The ejaculatory duct is a short passageway inside the prostate gland that delivers sperm and seminal fluid into the urethra during ejaculation. There are two of them, one on each side, and each is only about 15 to 23 millimeters long. Despite their small size, these ducts play a critical role in male fertility because they serve as the final merging point for sperm and the nutrient-rich fluid that makes up most of semen.
Where It Forms and What It Connects
Each ejaculatory duct forms at the junction of two structures: the vas deferens and the seminal vesicle duct. The vas deferens is the long tube that carries sperm upward from the testicle. Near the base of the bladder, it widens into a section called the ampulla, and there it joins with the duct leading out of the adjacent seminal vesicle. That junction creates the ejaculatory duct.
From that point, the duct enters the prostate gland. Cadaveric studies published in The Journal of Urology show that it first runs along the back surface of the prostate for about 10 to 15 millimeters, then angles sharply forward (roughly 75 degrees) and penetrates deeper into the prostate tissue for the final 5 to 8 millimeters. It empties into the prostatic urethra, the portion of the urethra that passes through the prostate, at a small raised area called the verumontanum.
What the Ejaculatory Duct Does
The duct’s job is straightforward but essential: it channels both sperm and seminal vesicle fluid into the urethra at the moment of ejaculation. The seminal vesicles produce the majority of the liquid portion of semen, a thick, fructose-rich fluid that nourishes and helps transport sperm. As ejaculation begins, muscular contractions push sperm from the vas deferens and fluid from the seminal vesicles through each ejaculatory duct simultaneously. Once this mixture enters the prostatic urethra, it combines with additional secretions from the prostate gland itself, forming the final semen that exits the body.
Because the ejaculatory duct is the only route for seminal vesicle fluid and sperm to reach the urethra, a blockage in even one duct can noticeably reduce semen volume and sperm count. A blockage in both ducts can cause near-complete absence of semen.
Ejaculatory Duct Obstruction
Ejaculatory duct obstruction (EDO) is the most clinically significant problem that affects these ducts. It can be present from birth or develop later in life. Congenital causes include being born without the ducts entirely or having ducts that are collapsed and nonfunctional. Acquired causes include stones (calculi) that form inside the duct, cysts that press on it from outside, scar tissue from pelvic surgery or urethral injury, chronic prostate inflammation, and repeated urinary tract infections.
Symptoms of a Blockage
The hallmark sign is unusually low semen volume. The World Health Organization’s 2021 reference manual sets the lower limit for normal semen volume at 1.4 milliliters. Men with EDO often produce less than 1.5 milliliters (roughly one-tenth of a tablespoon) per ejaculation, sometimes considerably less. Other common symptoms include:
- Low sperm count or no sperm in a semen analysis
- Infertility, typically identified after a year of trying to conceive
- Pain during or after sex, often felt deep in the pelvis or prostate area
- Blood in the semen (which may appear pink, red, or brown)
- Blood in the urine
Many men with EDO have no pain at all and only discover the problem during a fertility workup. A transrectal ultrasound is one of the primary tools used to visualize the ducts and look for cysts, stones, or dilation of the seminal vesicles that would suggest a downstream blockage.
How a Blockage Is Treated
The standard surgical approach for EDO is a procedure called transurethral resection of the ejaculatory ducts, or TURED. A thin scope is passed through the urethra to reach the area of the prostate where the ducts empty. The surgeon carefully opens the blocked ducts from the inside, restoring the pathway for semen to flow into the urethra.
To make the ducts easier to identify during surgery, doctors often inject a blue dye into the seminal vesicles through the skin under ultrasound guidance. When the surgeon sees the blue dye emerging during resection, it confirms the correct duct has been opened. At the end of the procedure, an imaging test called a vesiculography checks that both ducts are draining freely. The procedure is minimally invasive, performed through the urethra with no external incisions, and recovery is typically quick.
For men whose obstruction is caused by a cyst pressing on the duct from outside, draining or removing the cyst may be enough to restore normal flow without resecting the duct itself. In cases where surgical correction isn’t successful or isn’t an option, sperm can often be retrieved directly from the seminal vesicles or the reproductive tract and used for assisted reproduction.
Why It Matters for Fertility
Because the ejaculatory duct is the sole exit route for both sperm and seminal vesicle fluid, even a partial blockage can reduce fertility. Low semen volume means fewer sperm are delivered, and the sperm that do make it out may lack the supportive fluid they need to survive in the female reproductive tract. Complete obstruction of both ducts results in a condition called azoospermia, where no sperm appear in the ejaculate at all, even though the testicles are producing sperm normally.
This distinction matters because it means EDO is an obstructive, and therefore potentially correctable, cause of infertility. Unlike problems with sperm production itself, which can be much harder to treat, a mechanical blockage in the ejaculatory duct can sometimes be resolved with a single procedure, restoring natural fertility without the need for IVF or other assisted reproductive technologies.