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Laboratory Services

Assisted Hatching

Assisted hatching is a scientific technique used to improve the implantation of embryos by creating a small hole in the zona pellucida through which the embryo can hatch out as it develops. Assisted hatching has been used in clinics worldwide for a number of years and many babies have been born after its application.

The embryo is surrounded by a “shell” known as the zona pellucida. For an embryo to implant in the uterus, it must  hatch or break out of this shell. In some situations, this shell can become thickened or hardened preventing natural embryo hatching from occurring and it may reduce the  chances of implantation. 

Who would benefit from Assisted hatching?

There is currently no conclusive evidence to suggest assisted hatching improves the chance of pregnancy for all patients, however there is limited evidence to suggest that it may improve the chance of pregnancy for the following:

  1. ‍women with three or more failed embryo transfers 

  2. ‍women over the age of 38 

  3. ‍women with a high baseline FSH level 

  4. ‍women whose embryos have an unusually thick zona pellucida

What are the risks associated with Assisted hatching?

Assisted hatching results in extra handling of an embryo, which means it must be removed from the optimal environment inside the incubator to be performed. Less handling of the embryo means less stress due to temperature and pH changes.

The laser or acid Tyrode’s solution used to create the hole also gives off heat. If not done correctly, the heat from the laser/ acid may damage cells of the embryo.

Blastocyst Culture

Embryos can be grown in improved culture systems for up to 5 days and can be transferred to the uterus at blastocyst stage. The embryo starts to attach to the uterine lining at blastocyst stage during the process of implantation.

Blastocysts may have better potential to implant into uterine lining than cleavage stage embryos (4 cell to 8 cell stage embryos). Embryos which have successfully reached the blastocyst stage are probably more competent in development compared to earlier stage embryos.  

Blastocyst stage embryos should have a greater chances of implantation as the phase of embryo development matches the uterine environment. Transfer of a single blastocyst is recommended at Cairns Fertility Centre minimising the risk of a multiple pregnancy.

Why would a blastocyst-stage embryo transfer be suggested?

Traditional embryo culture methods have necessitated the transfer of more than one embryo to the uterus in order to obtain higher pregnancy rates. However, culturing embryos to the blastocyst stage will allow the identification of embryo which has the better potential for advance development and are more likely to implant. There is however a significant attrition rate from day 3 (when the embryos are usually between 6 and 8 cells) until day 5 (when the embryo often reaches a blastocyst stage of approximately 100 cells).  In order to consider culturing the embryos to the blastocyst stage, it is advised to have multiple good-quality embryos on Day-3. Extended culture may also be suggested if previous earlier stage (Day 3) embryo transfers have not resulted in favorable outcomes, to determine if your embryos are capable of developing to blastocyst.

What are the disadvantages of blastocyst culture?

The decision to grow your embryos to the blastocyst stage will be a carefully considered  and will be fully discussed with you.

The disadvantage of blastocyst is that fewer embryos will “survive” or develop to this stage (approximately about 40-45% of them). With a small number of good quality embryos there is a risk that no blastocysts will develop and occasionally we will be unable to perform an embryo transfer due to reduced quality embryo. Lower numbers of embryos may be available for freezing.

Sperm Freezing

Sperm can be frozen and then stored for future use. Sperm cells have been successfully frozen and recovered for more than 50 years. Sperm can be frozen from an ejaculated sample or from samples collected surgically from the testicles themselves. The sperm sample is mixed with a cryoprotectant before freezing and then stored in liquid nitrogen at -196 ºC. 

Under NHMRC guidelines, the sperm can be stored for a maximum length of 15 years. An annual storage consent form will be sent to you with options to either continue the storage or discard the sperm straws. More details can be discussed during your initial appointment with our clinician. Our nursing and laboratory staff will be able to help you should you require more information.


Who would need sperm freezing?


Situations where sperm freezing may be suitable include:

  • ‍Prior to having a vasectomy. 

  • ‍Prior to surgery. 

  • ‍Pre-chemotherapy treatment, and also prior to exposure to any toxins that may possibly have adverse effects on sperm quality or production. 

  • ‍If the male partner is likely to be unavailable to produce a semen sample at the time of his partner’s treatment. 

  • ‍In cases of impotency. 

  • ‍Where the semen quality is variable between one sample and the next. 

  • ‍In cases of sperm retrieval from the testis or epididymis. 

  • ‍For Fly in Fly out (FIFO) partners.


What are the risks with sperm freezing?


Sperm has been frozen for over 50 years and there appears to be no health risks associated with children born through it’s use. There is a very rare risk that all sperm frozen may not survive the thaw. CFC will thaw out one of your frozen straws to ensure the sperm survive before you undergo any treatment.


Donor Sperm


CFC also has an anonymous donor sperm bank for use by heterosexual, same sex couples and single women. Please contact the Cairns Fertility Centre Donor Co-ordinator for more information on this.

Oocyte (Egg) Freezing

Oocyte Cryopreservation is available at CFC for women who wish to store their eggs (oocytes) for later use. The technology for oocyte freezing was first developed in the mid-1980‘s, but has only recently been introduced into fertility clinics with improved success rates.

Oocytes can successfully be frozen using a new technique called vitrification (ultra-rapid freezing technique) and the survival rate is around 85% upon thawing. However, the pregnancy rates are still lower than that of embryo freezing. Despite of lower pregnancy rate, there are many reasons like medical & social where you may want to freeze your eggs instead of embryos.

Vitrification is an advent ultra rapid freezing technique where a rapid temperature drop occurs and therefore preventing the formation of ice crystals. Ice crystal formation is detrimental to chromosomal structures in oocytes and vitrification bypasses that. Frozen eggs may be stored for many years without significant deterioration. QLD regulations allow for frozen oocytes to be stored for a maximum of 15 years, and it is not possible for them to be used posthumously. 


Who would benefit from oocyte freezing?


Egg freezing may be beneficial in the following circumstances:


  • For women wanting to preserve their fertility while they are still at young age and wishing to start a family at a later stage. (Often known as ‘social’ egg freezing).

  • ‍Patients who require chemotherapy or radiotherapy due to serious illness such as cancer and wish to preserve their fertility.

  • People who are at risk of ovarian failure and premature menopause.

  • For ethical or religious reasons, the freezing of embryos is unacceptable for some people, and oocyte freezing is a preferable option.

  • ‍If a couple are undergoing an IVF cycle and the male partner is unable to provide a semen sample on the day of egg collection, it is possible to freeze the oocytes and fertilise them at a later stage when sperm becomes available.


What is the oocyte freezing process?


  • ‍The oocytes are harvested from the ovaries in a day theatre procedure lasting about half an hour. The woman undergoes stimulation of her ovaries through the use of fertility drugs in order to produce multiple mature oocytes (around 5-15). Once in the laboratory, the eggs undergo a freezing procedure called vitrification. This involves rapidly freezing the eggs to prevent potentially damaging ice crystal formation.  

  • ‍When the woman is ready to use her eggs, they are thawed out, then fertilised with sperm using the ICSI procedure. The aim is for the fertilised egg to develop into an embryo, which can then be transferred to the woman’s uterus giving a chance of pregnancy. 


What are the risk factors of oocyte freezing?


  • ‍Around 85% of all ova collected are mature and suitable for freezing. This proportion is variable between stimulation cycles and will determine how many eggs are stored.

  • ‍There is a risk that some oocytes may not survive through thawing process and that some oocytes once thawed will remain unfertilised even after ICSI. The reported average survival rate over many recent publications is that 69% of oocytes will remain intact after thawing. The initial results from the developmental work at CFC is that we anticipate our survival is similar to these observations.

  • ‍Thawed oocytes may not have a good fertilisation rate as compared to freshly collected ones in general; but overall, more promising results have been achieved through ICSI since oocyte vitrification has been used.


At Cairns Fertility Centre your embryos and oocytes will be frozen using a relatively new technique called Vitrification. It has been increasingly used worldwide and modification in the technique has significantly improved pregnancy rates.

Vitrification is an ultra-rapid form of freezing where embryos go from room temperature at 25 C to - 196 C in less than 1 second. The embryo is instantaneously frozen in a glass like state. Vitrification has shown to increase the survival of embryos over traditional slow freezing techniques at all developmental stages. Survival rates of above 90% for all stages of embryos are common at CFC. As a result, embryos are increasingly cultured to blastocyst for cryostorage using vitrification with improved survival and implantation rate.

At CFC oocyte freezing is also carried out by using vitrification for anonymous oocyte donation and for fertility preservation.

Embryo Glue / Vitrolife Medium

All embryos must be grown in culture medium. Vitrolife medium differs from our standard culture media in that it contains a compound called Hyaluronan, a complex macromolecule found in the tubal and uterine fluid of many species. Data suggests that it is involved in fertilization, embryo development and implantation and that its activity peaks around embryo implantation on Day 5. Eggs are placed into Vitrolife medium with Hyaluronan immediately after the egg collection and resultant embryos are cultured in this media until your embryo transfer. EmbryoGlue is the final stage of the Vitrolife media range, into which your embryos are placed before transfer. Some EmbryoGlue is transferred with the embryo(s) back into your uterus. EmbryoGlue can be used in the transfer of embryos at any developmental stage.

EmbryoGlue is an extension of the Vitrolife culture media but with increased amount of Hyaluronan. It has been proposed that EmbryoGlue may be beneficial at transfer by allowing improved mixing of the embryo with uterine secretions and that is could act as a binding agent between uterine lining and the embryo. There are some reports of higher pregnancy rates especially after the transfer of frozen embryos however, other unpublished presentations have not supported these observations. There is no data to suggest that using EmbryoGlue is detrimental to embryos. 

Vitrolife Media and EmbryoGlue are available to Cairns Fertility Centre patients. This will significantly increase the cost of the treatment cycle and due to this cost, if your cycle is cancelled and you are using EmbryoGlue / Vitrolife media, there is a fee that needs to be paid as your dishes are set up in the media the day before your egg collection.  If you are interested, please speak to your Clinician.

EmbryoGlue is an implantation promoting transfer medium which contains a substance known as hyaluronic acid. Hyaluronic acid is found in the human uterus, and by adding it to the culture media it more closely mimics the natural environment. A high concentration of hyaluronic acid is transferred with the embryo back into the uterus on the day of transfer.  It can be used in the transfer of an embryo at any stage.

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Who would benefit from Embryo Glue?

Embryo glue may benefit couples who have had multiple cycles without implantation although it is available to any patient. 

What is the cost of Embryo Glue?

Embryo Glue is a more expensive medium than our standard medium therefore it will cost you more to use. The cost for a fresh IVF cycle is $500 and for a FET cycle $300.

Are there any risks to using Embryo Glue?

There appears to be no risks to using Embryo Glue to yourself or resultant babies. Data analysis at Cairns Fertility Centre show’s that is does no damage to your embryos, and will give you the same chance of pregnancy as our standard medium however it may have an added benefit for patients with implantation failure.

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