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PubMed This is a summary of 15 peer-reviewed journal articles Updated
Urology · Congenital Bilateral Absence of the Vas Deferens

Diagnostics and Semen Analysis in CBAVD

At a Glance

CBAVD is primarily diagnosed using a combination of physical examinations, scrotal and renal ultrasounds, and a specific semen analysis signature. Men with CBAVD typically have semen that lacks sperm (azoospermia), has a very low volume, is highly acidic, and completely lacks fructose.

Diagnosing Congenital Bilateral Absence of the Vas Deferens (CBAVD) is a multi-step process that often begins with a routine semen analysis. While the absence of sperm is the most obvious sign, the chemistry and volume of the fluid itself provide the most critical clues [1].

The “Signature” of a CBAVD Semen Analysis

In a typical male, the seminal vesicles (two small glands near the bladder) provide about 65–75% of the total ejaculate volume [2]. This fluid is naturally alkaline (high pH) and rich in a sugar called fructose, which provides energy for sperm [2][3].

Because the vas deferens and the seminal vesicles develop from the same embryonic tissue, men with CBAVD often have seminal vesicles that are either missing, very small (hypoplastic), or blocked [4][5]. This leads to a very specific “signature” in your lab results:

  • Azoospermia: A total absence of sperm in the ejaculate [6].
  • Low Volume: The total amount of fluid is usually less than 1.5 mL (often much less) because the seminal vesicles aren’t contributing their share [1][7].
  • Acidic pH: Because the alkaline fluid from the seminal vesicles is missing, the naturally acidic secretions from the prostate dominate the mix. The pH is typically below 7.0 [1][2].
  • Absent Fructose: Fructose is produced specifically by the seminal vesicles. If it is missing from the lab report, it strongly suggests the seminal vesicles are missing or disconnected [1][8].

Physical Examination and Palpation

The most direct way a urologist suspects CBAVD is through a physical exam. By carefully feeling the scrotum (palpation), a specialist can often determine if the vas deferens is present [1][9].

In a standard exam, the vas deferens feels like a firm, spaghetti-like cord. In men with CBAVD, the doctor will find that this cord is entirely missing on both sides [6]. While this is a foundational diagnostic step, it is usually confirmed with imaging and lab work to be certain [1].

Diagnostic Imaging

Imaging helps the medical team “see” the internal anatomy that cannot be felt during an exam.

Scrotal Ultrasound

A scrotal ultrasound uses sound waves to create a map of your reproductive organs. In CBAVD, this tool is highly sensitive (approaching 100%) for identifying:

  • The absence of the vas deferens [10].
  • Abnormalities in the epididymis (the coil where sperm mature), such as swelling or “looping” caused by the blockage [10][11].

Renal (Kidney) Ultrasound

Because the reproductive system and the urinary system develop together in the womb, men missing their vas deferens have a higher chance of also missing a kidney (unilateral renal agenesis) [12]. A transabdominal ultrasound of the kidneys is a standard recommendation to ensure your urinary system is fully functional [12][13].

Confirmation Checklist

To confirm a diagnosis of CBAVD and prepare for future family planning, the following tests are generally required:

  1. Semen Analysis (Repeat): To confirm azoospermia, low volume (<1.5mL), and acidic pH (<7.0) [1].
  2. Semen Fructose Test: To check for the absence of seminal vesicle secretions [8].
  3. Physical Exam: Expert palpation of the scrotum to confirm the vas is not feelable [1].
  4. Scrotal Ultrasound: To visualize the epididymis and confirm the absence of the vas deferens [10].
  5. Genetic Screening: Testing for CFTR mutations is essential for all men with CBAVD [14][15].
  6. Renal Ultrasound: To check for the presence of both kidneys [12].

Common questions in this guide

What does a CBAVD semen analysis look like?
A typical CBAVD semen analysis shows zero sperm (azoospermia), a total fluid volume of less than 1.5 mL, an acidic pH below 7.0, and a complete lack of fructose. This specific combination strongly points to missing or blocked seminal vesicles.
Why is fructose absent in my semen analysis?
Fructose is a sugar naturally produced by the seminal vesicles to give sperm energy. If it is missing from your lab report, it strongly indicates that your seminal vesicles are either missing, underdeveloped, or blocked, which frequently happens alongside CBAVD.
Why do I need a kidney ultrasound if I have CBAVD?
The male reproductive system and urinary system develop together in the womb. Men born without a vas deferens have a much higher chance of also being born missing one kidney, making a renal ultrasound a standard safety precaution.
How does a doctor physically check for a missing vas deferens?
During a physical exam, a urologist will carefully feel your scrotum. Normally, the vas deferens feels like a firm, spaghetti-like cord. In men with CBAVD, the doctor will notice that this cord is entirely missing on both sides.
Will I need genetic testing if I am diagnosed with CBAVD?
Yes, genetic testing is an essential part of the diagnostic process. You will be tested for CFTR gene mutations, which are the primary genetic driver for men born without a vas deferens.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Can you explain exactly what you felt (or didn't feel) during the physical exam of my scrotum?
  2. 2.Does my low semen volume and acidic pH confirm that my seminal vesicles are also missing or blocked?
  3. 3.Since my fructose level was absent, does that point specifically to CBAVD rather than a different kind of blockage?
  4. 4.Will the scrotal ultrasound look specifically at my epididymis for any 'looping' or dilation?
  5. 5.If we find a CFTR mutation, does that change the way we approach sperm retrieval?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (15)
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    The impact of male factors and their correct and early diagnosis in the infertile couple's pathway: 2021 perspectives.

    Pallotti F, Barbonetti A, Rastrelli G, et al.

    Journal of endocrinological investigation 2022; (45(10)):1807-1822 doi:10.1007/s40618-022-01778-7.

    PMID: 35349114
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    Seminal vesicle status and its association with semen parameters in congenital bilateral absence of the vas deferens (CBAVD).

    Shamohammadi I, Haghpanah A, Eslahi A, et al.

    Basic and clinical andrology 2025; (35(1)):24 doi:10.1186/s12610-025-00267-0.

    PMID: 40533736
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    Congenital bilateral absence of the vas deferens (CBAVD) with bilaterally present seminal vesicles.

    Lin CH, Huang TY

    Urology case reports 2020; (31()):101131 doi:10.1016/j.eucr.2020.101131.

    PMID: 32257817
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    Prevalence of CBAVD in azoospermic men carrying pathogenic CFTR mutations - Evaluated in a cohort of 639 non-vasectomized azoospermic men.

    Fedder J, Jørgensen MW, Engvad B

    Andrology 2021; (9(2)):588-598 doi:10.1111/andr.12925.

    PMID: 33095972
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    Cystic fibrosis transmembrane conductance regulator (CFTR) gene abnormalities in Indian males with congenital bilateral absence of vas deferens & renal anomalies.

    Gajbhiye R, Kadam K, Khole A, et al.

    The Indian journal of medical research 2016; (143(5)):616-23 doi:10.4103/0971-5916.187110.

    PMID: 27488005
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    Compound heterozygous mutations in CFTR causing CBAVD in Chinese pedigrees.

    Yang B, Wang X, Zhang W, et al.

    Molecular genetics & genomic medicine 2018; (6(6)):1097-1103 doi:10.1002/mgg3.486.

    PMID: 30450785
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    Clinical and Laboratorial Evaluation of Male Infertility. A Detailed Practical Approach.

    Fraga LG, Gismondi JP, Sanvido LV, et al.

    Archives of medical research 2024; (55(8)):103139 doi:10.1016/j.arcmed.2024.103139.

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    Genetic analysis and intracytoplasmic sperm injection outcomes of Chinese patients with congenital bilateral absence of vas deferens.

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    Journal of assisted reproduction and genetics 2022; (39(3)):719-728 doi:10.1007/s10815-022-02417-z.

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    Epididymal Appearance in Congenital Absence of Vas Deferens.

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    Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine 2021; (40(6)):1085-1090 doi:10.1002/jum.15500.

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    Scrotal Ultrasonic Features of Congenital Bilateral Absence of Vas Deferens.

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    Ultrasonography in Diagnosis of Congenital Absence of the Vas Deferens.

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    PMID: 27458088
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    Unilateral Kidney Agenesis and other Kidney Anomalies in Infertile Men with Congenital Bilateral Absence of Vas deferens: A Cross-Sectional Study.

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    International journal of fertility & sterility 2022; (16(3)):152-155 doi:10.22074/ijfs.2021.535148.1166.

    PMID: 36029049
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    Congenital absence of vas deferens: Anatomical and embryological inputs from a series of autopsies reported in Europe throughout the 18th and 19th century.

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This page explains CBAVD diagnostic tests and semen analysis for educational purposes. Always discuss your specific lab results and imaging with a qualified urologist or fertility specialist.

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