Imaging Methods
To evaluate anatomical structures and detect pathologies of the excretory system, the following are used:
- TRUS (transrectal ultrasound).
- MRI (magnetic resonance imaging).
These methods allow for a detailed study of the seminal vesicles (vesiculae seminales), ejaculatory ducts (ductus ejaculatorii), ampullae of the vas deferens (ampullae ductus deferentis), and the prostate gland. If the obstruction is caused by a cyst in the region of the epididymis (epididymis), ultrasound will show enlargement of the epididymis itself proximal to the cystic mass.
Absence of the vas deferens
Congenital absence (agenesis) of the vas deferens (vas deferens) is an important cause of subfertility:
- Bilateral absence: detected in almost all men suffering from cystic fibrosis.
- Unilateral absence: occurs rarely (in 0.5% of men), but is often accompanied by unilateral renal agenesis.
Overall, agenesis of the vas deferens is associated with various renal anomalies (agenesis, pelvic kidney, or crossed dystopia) in 16–43% of cases.
Ejaculatory duct obstruction
Ejaculatory ducts are formed by the merger of the vas deferens and the duct of the seminal vesicle. They pass through the prostate gland and open into the urethra at the seminal colliculus (verumontanum).
Causes of their obstruction include:
- Congenital anomalies.
- Calculi.
- Post-infectious strictures.
- Compression by prostatic utricle cysts (utricle cysts) or Müllerian duct cysts.
Differential diagnosis of cysts: prostatic utricle cysts are always located on the midline, whereas Müllerian duct cysts are laterally displaced and extend more cranially than the seminal vesicles.
Pathology of the seminal vesicles
Seminal vesicle cysts can cause compression and obstruction of the pathways. They occur:
- As an isolated anomaly.
- In autosomal dominant polycystic kidney disease (ADPKD).
- As part of the rare Zinner syndrome.
Zinner syndrome includes a triad of features: seminal vesicle cyst, ejaculatory duct obstruction, and renal agenesis.
Briefly: answers to topical questions
What ultrasound signs indicate an obstruction caused by an epididymal cyst?
An indirect ultrasound sign of obstruction is the detection of an enlarged epididymis (epididymis) proximal to the cyst itself.
An epididymal cyst (epididymal cyst) or spermatocele (spermatocele) has the following echographic characteristics:
- Echogenicity — visualized as an anechoic (cystic) mass.
- Localization — a typical location is the head of the epididymis (caput epididymidis).
What anatomical parts (divisions) is the vas deferens divided into?
The available materials describe the following parts of the vas deferens (ductus deferens):
- Pelvic part (pars pelvina) — located in the subperitoneal part of the lesser pelvis. It courses from the internal opening of the inguinal canal downwards and backwards, runs along the lateral wall of the urinary bladder, and then between the ureter and the posterior surface of the urinary bladder.
- Terminal part — forms the ampulla of the vas deferens. The duct of the ampulla merges with the duct of the seminal vesicle to form the ejaculatory duct (ductus ejaculatorius).
Class and exam questions
How to distinguish a prostatic utricle cyst from a Müllerian duct cyst?
The prostatic utricle cyst is located strictly on the midline. The Müllerian duct cyst is displaced to one side and usually extends above the level of the seminal vesicle.
Which pathology is most often associated with bilateral absence of the vas deferens?
Bilateral absence of the vas deferens is observed in almost all patients with cystic fibrosis.
What does Zinner syndrome include?
Zinner syndrome is a combination of ejaculatory duct obstruction, seminal vesicle cyst, and renal agenesis.
What else to study on this topic
- Ultrasound diagnosis and hemodynamic criteria for varicocele
- The relationship between subclinical varicocele and male infertility
- Technique and efficacy of gonadal vein embolotherapy
- Arterial and venous Doppler sonography in erectile dysfunction
- Radiological diagnosis of Peyronie's disease and penile trauma
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