What is an Epididymal Cyst/Spermatocele?
An epididymal cyst (also called a spermatocele when it contains sperm) is a benign, fluid-filled sac that develops in the epididymis—the coiled tube sitting on top of and behind each testicle that stores and transports sperm.
Understanding the Basics
Think of your testicle as having a small storage and transport system attached to it. The epididymis is like a coiled tube warehouse where sperm mature and wait before traveling through the vas deferens. Sometimes, a small balloon-like pocket forms in this tube and fills with clear or milky fluid (and sometimes sperm), creating what doctors call an epididymal cyst or spermatocele 1.
Key Characteristics
- Location: These cysts sit above or behind the testicle, not inside it
- Feel: Usually smooth, separate from the testicle itself, and may feel like a "third ball" in your scrotum
- Size: Can range from tiny (3mm) to quite large (several centimeters)—men typically notice them when they grow to roughly the size of a normal testicle 2
- Appearance: If you could see inside, they look like clear or slightly cloudy water balloons
The Important Reassurance
These cysts are extremely common (found in up to 71% of men on ultrasound) and do NOT cause infertility 3, 4. Multiple high-quality studies have definitively shown that epididymal cysts have no association with:
What Causes Them?
The exact cause isn't fully understood, but they appear to develop when:
- Small tubes in the epididymis become blocked
- Fluid accumulates behind the blockage
- A cyst forms over time
They can occur at any age, though they're more commonly noticed in men over 40 2.
Symptoms (or Lack Thereof)
Most men have no symptoms at all—these are usually discovered accidentally during:
When symptoms do occur, men report:
- Feeling a lump or mass in the scrotum
- Dull aching or heaviness (especially if the cyst is large)
- Discomfort during physical activity
Important distinction: Unlike testicular torsion (a surgical emergency), epididymal cysts develop gradually over months to years, not suddenly 2.
How Doctors Diagnose Them
Ultrasound is the gold standard 1, 6. On ultrasound, these cysts appear as:
- Well-defined round structures
- Filled with clear fluid (appearing dark/black on the screen)
- Separate from the testicle itself
- No blood flow inside them (unlike tumors)
The ultrasound easily distinguishes these benign cysts from concerning conditions like testicular cancer 6.
Treatment Approach
The vast majority of epididymal cysts require no treatment—just observation 5, 7, 8.
Conservative Management (First-Line)
- Watchful waiting is appropriate for asymptomatic or minimally symptomatic cysts
- In children and adolescents, many cysts spontaneously resolve within 17 months on average 7
- No restrictions on activity or lifestyle needed 3
When to Consider Intervention
Surgery (spermatocelectomy) is reserved only for:
- Persistent, bothersome pain that affects quality of life
- Cysts that have grown to cause significant discomfort or cosmetic concern
- The rare complication of cyst torsion (twisting) causing acute pain 8
Reality check: Men typically tolerate these cysts for an average of 4 years before seeking surgical removal, and most are bothered by both pain AND the sensation of mass when they finally opt for surgery 2.
Surgical Options
- Aspiration (draining with a needle): Provides temporary relief but cysts often refill 8
- Surgical excision: Definitive treatment with removal of the entire cyst 2, 8
Common Pitfalls to Avoid
- Don't confuse with testicular cancer: Epididymal cysts are outside the testicle; cancers grow inside it 6
- Don't assume they cause infertility: Multiple studies confirm they don't 3, 4
- Don't rush to surgery: Conservative management is successful in the vast majority of cases 5, 7
When to Seek Immediate Care
While epididymal cysts are benign, seek urgent evaluation if you experience:
- Sudden, severe scrotal pain (could indicate torsion—a true emergency) 1
- Rapid swelling or redness
- Fever with scrotal symptoms (suggests infection)
These symptoms suggest different, more serious conditions that require immediate assessment 1.
Bottom Line for Patients
If you've been told you have an epididymal cyst or spermatocele, understand that this is a common, benign finding that almost never requires treatment. It won't affect your fertility, won't turn into cancer, and will likely cause you no problems. Most men live their entire lives with these cysts without ever knowing they're there 3, 5, 4.