Cryopreservation of oocytes and ovarian tissue

Fertility preservation program for women at risk

For whom is this program intended?

Some women prematurely lose their reproductive function due to poor ovary function, which leads to a situation similar to menopause. There are many causes and circumstances which may produce premature menopause. Among these are ovarian surgery, genetic or autoimmune diseases and oncologic treatments such as chemo- and radiotherapy.

What can be done in these cases?

In these situations there are several alternatives aimed at preserving the future fertility of the patient. When mature oocytes are obtained following hormone stimulation, cryopreservation of the embryos or just the oocytes may be carried out. If previous hormone stimulation has not been performed, the ovarian tissue itself may be directly cryopreserved.

How is cryopreservation of embryos performed?

This requires ovarian stimulation treatment which starts with the period and lasts from twelve to fourteen days. After this treatment ovarian follicular puncture is performed to obtain and fecundate oocytes, and thereafter, the embryos are cryopreserved. The results may vary depending on the response to treatment and the age of the woman but on average a 30% pregnancy rate per cycle may be expected.

How is the cryopreservation of oocytes done?

The same treatment as the previous case is done but since an adequate masculine sample is not available the oocytes are directly cryopreserved so that later, when the conditions are appropriate, these oocytes may be fecundated in the laboratory and, if all goes well, some embryos will be obtained for implantation in the uterus of the patient. This is a newer technique, the efficacy of which has increased greatly with the latest technical advances. It has been calculated that more than 100 children around the world have been born with the aid of this technique. In order to carry out this procedure in Spain, it is necessary for the Centre to have specific authorization from the public healthcare authorities such as was authorized to our Centre in October 2007.

In what cases is hormone stimulation not possible?

When the conditions are not ideal or there is not enough time to carry out the complete process, or there is some medical condition preventing ovarian stimulation. In this regard, it should be taken into account that in certain oncologic diseases it is not advisable to delay the initiation of chemotherapy and, in other cases, this hormone treatment may be contraindicated. Lastly, this stimulation should not be performed if the patient is very young and has not yet started her menstrual cycles. In all of these cases, a final therapeutic option may be considered; the cryopreservation of ovarian tissue.

How is cryopreservation of ovarian tissue done?

This is done with a laparoscopic surgical intervention in which a biopsy of the ovarian tissue is made and cryopreserved at the same time as the surgery. It may be done at any time during the cycle and does not require previous treatment. It does not delay the initiation of oncologic treatment and may be done in pre-pubescent patients. At present, this is an experimental technique that can only be done in authorized and highly specialized centres and it is aimed at patients with a high risk of losing ovarian function or those in whom other conventional techniques cannot be performed.
 
The worldwide results are still not very good since only a few pregnancies have been achieved with this technique. The patient must be in good physical condition before undergoing the surgery and the procedure is not recommended if the underlying disease involves the ovary.

How is the most suitable option decided upon?

It is necessary to do an individualized study of each case, since the age, the predictive factors of ovarian response and the type and urgency of oncologic treatment to be received will all play a part in determining what the best alternative is to preserve the patient’s fertility. In the case of oncologic disease it is essential for the decisions to be made in consensus with the remaining medical professionals who intervene in the clinical process of the patient.