Structural Problems

One reason for male infertility stems from problems with the overall structure of the reproductive organs. If the reproductive organs have not been formed properly or there is some sort of damage to them, it can obstruct sperm from leaving the body or even prevent it from being produced in the first place.

Blockage

When sperm is not present in a man's semen because of a blockage somewhere along the tubes, it is known as obstructive azoospermia. There are various factors that can contribute to blocking the sperm from leaving the body during ejaculation. Any surgery done in the groin or abdominal area can lead to scar tissue forming on the reproductive organs. These adhesions can act as barricades to sperm preventing some or all of it from leaving the body.

Additionally, infections, such as one in the urogenital tract or a sexually transmitted infection, can also lead to damage and scarring of the reproductive organs, thereby blocking some or all of the sperm and seminal fluid from escaping.

Men who have had a vasectomy are also considered to have obstructive azoospermia. Since a vasectomy involves cutting a small part of the vas deferens in order to prevent sperm from joining semen, a vasectomy reversal is necessary to correct this blockage. This is usually done through surgery, whereby the vas deferens is stitched back together.

Congenital Defects

Some men are born with structural problems that will affect their fertility.

Undescended testicles

If both (but usually just one) testicles fail to descend from the abdomen to the scrotum before birth and if it is left untreated, there can be serious consequences to a man's health. Often, the testicle will descend on its own within the first few months after birth.

However, if it doesn't, it is usually recommended that parents have the problem corrected surgically around the first birthday. While this won't necessarily restore a male's chances of avoiding future fertility problems, left untreated, the testicle is likely to shrink and cause infertility. Additionally, an undescended testicle increases a man's risk of developing testicular cancer.

CAVD

Although it is rare, some men may be born without a vas deferens, which is known as congenital absence of vas deferens (CAVD). While the testicles function normally, the absence of the vas deferens means that the sperm is never able to join the ejaculate. However, the sperm is still generally healthy and in vitro fertilization (IVF) can occur through intracytoplasmic sperm injection (ICSI). It is recommended, though, that genetic testing be done on the sperm first as men with CAVD tend to be carriers of cystic fibrosis.

Hyposadias