Ductus deferens !

The ductus deferens (vas deferens) is the firm tube that carries sperm from the epididymis up through the groin to the prostate; it is cut in a vasectomy.

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What it is

A firm muscular tube, about 30-45 cm long, from the epididymis up in the spermatic cord, through the inguinal canal, then along the side wall of the pelvis and behind the bladder to the prostate. It crosses over the ureter.

What it does

Moves sperm forward with strong contractions at ejaculation; its widened end (ampulla) stores sperm.

Key facts

Where: From the epididymal tail up the spermatic cord and inguinal canal, hooks round the inferior epigastric artery at the deep ring, down the pelvic wall, over the ureter, behind the bladder to the ampulla
Blood supply: Artery to the ductus deferens, usually from the superior vesical artery (varies: inferior vesical); anastomoses with the testicular artery
Nerve: Sympathetic fibres via the pelvic plexus (T10–L2); drive the peristalsis of emission
Function: Moves sperm by strong peristalsis at emission; the ampulla stores sperm; felt as a firm cord in the scrotum and divided in vasectomy

Relations

Superficial: In the scrotum and inguinal canal, the coverings of the spermatic cord, inside which it lies behind the vessels
Below: Near the bladder, the ureter, which it crosses from above
Behind: Behind the bladder, its ampulla lies medial to the seminal vesicle and in front of the rectum

How to find it

At the neck of the scrotum the spermatic cord is held between thumb and fingers; the ductus deferens is the firm, smooth, string-like tube at its back, distinct from the soft veins.

On imaging

Scrotal ultrasound shows it in the spermatic cord as a straight tube with a thick muscular wall and a tiny lumen; transrectal ultrasound shows its ampulla behind the bladder beside the seminal vesicle. In an infertile man, absence on examination and ultrasound points to congenital absence of the vas, linked to cystic fibrosis genes. Radiographs may show its walls calcified in diabetes.

Common problems

It can be injured in inguinal hernia repair.

How it is diagnosed

Felt in the scrotum as a firm cord; after a vasectomy, a semen analysis checks that no sperm remain.

Treatment

Vasectomy: both ducts are cut and closed through a small opening in the scrotum under local anaesthesia, as permanent contraception.
A vasectomy can be reversed by rejoining the duct (vasovasostomy), with variable success.

Clinical notes

Vasectomy divides and seals it through a small scrotal opening; sperm remain beyond the cut for a while, so semen analysis confirms success; reversal is possible but not always successful
Can be cut or tied by mistake in inguinal hernia repair, especially in children, where it is thin
Calcification of the ductus deferens on plain films is associated with diabetes

Anatomical variants

Congenital absence: on both sides with cystic fibrosis gene mutations; on one side, sometimes with an absent kidney on that side

Development

Derived from the mesonephric (Wolffian) duct, which also gives the ureteric bud; this explains its link with kidney anomalies.

Memory aid

'Water under the bridge': the ureter (water) runs under the ductus deferens (bridge).

Test yourself

Think of the answer, then tap the question to see it.

How is the ductus deferens identified in the spermatic cord, for example for vasectomy?

It is the firmest strand, a smooth string-like tube at the back of the cord, distinct from the soft veins.

Which structure passes under the ductus deferens near the bladder?

The ureter («water under the bridge»).

What is bilateral congenital absence of the ductus deferens linked to?

Cystic fibrosis gene mutations; it causes obstructive azoospermia.

Why is semen analysis needed after vasectomy?

Sperm remain beyond the cut in the ductus deferens for a while, so success must be confirmed.

What lies under the «triangle of doom» bounded by the ductus deferens and testicular vessels?

The external iliac vessels, at risk in laparoscopic groin surgery.

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Educational information, not medical advice. For any symptom, see a health professional.

Its names

Official Latin (TA2): ductus deferens
Official Spanish (DeCS): Conducto deferente
English (TA2): Ductus deferens
Also called: vas deferens · deferent duct

Sources: Anatomy, Abdomen and Pelvis, Male Genitourinary Tract.

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Representative model, for educational purposes only.