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Male Factor Infertility

Male factor infertility can be caused by a number of different characteristics of the sperm. To check for these characteristics, a semen analysis is carried out, during which a sample of semen is obtained and examined under the microscope. The four most basic characteristics evaluated are: (1) Sperm count or the number of sperm present in a semen sample. The normal number of sperm present in just one milliliter (ml) of semen is over 20 million. A man with only 5-20 million sperm per ml of semen is considered subfertile, a man with less than five million sperm per ml of semen is considered infertile. (2) Sperm motility. Better swimmers indicate a higher degree of fertility, as does longer duration of survival. Sperm are usually capable of fertilization for up to 48 hours after ejaculation. (3) Sperm morphology or the structure of the sperm. Not all sperm within a specimen of semen will be perfectly normal. Some may be developmentally immature forms of sperm, some may have abnormalities of the head or tail. A normal semen sample will contain no more than 25% abnormal forms of sperm. (4) Volume of a representative semen sample. The semen is made up of a number of different substances, and a decreased quantity of one of these substances could affect the ability of the sperm to successfully fertilize an ovum.

The semen sample may also be analyzed chemically to determine that components of semen other than sperm are present in the correct proportions. If all of the above factors do not seem to be the cause for male infertility, then another test is performed to evaluate the ability of the sperm to penetrate the outer coat of the ovum. This is done by observing whether sperm in a semen sample can penetrate the outer coat of a guinea pig ovum; fertilization cannot, of course, occur, but this test is useful in predicting the ability of the patient's sperm to penetrate a human ovum.

Any number of issues can affect male fertility as evidenced by the semen analysis. Individuals can be born with testicles that have not descended properly from the abdominal cavity (where testicles develop originally) into the scrotal sac, or they can be born with only one testicle, instead of the normal two. Testicle size can be smaller than normal. Past infection (including mumps) can affect testicular function, as can a past injury. The presence of abnormally large veins (varicocele) in the testicles can increase testicular temperature, which decreases sperm count. A history of exposure to various toxins, drug use, excessive alcohol use, use of anabolic steroids, certain medications, diabetes, thyroid problems, or other endocrine disturbances can have direct effects on spermatogenesis. Problems with the male anatomy can cause sperm to be ejaculated not out of the penis, but into the bladder, and scarring from past infections can interfere with ejaculation.

Treatment of male factor infertility includes addressing known reversible factors first, for example discontinuing any medication known to have an effect on spermatogenesis or ejaculation, as well as decreasing alcohol intake and treating thyroid or other endocrine disease. Varicoceles can be treated surgically. Testosterone in low doses can improve sperm motility.

Some recent advances have greatly improved the chances for infertile men to conceive. Azoospermia (lack of sperm in the semen) may be overcome by mechanically removing sperm from the testicles either by surgical biopsy or needle aspiration (using a needle and syringe). The isolated sperm can then be used for in vitro fertilization. Another advance involves using a fine needle to inject a single sperm into the ovum. This procedure, called intracytoplasmic sperm injection (ICSI) is useful when sperm have difficulty fertilizing the ovum and when sperm have been obtained through mechanical means.

Other treatments of male factor infertility include collecting semen samples from multiple ejaculations, after which the semen is put through a process which allows the most motile sperm to be sorted out. These motile sperm are pooled together to create a concentrate which can be mechanically deposited directly into the female partner's uterus at a time that will coincide with ovulation. In cases where the male partner's sperm is proven to be absolutely unable to cause pregnancy in the female partner, and with the consent of both partners, donor sperm may be used for this process. These procedures (depositing the male partner's sperm or donor sperm by mechanical means into the female partner) are both forms of artificial insemination.

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Science EncyclopediaScience & Philosophy: Incomplete dominance to IntuitionismInfertility - Male Factor Infertility, Female Factor Infertility