CBAVD

Congenital bilateral absence of the vas deferens (CBAVD) is when the tubes that carry sperm out of your testicles (vasa deferentia; singular vas deferens) don’t form as expected during fetal development. In most cases, your testicles still make healthy sperm. But without both vas deferens, your sperm can’t mix with your semen. This affects your ability to have a biological child (male infertility).

CBAVD isn’t common. It accounts for between 1% and 2% of all cases of male infertility.

While a CBAVD diagnosis may provide answers to infertility problems, it can still have a negative impact on your thoughts and emotions. But having CBAVD doesn’t always mean you can’t have biological children. CBAVD can still allow you to become a parent to a biological child.

What does CBAVD mean?

Congenital bilateral absence of the vas deferens is a big term. But what do the words mean?

• Congenital: The condition is present at birth.
• Bilateral absence: Bilateral means it relates to both sides of paired organs. Absence means something isn’t present or doesn’t exist in both organs.
• Vas deferens: The vas deferens is part of the male reproductive system. Most people have vasa deferentia in their left and right testicles. The vas deferens transports mature sperm to your urethra before you ejaculate.

In other words, this means you don’t have a vas deferens in either your left or right testicles.

What causes CBAVD?

There are two primary causes of CBAVD.

Genetic mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene

A mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene is the primary cause of most CBAVD cases. It’s the same gene that causes cystic fibrosis.

The CFTR gene makes a protein that acts as an ion channel on the surface of a cell. Ion channels are like gates in a cell’s membrane that only let certain molecules pass.

CFTR usually has a gate for chloride ions. When chloride moves out of the cell, it takes water with it. This thins out mucus and makes it more slippery.

If you have genetic mutations in the CFTR gene, the gate doesn’t work as expected, so there’s no regulation of the chloride and water flowing in and out of your cells. As a result, the mucus stays thick and sticky. This thick, sticky mucus blocks your vasa deferentia and prevents them from forming.

CFTR mutations are an autosomal recessive pattern. That means you must inherit the same mutated gene from both of your biological parents in order to develop CBAVD.

Unilateral renal agenesis

Unilateral renal agenesis (URA) is when you’re missing one of your kidneys at birth. One of the main causes of URA is a gene mutation that interferes with kidney formation during the first trimester of pregnancy. It may also affect the formation of vasa deferentia.

URA is an autosomal dominant condition. That means you’ll have URA if you inherit a copy of the mutated gene from one of your biological parents.

Symptoms of CBAVD

The primary symptom of CBAVD is the absence of sperm in your semen (azoospermia) or a lower sperm count than expected (oligospermia). It won’t cause low libido (sex drive) or affect your ability to ejaculate. You likely won’t realize you have CBAVD until you try to conceive a biological child, and your partner won’t get pregnant.

Other symptoms may include:

• The absence of seminal vesicles
• The absence of one of your kidneys
• Low levels of follicle-stimulating hormones (FSH)
• Cystic fibrosis symptoms, including long-lasting (chronic) pancreatitis, respiratory diseases (such as chronic obstructive pulmonary disease and bronchitis) and sinus infections (sinusitis)

How doctors diagnose CBAVD

If your partner can’t get pregnant, a semen analysis is one of the primary tests healthcare providers use to help diagnose male infertility. If your semen analysis results show no sperm and a provider suspects CBAVD, they’ll perform a physical examination, including feeling for (palpating) the vasa deferentia in your scrotum. If they can’t feel either vas deferens, they’ll order additional tests to help confirm a CBAVD diagnosis. These tests may include:

• Imaging tests, including an ultrasound, CT scan or MRI
• Genetic testing (CFTR gene)

How is CBAVD treated?

If you have CBAVD, you don’t necessarily need treatment. But if you’d like to have biological children, microsurgical testicular sperm extraction (microTESE) and assisted reproductive technology (ART) such as intracytoplasmic sperm injection (ICSI) can allow your sperm to fertilize an egg cell. ICSI is a type of in vitro fertilization (IVF).

If you choose not to treat CBAVD but still wish to add a child to your family, there’s a lot of value in adoption.

When should I see my healthcare provider?

If you and your partner can’t get pregnant after a year of unprotected sexual intercourse, contact a healthcare provider. They can help diagnose CBAVD. Schedule an appointment with a therapist if CBAVD causes feelings of depression, stress, grief or inadequacy.

Talk to a healthcare provider about genetic testing if you and your partner decide to use assisted reproductive technology to get pregnant. Genetic testing can help determine the likelihood that your biological child will have CBAVD.

During your appointment, you may wish to ask:

• What tests will you order to confirm CBAVD?
• If I don’t want biological children, will I need treatment?
• What’s the IVF success rate for people with CBAVD?
• What are the odds that I pass CBAVD to my biological child?
• Are there any clinical studies for CBAVD?
• Can I participate in any CBAVD clinical studies?
• Can you recommend a therapist or CBAVD support group?

When should I go to the ER?

CBAVD sometimes appears alongside cystic fibrosis. If you have CBAVD and cystic fibrosis, go to the nearest emergency room if you have breathing (respiratory) problems or signs of a severe infection, including:

• Difficulty breathing
• Bluish skin, lips and/or nails (cyanosis)
• Fever over 103 degrees Fahrenheit (40 degrees Celsius)
• Cough or fever that goes away and comes back

What can I expect if I have CBAVD?

There’s no cure for CBAVD. But you likely won’t have any pain or discomfort. You only need treatment if you wish to have biological children.

If you have CBAVD, you’re at a greater risk of having cystic fibrosis.

Can it be prevented?

Because CBAVD is something that’s present at birth, there’s no way to prevent it. If you have a gene mutation that associates with CBAVD, talk to a healthcare provider about prenatal genetic testing. They can help determine the chances that your biological children will have CBAVD.

What is congenital unilateral absence of the vas deferens?

Congenital unilateral absence of the vas deferens (CUAVD) is when you’re missing only one vas deferens. If you have CUAVD, your semen will likely contain sperm; a semen analysis may not show anything unexpected.