.
The timing of using your frozen eggs is completely under your control. First, identify the month-or even the week-when you would like to have your embryo transfer. Then count back three months to schedule your initial preconception and cycle-planning consultation. This window provides ample time to complete pre-treatment testing (see below).
In parallel, optimize your general health: check in with your primary doctor about any medical conditions or screening, and focus on diet, exercise, sleep hygiene, and stress management.
Picture A typical three-month timeline can guide your preparation for using frozen eggs.
A typical 3 month timeline to using your frozen eggs
ECS is a genetic blood or saliva test that screens for a broad panel of inheritable conditions (often hundreds), such as cystic fibrosis, spinal muscular atrophy, and Tay-Sachs disease. Results help individuals and couples understand carrier status and inform decisions. If indicated, affected individuals may consider testing embryos with preimplantation genetic testing for monogenic disorders (PGT-M).
Expanded carrier screening (ECS) before creation of embryos informs you of risks for certain inheritable genetic conditions.
A SIS is an in-office ultrasound that evaluates the uterine cavity. A small, soft catheter is passed through the cervix, and sterile saline is infused to gently expand the cavity, allowing better visualization of the endometrial lining (where the embryo implants). SIS can identify findings such as polyps, fibroids, or uterine adhesions that may not be obvious on routine ultrasound.
The inside of the uterus (where the embryo attaches) is evaluated with the use of saline water contrast and ultrasound: saline infusion sonogram (SIS)
When you are ready, the lab follows a coordinated process that aligns your body with the planned embryo transfer date.
Eggs can be removed from storage and thawed within minutes on the day chosen to synchronize with your scheduled embryo transfer. Warmed (thawed) eggs are fertilized by ICSI (intracytoplasmic sperm injection)-a precise technique in which a single sperm is injected into each mature egg.
ICSI involves mechanically injecting one sperm into one egg.
Intracytoplasmic sperm injection (ICSI) involves mechanically injecting a single sperm, into a single egg
Approximately 18 hours after fertilization, eggs that successfully received a sperm are identified as embryos. Embryos are then cultured under controlled conditions (media, temperature, humidity, pH) to allow natural cell division. After 5–7 days, some embryos reach the blastocyst stage-the developmental point typically used for implantation.
After 5-7 days of culture, an embryo reaches its most advanced stage called a blasotcyst.
At the blastocyst stage, embryos may undergo preimplantation genetic testing for aneuploidy (PGT-A). A small trophectoderm biopsy-a few cells from the outer layer destined to form the placenta-is taken and analyzed to determine whether the embryo has the correct number of chromosomes (euploid) or extra/missing chromosomes (aneuploid).
PGT-A is often recommended for individuals or couples undergoing IVF who have increased risk for chromosomal issues, such as advanced maternal age or a history of multiple miscarriages.
Biopsy and testing help identify embryos with a higher likelihood of implantation and reduce miscarriage risk related to chromosomal abnormalities.
Biopsy and testing helps identify embryos with a higher likelihood of implantation success and reduces the risk of miscarriage due to chromosomal abnormalities
Placing the embryo into the uterus is called an embryo transfer cycle. If you opt for PGT-A, you will undergo a frozen embryo transfer (FET)-embryos are frozen after biopsy and later thawed before placement. Patients who do not pursue PGT-A may have a fresh embryo transfer.
In either case, the uterus must be prepared and synchronized with the developmental age of the embryo using estrogen and progesterone under close monitoring.
Medication preparation for transfer typically takes about three weeks, with two in-office ultrasound appointments during this time.
Medication preparation for transfer takes about 3 weeks and during this time you will have 2 ultrasound office appointments.
The embryo transfer itself is a quick and gentle procedure that does not require anesthesia. A thin, flexible catheter is passed through the cervix into the uterine cavity under ultrasound guidance, and the embryo is carefully released.
At MFC, a large wall-mounted monitor with a live feed from the lab brings you face-to-face with your embryo before transfer.
Note: Discuss your individual IVF success rate considerations with your physician; outcomes depend on multiple clinical factors.
At MFC, a large wall-mounted monitor with a live-feed to the lab bring you face to face with your embryo before the transfer
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