Our skilled embryologists use a number of techniques to select the best embryo(s) for transfer. By studying them closely over a number of days this assessment is enhanced.
Traditionally in IVF, embryo checks are kept to a minimum, as any observations occur outside the incubator’s carefully controlled environment. This limits the amount of information we learn about their development.
Eeva is an imaging system located within our incubators in the laboratory. Eeva frequently photographs your embryos, closely monitoring their development, to provide information to our embryologists to help them select the best embryos to transfer. Eeva enables this to be done without disturbing your delicate embryos.
Your delicate embryos remain completely undisturbed in the incubator and an image is taken every few minutes showing their development in its entirety. This gives our embryologists additional information about subtle differences in early embryo development and may help predict more accurately those embryos are likely to grow to the blastocyst stage – a critical milestone in development, essential for implantation.
If, in discussion with one of our consultants, you decide Eeva is right for you, your treatment will be the same as for a cycle of IVF – the only difference is that your embryos will be nurtured in an Eeva incubator and left undisturbed until our embryologists recommend the time is right for your embryo transfer.
The early interaction between the embryo and the lining of the uterus is a complex process. You may elect to have intravenously-administered intralipid, which although scientifically unproven, may enhance the likelihood of success.
Intralipid has been used with IVF treatment to help women who suffer either from recurrent miscarriage or repeated failed implantation following embryo transfer.
Intralipid is a 20% fat emulsion that is administered by the intravenous route. The main constituents are soya oil and egg yolk, with trace amounts of peanut oil. If you are allergic to any of these ingredients, then you should not use intralipid.
There is yet to be consensus in the medical community about if or why intralipid works. One theory that has been advanced is that as an embryo contains only half the genetic material of the mother, her uterus may see it as an invader, like a germ or foreign body.
Normally, the lining of the uterus contains immune cells that are specially adapted to tolerate an embryo. However, when these ‘friendly’ cells are not present or effective, the mother’s immune system may attack or reject the embryo with so-called ‘natural killer’ (NK) cells. This would make it difficult or impossible for the embryo to implant in the lining of the uterus.
It is thought that intralipid is able to change the immune cells in the uterine lining, making the environments more receptive to the embryo. Unfortunately, there are currently no reliable tests that can completely confirm whether a woman’s immune system will reject any embryo that tries to implant in her uterus.
Currently, there is limited evidence about the efficacy of intralipid in IVF. However, there have been encouraging reports in the UK and elsewhere. This brings the success rate of these women – with a history of several failed treatments – in line with the average rate of success seen in the general IVF population.
Intralipid is administered at Bourn Hall by intravenous drip infusion over a period of 1-2 hours. Infusions are required every three to four weeks, for a total of four or five infusions.
The first infusion is administered a few days before the embryo transfer, the second after a positive pregnancy test, the third after a viable pregnancy has been confirmed by ultrasound scan at six or seven weeks of gestation, and the last infusion four or five weeks later.
After that the embryo should be well-enough established to develop without further intralipid support.
Although there is a lack of scientific evidence to prove that this technique makes a significant difference to treatment outcomes, many clinicians have observed improved implantation rates.
Endometrial scratching is a relatively simple procedure that makes a small scratch in the lining of the uterus – the endometrium– using a fine catheter, to improve the implantation rate when embryos are transferred into the uterus.
The scratch aims to induce a reaction within the uterus that makes the endometrium in the following menstrual cycle more receptive to embryos.
The fine catheter is passed into the uterine cavity through the cervix, and a single scratch is gently made in the wall of the uterus.
We normally advise endometrial scratching if you have had two or more unsuccessful treatments, despite transferring good quality embryos – whether fresh or frozen/thawed.
Reports from Bourn Hall, and from several other UK clinics, suggest this procedure is safe and that it improves implantation and IVF success rates. Constant research is taking place.
We advise that endometrial scratching is undertaken in the second half of the menstrual cycle, just before commencing IVF or FET treatment.
Before an embryo can begin the process of implantation it must shed the protective shell it has grown in for the last five or so days. Making a slit in the shell assists the embryo to hatch by reducing the resistance to mechanical pressure from the embryo.
Embryos are surrounded by a protective outer coating called the zona pellucida. The thickness of this varies between patients, and it may toughen after culture in vitro, and with increased female age.
Before an embryo can implant and pregnancy occur, it must hatch from this outer coating. Hatching occurs naturally when the embryos are in the uterus. If the zona pellucida has become excessively thick or tough, hatching may be impaired or may not occur at all. When implantation fails with good quality embryos, this can be considered as a possible cause.
Assisted hatching is a technique that involves making a small opening in the zona pellucida to enable the embryo to escape or ‘hatch’. The degree to which this improves the chances of pregnancy is difficult to measure, as the reasons for using hatching are not identical in each case.
Published evidence suggests that assisted hatching may be clinically useful in patients with a poor prognosis, including those with three or more failed cycles, poor embryo quality and for older patients.
You will undertake the same treatment as for an IVF cycle with the hatching carried out shortly before embryo transfer. The use of a specially designed laser enables the embryologist to make a permanent hole of a precise size. The embryo is held in position under the microscope and the laser fired at the zona pellucida in several short bursts.
Sometimes your eggs may need a little help to complete the process of fertilisation.
In order for successful fertilisation, your sperm must release a specific functioning enzyme called Phospholipase C zeta (PLCζ) when it enters the egg. This induces waves of calcium oscillations across the egg to ‘activate it’, allowing fertilisation to occur.
A deficient or abnormal PLCζ may be the cause of failed or low fertilisation. This can be overcome in some situations using a calcium ionophore solution to activate the egg artificially.
AOA may help you if:
- Fewer than 30% of your eggs have fertilised, even after ICSI
- You have severe male factor infertility
Following a cycle of IVF with ICSI, we will use a calcium ionophore solution to stimulate the calcium release.
Your eggs will be checked for fertilisation the following day and, if the embryos continue to develop to an appropriate stage, the embryo transfer procedure will follow two to five days after the egg collection.