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Sperm Cryopreservation

Semen cryopreservation (commonly called sperm banking) is a procedure to preserve sperm cells. Semen can be used successfully indefinitely after cryopreservation. For human sperm, the longest reported successful storage is 21 years. It can be used for sperm donation where the recipient wants the treatment in a different time or place, or as a means of preserving fertility for men undergoing vasectomyor treatments that may compromise their fertility, such as chemotherapy, radiation therapy or surgery.

Freezing

The most common cryoprotectantused for semen is glycerol(10% in culture medium). Often sucrose or other di-, trisaccharides are added to glycerol solution. Cryoprotectant media may be supplemented with either egg yolk or soy lecithin, with the two having no statistically significant differences compared to each other regarding motility, morphology, ability to bind to hyaluronate in vitro, or DNA integrity after thawing.

Semen is frozen using either a controlled-rate, slow-cooling method (slow programmable freezing or SPF) or a newer flash-freezing process known as vitrification. Vitrification gives superior post-thaw motility and cryosurvival than slow programmable freezing.

Thawing

Thawing at 40°C seems to result in optimal sperm motility. On the other hand, the exact thawing temperature seems to have only minor effect on sperm viability, acrosomal status, ATP content, and DNA.

Refreezing

In terms of the level of sperm DNA fragmentation, up to three cycles of freezing and thawing can be performed without causing a level of risk significantly higher than following a single cycle of freezing and thawing. This is provided that samples are refrozen in their original cryoprotectant and are not going through sperm washingor other alteration in between, and provided that they are separated by density gradient centrifugation or swim-up before use in assisted reproduction technology.

Effect on Quality

Some evidence suggests an increase in single-strand breaks, condensation and fragmentation of DNA in sperm after cryopreservation. This can potentially increase the risk ofmutations in offspring DNA. Antioxidants and the use of well-controlled cooling regimes could potentially improve outcomes.

In long-term follow-up studies, no evidence has been found either of an increase in birth defects or chromosomal abnormalities in people conceived from cryopreserved sperm compared with the general population.

Preserving & Storing Sperm

Sperm cryopreservation or sperm freezing is a method for men to preserve their sperm and store it in a bank for future use. Many medical treatments, including several cancer therapies, can damage sperm quality, which is why you may choose to freeze your sperm before receiving the medical treatment.

Although there is no information about how long frozen sperm can remain effective, sperm twenty years or older have been used successfully in pregnancies. Sperm freezing allows this sperm to be used in the future in fertility treatments, such as intra uterine insemination (IUI) or in vitro fertilization (IVF).

Sperm Freezing – What to Expect

Patients are usually referred to the andrology laboratory for sperm cryopreservation. At the first visit patients can ask questions and clarify anything they might want to know about sperm freezing and cryopreservation, such as storing the samples long term and billing, before the sample is collected and the semen storage agreement signed.

Additionally, patients are always welcome to call with additional questions or clarifications.

How Cryopreservation Is Performed

After a semen sample has been collected, it is placed on a warming block maintained at 37°C, to liquefy. At this time, the semen sample is mixed in a 1:1 ratio with a freezing medium that allows the sperm to survive the freezing and storage process.

Frozen in Liquid Nitrogen

Semen samples are slowly frozen in liquid nitrogen vapors. Once the samples have been frozen in the liquid nitrogen vapors, they are placed in special containers where they are stored in the liquid nitrogen until they are needed. Each ejaculate can yield from one to six vials. Each vial of a patient’s semen sample is labeled with the patient’s name, the date, and a unique number recorded on the side. This information will be used to catalog the semen sample into the storage facility.

Test Thaw Procedure

The survival rate of sperm after cryopreservation can vary widely. Depending on the amount of sperm banked, the lab recommends that one of the cryovials be thawed to examine how successfully an individual’s semen can be stored and thawed.

How long can sperm be stored?

There is no practical limit to the length of time sperm, correctly maintained in liquid nitrogen, can be stored.

Is freezing harmful to the sperm?

A percentage of the sperm will not survive the freezing process. The survival rate varies greatly between individuals.

How is semen stored?

Semen is stored in cryovials in liquid nitrogen.

What is the normal volume of an ejaculate?

1.5 to 5 milliliters (1.5–5cc)

How many samples should be frozen?

A minimum of two samples is recommended for storage prior to surgery and/or therapy; however, it’s the patient’s 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.

What is the ideal abstinence time between collections?

Between two and five days is ideal, but may be less time between collections, if necessary.

What is the procedure for using the frozen sperm?

A few weeks prior to the date you anticipate needing the samples, contact the andrology lab so that we can bring the samples out of long-term storage. If you plan to use the samples for artificial insemination, we will need to have a physician’s requisition order on file. When you know the day you will need the sample prepared, call and set an appointment to pick the sample up.

Many physicians have additional requirements, such as blood tests or a current pap and pelvic exam, that they require before they will perform an insemination. Be sure to communicate with your physician in advance to avoid any delays.

What is the procedure for terminating the storage agreement?

You (or, in the event of your death, your legally authorized representative) may terminate a storage agreement at any time by requesting and completing a final disposition form (contact the andrology lab to obtain this form). The form will need to be completed and signature witnessed.

Please note: An andrology employee or a notary public must witness the original signature. The original written notice must be received and acknowledged by the university before the agreement is terminated.

How can I guarantee that I will become pregnant using the samples?

Regardless of how many samples are frozen, it is impossible to guarantee success. The best advice is to carefully consult with both an andrologist and reproductive endocrinology and infertility specialist before beginning any use of the samples.

What if the initial semen quality is poor or concentration is very low?

Many cryopreserved samples may not be preserved well enough for artificial insemination. However, IVF is regularly performed with samples 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.

How can I be sure my semen sample is not contaminated with another sample or mislabeled?

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 patient’s 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. Certified andrology technicians will ensure there is no confusion in the handling of semen samples.

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