Prior to Artificial Insemination: One common cause of male infertility is a low concentration of sperm in the ejaculate. For some, the collection of one or more samples to be cryopreserved and later combined with a fresh sample and used for artificial insemination may be helpful in achieving a pregnancy.
Prior to the absence of the partner: For couples going through cycles of artificial insemination or in vitro fertilization (IVF), it can be frustrating when responsibilities or obligations require a spouse to be absent. If it is anticipated that the male partner will be unavailable during the optimal time for the procedure, it is possible to cryopreserve a semen sample prior to his departure as a backup in the event he is prevented from providing a sample at the time of the procedure. While this may not be optimal, it can often keep the time and finances invested in a procedure from being wasted due to unforeseen circumstances.
Vasectomy: The majority of men who choose a vasectomy as a form of birth control see it as a permanent decision. However, unexpected changes in a patient’s life such as a new marriage or death of a child or spouse can give rise to the desire to have more children. Vasectomies can be surgically reversed, but success is widely variable, and the surgery is expensive and invasive. Additionally, after an initially successful reversal, the ducts through which the sperm travel often develop scar tissue and become obstructed. As most individuals plan for a vasectomy well in advance, cryopreservation prior to having a vasectomy provides an effective form of insurance against a change in future plans.
Treatment for malignant disease: Hodgkin’s disease, leukemia, testicular cancer, and other malignancies often occur in juveniles, young adults and others who haven’t started or completed their families. Fortunately, early detection and improved therapies have dramatically increased the survival rate for these diseases. Unfortunately, the chemotherapeutic agents and radiation therapy used to treat these diseases affect the production of sperm.
The response to treatment varies considerably, depending on how far the disease has progressed prior to treatment, the type and quantity of agents used, and the specific individual’s reaction to the treatment. While many patients who have undergone chemotherapy will eventually have a return of sperm production to varying degrees, some therapies, such as treatment with platinum based agents, result in a high probability of sterility. Even though the time between diagnosis and initiation of treatment is short, there is often a window of several days in which a patient can cryopreserve his semen.
How is the semen cryopreserved?
After a semen sample has been collected, it is placed on a warming block maintained at 37°C, until the sample, which is highly viscous directly after collection, has become liquefied. At this time the semen sample is washed as in IUI and is mixed with a freezing medium that allows the semen sample to survive the freezing and storage process. The freezing medium used contains cyroprotectants. Cryoprotectants are salts or chemicals that help remove water from the cells being frozen. If the water is not removed from the sperm, ice crystals will form inside of the cell and break up it up, resulting in cell death.
Semen samples are slowly frozen in liquid nitrogen vapors. Once the semen samples have been frozen in the liquid nitrogen vapors they are placed on canes or in special containers where they are stored in the liquid nitrogen until they are needed. Liquid nitrogen has a temperature of -196°C, compared with a temperature of -20°C found in the average home freezer. The very low temperature essentially halts all metabolic activity in the cell, allowing them to be frozen and stored for very long periods.
When a sample is thawed, it is removed from the liquid nitrogen and placed in water until it has reached a liquid state. Once liquid, it is placed on a 37°C block, and allowed to warm to that temperature prior to being prepared for use. By thawing the sample in stages, the sperm are protected from thawing too quickly, which results in the sperm heads swelling and rupturing as water moves back into the cells.
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