Causes of lumps and swellings in the testicles

Causes of lumps and swellings in the testicles

Read about the author Samantha Evans

Testicular cancer is an uncommon cause of lumps and swellings in the testicles and it is estimated that only 4 out of every 100 lumps found are cancerous. There are many other conditions that cause lumps and swellings, many of which are easily treated.


This is caused by enlarged veins in the testicles which may look like a bag of worms. Similar to varicose veins that appear in your legs, a varicocele develops when blood collects in the vein instead of flowing properly causing it to swell. The majority of varicoceles occur in the left testicle, but can appear in both testicles at the same time. They usually occur after puberty and affect one in five men. The cause is unknown but may be genetic if a male relative has or has had the same condition. It can cause infertility.

Symptoms include:

  • A dull pain or heavy, dragging sensation in the groin or scrotum
  • Your left testicle looking swollen or hanging down lower than your right testicle
  • A swollen testicle when you stand but not when you lie down


You may not require treatment as the problem can resolve itself. However, there are various treatments that can alleviate the problem.


Wearing supportive underwear can alleviate any scrotal or groin discomfort and you can take over the counter pain relief as required. If the pain is severe, you should seek medical advice.


Surgical intervention may be required if the varicocele is causing pain or discomfort or it is affecting your fertility. Carried out under local anaesthetic, varicocele embolisation involves blocking the veins where the blood collects to make them disappear by injecting special fluid or metal coils into the veins. A varicocelectomy involves cutting and tying the veins and is done under a general anaesthetic.


Usually occurring in men and boys, a hydrocele is a collection of fluid that can build up in the spaces that surround your testicles and can occur on one or both sides of the scrotum. Three in every 100 male babies are born with a hydrocele.


The cause of a hydrocele can be as a result of any of the following:

  • An injury to the testicles
  • Infection
  • Some types of surgery, for example, after a vasectomy reversal
  • Testicular torsion – this is when your testicles get twisted, which affects their blood supply
  • A tumour


If it is not causing any pain or discomfort, a hydrocele is often left to resolve on its own. If it is uncomfortable, the excess fluid can be removed under local anaesthetic using a syringe and fine needle. If it is large, it can be removed under general anaesthetic using a simple keyhole cut in the scrotum.

Epididymal cyst

This is a lump caused by a collection of fluid in the epidydimus, the sperm-carrying tube. Usually starting as small, fluid-filled lumps, they may grow into bigger cysts called spermatoceles, which can contain sperm as well as fluid and are harmless.


Usually appearing as painless lumps near to your testicles, epididymal cysts are usually easy to separate from your testicle on self-examination. Your testicle may start to ache and you may have some pain and discomfort as the cyst begins to increase in size.


The cause of epididymal cysts is unknown and they do not cause cancer or affect fertility.


This usually involves removal of the cyst under general anaesthetic.

Orchitis or Epidiymo-orchitis

Orchitis is an inflammation of the testicles usually caused by an infection such as chlamydia or mumps. The infection may affect the epididymis, the sperm carrying tube resulting in epididymo-orchitis.



  • You may have a rapid onset of pain or heaviness in one or both testicles
  • The testicles may feel swollen, tender, red or purple
  • You may notice blood in your semen
  • You may have nausea, vomiting, pain on urinating, groin pain, pain during sex and a general feeling of malaise.


  • There is a slower onset of symptoms of including pain and swelling in the testicles for 1-5 days, gradually spreading to affect the whole testicle
  • Pain on urinating and often penile discharge


  • Both bacteria and viruses can cause orchitis.
  • Bacteria that commonly cause orchitis include E.coli, Staphylococcus, and Streptococcus.
  • Bacteria that cause sexually transmitted infections (STI), such as gonorrhoea, chlamydia and syphilis, can cause orchitis in sexually active men.
  • The mumps virus can also cause orchitis, affecting young boys. It is important for all children especially boys to receive the vaccination against mumps
  • You may be at risk of non-sexually transmitted orchitis if you have not had proper vaccination against mumps, if you get urinary tract infections, if you are older than 45, or if you frequently have a catheter placed into your bladder.


Treatment involve taking antibiotics. If symptoms do not resolve after antibiotic therapy, seek further medical advice from your GP or sexual health clinic.

Testicular torsion

This is an extremely painful condition whereby the testicles twist around inside the scrotal sack, preventing the blood flow. This is a medical emergency and requires immediate surgical intervention to untwist the testicle to allow normal blood flow. The reason for this is unknown.

More commonly occurring in teenage boys shortly after puberty, it can affect newborn babies and younger boys too. It is uncommon over the age of 25, but does occur sometimes in older adults. Some boys get warning pains when the testicle twists on itself then untwists. Medical advice should be sought if this occurs.

Testicular cancer

Testicular cancer is relatively uncommon, accounting for just 1% of all cancers in men. Affecting around 2,300 men in the UK each year, it is the most common cause of cancer to affect men between 15-49 years. An estimated 4 out of every 100 lumps detected in cancerous.

Self examination of the testicles is extremely important and should be learnt at an early age to encourage young men to get into the habit of examining their testicles every month and to seek medical advice as soon as they notice any changes to their testicles.

Useful Websites and Charities

Baggy trousers UK :
Testicular Cancer UK : @TesticularCuk
Testicular Cancer UK :
Orchid Male Cancer :
Testicular Cancer Awareness Foundation :