What is absence of the vas deferens?Men who have an absence of the vas deferens are missing part of the tube that sperm travel along after they leave the testes. These tubes do not grow or they degenerate in early life and the men are infertile, as sperm cannot pass from the testis into the ejaculate. Men born with this problem, known as congenital absence of the vas deferens (CAVD), are usually missing both their vas deferens and two thirds of their epididymis.
 More information: Male Infertility
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How does CAVD occur?CAVD is a genetic problem. The most common cause is a genetic change or mutation in the gene called the ‘cystic fibrosis transmembrane regulator’ (CFTR). Men with CAVD do not have cystic fibrosis even though they have the genetic change associated with this disease. Cystic fibrosis is a serious condition that causes breathing and bowel problems from early life. Most men with severe cystic fibrosis have absence of the vas deferens. Back to top
What is absence of the seminal vesicles?Very rarely the seminal vesicles do not develop. This problem usually occurs with congenital absence of the vas deferens. The prostate and seminal vesicles provide about 90 per cent of the fluid in the ejaculate, so absence of the seminal vesicles can cause a smaller amount of ejaculate (usually about 0.5 ml, normal men > 2 ml). The seminal vesicles also contribute to making the ejaculate alkaline, so when they are absent the acidity of the ejaculate is increased. Back to top
How is absence of the vas deferens and seminal vesicles overcome?At this stage there are no treatments that will overcome CAVD.
Intracytoplasmic sperm injection (ISCI), is usually needed if men wish to have a family. When the vas deferens and seminal vesicles are missing, it is usually possible to collect sperm directly from the testis or from the small remaining part of the epididymis and achieve pregnancies using assisted reproductive technologies.
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What are other considerations for men with CAVD?Due to the genetic basis of this problem, both the man and his partner must have a blood test to check for changes in the CFTR gene, before starting assisted reproduction treatments. If both partners have CFTR mutations, then there is a one in four chance of severe cystic fibrosis in their children. It may be possible to test the fertilised eggs, using a technique known as preimplantation genetic diagnosis (PGD). Only the embryos that are not affected by the CFTR mutations are transferred to the woman’s uterus.
 Download: Male Infertility fact sheet PDF (61kb)
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