The testicles are housed within the scrotum. Swelling in this area is a physical symptom, not a diagnosis, indicating an underlying issue that causes the scrotal tissue to enlarge or fill with fluid or mass. Because the testes are highly sensitive, any noticeable swelling often causes significant concern. Identifying the cause is necessary for proper medical management, as reasons range from simple fluid collections to urgent medical emergencies.
Acute Infections and Inflammatory Responses
Inflammation due to infection is a common cause of sudden-onset, painful testicular swelling. This category includes epididymitis and orchitis, which often occur together. Epididymitis is the inflammation of the epididymis, the coiled tube at the back of the testicle that stores and transports sperm. It is typically caused by a bacterial infection, often a sexually transmitted infection (STI) in younger men, or a urinary tract infection in older men.
Orchitis is the inflammation of the testicle itself, more commonly caused by a viral infection, such as the mumps virus. The inflammation process causes increased blood flow, leading to redness, warmth, and tenderness, with pain developing over one or two days. When both the epididymis and the testicle are involved, the condition is called epididymo-orchitis.
Structural Causes and Fluid Build-up
Swelling can result from anatomical changes or the accumulation of substances within the scrotal sac, often developing slowly and sometimes without pain. A hydrocele is a frequent cause, involving a collection of fluid between the two layers surrounding the testicle. This fluid accumulation creates a generally painless, smooth swelling that can make the scrotum feel heavy. Hydroceles can occur due to an imbalance in fluid production and absorption or secondary to injury or infection.
Varicocele
A varicocele is an enlargement of the pampiniform plexus, the network of veins within the spermatic cord, often described as feeling like a “bag of worms.” This swelling is caused by faulty valves in the veins, leading to a back-up of blood. Discomfort may increase during the day or with physical exertion.
Spermatocele
A spermatocele, or epididymal cyst, presents as a distinct, fluid-filled sac that forms near the top of the testicle due to a blockage in the sperm-carrying ducts. It is typically benign and painless.
Inguinal Hernia
An inguinal hernia can cause swelling if a section of the intestine or fatty tissue pushes through a weak spot in the abdominal wall and descends into the scrotum.
Immediate Medical Emergencies and Trauma
Some causes of testicular swelling require immediate medical attention due to the risk of permanent tissue damage. Testicular torsion is a time-sensitive emergency that occurs when the spermatic cord twists, cutting off the blood supply to the testicle. This vascular compromise leads to rapid swelling and excruciating, sudden-onset pain, often accompanied by nausea and vomiting. Torsion most commonly affects adolescents but can occur at any age.
Direct physical trauma, such as a blunt impact, can also cause acute swelling. This is typically due to a contusion or hematoma, which is a collection of blood resulting from damaged blood vessels within the scrotum or testicle. In severe cases of trauma, the testicle itself may be ruptured, leading to massive and painful swelling.
Indicators for Urgent Medical Consultation
Any noticeable swelling in the scrotum warrants a medical evaluation to determine the underlying cause. However, certain accompanying symptoms are red flags that indicate a need for immediate emergency care:
- Sudden, severe, and unrelenting pain, which suggests testicular torsion, where treatment delay can lead to the loss of the testicle.
- Swelling accompanied by systemic symptoms like a fever or chills, pointing to a rapidly progressing infection requiring urgent antibiotics.
- Swelling combined with nausea, vomiting, or abdominal pain, which frequently presents with torsion.
- Any firm, painless mass or lump that is distinct from the testicle, which requires assessment for serious issues like testicular cancer.