In the past several decades the technology of cryopreservation, or maintaining life in a frozen state, has advanced considerably. With the use of modern techniques, cryopreservation of sperm to preserve an individualís ability to reproduce has become successful, safe, and widely available.
Some common reasons why you may choose to store a semen sample include:
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 patientís 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: Hodgkinís disease, leukemia, testicular cancer, and other malignancies often occur in juveniles, young adults and others who havenít 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 individualís 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.
After a semen sample has been collected, it is placed on a warming block maintained at 37įC, 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 -196įC, compared with a temperature of -20įC 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 37įC 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.
Cryopreserved sperm are generally used in two different ways to achieve pregnancy. The first way is with artificial insemination. When artificial insemination is used the female partner, working with a fertility specialist, determines when she will be ovulating. At the appropriate time, an appointment is scheduled with the Andrology laboratory, and one of the cryopreserved samples is prepared by carefully thawing and washing the semen sample. The washing procedure removes the cryoprotectants and seminal fluid, and concentrates the sperm into a volume appropriate for insemination. Depending on the quality of the sample, the doctor may have more than one vial prepared at each attempt. Once the sample is prepared, the patients will take it to their care provider to have the insemination performed. The physician performing the procedure uses a small catheter that is inserted into the uterus and deposits the sperm.
If there is known female factor infertility, or sperm are not available in sufficient quantity or quality, In vitro fertilization (IVF) can be another option. With this technique the female partner, working with a reproductive endocrinologist, receives hormone injections that stimulate her ovaries to produce several follicles containing mature eggs. When the follicles have matured sufficiently, the eggs are retrieved and the cryopreserved sperm is prepared and used to fertilize the eggs. Advantages to this procedure include a much higher pregnancy rate and the ability to use semen samples with a very low concentration or poor motility.
Q. How long can sperm be stored?
A. There is no practical limit to the length of time sperm, correctly maintained in liquid nitrogen, can be stored.
Q. Is freezing harmful to the sperm?
A. A percentage of the sperm will not survive the freezing process. The survival rate varies greatly between individuals. There may be some loss of fertilization potential in the sperm that do survive. Freezing itself does not cause DNA damage to the sperm. Again, the effects of cryopreservation are variable between samples and patients.
Q. How is the semen specimen collected?
A. A single ejaculate is collected into a sterile container by masturbation. A private room is available specifically for the purpose of semen collection.
Q. How many samples should be frozen?
A. A minimum of two samples is recommended for storage prior to surgery and/or therapy, however itís the patientís choice as to how many samples he will freeze. The patient should discuss his future plans during the initial consult, and establish a plan based on time constraints and future need. The number of samples needed for adequate storage is different for each situation and varies with the quality of the sample once it is thawed.
Q. What if the initial semen quality is poor, or the concentration is very low?
A. Many cryopreserved samples may not be of sufficient quality for use with artificial insemination. However, advanced procedures used in association with ICSI are regularly performed with sample of very poor quality or concentration. Any sample containing sperm, regardless of concentration or quality, is routinely frozen. If there is a concern at the time of processing the sample for cryopreservation the laboratory director or your care-provider will be contacted.
Q. How long should the abstinence period be between collections?
A. Optimal abstinence time is from two to five days.
Q. How can I be sure my semen sample is not contaminated with another sample or mislabeled?
A. The specimen container used to collect the sample is labeled and verified by the patient prior to collection. Once the sample is received it is handled with extreme caution. All materials used in the process are labeled with the patients name, the current date, and a visit number unique to the patient and the sample collected. Each sample is assigned a physically isolated workstation. All tools and solutions used in preparing the sample for cryopreservation are sterile and single-use. This, and the use of trained, certified Andrology technicians will ensure there is no confusion in the handling of semen samples.