We know that in general, women have only one egg to develop and grow each month, and it is very difficult to get that one egg. In order to solve this problem, almost all IVF centers nowadays apply drugs in the first place, so that women have 7 or 8 or a dozen or even dozens of follicles developing and growing at the same time each month. The development of the follicles can be very easily observed with a vaginal ultrasound. Once the follicles are mature, the eggs are present in the follicular fluid when the follicles are aspirated through a fine needle (less than 2 mm in diameter) via vaginal puncture under vaginal ultrasound monitoring and guidance. The eggs are located under a microscope and placed in a special egg culture solution. The husband ejaculates the sperm, usually by masturbation, into a sterile cup, washes it and selects the best moving sperm. The selected sperm and egg are then placed together (i.e. in the same test tube, nowadays flat dishes are mostly used, this is how IVF got its name) and the sperm relies on its own movement and burrows into the egg to achieve fertilization. The fertilization is observed under a microscope and the successfully fertilized and divided egg (once the fertilized egg starts to divide, it is called an embryo) is returned to the patient’s uterus with a very thin tube (this is called a transfer). This completes the entire process of IVF. This is why the IVF technique, also known as in vitro fertilization-embryo transfer (abbreviated as IVF-ET). We also know that a normal male ejaculates hundreds of millions of sperm, of which more than 50% can move forward (class A and B sperm), how many of these hundreds of millions of sperm can enter the uterus through the opening of the cervix and the fallopian tube through the opening of the fallopian tube to reach the site of fertilization (the abdomen of the fallopian tube)? There are only hundreds of sperm, and only one of these hundreds of sperm will eventually make it directly to the egg to complete fertilization. What a cruel natural selection. It can be imagined that only the fastest sperm can cross all the mountains and reach the destination, and it can also be imagined that for those men who have seriously low sperm count and motility, it is very slim to make their wives pregnant in a normal way: one is that no sperm can move to the fertilization site, and even if some sperm reach the fertilization site and come to the egg, but its motility is too weak and it can’t drill into the egg by itself. What should we do? With the development of modern science and technology, this problem can be solved very well: we take out the egg, put it under a microscope (200-400 times magnification), use a needle with a diameter of only 0.005 mm to suck in the sperm, then insert the needle into the egg and release the sperm, this is intracytoplasmic single sperm microinjection (ICSI).