In vitro fertilization helps thousands of couples who cannot have a baby due to infertility become parents every year. However, IVF treatment is not sufficient to solve all infertility problems. The fact that fertilization did not occur, especially due to male infertility, led to the development of the microinjection method. Developed in the early 1990s, microinjection has become a powerful way to overcome infertility in azoospermic patients.
What is microinjection?
In the classical IVF treatment, the sperm and egg cell are brought together and the sperm is expected to fertilize the egg. However, if the number, motility and morphological characteristics of sperm cells are not sufficient to fertilize the egg, microinjection method is preferred. Microinjection (ICSI) is the process of injecting a single sperm cell, which is taken into a thin glass needle with a special tool, directly into the egg cell. It offers a good fertilization rate and oocyte activation, allowing more embryos per cycle and higher pregnancy rates. Except for the fertilization method, the treatment and follow-up of the patient is the same as the classical in vitro fertilization method.
Why is microinjection done?
A double comprehensive fertility study should be performed prior to microinjection. The following situations will be suitable for the application of the microinjection method:
Oligozoospermia / cryptozoospermia: It refers to a serious decrease in the number of sperm cells.
Asthenozoospermia: It is the condition of decrease in sperm motility, including the samples that are completely lacking in mobility.
Teratozoospermia: It is the presence of a high number of abnormal sperm.
Obstructive azoospermia: It is the complete absence of sperm in the ejaculate due to an obstruction. The most common causes are genetic factors, infection, or a failed vasovasostomy.
Secretory azoospermia: It is the complete absence of sperm in the ejaculate due to a defect in sperm production in the testis.
Anejaculation: Functional disorder caused by retrograde or paraplegic discharge. In cases of anejaculation, it is possible to obtain the sperm required for microinjection directly from the testis.
Immune system problems: The presence of a high number of anti-sperm antibodies adversely affects the fertilization ability of sperms.
Obtaining a small number of oocytes during ovarian stimulation and egg collection phase,
Very low overall egg quality.
Long-term infertility lasting more than two years
Failed fertility treatments,
Failure of fertilization in the previous classical IVF cycle,
Absence of pregnancy after several classical fertilizations.
What are the differences in IVF microinjection?
In IVF treatment, eggs are placed in a culture medium in a laboratory container together with the prepared sperm. Sperm naturally penetrate the egg and cause fertilization. The resulting embryos are developed in an incubator for three to five days and the best one is selected for transfer. In the microinjection method, a single sperm is taken into a thin glass needle and injected directly into each egg. Fertilized eggs are monitored for 5 days and transferred to the uterus in the same way.
Microinjection consists of similar stages with IVF treatment, except for the fertilization method. Since only one sperm is injected into each egg, the stage where only the sperm must naturally penetrate the egg will not exist.
How is microinjection done?
Ovarian stimulation: In a natural menstrual period, an egg develops in every woman. In the case of IVF, some injections of hormones are used daily to get more eggs and therefore more embryos. This process takes about 10-20 days, depending on the treatment protocol and the response of the patient's ovaries. The development of the eggs is monitored by ultrasound examination and hormone tests.
Egg collection: When the follicles reach the desired size and number, trigger injection (hCG or GnRH analogue) is performed. Within the following 34-36 hours, the eggs mature naturally with the effect of this injection. At the end of the maturation period, the woman is given light sedation and egg cells are collected one by one from all follicles. This process takes about 15-30 minutes.
Microinjection: The eggs are surrounded by nutrient cells called cumulus, which protect but also attract sperm. To make microinjection possible, it is necessary to begin by removing the cumulus by enzymatic digestion. The advantage of this technique is that the maturity of the eggs can be observed and only mature eggs with polar bodies can be selected.
Sperm selection is another stage of the microinjection technique. It is necessary to maximize the success of fertilization and to obtain a quality embryo. Sperm are selected by the embryologist based on the quality of different parameters such as head shape or flagella length.
When all preparations for the microinjection process are completed, the sperm are placed into the egg with the help of a small needle. From this period, embryo formation stages are followed. After a period of 3 to 5 days, the embryos can be transferred to the mother's womb.
Embryo development: While some of the embryos continue to develop in the following days, the development of some embryos ends. Continuing embryos are classified according to their morphology and division. Priority should be given to the transfer of quality embryos to increase the chances of success.
Embryo transfer: In the transfer process, the best selected embryos are placed in the uterus with a special cannula. This process is painless and simple, there is no need for anesthesia. Stress and excessive activity should be avoided during the period following embryo transfer. In about 2 weeks, a pregnancy test can be done to determine if the woman is pregnant.
If quality embryos that are not transferred are available, embryo freezing may be preferred. Thus, if another child is desired or the procedure fails, embryo transfer can be started without the need for many stages of IVF treatment.
What is the microinjection success rate?
Microinjection is the most important method that increases the chance of success in IVF treatment. Although the chances of success vary according to the age of the woman, the quality of the embryo and the type of infertility, the overall rate is between 29% and 35%.
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