Egg freezing, or oocyte cryopreservation

Egg freezing, technically oocyte cryopreservation, ( also known in English as “Oocyte cryopreservation” or “Egg Freezing”), is one of the most advanced frontiers of reproductive medicine. It can be performed at Sismer of the Nefrocenter group. The first pregnancy was achieved in 1986 in Australia, but the technique was then almost abandoned because it was considered unreliable and hard to reproduce. After about a decade, the technique finally became efficient and repeatable following the introduction of ICSI to inseminate thawed oocytes by the Bologna School, which quickly obtained the first birth in 1997 and several subsequent pregnancies. Since then, oocyte cryopreservation has made it possible to preserve female fertility by cryopreserving mature oocytes in the laboratory, so that they can be used at a later time, for personal or medical reasons. Sismer of the Nefrocenter group is recorded among the centers of excellence throughout Italy for this technique.

When and why egg freezing or oocyte cryopreservation is used

Cryopreservation is the concrete answer to the need to “store in the cold” the female gametes, that is, the eggs, and keep them unchanged over time, even for very long periods, when pregnancy cannot be undertaken right away, postponing motherhood while keeping the biological possibility of becoming a mother in the future.

The technique is intended for three main categories of patients:

• Women with cancer who must undergo therapies that are potentially harmful to fertility (chemotherapy, radiotherapy);
• Women with various types of non-neoplastic conditions that can nevertheless damage the ovaries and their reserve of eggs
• Healthy women who decide to postpone pregnancy for personal reasons, while keeping the oocyte quality tied to their biological age at the time of retrieval.

Stages of treatment

Oocyte cryopreservation consists of several stages, which include a preliminary evaluation by a specialist, ovarian stimulation, oocyte retrieval, vitrification and finally, if the oocytes are used, thawing and in vitro fertilization.

1. Preliminary visit and multidisciplinary consultations At Sismer it is possible to have a consultation with a specialist to assess whether egg freezing is appropriate. The aim of the Nefrocenter group facility is fertility preservation for women with various conditions or predisposing genetic factors, or who wish to freeze their oocytes for personal reasons. For this reason, in the evaluation, particularly when there are health conditions or problems, a multidisciplinary team is involved in assessing the case. To evaluate the feasibility of the procedure, blood tests, an ECG, an anesthesiology evaluation and informational interviews are scheduled.

2. Ovarian stimulation The patient starts a cycle of hormonal stimulation with gonadotropins for about 10-14 days. During the cycle, follicular activity is monitored through transvaginal ultrasound and hormone measurements. Once the follicles have matured (17-18 mm), ovulation is triggered.
3. Oocyte retrieval The oocytes are retrieved through a minimally invasive transvaginal procedure, under deep sedation, as day surgery. The mature oocytes are identified in the laboratory.
4. Vitrification The oocytes undergo vitrification: an ultra-rapid freezing technique at -196°C in liquid nitrogen that prevents the formation of ice crystals, the main cause of cell damage. The oocytes can be stored for years.
5. Thawing and fertilization When the patient decides to begin a pregnancy path, the oocytes will be thawed and fertilized with the partner’s sperm using the ICSI technique (intracytoplasmic sperm injection). Embryo transfer will follow.

Factors that influence the success of the procedure

The success of oocyte cryopreservation depends heavily on a variety of factors. The woman’s age at the time of retrieval is decisive: the best chances of success are under age 35. Beyond this threshold, oocyte quality declines rapidly. The number of mature oocytes vitrified is also influential: studies indicate that at least 8-15 mature oocytes are needed for a good reproductive prognosis. In addition, individual ovarian reserve is assessed through hormone tests and an antral follicle count is performed. Other essential conditions are the quality of the partner’s semen and the condition of the uterus at the time of fertilization and implantation. The chances of achieving a pregnancy range between 30% and 60%, with the highest success rates for younger patients.

Risks of the egg freezing procedure

Oocyte cryopreservation is generally minimally invasive, but it carries some potential risks such as:

• Ovarian hyperstimulation syndrome (OHSS);
• Reactions to anesthesia;
• Minor complications (pelvic pain, spotting after the procedure).

All risks are explained to the patient during the pre-treatment counseling process.

This procedure makes it possible to biologically separate a woman’s chronological age from the reproductive capacity of her eggs, giving her back freedom of choice and awareness. It remains a fact not to be overlooked that having oocytes biologically frozen in time does not mean they can be used to push pregnancy too far into the future, beyond the safety limits for the woman’s health, which may be put at risk by motherhood at an advanced age.
with the scientific advice of Professor Eleonora Porcu

• Join the Open Day on ART and Fertility on June 19-20 in Bologna
• Learn more about ART, visit the website of Sismer – NefroCenter Group

Read also: How much does egg freezing cost in Italy? · Egg freezing: advantages, risks and limits of a choice