The ductus deferens (plural: ductus deferentes), formerly known as the vas deferens (plural: vasa deferentia), forms part of the male internal genitalia where it transports sperm from the epididymis to the ejaculatory duct.

Terminology

In modern anatomic nomenclature, it is no longer referred to as the vas deferens as it may give the impression that the anatomical structure referred to is a vessel, although in classical Latin, vas may also refer to a duct ⁵! Confusingly the ligation of the ductus deferentes is still referred to as a vasectomy ⁷.

The pluralisation of ductus deferens is confusing to those without a classical education. Many may erroneously think that it is similar to the word humerus and humeri, second declension nouns, and therefore should be "ducti". However, ductus is a fourth declension noun which means that its plural form is still "ductus" ⁶. 

Gross anatomy

The ductus deferens is a paired 30-45 cm muscular small calibre tube that connects the epididymis to the ejaculatory duct ¹. 

Course

The ductus deferens is the continuation of the tail of the epididymis. It ascends along the medial side of epididymis posterior to the testis and runs in the posterior part of the spermatic cord through the scrotum, inguinal canal and into the abdominal cavity through the deep inguinal ring, where it is extraperitoneal.

After hooking around the interfoveolar ligament and the inferior epigastric artery at the deep inguinal ring, it crosses over the external iliac artery and vein, obliterated umbilical artery and the obturator nerve, artery and vein, lying on the obturator fascia and always being covered by peritoneum. 

It curves medially and forwards, crosses above the ureter and approaches its opposite fellow. The two ducts now turn downwards side by side and each dilates in a fusiform manner to form the ampulla, the storehouse of sperm. The ampulla lies parallel and medial to the seminal vesicles at their lower ends and fuses with the duct of the seminal vesicle to form the ejaculatory duct. Each ejaculatory duct passes through the prostate to open on the side of the urethral crest^1,2. 

Arterial supply

• artery of the ductus deferens from the superior vesical artery (branch of the anterior division of the internal iliac artery) 

Venous drainage

• veins from vas deferens join the vesical venous plexus which in turn drains into the internal iliac veins.

Lymphatic drainage

• drains to the external and internal iliac nodes

Innervation

• inferior hypogastric plexus

Variant anatomy

• artery of the ductus deferens from the inferior vesical artery, middle rectal artery, or directly from the internal iliac artery

• agenesis of the ductus deferens is rare and is commonly associated with other urogenital abnormalities such as seminal vesicle agenesis (bilateral or unilateral) and renal agenesis ²

• ductus deferens duplication ³

• ductus deferens diverticulum ⁴

• ductus deferens dystopy ⁴

Radiographic features

Plain radiograph

• it is not usually seen unless it is calcified; this occurs particularly in patients with diabetes mellitus

Ultrasound

• tubular structure medial to the seminal vesicle ²

CT

• tubular structures running posteriorly along the pelvic side wall ²

MRI

• T1 and T2: low signal tubular structure running from the deep inguinal ring to the ejaculatory duct ²

Related pathology

• ductus deferens cyst

• ductus deferens calcification

• obstruction of ductus deferens

• vasitis