IVF - Special Treatments
Which special forms of IVF exist and which ones apply when?
If a sperm sample contains a sufficient number of motile sperm and there are also sufficient eggs available, direct fertilisation is used. If the sperm count does not meet the required conditions, there are alternative treatments that can also be given at our fertility centre. These treatments include ICSI, MESA, TESE, Assisted Hatching and PGD or PGS.
Intracytoplasmic sperm injection (ICSI)
In the ICSI technique, a single sperm cell is injected into the cell plasma of each egg cell with an ICSI needle. An ICSI needle is only 7/1000 of a millimetre wide (exterior diameter). The sperm is introduced into the egg cell itself through the cell wall.
ICSI is used when there are too few sperm for spontaneous penetration of the cell wall of an egg to occur, or when the sperm are too weak because their motility (mobility) is too low.
The perfection of the ICSI technique in 1993 made it possible to achieve fertilisation in the vast majority of all cases of male infertility.
Microscopic Epididymal Sperm Aspiration (MESA)
MESA is an operation in which mature sperm cells are taken from the epididymis under general anaesthetic. This kind of operation is used in men whose semen does not contain any sperm, for example because the vas deferens is blocked (obstructive azoospermia). A blockage of this kind can be innate or acquired, but often the exact cause is not known. A typical indication is when a man who has previously been sterilised (sealing of the vas deferens) decides he does want to have children after all.
Testicular Sperm Extraction (TESE)
If no sperm cells can be found in the man's ejaculate, TESE is used to extract the sperm directly from the testicle (testis). Then the extracted sperm are introduced into the egg by ICSI. A disadvantage of the TESE procedure is that the chance of pregnancy is somewhat lower per cycle than with ordinary ICSI attempts, because the sperm are often still very immature.
This technique is used to assist the implantation phase. Particularly with patients who have experienced repeated implantation failures, it may be important to weaken the wall around the embryo. In assisted hatching, an ultraviolet laser is used to make holes in the zona pellucida (wall) of the embryo, to allow the embryonic structures to grow through it more quickly and make contact with the lining of the womb (endometrium). In the latest techniques, however, the aim is to achieve thinning of the wall rather than making holes in it, to avoid any thermal effects on the blastomeres (assisted thinning).
Preimplantation Genetic Diagnosis (PGD) or Screening (PGS)
For couples who are carriers of genetic conditions and who do not have any actual fertility issues, PGD can be used.
In this method, one or two blastomeres are removed at the eight-cell embryonic stage for genetic examination. During this examination, the embryos continue to grow. Only those embryos that are not carriers of the specific genetic condition being investigated are returned to the womb. This is a way of avoiding diseases such as Duchenne muscular dystrophy or Huntington's disease, and moreover of removing them for good from the family tree.
For example, this technique has also been used recently in families with the inherited form of breast cancer. However, an obvious problem is that not all genetic conditions can be traced within the short time frame available (two days) in one or two cells.
In PGS, the chromosomes are examined at a more general level by means of one or two blastomeres that are also removed at the eight-cell stage. In this way, chromosomal abnormalities such as Down's syndrome can be avoided. For example, if implantation repeatedly fails, an increased incidence of chromosomal abnormalities is sometimes found. PGS may offer a potential solution here.
The selection of sex can also be done in this way, but in Belgium it is strictly limited by law to medical indications (for example, inherited conditions that are closely related to sex). ‘Designer babies,' as they are known, are not possible at present, and in any case there is not yet any legal framework that would allow such selection.
The biopsy of the embryo and the preparation of the cells to be examined are done in the fertility centre at Jan Palfijn General Hospital. Then the cells are transferred in a suitable medium - depending on the medication - to the genetic centre at Ghent or Brussels University Hospital, with which Jan Palfijn General Hospital has partnership contracts.