A varicocele is caused by faulty valves in the veins of your scrotum. When these tiny valves fail, blood pools instead of flowing back to your heart. This makes the veins swell, much like varicose veins in your legs.
This page explains why varicoceles form, who gets them, and what raises your risk. You will also learn the difference between common and rare causes.
What Is a Varicocele?
A varicocele is a group of enlarged veins inside your scrotum. These veins are called the pampiniform plexus. Their job is to carry blood away from your testicles.
Varicoceles are common. They affect about 15% to 20% of all men, according to Medscape. They show up in roughly 40% of men with fertility problems.
Most varicoceles form on the left side. This is due to the way your veins are built, which we explain below.
What Causes a Varicocele to Form?
The main cause is broken valves inside your scrotal veins. Healthy veins have one-way valves. These keep blood moving in the right direction.
When a valve stops working, blood flows backward. This is called reflux. The trapped blood stretches the vein over time, and a varicocele forms.
Doctors call this type a primary varicocele. It is the most common form by far.
Why the Left Side Is Affected Most
Your anatomy explains the left-side pattern. The left testicular vein is longer than the right. It also joins the left renal (kidney) vein at a sharp 90-degree angle.
This setup raises pressure in the left vein. Higher pressure makes valve failure more likely. That is why most varicoceles appear on the left.
What Are the Risk Factors for a Varicocele?
Some factors make a varicocele more likely. These do not always cause one, but they raise your risk.
- Age: Varicoceles often appear during puberty, when blood flow to the testicles increases.
- Family history: Weak vein valves can run in families.
- Being tall: Taller men may have more pressure in their leg and pelvic veins.
- Body type: A lower body mass index has been linked to varicoceles in some studies.
A varicocele is not caused by lifting, exercise, or sexual activity. These common worries are myths.
Are There Other, Rarer Causes?
Yes. A small number of varicoceles come from a secondary cause. This means another condition is blocking or squeezing your veins.
These cases need careful checking by a specialist like Dr Nudell. A few warning signs make a secondary cause more likely.
Nutcracker Syndrome
Nutcracker syndrome is one rare cause. Here, the left renal vein gets compressed, often between two arteries in your abdomen.
This pinch raises pressure in the veins below it. That pressure can lead to a varicocele. Studies in the National Institutes of Health (NIH) library link this syndrome to large or stubborn varicoceles.
A Mass or Tumor
A growth in your abdomen or kidney can press on a vein. This blocks normal blood flow and causes a varicocele.
See a doctor if a varicocele appears suddenly after age 40. A right-sided varicocele alone is also a reason to get checked. Both can point to a secondary cause.
How Is a Varicocele Diagnosed?
A doctor finds most varicoceles during a physical exam. You may be asked to stand and bear down. This move, called the Valsalva maneuver, makes the veins easier to feel.
Doctors grade varicoceles by size using the Dubin and Amelar system:
- Grade 1: Felt only when you bear down.
- Grade 2: Felt at rest, but not seen.
- Grade 3: Large enough to see through the skin.
If the exam is unclear, you may get a scrotal ultrasound. This scan confirms the diagnosis and rules out other problems.
When Should You See a Doctor?
Many varicoceles cause no symptoms and need no treatment. Still, some signs are worth a visit.
Book an appointment if you notice:
- A dull ache or heaviness in your scrotum
- A lump you can feel or see
- One testicle that looks smaller than the other
- Trouble conceiving with a partner
Early advice helps you understand your options and protect your fertility.
Taking the Next Step
A varicocele almost always comes from faulty vein valves, most often on the left side. Risk factors like age and family history play a part, while rare causes such as nutcracker syndrome need a closer look.
If you have symptoms or questions, speak with a qualified medical professional. A simple exam can give you clear answers and peace of mind.
Frequently Asked Questions
Can a varicocele go away on its own?
No, a varicocele rarely disappears without treatment. The faulty valves do not repair themselves. Many cases are harmless, but only a doctor can confirm yours is safe to leave alone.
Does a varicocele affect fertility?
It can. Varicoceles are found in about 40% of men with fertility issues, per Medscape. The pooled blood may raise testicle temperature and harm sperm quality. Not every man with a varicocele has trouble conceiving.
Is a varicocele dangerous?
Most varicoceles are not dangerous. The main concerns are discomfort, fertility problems, and slower testicle growth in teens. A sudden or right-sided varicocele should be checked, since it can signal a rarer cause.
What is the difference between a primary and secondary varicocele?
A primary varicocele comes from faulty vein valves and is by far the most common. A secondary varicocele comes from another condition, such as a mass or nutcracker syndrome, that blocks blood flow.