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Congenital Bilateral Absence of the Vas Deferens (CBAVD) is a condition present since birth in which the tubes that carry the sperm out of a man's testes (the vas deferens), fail to develop properly. This can cause male infertility because the sperm does not have a way to exit the body.
Men who have this condition may be able to father children through fertility treatments in which the sperm is retrieved surgically from the body.
Rates of CBAVD
CBAVD accounts for approximately 1 to 2 percent of all infertility in males. The Center for Male Reproductive Medicine and Microsurgery at Cornell University estimates that CBAVD is responsible for nearly 30 percent of obstructive azoospermia cases, which give men a zero sperm count.
Causes of CBAVD
CBAVD is the result of a genetic abnormality. More than half of the men with CBAVD carry a mutation on their CFTR gene. This is the same gene that causes cystic fibrosis, a progressive genetic disease that causes problems with the lungs and the pancreas.
Men who have CBAVD as a result of a mutation on the CFTR may be considered to have a mild form of cystic fibrosis, which is demonstrated only by the reproductive tract disorder, not with the respiratory or digestive problems that come with a more severe form of the disease.
If you have been diagnosed with azoospermia, a condition which results in a zero sperm count, your doctor will want to identify the cause of it.
Genetic testing is the only way to definitely diagnose CBAVD. Because the gene mutation that causes CBAVD is inheritable, it is important that both you and your partner undergo genetic testing and counseling. This can determine the risk of passing a CFTR mutation onto your child, or having a child with cystic fibrosis.
There is no surgical procedure to reconstruct the vas deferens. However, men can father children by undergoing sperm retrieval and ICSI and IVF.
Pregnancy and CBAVD
Sperm retrieval techniques can be used to help men with CBAVD father children through assisted reproduction technology. This type of sperm retrieval is called microsurgical epididymal sperm aspiration (MESA). In this technique, a surgeon makes an incision in the scrotum to retrieve sperm from the epididymis, the coiled tube that gives the sperm a place to mature. This results in sperm that can be used immediately for ICSI or that can be frozen.
Before IVF, you and your partner should utilize genetic testing to make sure that both of you do not carry the gene that causes cystic fibrosis. If you are both carriers, you may want to consider preimplantation genetic diagnosis (PGD), which can test for embryos that carry the gene before they are implanted.