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Condition

Spermatocele

Spermatocele explained: real causes, when treatment is needed, and what the evidence says — with sources, not guesswork.

Also known as: spermatic cyst, epididymal cyst

Symptoms5 listed
ICD-10N43.40
TreatableYes
DE
Medically reviewed by Dr. Elif Yılmaz, MD, FECSM
Last reviewed 22 July 2026
✓ Clinician reviewed
Spermatocele✓ Clinician-reviewed information
Key takeaways
  • A spermatocele is a benign cyst arising from the epididymis, usually felt as a smooth, separate lump above or behind the testicle rather than part of the testicle itself.
  • It is genuinely common — found incidentally in roughly 30% of men undergoing scrotal ultrasound for unrelated reasons — and the exact overall prevalence in the general population has not been precisely defined.
  • Most spermatoceles cause no symptoms, do not affect fertility, and never need active treatment beyond an initial proper diagnosis.
  • Surgery, when needed, carries a real risk of affecting fertility by damaging the epididymis, which is why it is generally reserved for cases causing significant symptoms and approached cautiously in men who still want children.
  • Recurrence after treatment is a genuine possibility rather than a rare exception, which is worth knowing before deciding whether treatment is right for a mild or symptom-free case.

Overview

A spermatocele is a harmless, fluid-filled cyst in the epididymis. The epididymis is the long, coiled tube above and behind each testicle that stores and moves sperm as it matures. The fluid inside is usually clear or slightly cloudy, and often contains sperm — which is where the name comes from. A plain epididymal cyst without sperm is a very close relative, and in everyday practice the two names are used to mean much the same thing.

On examination, a spermatocele is usually a smooth, round, well-defined lump above and slightly behind the testicle. Crucially, it feels separate from the testicle, not part of it. Like a hydrocele, it usually lets light through: shine a torch on it in a dark room and it glows, because it is full of fluid. A lump that does not glow is more likely to be solid, which shifts attention towards ruling out other things, including, rarely, a tumour.

The exact cause is not fully settled. The leading idea is a small blockage in one of the many tiny tubes of the epididymis. Fluid, and sometimes sperm, then build up behind it and slowly form a cyst. Why this happens in a given man is usually not clear, so most spermatoceles are simply idiopathic. There is one specific, historical risk factor worth knowing. Men whose mothers took a medicine called DES during pregnancy — used mainly from the 1940s to the early 1970s — have a higher chance of them. This is now rare, given how long ago DES was withdrawn, but it is worth mentioning if it applies to you.

Spermatoceles are common, though the true rate in the general population has never been pinned down, because most cause no symptoms. Many are found by chance — on self-exam, a routine check, or a scan done for something else. In fact, they turn up in as many as 30% of men having a scrotal scan for other reasons. They can appear at any adult age, but are most often found in middle age.

One reassuring, and important, fact: having a spermatocele does not usually affect fertility. The cyst itself does not tend to block sperm production or transport. Where fertility does come into play is around treatment, not the cyst. Surgery to remove a spermatocele, and to a lesser extent sclerotherapy, can damage the nearby epididymis and, in some cases, create a new blockage. That is exactly why current advice is clear: surgery is generally not recommended for a symptom-free, incidentally found spermatocele, and is approached with real caution in men who still want children.

Current clinical guidance is consistent: surgery is generally not recommended for an asymptomatic, incidentally found spermatocele, and is approached with particular caution in men who still want to have children — because the treatment, not the cyst, is what carries the fertility risk.

Types of spermatocele

Spermatocele
Technically an epididymal cyst whose fluid contains spermatozoa, usually only confirmed on histology, though used broadly in everyday clinical language.
Simple epididymal cyst
A closely related, benign fluid-filled cyst of the epididymis without confirmed sperm content; managed the same way in practice, and the two terms are frequently used interchangeably.
Single vs multiple
Spermatoceles can occur singly or as multiple small cysts along the epididymis, sometimes giving a somewhat irregular or multilobed feel on examination.
Unilateral vs bilateral
Most commonly affects one side, though bilateral spermatoceles do occur.
How common is it?
The exact population prevalence of spermatocele has not been precisely defined, since most cases are asymptomatic and only found incidentally. Spermatoceles have been identified incidentally in roughly 30% of men undergoing scrotal ultrasound for unrelated reasons. A large Swedish national registry study found an annual incidence of specialist-diagnosed spermatocele of approximately 38.5 per 100,000 men.
Source: pubmed.ncbi.nlm.nih.gov

Symptoms

Often no symptoms at all — many are found incidentally during self-examination or unrelated scans
A smooth, distinct, movable lump above or behind the testicle, separate from the testicle itself
A feeling of fullness, heaviness, or mild pressure in the scrotum, particularly with larger cysts
Occasionally, mild discomfort or a dull ache, though significant pain is uncommon and worth separate evaluation
Gradual enlargement over time in some cases, though many remain stable in size for years

Causes

A localised blockage within one of the small tubules of the epididymis, allowing fluid to accumulate and form a cyst over time — the leading, though not definitively proven, explanation
No identifiable cause in the large majority of cases (idiopathic)
Maternal use of diethylstilbestrol (DES) during pregnancy — a specific, historically relevant risk factor for men born before this medication was withdrawn in the early 1970s

Risk factors

Middle age (most commonly diagnosed in this age group, though it can occur at any adult age)
A history of maternal DES exposure during pregnancy
Beyond these, there are few well-established, consistently reproducible risk factors identified in the current literature

How it is diagnosed

Diagnosis usually starts with a physical examination, where a spermatocele is typically felt as a smooth, distinct, mobile lump above or behind the testicle, separate from the testicle itself. Transillumination — shining a light against the scrotum in a dark room — is a simple bedside test that helps confirm the fluid-filled nature of the lump, since it characteristically glows; failure to transilluminate suggests a solid lesion and prompts further investigation.

Scrotal ultrasound is the standard way to confirm the diagnosis with precision, distinguish it clearly from other causes of scrotal swelling (including hydrocele, varicocele, hernia, and, importantly, testicular tumour), and assess its size. If a man has scrotal pain, a urine test may be used to help rule out infection, since a spermatocele itself does not typically cause significant pain or infection.

When to see a doctor
  • You notice a new lump in your scrotum, even if it is painless
  • An existing, previously stable spermatocele has grown noticeably or become painful
  • You experience sudden, severe scrotal pain — this needs urgent assessment to rule out testicular torsion, regardless of any known spermatocele
  • A lump fails to transilluminate or feels hard, fixed, or irregular on self-examination
  • You are considering treatment and want to understand the fertility-related risks and alternatives beforehand
Reducing your risk
  • Regular testicular self-examination, which helps a man become familiar enough with his own anatomy to notice new lumps promptly, whatever they turn out to be
  • Prompt evaluation of any new scrotal lump, to confirm it is a straightforward spermatocele rather than something requiring different management
  • Being aware, before considering treatment, of the specific fertility-related risks associated with surgery or sclerotherapy for an otherwise mild or symptom-free spermatocele

Common questions

Is a spermatocele cancer?
No — a spermatocele is a benign, non-cancerous cyst, and current guidance is clear that it is not a cancer-predisposing condition. Proper examination and, where needed, ultrasound are still worthwhile to confirm the diagnosis with confidence, since other scrotal lumps can occasionally feel similar without a formal assessment.
Does a spermatocele need to be treated?
Not usually. Most spermatoceles are small, cause no symptoms, and are simply left alone once properly diagnosed, since treatment carries its own real risks that generally outweigh any benefit for a mild, symptom-free cyst. Treatment is typically reserved for cases causing genuine discomfort, significant enlargement, or noticeable distortion of the scrotum.
Will a spermatocele go away on its own?
Generally, no — unlike some other scrotal fluid collections, spermatoceles typically do not resolve spontaneously and tend to remain stable or grow gradually rather than disappearing. This is not a reason for concern on its own; it simply means "watching and monitoring" rather than "waiting for it to go away" is the more accurate way to think about an untreated, asymptomatic spermatocele.
Does a spermatocele affect fertility?
Generally, no — the cyst itself typically does not interfere with normal sperm production or transport. The more relevant fertility consideration is around treatment rather than the spermatocele itself, since surgery or sclerotherapy carry a real risk of damaging the epididymis and creating a new blockage affecting fertility.
If treatment could affect fertility, why would anyone have surgery for this?
Surgery becomes a reasonable option when a spermatocele is causing genuine, persistent discomfort, has grown large enough to be physically bothersome, or is causing significant cosmetic or psychological distress. In these situations, the trade-off between symptom relief and fertility risk is a personal, informed decision made with a specialist, particularly weighted differently depending on whether future fertility is still a goal.
What is the difference between a spermatocele and a hydrocele?
A spermatocele is a distinct cyst arising specifically from the epididymis, typically felt as a separate lump above and behind the testicle; a hydrocele is a broader fluid collection surrounding the testicle itself. Both are generally benign, both transilluminate, and both are diagnosed similarly, but they represent different anatomical findings and are sometimes present in the same man at once.
Should I be worried if a doctor says my spermatocele is "multiple" or "multilobed"?
Not automatically — multiple small cysts along the epididymis are a recognised, still-benign variation of the same basic condition, rather than a sign of something more serious. This is a descriptive finding about the shape and number of cysts present, not a different diagnosis or a marker of increased risk.
Can a spermatocele become infected?
This is genuinely uncommon — spermatoceles do not typically become infected the way some other scrotal conditions, such as epididymitis, can. New pain, redness, warmth, or fever with scrotal swelling is more suggestive of a separate infective process and warrants its own specific evaluation rather than being attributed automatically to a known spermatocele.
How likely is a spermatocele to come back after treatment?
Recurrence is a genuine, well-documented possibility rather than a rare exception — some data suggests recurrence in a meaningful proportion of cases (reported by some sources in roughly two out of five treated cases), which is worth factoring into the decision about whether treatment is right for a mild or moderate case in the first place.
What does spermatocele surgery actually involve?
Surgical removal (spermatocelectomy) involves excising the cyst from the epididymis, sometimes requiring removal of part or all of the epididymis depending on the anatomy encountered. This is generally performed as an outpatient or short-stay procedure under anaesthetic, with recovery and specific technique details best discussed with the operating surgeon.
Is aspiration a good alternative to surgery?
Aspiration alone — draining the fluid with a needle — often provides only temporary relief, since fluid frequently re-accumulates, and it is sometimes combined with sclerotherapy to improve on this. Both aspiration and sclerotherapy carry their own risk of epididymal damage affecting fertility, similar to surgery, so neither should be assumed to be automatically lower-risk simply because it is less invasive.
Can spermatoceles occur on both sides at once?
Yes, bilateral spermatoceles do occur, though a single, one-sided spermatocele is more typical. Bilateral involvement does not inherently indicate a different or more serious underlying cause — it is managed using the same principles applied to each side individually.
Is torsion of a spermatocele something I should worry about?
This is genuinely, extremely rare — reported only a small handful of times in published medical literature — so it is not something to actively worry about day to day. That said, any sudden, severe scrotal pain always warrants urgent medical assessment regardless of a known diagnosis, since testicular torsion itself (a separate, genuine emergency) needs to be reliably ruled out quickly.
Can lifting weights or physical activity make a spermatocele worse?
There is no strong evidence that physical activity causes spermatoceles to form or significantly worsens an existing one, since the mechanism relates to internal tubular blockage rather than external strain. Some men notice more awareness of discomfort during vigorous activity, which is a different thing from the condition itself being made worse.
Is it worth getting a spermatocele checked even if it is small and does not bother me?
Yes, at least once — mainly to confirm the diagnosis through proper examination and, if needed, ultrasound, so you and your doctor both know with confidence what it is rather than assuming. After that confirmation, a small, stable, symptom-free spermatocele generally does not need ongoing active treatment or frequent follow-up, though it is reasonable to keep an eye on any changes over time.

Sources

  1. Lundström KJ, et al. Epidemiology of hydrocele and spermatocele; incidence, treatment and complications. Scand J Urol. 2019;53(2-3):134-138. https://pubmed.ncbi.nlm.nih.gov/30990342/
  2. Medscape/eMedicine. Spermatocele: Practice Essentials. https://emedicine.medscape.com/article/443432-overview
  3. Urology Care Foundation (AUA). Spermatoceles: Symptoms, Diagnosis & Treatment. https://www.urologyhealth.org/urology-a-z/s/spermatoceles
  4. Mayo Clinic. Spermatocele — Symptoms and Causes. https://www.mayoclinic.org/diseases-conditions/spermatocele/symptoms-causes/syc-20377829
  5. NHS. Epididymal cyst. https://www.nhs.uk/conditions/epididymal-cyst/