Frozen embryo transfer is one of the processes of a series of IVF procedures carried out by thawing embryos that have been previously frozen. This procedure can be an alternative choice to undergo, if there are certain conditions that cause embryo transfer must be postponed first.
In the process of IVF, most doctors will advise prospective pregnant women to directly undergo embryo implantation in the uterus. But in some cases, embryo implantation can be considered to be postponed. The delay is done by freezing the embryo using a special tool, then stored, and thawed again at the right time. Melting embryos that have been frozen will follow the fertile cycle of expectant mothers so that the success rate of IVF is also high.
Indications of Frozen Embryo Transfer
There are several conditions that cause doctors to recommend expectant mothers to undergo frozen embryo transfer, compared to direct embryo transfer. Such as:
- Planning to carry out genetic screening of embryos. A prospective pregnant woman can undergo frozen embryo transfer, if she plans to carry out genetic testing in advance of the resulting embryo. Genetic testing will usually take a long time, so to prevent damage during the process, the embryo will be frozen first. After genetic testing is complete, frozen embryos will be thawed again, then implanted in the womb of expectant mothers.
- More than one embryo is produced. At the time of fertilization or in vitro fertilization, the resulting embryo can amount to more than one. However, doctors will only allow expectant mothers to transfer one embryo. The aim is to prevent the occurrence of triplets or quadruplets. The remaining embryos that are not used at the time of transfer can be frozen and reused if the first embryo implantation process fails. Frozen embryos can also be reused even though the first embryo implantation is successful, if both parents want a repeat pregnancy with IVF.
- Still in the effect of fertility drugs. In the process of IVF, pregnant women can be given drugs to increase egg production. However, fertility drugs are thought to make the uterine lining not ideal for embryo attachment and have an effect on success rates. Therefore, doctors may recommend delaying implantation of the embryo into the uterus, until the next fertile cycle. For the purposes of the delay, the embryo will be frozen first, then thawed when implanted in the uterus.
- Cannot undergo direct embryo transfer. Some prospective pregnant women who are at risk of ovarian hyperstimulation syndrome due to fertility drugs, cannot directly undergo embryo transfer, because it can cause infertility or even death, in severe cases. Prospective pregnant women who have these conditions will be encouraged to undergo frozen embryo transfer.
The choice to undergo direct or frozen embryo transfer in advance is the full right of prospective parents who will undergo pregnancy. The doctor will only explain the two types of procedures for the patient to consider.
Frozen Embryo Transfer Warning
Because this procedure can involve administering fertility drugs, the hormones estrogen and progesterone, patients with the following conditions are advised to be cautious in undergoing it:
- Allergy to estrogen or progesterone
- Severe liver disease
- The cause of vaginal bleeding is unknown
- Have a history or suffer from arterial disease
- Thrombophlebitis
- Breast cancer
- Deep vein thrombosis
Preparing for a Frozen Embryo Transfer
Prospective parents who will undergo frozen embryo transfer, will go through the stages of the test as conducted by patients who undergo direct embryo transfer. Among others are:
- Ovarian reserve test. This test is done to check the quality and number of eggs that can be produced by expectant mothers. In this case, the doctor will examine the hormones FSH, estrogen, and AMH from a blood sample. Prospective mothers can also undergo an ultrasound so that the condition of the ovaries can be known visually.
- Sperm analysis test. In this test, sperm samples from the prospective father will be checked for quality.
- Uterine examination. The doctor will visually examine the condition of the uterus using sonohisterography. Through this examination method, the condition of the uterine cavity can be known in detail.
- Examination of infectious diseases. This examination is carried out to check whether both prospective parents are suffering from an infectious disease or not, before undergoing IVF.
After the prospective parents decide to choose the method of transfer of frozen embryos rather than directly, based on the explanation and also the consideration of the doctor, the fertilization procedure will first be done.
The fertilization process begins by stimulating ovulation or maturation of the expectant mother's egg. The goal is to get eggs in large quantities. Ovulation induction is done by administering a number of hormones, such as FSH, LH, and HCG.
Giving hormones to stimulate ovulation is done in accordance with the menstrual cycle of the prospective mother, and is carried out for 1-2 weeks. If the egg is ready to be taken, the prospective mother will undergo egg collection, which is done in a conscious state. Eggs that have been taken will be put into the medium, and incubated in a special tool. If the egg is ready to be fertilized by sperm, the doctor will take sperm from the prospective father, then mixed with eggs in the medium, or injected directly into the egg. The fertilized egg and successfully developed into an embryo, will be frozen before being transferred into the mother's womb in the future.
Frozen Embryo Transfer Procedure
The freezing process begins after the fertilized egg develops into an embryo, after incubation in a special laboratory. The embryo is then put into a special fluid or CPA (cryoprotective agent) before being frozen. This liquid will protect cells from damage, when the process of freezing and storage is done.
Cells that have been mixed with liquid CPA will then be cooled, both slowly and rapidly (vitrification). Cooling the embryo slowly can take 1-2 hours. Generally the method of rapidly cooling the embryo requires a stronger CPA. After the cooling process is complete, frozen embryos will be stored at -196 oC in liquid nitrogen. Embryo freezing will take place 1-6 days after fertilization. Embryos that have been stored at very low temperatures can last a very long time, even for years after the fertilization process is carried out.
If a prospective mother is ready to undergo an embryo transfer that has been frozen, the embryo implanting process can be carried out. Embryos that have been frozen will be thawed first, by being immersed in a special liquid. This liquid also functions to remove the CPA that protects the embryo during storage, and returns the water content in the embryonic cell.
As the previous explanation, planting embryos that have been liquid will be adjusted to the fertile period of the prospective mother. Doctors can give hormones or wait for fertility to occur naturally.
Prospective mothers who are given hormones before embryo implantation will be monitored for hormone levels through blood sampling since menstruation occurs. After menstruation is complete, the doctor will start giving hormones. If the condition of the uterus is ready to accept the embryo, implantation will be carried out.
In embryo implantation adapted to the fertile period of the expectant mother, monitoring the condition of the body's natural hormones and uterus will be done more intensively, compared to patients given hormone therapy. Hormone monitoring is carried out through blood samples, while monitoring the condition of the uterus is done through ultrasound. If the fertility is confirmed, expectant mothers will receive additional progesterone to prepare the uterine lining before embryo implants.
The embryo implantation process is done with the condition of expectant pregnant women in a conscious state, but given sedatives to help calm during the procedure. The doctor will insert a catheter into the cervix until it reaches the uterus. Through this catheter, one or more embryos that have been thawed will be inserted into the uterus using a special tool. The embryo implantation process is generally painless, but expectant mothers may experience mild discomfort and stomach cramps during the procedure.
After the Frozen Embryo Transfer
Prospective mothers who have undergone embryo transfer are encouraged to avoid strenuous activities, but can still be active as usual. If a prospective mother has a successful pregnancy, the obstetrician will monitor the patient's condition until delivery.
If you don't have a pregnancy, the patient will be instructed to stop taking progesterone. The patient will menstruate about a week after stopping using progesterone. However, if there is abnormal bleeding from the uterus or no menstruation after stopping taking progesterone, the patient should immediately contact the relevant doctor. If the patient wants to undergo embryo implantation again, the doctor will arrange the next planting schedule. Frozen embryos that are still stored in the storage room, the remaining results of fertilization, can be thawed for replanting purposes.
Risk of Frozen Embryo Transfer
After embryo implantation is complete, the patient can experience several things, such as:
- Bloated
- Constipation
- Breasts harden
- Stomach cramps
- The discharge from the vagina some time after planting
If you experience severe pain after embryo implantation, the patient should immediately contact the relevant doctor to check whether complications occur.
The frozen embryo transfer procedure is a safe procedure for both prospective parents to follow. Nevertheless, the risk of complications remains. Among others are:
- Ovarian hyperstimulation syndrome (OHS)
- Ectopic pregnancy
- Twin pregnancy
- Infection in the reproductive organs
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