CRYOPRESERVATION

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CRYOPRESERVATION 2017-05-23T12:36:57+00:00

OVUM CRYOPRESERVATION

Giving solution to the major problem of infertility, IVF is the most effective way to have healthy children. Ovum Cryopreservation, a revolutionary technique that allows to freeze eggs for use in IVF cycles, offers women new options in fertility preservation.

Freeze time; freeze your oocytes!

Nowadays, more and more women are delaying pregnancy until their late thirties and early forties. Often, they are surprised and distressed when they learn they no longer have eggs that will produce a pregnancy because they waited too long. They are in their early forties, they look great and feel great, and, yet, they are faced with deep disappointment. Nevertheless, age is the single most important factor influencing a woman’s chance of conceiving. According to studies, once a woman turns 36, her chance of conceiving is naturally halved. At the age of 41, this chance falls to just 4%! The good news is that with advances in reproductive technology, women can now improve their chances of conceiving and carrying a child. And if IVF fails, they can always resort to egg donation.

What kind of tests should a woman take to determine her fertility, and at what age?

Most women assume they’ll be able to have kids if they do it at a relatively young age, ignoring the obvious: they have no idea if their bodies will let them. Prevention is the best way to treat possible fertility problems and ensure the conception of a child. Nowadays, it’s possible to diagnose issues relating to fertility by simple, regular fertility tests, that, according to most doctors, women should start having at an early age—before the age of 30 and not later than the age of 35. This way, when a woman has an idea of her child-bearing abilities, or lack thereof, she can plan for her future based on facts instead of… wishful dreams.

Fertility tests should include: hormone testing (FSH, LH, and AMH anti mullerhian hormone) and a transvaginal ultrasound scan that checks the size and quality of the ovaries as well as  if there are many small follicles. The two above-mentioned tests can estimate a woman’s potential to get pregnant and thus help the fertility specialist recommend an appropriate treatment plan.

What affects a woman’s fertility most?

It is common knowledge that a woman’s fertility decreases as she gets older. The reason that women in their late 30s and 40s have a lower chance of conceiving is that the number of healthy eggs they produce rapidly declines as they get older, especially after the age of 36.

IVF and other forms of assisted conception can improve the chances of conceiving and carrying a child, but age causes cells to start to divide abnormally and may distribute unequal amounts of genetic material. Unfortunately, this means that for older women it’s not just more difficult to fall pregnant, there is also a greater risk of miscarriage, even in a case of a successful conception.

How can we ensure an increased chance of getting pregnant at an older age?

Ovum Cryopreservation has been applied for several years in the IVF, and both cryopreservation of spermatozoons and cryopreservation of ovums are considered, now, routine techniques, with very good results. Although sperm and embryos have proved easy to freeze, the egg is the largest cell in the human body and contains a large amount of water. When frozen, ice crystals form that can destroy the cell.

Over the years new techniques have been developed to prevent ice crystal formation and to significantly increase both survival and fertilization rates. Nowadays, eggs are frozen using either a slow-freeze method or a flash-freezing process known as vitrification.

The best way to pursue egg freezing, or oocyte cryopreservation, is in the prime reproductive years—a woman’s 20s and early 30s—and take advantage of premium egg quality and quantity. Therefore, the younger the woman freezing her eggs, the higher the success rates for pregnancy in the future. Pregnancy rates for in vitro fertilization (IVF) cycles using frozen oocytes appear to be slightly lower than for those using fresh ones.

What exactly is Ovum Cryopreservation, and what is the process?

Ovum Cryopreservation or egg freezing is a method of storing a woman’s unfertilised eggs to allow her to try to conceive at a later date, when natural conception would be unlikely. Frozen eggs may be stored for many years without significant deterioration. When the woman is ready to use her eggs, they are warmed, and then fertilised with sperm. To obtain eggs for freezing, a woman will usually have hormonal stimulation with gonadotropin administration and simultaneous ultrasound monitoring. The eggs are, then, collected from the ovaries using an ultrasound guided probe inserted into the vagina.

The procedure is usually carried out under light general anaesthetic or with sedation. The number of oocytes obtained each time are usually large in younger women, while it is lower in older women and may require more than one egg collections. Once in the laboratory, the eggs undergo a freezing procedure called vitrification. This involves rapid freezing the eggs using a process that extracts fluid from the eggs to prevent potentially damaging ice crystal formation. Ovums are placed in solutions with special cryoprotective factors. Then, follows a gradual decrease of the temperature, with the use of special machines and finally, their storage at a temperature of -196ºC, in liquid nitrogen.Once vitrified, eggs may be stored for many years.

In spite of possible difficulties, these techniques have given hopes for the birth of a child to many women. Ovum Cryopreservation gives women the chance to freeze their eggs while younger, preserve their fertility, and, when older (after their 40th year), reduce the chances of miscarriage and birth defects associated with “egg age.” Why would a woman consider preserving her eggs? To preserve her options. She might not be ready for babies right now (because of her relationship status, career, finances, etc.), but knows she will or might want kids later. Or she really has no idea whatsoever, but she wants to keep that option open. Freezing her eggs buys a woman time and can give her more choices in the future.

Why should a woman choose Ovum Cryopreservation?

Because female fertility decreases dramatically as a woman ages, women may want to increase their chances of conceiving a child later in life by storing their viable eggs as early as possible. Ovum Cryopreservation is also recommended in the following cases:

  • Women with predisposition to premature menopause (usually inherited).
  • Women pursuing the career of their choice.
  • The absence of a partner; women who do not wish to raise their child in a single-parent family.
  • Radiation therapy, chemo and surgery can all cause infertility by destroying a woman’s eggs. Depending on the type of cancer being treated, egg freezing may be an option that gives a woman facing cancer the opportunity to preserve her fertility before she undergoes therapy.
  • Women with significant and chronic health problems.
  • Religious or ethical reasons: as surplus eggs are often generated during ovarian stimulation, women may opt to freeze surplus eggs versus surplus embryos to avoid potential concerns involving the discard of frozen embryos.

SPERM CRYOPRESERVATION

Sperm freezing, or cryopreservation, is the process of preserving sperm cells for later use, which was introduced in the 1950s. It preserves a man’s sperm cells, to maintain fertility if he is facing treatment that risks his future fertility and benefits men at hazard of reduced fertility from several diseases or other health concerns.

There is no known time limit on the viability of cryopreserved sperm, as it seems to be less sensitive to cryopreservation damage than other cell types because of the low water content. Some studies have reported that cellular damage can occur during the freezing and thawing of sperm, but there is no known risk to a baby conceived from donor sperm. Pregnancies have been reported in cases where the sperm was stored for 20 years before thawing and insemination.

Benefits of sperm cryopreservation

Sperm freezing can preserve fertility for men who:

  • Are about to have treatment for cancer, or undergo prostate or testicular surgery, all of which can harm sperm quality or production.
  • Plan to have a vasectomy.
  • Are in high-risk professions with exposure to chemicals, radiation or extreme heat that can cause sterility.
  • Suffer ejaculatory dysfunction.

Freezing process

Cryoprotectant is added to the semen to control sperm damage caused by freezing. Cryoprotectants are low-molecular-weight and highly permeable chemicals used to protect sperm from freeze damage by ice crystallization. In Medimall IVF Clinic we use the rapid freezing cryopreservation technique. It requires direct contact between sterile straws holding the samples and nitrogen vapors for eight to 10 minutes, followed by immersion in liquid nitrogen at minus 196 degrees Celsius.

Thawing process

The thawing of sperm is an equally important step as freezing: the cell must be allowed to recover its normal biological activities while avoiding abrupt thermal changes. Generally, the cryopreservation protocols use a thawing temperature of 37 degrees Celsius. Even if higher thawing temperatures allow for more rapid heating, they are not used because of the risks of cell damage. Once the sperm cells are thawed, they are separated from the cryopreservation medium by being washed in culture medium and centrifuging.

The process

  1. Semen collection. Sperm donors will first have blood tests, primarily to check for:
  • HIV I-II (AIDS)
  • HepatitisB (HBsAG)
  • HepatitisC (HCV)
  • Syphilis (RPR)
  1. The man may be given a choice of producing a specimen at home or at the lab site. Men who opt to give a specimen at the lab will be given a private room and visual material. Those collecting at home will be given exact instructions for semen collection and transportation.
  1. For best results, it is recommended that a man does not have an ejaculation for two to five days prior to providing a sample. If he ejaculated too recently, the count may be low. If his last ejaculation was too long ago, many of the sperm may be immotile.

The semen from a single ejaculation may contain 40 million to 600 million sperm, depending on the volume of the ejaculate and the length of time since the last ejaculation. Patients may choose to bank sperm from one ejaculation (one collection can yield one to six vials of sperm), but providing additional samples is recommended. Semen samples are collected in a sterile container, then lab technicians analyse the samples for volume, viscosity and pH levels. The sperm are also microscopically evaluated to determine motility, sperm count, morphology and other important factors.