Microinjection (ICSI)

Intracytoplasmic sperm injection, usually shortened to ICSI or microinjection, is a method of fertilising eggs in the IVF laboratory. In conventional IVF the collected eggs are placed in a dish with prepared sperm and fertilisation is left to happen on its own. In ICSI the embryologist first removes the cloud of supporting cells around each mature egg, then selects a single sperm, draws it into a micropipette and places it inside the egg under high magnification. Everything else, from stimulating the ovaries to transferring the embryo and supporting the early pregnancy, is the same as a standard IVF cycle. Because one sperm is enough for each egg, ICSI can be combined with sperm that has been retrieved surgically from the testicle or frozen earlier, and with genetic testing of the embryos before transfer.

ICSI is recommended mainly when the man's semen makes natural fertilisation unlikely: a low sperm count, poor movement or a high share of abnormally shaped sperm. It is the method of choice when sperm have to be collected directly from the testicle by procedures such as TESA, TESE or microscopic TESE, including sperm that was frozen and thawed. It is also advised when eggs did not fertilise, or fertilised poorly, in an earlier IVF cycle, and when the embryos will undergo preimplantation genetic testing, because injection avoids extra sperm sticking to the outside of the egg. Some clinics use it for unexplained infertility or for a small number of eggs so that every mature egg has a good chance of fertilising. The decision is made together with the fertility specialist after both partners have been assessed.

The cycle begins on the second or third day of a period with daily hormone injections that encourage several follicles to grow; the dose is tailored to the woman's age, body weight, egg reserve and any earlier cycles, and growth is checked with ultrasound and blood tests over roughly ten to twelve days. When enough follicles have reached the right size a trigger injection matures the eggs, and about a day and a half later they are collected through the vagina with a fine needle guided by ultrasound, under short general anaesthesia or sedation. The same morning the partner provides a semen sample, or sperm obtained earlier by a testicular procedure is thawed. In the laboratory the embryologist cleans the mature eggs, chooses one normal-looking sperm for each and injects it. Fertilisation is checked the next day, the embryos are cultured for three to five days, and the chosen embryo is placed in the womb through a thin catheter without anaesthesia; surplus good-quality embryos can be frozen. Progesterone is given to support the lining, and a blood test about ten to twelve days after transfer shows whether pregnancy has started.

Good candidates are couples with a male-factor problem, a previous fertilisation failure or a plan for surgically retrieved sperm or embryo genetic testing, in whom the woman still has eggs that can be stimulated. Preparation starts with a joint consultation that reviews earlier tests and treatments so nothing is repeated unnecessarily, followed by hormone and ultrasound assessment of the egg reserve, a semen analysis and, where needed, an andrology review of the man. Conditions in the womb that can lower the chance of implantation, such as polyps, fibroids, adhesions or fluid in blocked tubes, are treated by hysteroscopy or laparoscopy before the cycle. Infection screening, a general health check and advice on weight, smoking, alcohol and caffeine complete the work-up. For international patients much of this can begin remotely from existing reports, with the protocol confirmed and the first scan done on arrival.

Egg collection is a short day procedure; mild cramping or spotting afterwards is common and most women are back to normal light activity the next day. The embryo transfer takes a few minutes, needs no anaesthesia and is followed by a short rest, after which ordinary daily life can continue while progesterone support runs until the pregnancy test. Planning a trip abroad, the whole fresh cycle from the first injection to the transfer usually takes about two and a half to three weeks in the destination city, so monitoring scans, the collection and the transfer can be done by the same team; some couples choose to freeze the embryos and return for a transfer in a later cycle, which shortens each stay. Flying home is usually possible soon after the transfer, on the advice of the treatment team, and the pregnancy blood test can be arranged near home with the result shared remotely. Follow-up continues by message or video with interpreter and coordinator support, and early pregnancy care is handed over to a local obstetrician.

ICSI is an established technique and the laboratory step itself is safe for the woman; the risks of a cycle are those of IVF in general. Hormone stimulation can cause bloating and discomfort and, less often, over-stimulation of the ovaries that needs monitoring or a change of plan. Egg collection carries a small risk of bleeding or infection. Not every collected egg is mature, not every mature egg fertilises, and some embryos stop developing, so the number available for transfer or freezing is only known a few days into the cycle. Transferring more than one embryo raises the chance of a twin pregnancy, which is why the number is decided from the woman's age, embryo quality and earlier attempts. Pregnancy rates fall as the woman's age rises, and the quality of the eggs and sperm matters more than the injection technique itself; sperm selection methods such as IMSI, embryo monitoring and genetic testing are offered in some laboratories to improve selection. Your specialist will discuss the expected chances for your situation before you start.