One Testicle Bigger Than the Other? Is It Normal or Problematic?

Having one testicle that's bigger than the other is more common than many people may think. This size difference commonly occurs because the testis on the right seems to develop more quickly than on the left. 

This right-sided growth also is true of a fetus in the womb. It's the opposite for people with ovaries, with the ovaries developing first on the left.

But it’s not always normal for one testicle to be bigger than the other. So it’s important to know the usual size differences and what may be a symptom of something more serious.

This article explains testicle anatomy, unusual symptoms to watch out for, and conditions that affect the testicles.

Anatomy

Before you check for testicular problems, it’s helpful to understand their structure and function:

• Testicles (also called testes) are small oval-shaped glands. They produce sperm and sex hormones (testosterone).
• The scrotum is the sac of skin and tissue that surrounds the testicles. The scrotum protects the testicles and allows them to sit outside of the body, staying cooler than body temperature. This lower temperature is ideal for testicles to function.
• The epididymis is a small, coiled tube located behind the testicles. It collects and stores sperm produced by the testicles. The epididymis connects to the vas deferens—a larger tube that carries the sperm out of the body during ejaculation.  

Important Symptoms

Often, different-sized testicles are not an indication of a problem. However, the following may be signs of something more serious:

• Pain
• Redness
• Swelling
• One testicle is a different shape than the other

Being familiar with the testes' standard shape, appearance, and feel will help you notice when a change occurs. Normal anatomy includes:

• Shape: Each testicle feels like a firm, smooth egg.
• Size: Adult testicles are approximately two to three inches long and one inch wide.
• Symmetry: It's typical for one testicle to be slightly larger than the other and for one to hang slightly lower than the other.
• Pain: There is no pain or discomfort when you examine the testicles.

Self-Examination

You should perform a testicular self-exam monthly. To do a testicular self-examination, follow these steps:

1. Shower or bathe to ensure the scrotum is relaxed and warm.
2. Stand in front of a mirror if it helps.
3. Use the fingers and thumbs on both hands to gently roll the testicle, checking for lumps or any painful areas.
4. Feel along the underneath and back of the scrotum to locate the epididymis (it should feel like a bundle of tightly coiled tubes). 
5. Repeat on the other testicle.

Testicular Conditions

There are some common conditions involving lumps, pain, or swelling of the testicles. These are usually are not life-threatening, but they do require medical attention. They include:

• Cysts are an abnormal but harmless collection of fluid.
• Blood clots occur as a result of trauma or injury.
• Hydroceles occur when the scrotum swells from fluid buildup. A hydrocele can be present at birth or result from an injury. It often clears on its own within six months.
• Varicose veins (called varicocele) can be a cause of low sperm count and infertility.
• Orchitis is inflammation of the testicle caused by an infection.
• Inguinal hernia is when part of your intestines pushes down into the scrotum.
• Testicular torsion is a twisting of the spermatic cord, the bundle of tubes, nerves, and blood vessels that attaches the testicle to the body. This condition causes excruciating pain.

These symptoms may feel scary or embarrassing, but don't let that stop you from seeing your healthcare provider. It's essential to get checked out quickly so that your symptoms do not become worse.

Testicular Cancer

Performing monthly self-examinations is an important part of finding testicular cancer early. Symptoms of testicular cancer include:

• Lumps
• New growths
• Pain (sometimes)

A scrotal ultrasound is a diagnostic exam that can identify structural changes of the testes. It can help your healthcare provider identify things like varicoceles, cysts, and testicular cancer.

Summary

Having one testicle that is slightly larger than the other is entirely normal. However, swelling, pain, redness, and lumps are not. Doing monthly self-exams is an excellent way to watch for changes in your testicles that could indicate a problem. If you notice any changes, it's a good idea to see your healthcare provider to rule out any issues.

A Word From Verywell

It’s important to note that testicular cancer is rare. Although it’s vital to seek medical attention when you find a lump, pain, or other abnormality, there is no need to panic. The symptoms are often the result of a less serious condition.