When a man has a severely low sperm concentration (less than 10 million sperm per cubic centimeter of semen) there is a chance that he may have a genetic cause for it. There are a few known genetic causes of very low or even no sperm production. If there are too many chromosomes in the nucleus of a cell, or some parts of a chromosome switch place with other parts of another chromosome, or if some parts of a chromosome are missing, low sperm counts or even no sperm counts may result. The test for the number or arrangement of chromosomes is called a karyotype test. Another test which looks for missing genes along the Y chromosome (the male determining chromosome) is called a Y chromosome micro deletion test. There are also genes which may cause a blockage of the sperm from leaving the testicle. These genes can also cause cystic fibrosis and the test for these genes is called a Cystic Fibrosis Mutation Panel. These are all blood tests. The importance of genetic testing is that it not only allows the patient and the doctor to understand the cause of the man’s severe infertility, but it also provides important information which may help protect a baby from harm. Men with genetic causes for infertility usually require in-vitro fertility with intracytoplasmic sperm injection to father a child. In many cases, the genetic abnormality which caused the man to be infertile will cause the mans child to be infertile if it is a male. Less commonly, the genetic condition may have much worse results in a child such as physical and mental impairment. If a man has a cystic fibrosis gene mutation and the woman is a carrier their child can be born with full-blown cystic fibrosis. For these men, genetic screening of the woman is just as important as screening of the man. Preimplantation genetic screening of embryos during an in-vitro fertility cycle can often screen out embryos that are at risk for these problems and allow healthy, unaffected embryos to be selected. Current genetic tests are only able to recognize those abnormal genes that we know about. There may be other genetic causes of male infertility that we have yet to discover and until that time, the genetic tests that are available now will not reveal those causes of male infertility.
The physical examination of the male should include a careful evaluation of the genitals. The size and consistency of the testicles often correlate with the amount of sperm production happening and can help distinguish between a blockage and poor production. The presence of abnormal veins in the testicles is a known cause of male infertility and is detected on a careful examination of the scrotum. Some men are born without one or both vas deferens and this can only be diagnosed with a careful exam of the scrotum because there is no x-ray that can reliably show the absence of such a small structure. Tumors of the testicle may be discovered only when a patient is having trouble getting his wife pregnant and if the man is not examined it could be missed until it has already spread. Prostate infection may be detected on a physical exam. Even a pituitary tumor or thyroid abnormality can be discovered. A physical exam can reveal signs of hormonal imbalances such as gynecomastia, an abnormal enlarging of the male breast tissue, or abnormalities in the shape of the man’s pelvis or of the distribution of his body hair.
Ultrasound evaluation of the testicles can be helpful in confirming the presence of abnormal veins or evaluating the testicles for the possible presence of a cancer. An ultrasound can provide a precise measurement of the size of the testicles and help the physician recognize if there has been actual deterioration of one or both of the testicles size. Ultrasound of the prostate can help the physician discover a blockage of the semen as it flows into the urethra at the level of the prostate. Surgical biopsy of the testicle may be required to determine if there is a blockage versus the testicle is failing to produce sperm. X ray studies with dye injected into the vas deferens or seminal vesicles (small glands next to the prostate) may be required to precisely locate the position of a blockage.