Men with an absent vas deferens ( the tube which carries the sperm from the epididymis to the urethra ) have azoospermia, with a low volume ejaculate; acidic pH; and no fructose in the semen. This is because their seminal vesicles are also absent. The vas deferens is absent from birth, this being a congenital defect, but one which is diagnosed only when they are trying to conceive.
This diagnosis can be suspected by analysing the semen analysis report carefully. It is easy to confirm this with a clinical examination. This needs to be done by a careful clinician, and shows that the man has normal testes; the epididymis is often full and turgid ( because it is full of sperm); and the vas ( which normally feels like a hard cord like structure above the epididymis) cannot be felt at all. Unfortunately, this diagnosis is often missed, and these patients are subjected to an unnecessary testis biopsy !
For more than half of all men with this condition , the problem is genetic and they have mutations in the CFTR gene. Mutations in this gene also cause cystic fibrosis.
You can have genetic tests done to see if you have a mutation of the CFTR gene ; and if both you and your wife have the mutation, you may need genetic screening of your embryos to ensure they do not have cystic fibrosis.
Conventional treatment in the past consisted of creating a pouch surgically, into which the epididymis was made to open. This was called a spermatocele and sperms were aspirated from this and used for artificial insemination. However, pregnancy rates were very poor. The technique of PESA with ICSI has revolutionised our approach to these men, and allows nearly all of them to father a pregnancy with their own sperm.