A difference in size is usually nothing to worry about, though it can occasionally indicate a problem. If a testicle is painful or changes shape, a person should see their doctor as soon as possible.
In this article, we look at reasons why one testicle may be bigger than the other. We discuss complications, treatments, and explain how to perform a testicular exam at home.
It is common for one testicle to be bigger than the other without a serious cause.
There are several reasons why one testicle may be bigger. These include:
The epididymis is a duct behind the testes. Epididymitis occurs when this duct becomes inflamed, usually as a result of infection. This condition can be a sign of the sexually transmitted infection (STI) chlamydia.
See a doctor if the following symptoms are present:
- pain when urinating
- discharge from the penis
- inflammation in the testicle
Orchitis happens when an infection causes inflammation in the testicle. It may occur after a person catches the mumps virus.
If an individual experiences testicular pain and suspects that orchitis is the cause, they should see a doctor. This condition can damage the testicles.
A cyst is a thin sac filled with fluid. Epididymal cysts may occur when there is excess fluid in the duct. They may also form while the epididymis is developing.
These cysts are harmless and usually painless. No treatment is necessary, and they will often go away on their own. If epididymal cysts cause discomfort, however, they can be surgically removed.
A hydrocele refers to a sac that forms around the testicles and fills with fluid.
While it usually does not require treatment, a hydrocele can indicate inflammation, in which case a person should see a doctor.
When the veins within the scrotum become enlarged, this is called a varicocele.
It usually does not require treatment if there are no additional symptoms, but a varicocele can cause a low sperm count.
Testicular torsion occurs when the testicle rotates and the spermatic cord is twisted.
This can cause testicular pain that is severe and lasting. If this pain follows an injury, it may subside then suddenly return.
Testicular torsion is severe and should be treated as an emergency. The twisting of the cord can reduce or block blood flow to the testicle, and without treatment the testicle may need to be removed.
Cancerous cells can appear and multiply in the testicle. A doctor should investigate lumps or new growths in the area as soon as possible.
When should a person worry?
Pain in the lower abdomen may signal a testicular issue.
Several signs and symptoms can indicate a problem with testicular health.
If any of the following symptoms occur with an enlarged testicle, seek medical attention as soon as possible:
- a sharp pain or ache in or around the testicles
- swelling of the testicles
- discharge from the penis
- trouble passing urine
- pain in the back or lower abdomen
- swelling or tenderness in the breast tissue
A doctor will help to identify the underlying cause by examining the scrotum and testicles for lumps or abnormalities. If they suspect testicular cancer, they will take a blood test and ask about family history.
Other tests a doctor may recommend include:
- a urine test to check for infections and kidney problems
- an ultrasound to look for growths and check blood flow
- a CT scan to look for testicular abnormalities
If an underlying condition is diagnosed, a doctor may prescribe medication or other treatment.
Treatment for differently sized testicles depends on the cause. Below are common underlying conditions and their treatments.
Orchitis. If an STI is causing orchitis, a doctor will usually prescribe medication to fight the infection. Common medications include ceftriaxone (Rocephin) or azithromycin (Zithromax). Painkillers and an ice pack may help to relieve discomfort.
Testicular torsion. Testicular torsion requires treatment as soon as possible. A doctor may be able to untwist the testicle, in a procedure called manual detorsion, but surgery is often necessary to prevent reoccurrence. A delay in treatment increases the likelihood that the twisted testicle will need to be removed.
Testicular cancer. A doctor may recommend removing the testicle where the cancer is present. Radiation therapy, chemotherapy, or a combination may help to reduce or destroy cancer cells. If the cancer has spread, or if it originated in another part of the body, additional treatments and surgeries may be necessary.
How to perform a testicular self-exam
Any unexplained changes to the testicles should be discussed with a doctor.
It is very important to monitor the size and shape of testicles so that any change can be detected.
Perform a self-examination once a month. Be on the lookout for lumps, growths, pain, swelling, and other abnormalities.
A healthy testicle is smooth, and closer to egg-shaped than round. Lumps or abnormal protrusions should be investigated by a doctor right away.
To perform a testicular self-exam:
- Ensure that the scrotum is loose before beginning.
- Carefully and slowly roll the testicle between the fingers and thumb.
- Thoroughly check the surface of each testicle, looking for lumps, areas that feel tender or sore, protrusions, swelling, or changes in size.
- Feel along the bottom of the scrotum, reaching the epididymis, which should feel like several grouped tubes.
Check both testicles at least once a month.
Having differently sized testicles is common.
If one testicle becomes noticeably bigger, most underlying causes are easily treated. The sooner a person consults a doctor, the better the outlook is likely to be.
If other symptoms are present, such as pain, lumps, or swelling, seek medical attention right away.
While a diagnosis of cancer is concerning, the outlook for testicular cancer is good. Treatment and support can help a person and their family to deal with this condition.