The following pages contains information regarding the second phase of receiving eggs.
Insemination of the eggs
Although the time that the sperm sample is produced is not critical, we ask that the male partner attends at the specified time in order to avoid an undue delay in treatment. Many men would have frozen the sperm sample in advance of donation.
After the sample is given, the sperm are washed and prepared. The live and progressively motile sperm are selected to inseminate the eggs 40-42 hours after your hCG injection i.e. 3-7 hours after the egg collection. Overall 50-70% of the eggs will fertilise but this number is variable in different patients and varies with age (both male and female).
Fertilisation of the eggs (Insemination or ICSI)
If the sperm count is normal and the sperm preparation is satisfactory we will conclude that the risk of failure of fertilisation is very low (not completely eliminated still) and will inseminate the eggs with a preparation of the sperm approximately 4 to 5 hours after egg recovery.
If the sperm count or motility is known to be low, there is a substantial increase in the risk of failure of fertilisation. We would have assessed this risk as part of our mandatory pre-assessments. In this situation, we would have also advised the recipient of the need for ICSI.
Sometimes the sample given on the day of egg collection is not satisfactory unlike the pre-assessment. In those circumstances we may feel that the risk of sperm not fertilising the eggs is increased. We would discuss this risk with the recipient and proceed with ICSI. Therefore all donors and recipient couples are advised to read through the section of ‘risks of ICSI’ very carefully. This is still considered to be an experimental procedure. We therefore ask you to consider this possibility in advance and also consent (if you agree) for this to happen at the time of your nurse consultation.
This simply involves making a preparation of the sperm and transferring a measured number of sperm that are suspended in an appropriate fluid at the correct temperature and ph into the vicinity of the egg. The sperm will then find and fertilise the egg naturally.
INTRA-CYTOPLASMIC SPERM INJECTION
Checking FertilisationThis technique involves injection of one sperm inside the egg under microscopic vision. The egg is very small, smaller than a pin prick and the sperm is smaller still. the procedure is done under 300 times magnification where a sperm is lifted out individually using a micropipette or needle and this then is directed to the sheel of the egg penetrating it and the membrane of the egg, the whole sperm left inside the egg. The sperm and the egg have to undergo necessary changes after this for fertilisation to take place.
This assessment is performed approximately 18-20 hours after insemination or ICSI procedure.
Please ensure that we have your day time contact number. Our embryology team will be pleased to ring you to give you the result of this assessment. If fertilisation has occurred we will also give you a provisional appointment for embryo transfer which could be the following day (day 2 after egg collection), the day after next (day 3) or even on day 5.
Prolonged culture of embryos
Prolonged culture of embryos provides us with more time to observe the developmental potential of the embryos and select those suitable for transfer better. It does not make the embryos more or less capable. It also does not help in removing all abnormal embryos from those that are available and your risks will remain as they would be appropriate for the donor’s and the male partner’s age along with your clinical circumstances. We would have discussed risks in specific circumstances beforehand but you can ask further if you wish when you attend the follow-up appointment before you start your cycle.
Why choose prolonged culture?
This is a clinical decision. We choose to culture the embryos until such time we feel appropriate to select the best for transfer. Hence this is an option for only those couples where a number of equally good embryos are available. Pregnancy rate is higher when appropriately growing day 3 embryos or day 5 blastocysts are transferred than with day 2 embryos or day 6 blastocysts.
When there a lot of embryos with an equivalent appearance and growth, we may put them into prolonged culture in order to differentiate and select those with a better continued growth. It also gives us time to observe when you are at risk of ovarian hyperstimulation so that we can avoid doing a transfer for those who develop problems early but at the same time do not deprive those who remain well from a fresh transfer which has a higher success rate. The developmental potential of fresh embryos tends to be higher than that are frozen and thawed.
The spare embryos can also be maintained in culture until they are deemed suitable for freezing, stop growing or develop into the blastocysts when they can be frozen also if deemed suitable.
The risk of keeping embryos in culture is that you will find information about the embryo’s development before your pregnancy test. None may progress sufficiently and despite having a number of embryos, none may be frozen because of suboptimal growth.
As explained above, the fertilised eggs are called `embryos’. These are examined the day following fertilisation and then daily to monitor cell division and growth to determine the day of embryo transfer. If the embryos have not grown after fertilisation, an embryo transfer is not performed.
Risk of a multiple pregnancy
This is a very important clinical matter for both us and you. We know that transfer of multiple embryos increases the likelihood of at least one continuing growth and implanting. However your risk of a multiple pregnancy is also increased with the transfer of multiple embryos. Your chance of conceiving a multiple pregnancy depends most of all upon your donor’s age, your cause of sub-fertility and also the programmes overall success rate. Occasionally embryos split to form two identical babies. This risk is also increased with IVF and ICSI.
In the past even though approximately 85-90% of our cycles receive 2 embryos only, 25-30% of all our births were still twins. The risk is greatest when the donor is under 35 years of age and in those who respond well which is true for the vast majority if not all donors. Legally we are permitted to transfer up to 2 embryos when the donor is less than 35 years in age and never more.
The complications of multiple pregnancies include miscarriage, prematurity, fetal growth retardation, increased risk of pregnancy complications in the mother and the need for delivery by caesarean section. Additional complications of identical twinning include polyhydramnios and twin to twin transfusion syndrome. These complications have high risks for premature delivery. Extremely premature birth has the risk of death in infancy or survival with long-term mental and physical handicap in the children.
Our mission ‘One at a time’
Our intention is to give the best chance of a pregnancy but without a high risk of a multiple pregnancy. Whilst trying to come to a decision we balance the probability of a pregnancy against the risks of a multiple pregnancy. We therefore analyse our data extensively and we know of a number of features that will help us identify those couples who are specifically at high risk of a multiple pregnancy. The same couples also have a good chance of getting pregnant even with a single transferred embryo provided we select well. We therefore choose methods of prolonged culture and optimal day of embryo transfer so that we do not compromise your success rate but at the same time we give you a low risk of a multiple pregnancy.
Our embryology team will keep you informed of the embryo’s progress and choose the best day for your transfer as per our centre’s ‘strategy to minimise multiple pregnancies. All couples will have a further discussion on the day of the embryo transfer.
The term `fetal reduction’ is used for an ultrasound directed procedure that selectively terminates one foetus while permitting the other to continue growth and development as normal. Sometimes this procedure is employed to reduce the number of foetuses that have implanted after infertility treatment e.g. for reducing a triplet pregnancy to twins. Some pregnancies with a triplet implantation will spontaneously reduce to twins or singleton. Details regarding this `natural’ risk of ‘spontaneous reduction’ are available in our annual report and we can discuss this with you. If you have an ongoing triplet pregnancy of non -identical foetuses, then fetal reduction may be considered in line with the requirements of the Abortion Act. Equally you may consider this option if you conceive a set if identical twins with a non-identical triplet at the same time after the transfer of 2 embryos. Further discussion with your obstetrician will be necessary at that time.
This procedure is performed by passing a fine needle into the pregnancy sac and injecting potassium chloride into the fetal heart. The procedure carries a 4-5% risk of miscarriage. The world’s combined data suggests that the duration of pregnancy is unlikely to be altered greatly by embryo reduction. Please ask for more up to date information or clarification regarding our own programme.
Technique of embryo transfer
Usually at least 80-90% of those eggs that have shown normal fertilisation will grow in culture to day 2. However some of these will slow down or discontinue growth completely between day 3 and day 5. We check the embryos every morning before we call you for an embryo transfer. If there is no growth after fertilisation, we regret that we will need to cancel the transfer and arrange a follow-up. In others, we will discuss the number, growth rate and appearance of the embryos and what we have selected for your transfer when you arrive.
Preparation for embryo transfer
The procedure of embryo transfer itself is quite simple and normally pain free. The embryos are very sensitive to light, temperature and pH changes. Ideally therefore for the embryo survival and growth the transfer procedure should be quick, simple and a traumatic.
We take the following preparation for this to happen.
- You are advised to have a full bladder before the transfer because in most circumstances doing so straightens the uterine shape and makes the transfer procedure which is good.
- The outer sheath of the embryo transfer catheter is inserted first in order to only remove the embryos from their environment when all at your end is ready to receive them.
- The selected embryos are put into a fine catheter and transferred gently into the uterus in a very small volume of fluid.
- Occasionally and especially when the bladder is not full, an instrument to hold and straighten the neck of the womb may become necessary. This can give you temporary discomfort.
The embryos are not visible to the naked eye at this stage but can be seen with the microscope or on the television screen attached via a camera to the microscope. The embryo transfer procedure literally takes under a minute and you do not require pain relief. After the embryo transfer, we will check that the embryos have left the catheter and reached the uterus. Very occasionally, the embryos will not have left the catheter and the transfer procedure has to be repeated. You may rest for a few minutes afterwards before returning home.
After the embryo transfer
You are advised to continue with your daily routine as normal and there is no need to take special rest. However, we would advise you to refrain from strenuous physical exercise, taking of any form of drugs or medicines without checking with us first and avoid contact with contagious illnesses including `flu like illnesses’ as much as possible.
You may experience discomfort in the lower part of your abdomen because of enlargement of your ovaries after the egg collection. These once again enlarge to provide hormonal support for the implanting embryos. There are sac-like structures in the ovary called ‘corpora lutea’ and may be mistakenly called `cysts’. These have an important role and are essential for a pregnancy to take place. This enlargement of the ovary and discomfort after the egg collection is normal and expected. You may take some paracetamol tablets or suppositories safely if needed.
In this cycle your symptoms of premenstrual syndrome are likely to be exaggerated because of high hormone levels. If unluckily you fail to conceive then the pattern of menstruation may also be different.
If you have any worries you can get in touch with us at any time of the day during the week on our direct telephone line and at other times via the hospital switchboard as instructed in the front of this booklet. We would very much advise you to contact us during the working week as far as is possible so that you receive timely advice. We do not mind if you ring us for what you may consider a trivial matter.
*Please note that this is a much specialised form of treatment. Although your G.P. would gladly attempt to help you, he/she will not be fully aware of the details of your treatment or the necessary action. Hence it is in your interest to contact us first and before the problem is too advanced.*