Vas deferens are part of the male reproductive system. After the body makes sperm, it travels from the epididymis through the vas deferens. It is here the seminal vesicles meet with the sperm. The slippery milky colored substance visible in the semen is made up of seminal vesicles. When there are vas deferens problems, sometimes they go undetected until the man wishes to conceive.
The two main types of vas deferens problems are blockages and a congenital absence of vas deferens (CAVD). Men with blocked tubes physically have all their reproductive parts, there is simply a barrier blocking the sperm from entering the ejaculatory duct. Men with CAVD, however, are born without any vas deferens, as a congenital defect.
The only real significant problem of blocked vas deferens, or no tubes at all, is the inability to conceive without medical intervention. These men are considered infertile and can only father children through invasive measures.
Men with a congenital absence of vas deference are often born with a mutated CFTR gene, according to AccessDNA.com. This can be passed down from father to son. Blocked vas deferens are often caused by a previous injury, or surgery in the reproductive area. The damaged tissue or scaring can block the tubes.
If the vas deferens problems are due to a blockage, sometimes surgery can fix the problem. Those born without any vas deferens, however can still father biological children through Intracytoplasmic sperm injection and in vitro fertilization, according to FertilityFactor.com. In both cases, there are healthy sperm that simply can't make it out of the penis. Harvesting the sperm is necessary for conception.
Over half of all men with CAVD have a genetic CFTR mutation, according to AccessDNA.com. Unfortunately, Cystic fibrosis is caused by mutations of the same gene. This means men who choose to attempt fertility treatment should get genetic testing because they could father a child with cystic fibrosis.