Embryo, Egg and Sperm Freezing

The Latest Advances in Embryo, Egg and Sperm Freezing Techniques

Embryo freezing is today an extremely important technique that should be available in any high-quality, well-standardized IVF (In Vitro Fertilization) center. The technique used, the experience of the center performing it, and the outcomes of previous cases are the main factors determining success. At the final stage of IVF treatment, the best-quality embryos are selected and the number of embryos to be transferred is determined according to the patient’s age, hormone levels, uterine quality, and embryo quality. If the remaining embryos are frozen, they can be thawed and transferred again after a subsequent successful or unsuccessful treatment. After a successful attempt resulting in a child, a couple can later have their frozen embryos thawed to achieve a new pregnancy. After an unsuccessful attempt, without the need for a new ovulation treatment or egg retrieval procedure, the embryos can be thawed, the best ones selected and transferred, giving the patient another chance of pregnancy. Technical expertise and experience in embryo freezing and thawing are extremely important. If an incorrect or incomplete technique is used, embryos may not be frozen and/or thawed in a healthy way, may lose their quality, or may completely lose their viability. If the technique used is correct and performed by an experienced team, success rates close to, or sometimes even higher than, those of fresh cycles can be achieved. In some special situations, embryos may be intentionally frozen and their transfer to the uterus planned for a more suitable period. The most recently developed “vitrification” method is being applied successfully and professionally. With this technique, damage to embryos is prevented.

Egg freezing is also an important topic. It may be required for many medical or social reasons. In Turkey, at present, eggs can only be frozen if there is a medical necessity. These situations can be listed as follows: In patients who will undergo ovarian surgery, or receive chemotherapy or radiotherapy due to any cancer or similar condition, these treatments may damage the ovaries and egg cells, and the effects of many similar treatments on fertility are well known. Once these patients complete their treatment, egg freezing can be performed for a very important purpose: to preserve their ability to become a mother. In this way, the frozen eggs can later be thawed, fertilized with the partner’s sperm, embryos can be developed and transferred. Compared with embryo freezing, egg freezing is more difficult and more specialized. Technically, it is also a method that has been developed in more recent years. This is because the egg is very sensitive to external factors and is highly affected by freezing and thawing techniques. For this reason, egg freezing must be performed with very delicate and highly successful specialized vitrification techniques. The experience of the team performing the procedure is extremely important in both freezing and thawing.

SPERM FREEZING PROCEDURE

Sperm freezing techniques have reached a very successful level in recent years with the development of new methods. The center performing these procedures must have clearly defined freezing and thawing protocols, sufficient case numbers, and proven successful outcomes. Otherwise, very low success rates may be obtained.

Sperm freezing may be necessary for many reasons. To summarize briefly: medically, if a married or single man currently has sufficient sperm but there is a possibility that, for various reasons in the future, his sperm count may decrease or completely disappear, sperm freezing should be performed in advance as a precaution to preserve his fertility, in other words, his ability to become a father. As an example, many drugs (chemotherapy) and radiation (radiotherapy) used in some cancer treatments can have serious effects on sperm, causing a decrease in number or complete loss (azoospermia). Similar drugs and treatments may also be used in the treatment of some non-cancer immunological diseases, and the same risk applies to this group of patients. Before surgeries that need to be performed on the testis due to certain conditions, this issue should not be overlooked. Therefore, in addition to IVF specialists, internal medicine specialists, urologists, and surgeons should also be knowledgeable about this subject and should inform patients and refer them to centers where sperm freezing can be performed.

In addition, in patients whose sperm is not seen in the semen (azoospermia), within the scope of IVF treatment, when sperm is obtained from the testis by TESE or TESA–PESA, that is, by testicular biopsy or needle aspiration for use in microinjection, the amount needed to fertilize the eggs is used and the remaining high-quality sperm can be frozen for later use. Thus, in the next treatment, if the frozen sperm are of very good quality, they can be thawed and used without repeating the procedure.

In some cases, the sperm count in the semen is extremely low and in some analyses no sperm may be seen. In such cases, when sperm is detected in the semen with a detailed analysis, it can be frozen and used later without intervening in the testes when needed. Depending on the individual’s sperm quality, it may be preferable to use sperm obtained from the semen or from the testis.

Furthermore, in a couple undergoing a treatment protocol (IVF or IUI), if for any reason the prospective father cannot be with his partner on the egg retrieval day or IUI day, a sperm sample can be obtained in advance, frozen, and used when needed.

Sperm freezing, egg freezing, and embryo freezing should be performed using the latest techniques by a specialized expert team. It should also be remembered that when frozen-thawed sperm are to be used, the criteria for sperm selection are very important. In such cases, the IMSI technique, that is, high-magnification microinjection, should be used. In this way, the structurally and genetically healthiest sperm are selected for the procedure, achieving high fertilization and success rates.