What causes epididymal cyst

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Last updated: April 4, 2026

Quick Answer: Epididymal cysts are typically caused by a blockage in the epididymis, the coiled tube located at the back of the testicle that stores and carries sperm. This blockage can lead to a buildup of fluid, forming a cyst. Other less common causes include inflammation or injury to the epididymis.

Key Facts

Overview

Epididymal cysts, also known as spermatoceles or epididymal cysts, are common, benign lumps that can develop in the scrotum. They are fluid-filled sacs that arise from the epididymis, a tightly coiled tube situated behind the testicle responsible for storing and transporting sperm. While often a source of concern for men due to their location, these cysts are generally harmless and do not typically indicate a serious underlying medical condition. Understanding their causes, symptoms, and when to seek medical advice is crucial for peace of mind and appropriate management.

What is the Epididymis?

Before delving into the causes of epididymal cysts, it's helpful to understand the anatomy of the epididymis. This structure is approximately 6 meters (20 feet) long when uncoiled and plays a vital role in sperm maturation and motility. Sperm produced in the testes travel through the epididymis, where they gain the ability to move and fertilize an egg. The epididymis is divided into three parts: the head (where sperm enter from the testes), the body, and the tail (where sperm are stored before ejaculation).

Primary Causes of Epididymal Cysts

The most frequent cause of epididymal cysts is a blockage within the epididymis. This obstruction can impede the normal flow of seminal fluid, leading to a buildup of fluid and the formation of a cyst. The reasons for this blockage are varied and can include:

Inflammation (Epididymitis)

Inflammation of the epididymis, known as epididymitis, can be caused by bacterial infections (often sexually transmitted infections like chlamydia or gonorrhea, or urinary tract infections) or, less commonly, by non-infectious causes. This inflammation can cause swelling and potentially obstruct the delicate tubules of the epididymis, leading to cyst formation.

Injury or Trauma

Direct injury or trauma to the scrotum or testicles can also contribute to the development of epididymal cysts. A blow to the area can damage the epididymis, causing swelling, scar tissue formation, or disruption of the normal flow of seminal fluid, which can then lead to a cyst.

Blockage of Sperm Ducts

The epididymis contains numerous small ducts that transport sperm. These ducts can become blocked for various reasons, including:

Idiopathic Causes

In many instances, the precise cause of an epididymal cyst cannot be identified. These are often referred to as idiopathic. The exact physiological process leading to the blockage and fluid accumulation remains unclear, but it is believed to be a benign, spontaneous event in most cases.

What is a Spermatocele?

A spermatocele is a type of epididymal cyst that specifically contains sperm. It is essentially a cyst that forms in the epididymis and is filled with a milky or clear fluid containing sperm. Spermatoceles are the most common type of epididymal cyst and share the same underlying causes related to blockage and fluid accumulation within the epididymis.

Symptoms and Diagnosis

Epididymal cysts are often asymptomatic, meaning they do not cause any noticeable symptoms. When symptoms do occur, they are usually mild and may include:

A healthcare provider can usually diagnose an epididymal cyst through a physical examination. They will feel the lump and differentiate it from the testicle. Transillumination, where a light is shone through the scrotum, can help confirm if the lump is fluid-filled. An ultrasound scan of the scrotum is often used to confirm the diagnosis, assess the cyst's size and location, and rule out other conditions like testicular tumors or hernias.

When to See a Doctor

While epididymal cysts are benign, it is always advisable to consult a doctor if you notice any lump or swelling in your scrotum. This is important to ensure an accurate diagnosis and to rule out more serious conditions, such as testicular cancer, which requires prompt medical attention. Seek medical advice if:

Treatment Options

In most cases, epididymal cysts do not require treatment, especially if they are small and asymptomatic. They often resolve on their own over time. If the cyst causes discomfort or significant concern, treatment options may include:

It is important to remember that epididymal cysts are very common and rarely serious. However, any new lump in the scrotum should be evaluated by a healthcare professional to ensure a correct diagnosis and appropriate management.

Sources

  1. Spermatocele - WikipediaCC-BY-SA-4.0
  2. Spermatocele - NHSfair-use
  3. Spermatoceles - Symptoms and causes - Mayo Clinicfair-use

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