Abnormally formed sperm is known as Teratozoospermia. The sperm may have, for example an abnormally formed head which may then prevent the sperm from penetrating the shell (zona) of the egg to enable fertilisation to occur.

In some samples there may be no sperm present in the ejaculate. There can be a variety of reasons for an absence of sperm known as Azoospermia.

There may be a blockage of the tubules that carry the sperm from the testicles to the penis.
The passages themselves may not have developed so sperm cannot be transported. This is known as absence of the vas deferens. If the latter is diagnosed then genetic counselling may be offered as there can be a high risk of males with this diagnosis carrying cystic fibrosis.
In some cases sperm may be produced but in low numbers, and therefore not seen in the semen sample.
The male may have had a vasectomy performed which means that the passages that carry the sperm have been severed.

<Previous | Next >| Pages 1, 2, 3, 4

return to top of male infertility page