Congenital Absence of the Vas Deferens is a relatively rare condition in the population at large but not uncommon in the male factor fertility subpopulation.
It results from abnormalities taking place in the developing male fetus. It may occur on one side or both sides. The vas deferens connects the sperm producing testicles to the ejaculatory ducts, seminal vesicles and the penis. Therefore, if there is absence of the vas on both sides, the male will present with infertility and azoospermia.
There are two main subgroups of patients. The larger group (~ 60 – 70% of cases), is associated with cystic fibrosis and occurs because of a mutation in the CFTR gene. It is therefore important to evaluate any patient suspected of having this condition, for carrier status as it relates to Cystic Fibrosis. The smaller group (30 -40% of cases) is associated with Unilateral Renal Agenesis (absence of the kidney on one side). This occurs due to similar embryologic origins of both the renal and the genital systems.
The diagnosis is established by history (infertility), scrotal exam (palpable absence of the muscular vas deferens but normal sized testes) and hormone testing (normal FSH, LH, Testosterone and Prolactin levels and possible carrier status for Cystic Fibrosis). If necessary, scrotal ultrasonography or trans rectal ultrasonography may be useful in detecting unilateral or bilateral absence of the vas as these tests may demonstrate visible abnormalities or agenesis of the epididymis, seminal vesicles, or a kidney.
If the diagnosis of CAVD is established, patients are usually treated with IVF, Testicular Sperm Extraction (TESE) to harvest sperm and ICSI (IntraCytoplasmic Sperm Injection) and favorable results can be obtained. It is usually not possible to do IUI (Intra Uterine Insemination), because although sperm are usually recovered by TESE, they are insufficient in number to perform IUI. It is important to provide genetic counselling to intended parents with CAVD, to address risks of Cystic Fibrosis or Renal Agenesis in the resulting offspring. Further, both intended parents should be tested for carrier status of Cystic Fibrosis because if present, Pre Implantation Genetic Screening of embryos is important to ensure unaffected embryos are transferred back.
Fortunately, nowadays patients who have CAVD can have optimistic expectations of successful reproduction.