In men with very low sperm count or absent sperm in the ejaculate, it is necessary to perform a blood test to check levels of the hormones FSH, LH and testosterone. This test can help in telling us whether a man a blockage or the testicles are failing to produce sperm.
This is a genetic blood test to check the number and structure of our chromosomes (packages of DNA in our cells). Men with no or very low number of sperm in their ejaculate are advised to have a karyotype to exclude chromosomal abnormalities. About 7% of infertile men have an underlying chromosomal abnormality. The prevalence of such abnormality relates inversely to sperm concentration; the prevalence is 10%-15% in men with no sperm seen (azoospermia), approximately 5% in men with low sperm count (oligozoospermia) and less than 1% in men with normal sperm. Men with abnormal chromosomes will need genetic counselling. A genetic counsellor will explain the type of chromosomal abnormality and the implication of this abnormality on fertility, pregnancy outcome and children.
Cystic fibrosis screening
Congenital absence of the vas deferens (CAVD) is a syndrome in which a portion or all of the reproductive ducts (including the epididymis, vas and seminal vesicles) are missing. About 1%-2% of infertile men are born with this condition resulting in an obstruction to the passage of sperm. These sperm, which are being produced normally in the testicle, become “trapped” in the testicle for lack of a pathway to the ejaculate. CAVD may be associated with several diseases, including cystic fibrosis (CF) and malformations of the kidneys (renal malformations). 65% of men with CAVD will have a detectable genetic mutation in one of the cystic fibrosis genes, and 15% will have a missing or misplaced kidney. This does not imply that the man has or will develop cystic fibrosis but it means that he could be a carrier of the gene. If his spouse is also a carrier, this means that there is a 25% chance of a child born to them having cystic fibrosis.
An ultrasound scan of the scrotum can detect problems such as varicocele (varicose veins on the testicles) and hydrocele (liquid filled cysts on the testicles) which can affect sperm quality.