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Preparing Sperm for IUI and ART
Before fertilization using IUI or ART can take place, the sperm must be collected and prepared for optimal chances for success. Sperm can be fresh or frozen in advance. Studies are reporting that frozen sperm provides excellent results and can be used confidently for fertilization procedures. A number of methods have been devised for this. It should be noted that in some cases of severely low sperm count, a biopsy is used to remove sperm from the testicles. If multiple incisions are required, the size of the testes may be reduced afterward and may even reduce androgen levels to the extent that replacement therapy may be needed. Men should be aware that success rates are lower than average in such cases. New techniques using needle aspiration may prove to be effective for sperm retrieval in some men and reduce such risks.
A sperm’s energy output is twenty times greater once it is removed from the seminal fluid, so researchers have devised methods for washing sperm that have a dramatic effect on the ability of sperm to move towards the egg. The simplest method involves mixing the sperm with nutrient fluid or culture media in a test tube and then centrifuging (spinning) it for about five minutes. The heavy sperm settle on the bottom, forming a dense button of millions of pure sperm. The fluid left on top is siphoned off. This procedure may be repeated again. This simple method of sperm washing, however, does not eliminate heavy debris, such as dead sperm, white blood cells, or bacteria.
The swim–up technique is not only a useful diagnostic procedure but also achieves the goal of removing sperm from semen. It is superior to sperm washing, because the live sperm will swim up to the culture media leaving behind most of the debris, although some may float up into the medium. The strongest sperm, which are those at the top of the medium, can be collected for in vitro fertilization or artificial insemination. A good swim test yields about 1/2 million very active sperm.
Percutaneous Epididymal Sperm Aspiration (PESA)
A technique called percutaneous epididymal sperm aspiration (PESA) uses a needle to obtain mature sperm from areas in the upper parts of the epididymis. PESA is useful in men with tubular obstruction and even in those with no vas deferens.
Other Methods of Separation
One technique uses a special device called a Jondet tube, which contains a doughnut–like plug at the bottom with the opening in the center forming a tiny well. The sperm are placed on the plug and a culture media is added to the tube. Active sperm attempt to swim off the plug and up into the culture media, but gravity pulls them into the well at the bottom of the tube from which they cannot escape. Another method uses layers of a very dense fluid called Percoll, which is centrifuged with the sperm and forces the best sperm to the bottom of the test tube.
A number of techniques can improve the ability of sperm to fertilize an egg. Injections of stimulants, such as caffeine, may enhance motility for a period of time. (No one has yet been able to show increased fertilization rates from this process, but the timing of the enhancement has not been perfected.) Calcium improves sperm cap citation and is sometimes added to the sperm washing solution, although like the stimulants, the precise degree of improvement is not clear. Sperm stored for 24 hours in a solution containing slightly heated egg yolk have a higher fertilization rate in IVF procedures Treatment with platelet activating factor (PAF) has also been shown to increase the penetration ability of sperm.