LAUSR

Semen cryopreservation is the only available method to preserve the fertility in young and adult men. Semen freezing is the first line option for the group of patients in which fertility preservation is required. Conventional slow freezing of spermatozoa is commonly used for cryopreservation of both ejaculated and surgically retrieved spermatozoa for preservation of fertility before cancer treatment, in severe male factor infertility (obstructive azoospermia) and for establishment of donor banks. Cryopreservation of spermatozoa is therefore an important part of a successful assisted reproductive technology program. Sperm cryopreservation should be considered in cases of azoospermia so repeated surgical sperm retrieval techniques are avoided; also, regarding male patients who present impaired semen parameters, sperm cryopreservation is indicated to prevent the risk of azoospermia [1]. In addition, fertility preservation is a major concern for male cancer patients who are undergoing chemotherapy or radiotherapy because these gonadotoxic agents threaten their reproductive potential [2]. Moreover, some studies suggest that not only malignancies but also other non-malignant diseases including autoimmune disorders affect male fertility. Nowadays, there is an increasing interest in fertility preservation of patients with cancer or systematic diseases, since survival rates are increasing due to the new therapeutic options [3, 4]. Therefore, as long-term quality of life after cancer treatment has become a significant fact, semen cryopreservation before chemotherapy is seen as a real possibility of maintaining male reproductive potential after cancer treatments. Unfortunately, semen cryopreservation has a great impact on the quality of thawed samples. According to several studies in this field, viability of semen samples after freezing and thawing process only raise 50% [5]. The drastic decrease in viability of thawed spermatozoa is due to cell damage caused by intracellular ice formation, and osmotic and oxidative stress during the freezing process [6–8]. During the freezing process, freezing rates and concentration of cryoprotectant agents have to be balanced, to minimize mechanical and osmotic damage. Despite all the research done to date, there is no standardized freezing protocol leading consistently to higher viability rates. Moreover, in the literature, there are a wide range of sperm parameters that are thought to be affected by sperm freezing, but only a few are really useful in clinical practice.