Freezing of human sperm, eggs and embryos
Within the laboratory at Kamineni Fertility Centre we have a tissue bank where we freeze and store oocytes (eggs), sperm and embryos for our patients. All tissue in the bank is stored frozen in liquid nitrogen at a temperature of -190 in vacuum lined tanks. The embryologists are responsible for maintaining the bank and no other Kamineni Fertility Centre employee has access to them.
At Kamineni Fertility Centre, we have full-fledged facility to freeze sperm samples, testicular tissue TESA/PESA, Embryo and blastocyst. These are then stored frozen until they are needed.
Indications for Freezing Sperm:
Fertility treatment (medical and non-medical)
- Severe Oligozoospermia
- Absence of partner during ART treatment
- Masturbation problem
- anxiety about producing a sample on the day of his partner's insemination or egg retrieval.
- Avoid repeated surgery for sperm retrieval (azoospermia)
- Avoid problems in coordinating Ovum pick up (OPU) and testicular surgery
- Ensure presence of sperm before ovarian stimulation
- Before gonadotoxic cancer treatment
- Before sterilization (vasectomy)
When sperm is thawed from the bank it is normal for some of the sperm to die. Not all cells survive freezing and thawing, but since most sperm samples have many millions of live sperm, losing a small fraction of them has little consequence. However, it is important to be aware of the expected drop in the number of live sperm after freezing so that enough sperm can be frozen up front for the purpose of having one or more pregnancies.
The reasons for freezing oocytes at our centre are :
- Fertility preservation in cancer patients or other fertility impairing conditions.
- Risk of premature ovarian failure (genetic reasons such as Turner mosaic, Fragile X , Balanced translocations and Mosaicism) or family history.
- Storing healthy unfertilized eggs(oocytes) retrieved during a current IVF program ,if excess in number, to be used in future IVF cycles if required.
- The procedure for freezing eggs is as follows:
- Step 1. Before you agree to the freezing and storage of your eggs, your clinician will explain the process involved, including the risks. We offer you the opportunity to discuss your feelings and any concerns with a specialist counsellor.
- Step 2. You will be screened for infectious diseases, including HIV and Hepatitis B and C.
- Step 3. You will need to give written consent for your eggs to be stored.
- Step 4. Eggs are collected using the same procedure as for conventional IVF.
- Step 5. Cryoprotectant (freezing solution) added to protect the eggs when they are frozen.
- Step 6. The eggs are frozen by vitrification (fast freezing) and then stored in tanks of liquid nitrogen.
The standard storage period for eggs is normally 10 years. This period can be exceeded only in certain circumstances. Your clinician will be able to explain whether you can do this, and for how long you may be able to store your eggs.
Freezing and storing human embryos
Our experience with freezing embryos is not quite as substantial as with freezing sperm. Nevertheless, since the first human embryos were successfully frozen back in 1984, hundreds of thousands of babies have been born from embryos that spent some time in the freezer. Embryo freezing is a very routine part of the IVF process and approximately 60% of patients end up with some embryos in storage.
Freezing of excess good quality embryos after IVF allows for the transfer of fewer embryos in the stimulated IVF cycle and, therefore, ensures fewer high-order (triplets or more) multiple births. This process provides patients with a "back-up" should the initial fresh embryo transfer not result in a pregnancy, at a much lower cost than starting IVF all over again and often with minimal medications. Frozen embryo transfers have allowed many of our patients to achieve more than one pregnancy from a single cycle of ovarian stimulation. Embryos can be frozen at any stage of development during the IVF process. Eggs that are fertilized can be frozen as early as 1 day after an egg retrieval procedure, but it is more common to allow embryos to develop for a number of days before freezing them. This allows us to observe how well the embryos are developing so that we only end up with embryos in the freezer that we think have a good probability of establishing a pregnancy.
Embryos tolerate freezing very well and we expect over 90% of embryos to survive the process. Pregnancy rates with frozen/thawed embryos are as good as pregnancy rates for embryos that were transferred fresh without ever being frozen.