CBAVD: What It Means, What Causes It, and How People With CBAVD Have Biological Children
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick answer
CBAVD is a condition present at birth where both vas deferens tubes never form, so sperm cannot enter semen. [1] [3] It accounts for 1% to 2% of male infertility and is most often caused by a CFTR gene mutation. [1] [3] [4] It does not affect sex drive, and sperm extraction plus IVF can make biological fatherhood possible. [1] [3]
What the research says
According to PubMed:
Sperm retrieval worked in every man with CBAVD in one series. In 146 men with obstructive azoospermia, sperm retrieval succeeded in 100% of the 32 men with CBAVD, and live birth rates after ICSI were similar across causes: 34.4% for CBAVD, 32.2% after vasectomy, and 36.4% after prior infection. (Esteves et al., Journal of Urology, 2013) [6].
The father's age affected ICSI success. In 85 men with CBAVD who had percutaneous epididymal sperm aspiration with ICSI, clinical pregnancy rates were 55.5%, 43.7%, and 23.1%, and "take-home baby" rates were 48.1%, 40.6%, and 11.5%, for men under 30, aged 30–40, and over 40. (Elhanbly et al., Fertility and Sterility, 2015) [7].
Live birth rates varied widely in a review of CFTR-related CBAVD. The review found both epididymal and testicular sperm extraction to be viable options, with live birth rates of 8% to 50% in most small retrospective series and no clear difference in live birth rate or complications between techniques. (Persily et al., Translational Andrology and Urology, 2021) [8].
What is CBAVD?
Congenital bilateral absence of the vas deferens — usually shortened to CBAVD — is when the tubes that carry sperm out of your testicles (the vasa deferentia; singular, vas deferens) don't form as expected during fetal development. [1] In most cases, your testicles still make healthy sperm. [1] [4] But without both vas deferens, your sperm can't mix with your semen. [1] This affects your ability to have a biological child (male infertility).
While a CBAVD diagnosis may provide answers to fertility 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. Here's what the words mean:
Word | What it means |
|---|---|
Congenital | The condition is present at birth [1] |
Bilateral absence | Bilateral relates to both sides of paired organs; absence means it isn't present on either side [1] |
Vas deferens | Part of the male reproductive system; most people have one on each side, leading from each testicle, and it transports mature sperm to the urethra before ejaculation [1] |
In other words, this means you don't have a vas deferens on either the left or the right side.
What causes CBAVD?
Congenital bilateral absence of the vas deferens (CBAVD) has two primary causes: mutations in the CFTR gene, which cause most cases, and unilateral renal agenesis. [1]
Genetic mutations in the CFTR gene
A mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene is the primary cause of most CBAVD cases. [1] [4] It's the same gene that causes cystic fibrosis. [1]
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. [1] [3]
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. [1] [3]
CFTR mutations follow an autosomal recessive pattern. That means you must inherit the same mutated gene from both of your biological parents in order to develop CBAVD. [1] [3]
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, and it may also affect the formation of vasa deferentia. [1]
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. [1]
What are the 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). [1] [2] It won't cause low libido (sex drive) or affect your ability to ejaculate. [1] You likely won't realize you have CBAVD until you try to conceive a biological child, and your partner won't get pregnant. [1]
Other symptoms may include:
How is CBAVD diagnosed?
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. [1] If they can't feel either vas deferens, they'll order additional tests to help confirm the diagnosis:
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. [1] [4] ICSI is a type of in vitro fertilization (IVF). [1]
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. [1]
What's the difference between CBAVD and CUAVD?
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. [1]
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. [1] Schedule an appointment with a therapist if CBAVD causes feelings of depression, stress, grief, or inadequacy. [1]
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. [1]
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:
What's the outlook?
There's no cure for CBAVD. But you likely won't have any pain or discomfort. [1] 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. [1]
Can CBAVD be prevented?
Because CBAVD is present at birth, there's no way to prevent it. [1] If you have a gene mutation associated with CBAVD, talk to a healthcare provider about prenatal genetic testing. They can help determine the chances that your biological children will have CBAVD. [1]
What questions should I ask my provider?
During a CBAVD appointment, you may wish to ask about confirmatory tests, treatment needs, IVF success rates, the odds of passing CBAVD on and available support.
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?
Can you recommend a therapist or CBAVD support group?
What's the bottom line?
CBAVD is a condition present at birth in which the tubes that carry sperm out of the testicles never form on either side, so sperm can't enter semen — even though the testicles usually still produce healthy sperm. It accounts for 1% to 2% of male infertility cases, is most often tied to a CFTR gene mutation, and never affects sex drive or ejaculation. There's no cure and no pain or discomfort, and the only reason to seek treatment is a wish for biological children. For that, modern medicine offers a real path: sperm extraction through microTESE combined with IVF and ICSI, supported by genetic counseling for the next generation. And for couples who choose a different route, adoption remains a meaningful and valuable way to grow a family.
Ready to learn more? Visit Rinnit.com for trusted, easy-to-understand health guides like this one.
Conclusion
CBAVD answers a difficult question many couples face — why conception isn't happening — with a clear, physical explanation: the transport tubes for sperm never formed, even though sperm production itself is usually normal. Understanding the genetics behind it, especially the CFTR connection, empowers couples to make informed choices about testing and treatment. With compassionate care, genetic counseling, and advanced reproductive technology, many men with CBAVD go on to become biological fathers, and those who choose other paths find fulfillment there, too.
Find more compassionate, plain-English health guides at Rinnit.com.
Frequently Asked Questions
What is CBAVD?
Congenital bilateral absence of the vas deferens (CBAVD) is a condition present at birth where the tubes that carry sperm out of the testicles (vasa deferentia) don't form as expected during fetal development. As a result, sperm can't mix with semen, which prevents getting a partner pregnant through unprotected sex.
Is CBAVD the same as not making sperm?
No. In most cases, the testicles still make healthy sperm. The problem is the missing tubes, not sperm production.
Does CBAVD affect my sex drive or ability to have sex?
No. CBAVD won't cause low libido (sex drive) and doesn't affect your ability to ejaculate.
How common is CBAVD?
CBAVD isn't common — it accounts for between 1% and 2% of all cases of male infertility.
What causes CBAVD?
There are two primary causes. Most cases come from a mutation in the CFTR gene (the same gene that causes cystic fibrosis). Other cases are linked to unilateral renal agenesis — a condition where one kidney is missing at birth due to a gene change that can also affect the formation of the vasa deferentia.
How does the CFTR gene cause CBAVD?
The CFTR gene makes a protein that acts as an ion channel — like a gate in the cell's membrane. Normally, when chloride moves out of the cell, water follows, which thins mucus. With CFTR mutations, this gate doesn't work, mucus stays thick and sticky, and that thick mucus blocks the vasa deferentia and prevents them from forming.
Is CBAVD inherited?
Often, yes. CFTR-related CBAVD follows an autosomal recessive pattern, meaning you must inherit the same mutated gene from both biological parents. The renal agenesis form follows an autosomal dominant pattern, where inheriting the mutation from just one parent can cause it.
What are the symptoms of CBAVD?
The primary symptom is the absence of sperm in semen (azoospermia) or a lower sperm count than expected (oligospermia). You likely won't realize you have CBAVD until you try to conceive and your partner won't get pregnant.
Does CBAVD cause pain?
No — you likely won't have any pain or discomfort from CBAVD. There's no cure, but treatment is only needed if you wish to have biological children.
Can CBAVD be linked to other health problems?
Yes. People with CBAVD have a greater risk of having cystic fibrosis, so they may also have CF symptoms such as chronic pancreatitis, respiratory diseases like COPD and bronchitis, and frequent sinus infections. CBAVD can also appear alongside the absence of one kidney, absence of the seminal vesicles, or a normal FSH hormone level.
How is CBAVD diagnosed?
Diagnosis usually begins with a semen analysis. If it shows no sperm and CBAVD is suspected, a provider examines you physically — feeling for the vasa deferentia in the scrotum. If neither can be felt, imaging tests (ultrasound, CT, or MRI) and CFTR genetic testing help confirm the diagnosis.
How is CBAVD treated?
You don't necessarily need treatment. If you'd like biological children, microsurgical testicular sperm extraction (microTESE) plus assisted reproductive technology such as ICSI — a type of IVF — can allow your sperm to fertilize an egg. If you choose not to treat CBAVD, adoption is a valued path to parenthood.
What is microTESE?
Microsurgical testicular sperm extraction (microTESE) is a procedure that retrieves sperm directly from the testicles for use with assisted reproductive technology.
What is ICSI?
Intracytoplasmic sperm injection (ICSI) is a type of in vitro fertilization (IVF) in which a single sperm is injected directly into an egg cell, allowing fertilization even when only small numbers of sperm are available.
Will I need treatment if I don't want biological children?
No. Treatment is only needed if you wish to have biological children. Many people with CBAVD choose adoption or other paths to parenthood instead.
Can CBAVD be prevented?
No — because CBAVD is present at birth, there's no way to prevent it. However, prenatal genetic testing can help determine the chances that your biological children will have CBAVD.
What is unilateral renal agenesis?
Unilateral renal agenesis (URA) is when you're missing one of your kidneys at birth, often caused by a gene mutation that interferes with kidney formation during the first trimester of pregnancy. The same gene change may also affect the formation of the vasa deferentia.
What is CUAVD?
Congenital unilateral absence of the vas deferens (CUAVD) is when you're missing only one vas deferens. With CUAVD, your semen will likely still contain sperm, and a semen analysis may not show anything unexpected.
What are the odds I'll pass CBAVD to my biological child?
That depends on your specific gene changes. Talk to a healthcare provider about genetic testing before using assisted reproductive technology — it can help determine the likelihood that your biological child will have CBAVD.
When should I contact a doctor?
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.
What should I do if CBAVD is affecting my mental health?
Schedule an appointment with a therapist. A CBAVD diagnosis and difficulties getting pregnant can cause feelings of depression, stress, grief, or inadequacy — and it's frustrating and isolating to live with a rare condition. Lean on your partner, trusted family members, and friends for support, and ask your provider about therapy or a CBAVD support group.
When should I go to the ER?
If you have CBAVD and cystic fibrosis, go to the nearest emergency room for breathing problems or signs of a severe infection: difficulty breathing, bluish skin, lips, or nails (cyanosis), fever over 103°F (39.4°C), or a cough or fever that goes away and comes back.
Can I join a clinical study for CBAVD?
Ask your healthcare provider whether any CBAVD clinical studies exist and whether you can participate.
This article is for general informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the guidance of your physician or other qualified health provider with any questions about a medical condition. Never disregard professional medical advice or delay seeking care because of something you have read here. If you or someone else has trouble breathing, a bluish tint to the skin or lips, or a high fever, call 911 or your local emergency number or go to the nearest emergency room immediately.
References
Cleveland Clinic. CBAVD (Congenital Bilateral Absence of the Vas Deferens). Cleveland Clinic. Last updated November 5, 2025. https://my.clevelandclinic.org/health/diseases/cbavd
Genetic and Rare Diseases Information Center (GARD), National Institutes of Health. Congenital bilateral absence of vas deferens. Genetic and Rare Diseases Information Center. Last updated June 2026. https://rarediseases.info.nih.gov/diseases/5461/congenital-bilateral-absence-of-vas-deferens
National Library of Medicine. Congenital bilateral absence of the vas deferens. MedlinePlus Genetics. Last updated October 1, 2018. https://medlineplus.gov/genetics/condition/congenital-bilateral-absence-of-the-vas-deferens/
Cai Z, Li H. Congenital bilateral absence of the vas deferens. Front Genet. 2022;13:775123. PMID 35222530. https://doi.org/10.3389/fgene.2022.775123
Lin CH, Huang TY. Congenital bilateral absence of the vas deferens (CBAVD) with bilaterally present seminal vesicles. Urol Case Rep. 2020;31:101131. PMID 32257817. https://doi.org/10.1016/j.eucr.2020.101131
Esteves SC, Lee W, Benjamin DJ, et al. Reproductive potential of men with obstructive azoospermia undergoing percutaneous sperm retrieval and intracytoplasmic sperm injection according to the cause of obstruction. J Urol. 2013;189(1):232-237. PMID 23174251. https://doi.org/10.1016/j.juro.2012.08.084
Elhanbly S, El-Saied MA, Fawzy M, et al. Relationship of paternal age with outcome of percutaneous epididymal sperm aspiration-intracytoplasmic sperm injection, in cases of congenital bilateral absence of the vas deferens. Fertil Steril. 2015;104(3):602-606. PMID 26144574. https://doi.org/10.1016/j.fertnstert.2015.06.020
Persily JB, Vijay V, Najari BB. How do we counsel men with obstructive azoospermia due to CF mutations? A review of treatment options and outcomes. Transl Androl Urol. 2021;10(3):1467-1478. PMID 33850781. https://doi.org/10.21037/tau-19-681
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