ConditionMen's health
Spermatocele
A spermatocele is a benign, fluid-filled cyst in the epididymis, the coiled tube behind the testicle, that contains sperm. It feels like a smooth, painless lump separate from the testicle, usually above or behind it. Spermatoceles are common, grow slowly, and do not turn into cancer. Most need no treatment. Surgery (spermatocelectomy) is offered when the cyst becomes large, painful or bothersome, but it can affect fertility on that side, so the timing matters if you plan to have children.
Also called: Spermatic cyst, epididymal cyst containing sperm, seminal cyst
At a glance
- What it is
- A sperm-containing cyst in the epididymis, above or behind the testicle.
- How common
- Found on ultrasound in a large proportion of adult men; often after age 40 and after vasectomy.
- Symptoms
- A smooth, painless lump; sometimes heaviness or a dull ache if large.
- Cancer risk
- None; spermatoceles are benign.
- Diagnosis
- Examination, flashlight test and scrotal ultrasound.
- Treatment
- Usually none; surgery for large or painful cysts.
When to get help
Call 911 or go to the ER
- Sudden, severe pain in a testicle, with nausea or vomiting, or a testicle that sits higher than usual (possible torsion): go to the ER now
See a doctor within a day or two
- A painful, red, swollen scrotum with fever or burning on urination (possible infection)
- A cyst that suddenly becomes much larger or very painful
Book a routine appointment
- Any new lump in the scrotum, so it can be confirmed with ultrasound
- A lump that is part of the testicle itself, hard, or getting bigger, which needs prompt imaging to rule out testicular cancer
- A known spermatocele that has become large, heavy or uncomfortable
Usually safe to manage at home
- A small, painless spermatocele already confirmed by ultrasound: monthly self-checks and supportive underwear if needed
Spermatocele vs epididymal cyst
Both are cysts in the epididymis and look and behave alike. The difference is what is inside:
- Spermatocele: fluid containing sperm, often milky or cloudy
- Epididymal cyst: clear fluid without sperm
In practice, the difference can only be confirmed if fluid is drawn off and examined, and treatment is the same. Many doctors use the terms interchangeably. For an overview of these lumps and how they differ from other scrotal swellings, see epididymal cyst. This page focuses on spermatoceles specifically and on treatment decisions.
Causes
The exact cause is unknown. Spermatoceles are thought to form when one of the small ducts that carry sperm out of the testicle becomes blocked or widened, so sperm and fluid collect. They are more common:
- after age 40
- after a vasectomy, when back-pressure builds in the epididymis
- after injury or infection of the epididymis (epididymitis)
- in sons of women given the hormone DES during pregnancy, a drug no longer used
Symptoms and size
Most spermatoceles are found by chance during self-examination or an exam for something else. They:
- feel smooth, round and firm or squishy, from pea-size to several centimeters
- sit above or behind the testicle and feel separate from it
- are usually painless; larger ones can cause heaviness, a dragging sensation or a dull ache, especially after exercise or long periods of standing
- glow when a flashlight is shone through the scrotum (transillumination), because they are filled with fluid
Most remain under about 2 cm and stay stable for years. A minority grow large enough to be visible through clothing or to be confused with a third testicle.
How it is diagnosed
- Examination: a doctor feels the lump, checks whether it is separate from the testicle and shines a light through it.
- Scrotal ultrasound: the key test. It confirms a simple fluid-filled cyst in the epididymis and checks the testicle itself. Any solid lump within the testicle is treated as possible testicular cancer until proven otherwise.
Other scrotal lumps to rule out
| Lump | Key features |
|---|---|
| Spermatocele | Separate, above or behind testicle, glows with light |
| Hydrocele | Fluid surrounding the whole testicle, glows with light |
| Varicocele | "Bag of worms" of veins, usually left side, bigger when standing |
| Inguinal hernia | Bulge from the groin into the scrotum, may go back when lying down |
| Testicular cancer | Hard, painless lump in the testicle itself |
When to treat a spermatocele
Treatment is not needed just because a spermatocele is present. Reasons to consider it include:
- pain or aching that interferes with daily life
- size that causes embarrassment, discomfort in clothing or problems with exercise
- steady growth
Pain relievers such as ibuprofen or acetaminophen (paracetamol) at the label dose, and supportive underwear or an athletic supporter, help occasional aches.
Surgery: spermatocelectomy
The main treatment is surgical removal through a small cut in the scrotum, usually as day surgery under general or spinal anesthesia. The surgeon separates the cyst from the epididymis and testicle and removes it.
Recovery:
- scrotal swelling and bruising for 1 to 2 weeks
- ice packs, supportive underwear and pain relief
- desk work after a few days; avoid heavy lifting, cycling and sex for about 2 weeks or as advised
Risks:
- bleeding (hematoma) or infection
- the cyst returning, which happens in a minority of people
- ongoing scrotal pain in a small number
- damage to the epididymis, which can block sperm transport from that testicle and reduce fertility
Because of the fertility risk, many urologists recommend delaying surgery in men who still plan to have children, unless symptoms are significant.
Aspiration and sclerotherapy
Draining the cyst with a needle is quick, but fluid usually comes back. Injecting a substance afterward to scar the cyst shut (sclerotherapy) lowers recurrence, but it can also damage the epididymis and cause inflammation and pain. It is used less often than surgery, mainly in men who cannot have an operation.
Outlook
Spermatoceles are harmless. Most stay small and cause no problems for life. Surgery is effective for symptomatic cysts, with most men having no further trouble.
Frequently asked questions
Is a spermatocele dangerous?
No. A spermatocele is a benign cyst that does not turn into cancer or harm the testicle. The main reasons to see a doctor are to confirm the diagnosis with ultrasound, since any new scrotal lump needs checking, and to discuss treatment if it becomes large or painful.
Can a spermatocele go away on its own?
Small spermatoceles occasionally shrink, but most stay the same size or grow slowly over years. They do not usually disappear without treatment. Since most cause no symptoms, leaving them alone is the usual approach.
Does a spermatocele affect fertility?
The cyst itself usually does not affect fertility, because the other ducts and the opposite testicle still carry sperm. Surgery to remove it, however, can damage the epididymis and block sperm transport on that side. Men who want children in future should discuss timing with their urologist.
What size spermatocele needs surgery?
There is no fixed size. Surgery is based on symptoms rather than measurements: pain, heaviness, embarrassment or interference with activities. Some men live comfortably with large cysts, while others choose removal of a moderately sized cyst that aches.
How long is recovery after spermatocele surgery?
Most men go home the same day. Swelling and soreness typically last 1 to 2 weeks, and most return to desk work within a few days. Heavy lifting, intense exercise and sex are usually avoided for about 2 weeks. Full settling of swelling can take a few weeks longer.
Sources
This guide was written from current patient and clinical guidance, including:
- Urology Care Foundation (American Urological Association): Spermatocele
- Mayo Clinic: Spermatocele
- MedlinePlus: Spermatocele
- NHS: Testicular lumps and swellings
- European Association of Urology: Guidelines on Male Infertility