Embryo pooling is the practice of freezing and storing suitable embryos developed during two or more retrieval cycles rather than transferring them immediately. This allows embryos from different cycles to be evaluated as part of a unified plan. If medically indicated, genetic testing may also be included in this plan.
This approach can expand transfer options, particularly for patients with low ovarian reserve. Having more embryos available for evaluation may provide the opportunity to select the most suitable embryo for transfer. However, pooling does not directly increase the implantation probability of each embryo. The potential benefits of this method should be evaluated in conjunction with age, ovarian response, embryo development, and previous treatment outcomes.
Embryo banking is the process of freezing and storing suitable embryos obtained over multiple egg retrieval cycles. Once a sufficient number of embryos has been accumulated or the predetermined treatment plan has been completed, embryo transfer is performed.
In each treatment cycle, mature eggs obtained through ovarian stimulation are fertilized using either conventional in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Not every egg will fertilize successfully. Embryos that demonstrate appropriate development are frozen using a technique called vitrification. Embryos obtained in subsequent cycles may also be added to this collection. In this way, the decision to proceed with embryo transfer can be based not on the outcome of a single egg retrieval cycle but on the total number of embryos accumulated over several cycles.
The term “banking” may sometimes be misunderstood to mean that all embryos will be transferred to the uterus at the same time. This is not how the method is applied. Instead, it can be thought of as a personal archive in which embryos obtained at different times are stored safely. When the time for embryo transfer arrives, the embryo that best fits your treatment plan is selected. The number of embryos stored in the bank and the number of embryos transferred to the uterus are two separate decisions.
Embryo banking is not necessary for everyone undergoing IVF treatment. However, it may be considered as an individualized option in the following situations:
A low anti-Müllerian hormone (AMH) level alone is not sufficient to justify embryo banking. AMH provides information about how the ovaries are likely to respond to stimulation medications, but it does not by itself indicate an embryo’s implantation potential. Age, the number of small follicles seen on ultrasound, previous egg retrieval outcomes, and embryo development are also taken into consideration.
Although every treatment plan is individualized, the embryo banking process generally follows these steps:
1. An individualized treatment plan is prepared: Your age, ovarian reserve, previous treatment history, and semen analysis are evaluated. The expected benefits of embryo banking and the criteria for proceeding to embryo transfer are discussed.
2. Ovarian stimulation is performed: The dosage of medications used to stimulate egg development is determined according to the expected ovarian response. Follicular development is monitored with ultrasound examinations and, when necessary, blood tests.
3. Egg retrieval is performed: Eggs that have reached sufficient maturity are collected. In the laboratory, fertilization is attempted using either conventional IVF or intracytoplasmic sperm injection (ICSI).
4. Embryo development is monitored: The development of fertilized eggs is observed in the laboratory. Embryos that reach the appropriate developmental stage are preserved by rapid freezing (vitrification). If genetic testing is planned, the required cell sample may be obtained before freezing.
5. Additional retrieval cycles are planned if necessary: Suitable embryos obtained in subsequent treatment cycles are added to the patient's personal embryo bank.
6. Preparation for embryo transfer: Once the embryo accumulation process has been completed, the selected embryo is carefully thawed. After the uterine lining has been prepared for transfer, the embryo is transferred into the uterus.
In some patients, two separate ovarian stimulation cycles may be performed within the same menstrual cycle. This approach, known as double stimulation (DuoStim), may help accumulate eggs or embryos without waiting for two separate menstrual cycles. It is not necessary for every patient. It may be considered when a fresh embryo transfer is not planned and shortening the overall treatment timeline is expected to provide a meaningful benefit.
Current research does not demonstrate that DuoStim increases the number of mature eggs or the likelihood of live birth compared with two conventional ovarian stimulation cycles. Its potential advantage lies primarily in reducing the calendar time between two egg retrieval procedures.
There is no fixed number of embryos that every patient should aim to achieve through embryo banking. Before treatment begins, discussing the target number of embryos, the estimated number of treatment cycles, and the criteria for proceeding with embryo transfer may help reduce uncertainty.
The contribution of embryo banking to the chances of pregnancy is not direct but may occur through treatment planning. Having a greater number of suitable embryos available may provide the opportunity for multiple embryo transfer attempts in the future. This may be particularly valuable for patients who produce only a limited number of embryos in a single treatment cycle.
Embryo banking does not change the cellular quality of existing embryos. Evaluating multiple embryos together may help determine the order of embryo transfer based on their developmental characteristics and, if performed, the results of preimplantation genetic testing.
Evidence regarding the effect of embryo banking on pregnancy and live birth rates remains limited. In a retrospective study involving patients with poor ovarian response, embryo banking was associated with a lower cumulative live birth rate and a longer time to achieving a live birth. However, because of the observational nature of the study, a direct cause-and-effect relationship cannot be established. Current evidence does not support embryo banking as a routine method for improving treatment success.
The key question is not, “Is embryo banking generally successful?” A more meaningful question is whether this approach is likely to provide an additional embryo transfer opportunity within your individual treatment plan. For some patients, delaying embryo transfer after a suitable embryo has already been obtained may not provide any benefit. For others, accumulating embryos over a limited period may allow for a broader evaluation of available embryos before proceeding with transfer.
The potential advantages of embryo banking include:
Potential limitations of embryo banking include:
Waiting to learn the total number of embryos available and receiving updates on embryo development can be emotionally challenging. These feelings are common and understandable during fertility treatment. Knowing in advance how many treatment cycles are planned, under what conditions embryo transfer will take place, and what alternative options are available may help make the process more predictable.
Preimplantation genetic testing may be performed on banked embryos that have reached an appropriate stage of development when there is a medical indication. Genetic testing does not refer to a single type of analysis. Different tests are selected depending on the family history and the condition being investigated.
The test is usually performed by removing a few cells from an embryo that has reached the fifth or sixth day of development. The embryo is then frozen and stored until the test results become available. This analysis is not a treatment that improves the embryo. Rather, it provides additional information to help determine which embryos may be considered for transfer. Current clinical guidelines do not recommend the routine use of PGT-A for every IVF patient. In particular, patients with only a limited number of embryos should be informed that genetic testing may result in no embryos remaining suitable for transfer.
The decision to perform genetic testing is based on your age, family history, the expected number of embryos, and whether the test results are likely to influence your treatment plan. It is also possible for genetic testing to produce inconclusive results, mosaic findings, or findings of uncertain significance. Before the procedure, the limitations of testing, the option of not undergoing testing, and the potential need for genetic counseling should all be discussed.
It may be technically possible to thaw a previously frozen embryo that was not biopsied, perform genetic testing, and then refreeze the embryo. However, this approach is not the preferred first option in every case. The decision should be based on the embryo's developmental characteristics and the laboratory's capabilities.
For patients in İzmir seeking an evaluation of embryo banking, the first step is to determine which specific need this approach is intended to address.
When developing your individualized treatment plan, your age, ovarian reserve, previous egg retrieval outcomes, embryo development, semen characteristics, and pregnancy goals are considered together. If genetic testing is being considered, the information it may provide, as well as its potential limitations, should be discussed in advance.
Whether it is more appropriate to proceed with embryo transfer once an embryo has been obtained or to continue accumulating embryos for a certain period is determined based on these factors. In this way, embryo banking becomes not a standard step offered to every patient, but a well-justified component of an individualized treatment plan.
To find out whether embryo banking is likely to provide a real advantage in your specific situation, you may seek an expert opinion from Assoc. Prof. Funda Göde, MD. By scheduling a consultation, you can learn about the treatment options most appropriate for your ovarian reserve, previous treatment responses, and pregnancy goals.
Embryo banking does not increase the implantation potential of a single embryo. It can create new transfer options by utilizing embryos obtained from multiple cycles. The benefits this method can provide depend on your age, ovarian response, embryo development, and whether postponing the transfer is appropriate for you.
There is no fixed number of cycles that applies to everyone. For some patients, two egg retrieval procedures may be planned. For others, a different approach may be taken depending on their response to treatment. The duration is determined by considering the expected number of embryos, age, cost, and pregnancy goals.
If only a small number of embryos develop in a single cycle due to low egg reserves, pooling may offer new transfer options. It is not necessary in every case of low AMH.
No. In patients for whom a suitable embryo has been obtained for transfer during a single cycle and for whom waiting would not provide any significant benefit, direct transfer may be considered more appropriate.
Suitable embryos are preserved using a rapid freezing method called vitrification. The embryos are matched with their identification and laboratory records and stored in special liquid nitrogen tanks. When the time comes for transfer, the selected embryo is thawed under controlled conditions, and its development is assessed in the laboratory.
Note: This content is for general informational purposes only and does not replace diagnosis or treatment. A physician evaluation is required for personal diagnosis and treatment planning.
