A varicocele is not a new type of pasta, although its name may sound suspiciously at home on an Italian menu. It is an enlargement of the veins inside the scrotum, usually above one testicle. The condition is similar to having varicose veins in the legs, except it develops in a considerably more private neighborhood.
Many varicoceles cause no symptoms and are discovered during a routine physical examination or fertility evaluation. Others produce a dull ache, visible swelling, testicular size differences, or changes in sperm production. Although a varicocele is generally not dangerous, any new scrotal lump, swelling, or pain deserves professional evaluation because several conditions can produce similar symptoms.
This guide explains what causes a varicocele, why it is usually found on the left side, which symptoms may occur, and how healthcare professionals make an accurate diagnosis.
What Is a Varicocele?
A varicocele is an abnormal widening of veins in the pampiniform plexus, a network of small veins surrounding the testicular artery within the spermatic cord. These veins carry oxygen-depleted blood away from the testicle and toward larger veins in the abdomen.
Normally, one-way valves inside the veins help blood travel upward against gravity. When blood does not drain efficiently, it can collect in the pampiniform plexus. The veins gradually stretch, twist, and become more prominent.
Varicoceles usually develop during puberty, when blood flow to the testicles increases. They may become larger or more noticeable over time. Roughly 15% of males have a varicocele, although estimates vary depending on age and how the condition is detected. The condition is more common among men being evaluated for infertility.
Why Varicoceles Usually Develop on the Left
Most clinically detectable varicoceles occur on the left side. This lopsided preference is mainly a matter of plumbing.
The right testicular vein drains more directly into the inferior vena cava, a large vein carrying blood toward the heart. The left testicular vein follows a longer path and empties into the left renal vein at nearly a right angle. This arrangement may create greater pressure and make backward blood flow more likely.
A varicocele can occur on the right side or on both sides. However, a newly developed varicocele that appears suddenly, remains enlarged when a person lies down, or occurs with abdominal, back, or urinary symptoms should be evaluated promptly. A clinician can determine whether additional imaging is appropriate.
What Causes a Varicocele?
The immediate cause is inefficient drainage through the testicular veins. In many cases, the precise reason the valves fail is not known. Several anatomical and physiological factors may contribute.
Weak or Incompetent Vein Valves
Veins contain valves designed to keep blood moving in one direction. If these valves are absent, weak, or unable to close correctly, blood may flow backward and pool around the testicle. Over time, the increased pressure enlarges the veins.
Differences in Venous Anatomy
The anatomy of the left testicular vein makes left-sided varicoceles especially common. Increased pressure within the left renal vein can interfere with drainage from the testicle. In some people, compression of nearby blood vessels may further increase venous pressure.
Rapid Growth During Puberty
The testicles grow quickly during puberty and require increased blood flow. If venous drainage cannot keep pace, a varicocele may develop. This is why the condition is frequently first identified in teenagers or young adults rather than small children.
Rare Secondary Causes
Less commonly, a mass, blood clot, or other obstruction in the abdomen can interfere with venous drainage. These secondary causes are not the usual explanation for a long-standing left-sided varicocele. They become more relevant when swelling begins abruptly, develops later in life, does not decrease while lying down, or is accompanied by other concerning symptoms.
What Does Not Usually Cause a Varicocele?
Masturbation, sexual activity, tight pants, and ordinary exercise are not established causes of varicoceles. Heavy lifting or prolonged standing may make an existing varicocele feel fuller or more uncomfortable because gravity increases pressure in the veins, but that does not necessarily mean the activity created the condition.
Common Varicocele Symptoms
Most varicoceles are painless and may remain unnoticed for years. When symptoms occur, they can vary from a barely perceptible heaviness to visible enlargement of the veins.
A Dull or Aching Pain
Varicocele pain is typically described as a dull ache, pressure, dragging sensation, or heaviness rather than sharp pain. The discomfort often:
- Develops gradually during the day
- Becomes worse after standing for a long time
- Increases after exercise or physical exertion
- Feels more noticeable in hot weather
- Improves when lying down
Sudden, severe testicular pain is not typical of a varicocele. It may indicate testicular torsion or another urgent problem and requires immediate medical attention.
Visible or Palpable Enlarged Veins
A large varicocele may look or feel like a cluster of soft, twisted cords above the testicle. Doctors have traditionally described this texture as a “bag of worms.” It is not the most appetizing medical comparison, but it is memorable.
The veins are generally easiest to notice while standing. They may become less prominent or disappear when lying down because gravity is no longer encouraging blood to collect in the scrotum.
Scrotal Swelling or Fullness
One side of the scrotum may appear fuller, hang lower, or feel heavier. Mild swelling can be difficult to distinguish from normal asymmetry, since one testicle naturally hangs lower than the other in many people.
A Smaller Testicle
A varicocele may be associated with reduced growth or shrinkage of the affected testicle, known as testicular hypotrophy or atrophy. In adolescents, healthcare professionals may monitor testicular size over time to determine whether one testicle is falling behind in development.
Fertility Problems
Some men first learn that they have a varicocele during an infertility evaluation. The condition may be associated with:
- Lower sperm concentration
- Reduced sperm movement, or motility
- A higher percentage of abnormally shaped sperm
- Increased sperm DNA damage or oxidative stress
Having a varicocele does not automatically mean a man is infertile. Many men with the condition have normal semen results and father children without difficulty. Fertility depends on numerous factors involving both partners, so a varicocele should be considered as one part of the larger clinical picture.
Possible Effects on Testosterone
Testicles produce both sperm and testosterone. Some studies have linked clinically significant varicoceles with reduced testicular function and lower testosterone levels in certain men. However, fatigue, reduced libido, erectile problems, and other symptoms associated with low testosterone have many possible causes. Blood testing is needed before drawing conclusions.
How Can a Varicocele Affect the Testicle?
Researchers continue to study exactly how enlarged scrotal veins interfere with testicular function. Several mechanisms may work together.
Increased Temperature
The pampiniform plexus helps cool arterial blood before it reaches the testicle. Sperm production works best at a temperature slightly below core body temperature. When warm blood pools in enlarged veins, the testicular environment may become warmer than ideal.
Reduced Oxygen Delivery
Sluggish circulation may interfere with normal oxygen exchange and expose testicular tissue to metabolic stress. This can affect the specialized cells responsible for producing sperm and hormones.
Oxidative Stress
A varicocele may increase reactive oxygen species, unstable molecules that can damage cell membranes and sperm DNA when present in excessive amounts. Oxidative stress is one proposed explanation for changes in semen quality.
Backflow of Metabolic Substances
Abnormal venous flow may expose the testicle to substances returning from the kidneys or adrenal glands. The clinical importance of this mechanism remains under investigation.
How Is a Varicocele Diagnosed?
A physical examination is the primary method used to diagnose a clinical varicocele. Imaging may be used when the examination is uncertain, symptoms suggest another condition, or more information is needed.
Medical History
The healthcare professional may ask when the swelling or discomfort began, what makes it worse, and whether it improves while lying down. Additional questions may cover:
- Previous injuries, infections, or surgeries
- History of undescended testicles
- Fertility goals and previous pregnancies
- Medications, testosterone products, or anabolic steroid use
- Urinary or sexual symptoms
- Family and reproductive history
Clear answers help the clinician separate a varicocele from conditions such as a hydrocele, spermatocele, inguinal hernia, epididymitis, testicular tumor, or torsion.
Standing and Lying Physical Examination
The clinician usually examines the scrotum while the patient is both standing and lying down. Standing makes venous enlargement more apparent, while lying down shows whether the veins decompress normally.
The testicles are gently examined for size, firmness, tenderness, and masses. The clinician also feels the spermatic cords and the area above each testicle.
The Valsalva Maneuver
For a small varicocele, the patient may be asked to take a deep breath, hold it, and bear down as though having a bowel movement. This is called the Valsalva maneuver. It temporarily increases abdominal pressure and can make enlarged veins easier to feel.
Clinical Varicocele Grades
Varicoceles found during a physical examination may be described using three grades:
- Grade I: Felt only while performing the Valsalva maneuver
- Grade II: Felt while standing without the Valsalva maneuver but not clearly visible
- Grade III: Large enough to be visible through the scrotal skin
A subclinical varicocele is detected on imaging but cannot be felt during examination. Size alone does not determine how much the condition affects fertility or whether treatment is needed.
Scrotal Doppler Ultrasound
Ultrasound uses sound waves to produce images of the testicles, surrounding structures, and blood vessels. Doppler technology evaluates the direction and speed of blood flow.
A scrotal ultrasound may be ordered when:
- The physical examination is inconclusive
- The anatomy is difficult to assess
- Pain or swelling could have another cause
- A testicular mass must be ruled out
- Testicular size needs objective measurement
- A varicocele develops in an unusual pattern
The sonographer may take measurements while the patient is lying down and standing, with and without the Valsalva maneuver. Enlarged veins and backward venous flow support the diagnosis.
Routine ultrasound screening solely to find a nonpalpable varicocele is generally not recommended during every male infertility evaluation. A physical examination remains central because treating an imaging-only varicocele has not consistently shown meaningful fertility benefits.
Semen Analysis
If fertility is a concern, a semen analysis measures sperm concentration, movement, shape, and semen volume. Because results naturally vary, an abnormal test may need to be repeated.
A semen analysis does not prove that a varicocele caused the abnormality. It helps determine whether testicular function is affected and whether further evaluation by a reproductive urologist is appropriate.
Hormone Testing
Blood tests may be considered when a man has infertility, reduced testicular size, low sperm concentration, sexual symptoms, or signs of hormonal dysfunction. Tests may include testosterone, follicle-stimulating hormone, luteinizing hormone, and other hormones selected according to the clinical situation.
Evaluation in Teenagers
For adolescents, the evaluation focuses on symptoms, testicular growth, and changes over time. Testicular volume can be measured with an examination tool called an orchidometer or with ultrasound. Significant or persistent asymmetry may justify referral to a pediatric urologist.
Not every teenage varicocele requires a procedure. Regular follow-up may be appropriate when there is no pain and both testicles are growing normally.
Conditions That Can Resemble a Varicocele
A scrotal lump should not be diagnosed by touch alone at home. Possible alternatives include:
- Hydrocele: Fluid surrounding the testicle
- Spermatocele: A fluid-filled cyst near the epididymis
- Inguinal hernia: Abdominal tissue extending into the groin or scrotum
- Epididymitis: Inflammation or infection behind the testicle
- Testicular torsion: Twisting that cuts off the testicle’s blood supply
- Testicular tumor: A growth within the testicle
A varicocele is usually soft and located above or around the testicle. A hard lump within the testicle itself requires prompt medical assessment, even when it does not hurt.
When Should You Seek Medical Care?
Schedule a medical appointment for a new lump, persistent ache, scrotal heaviness, visible enlarged veins, testicular size differences, or fertility concerns.
Seek urgent or emergency care for:
- Sudden, severe testicular or scrotal pain
- Pain accompanied by nausea or vomiting
- Rapid swelling after an injury
- A testicle that appears unusually high or rotated
- Fever, redness, warmth, or urinary symptoms
- A new hard lump within a testicle
These symptoms are not typical of an uncomplicated varicocele and may signal a time-sensitive condition.
Experiences Related to Varicocele Evaluation
The following experiences are fictional composites based on common clinical situations. They are included to illustrate how symptoms and diagnosis may unfold and are not accounts of specific patients.
The Gym Ache That Kept Returning
Imagine a 24-year-old who notices a dragging sensation on the left side of his scrotum after long workouts. At first, he assumes he has strained a muscle. The discomfort is mild in the morning, becomes more noticeable after standing all day, and improves within 20 minutes of lying on the couch.
Because the pain is not severe, he postpones an appointment. Then he feels a soft cluster of cords above the testicle while showering. Internet searching produces everything from “harmless vein” to “certain disaster,” which is the internet’s traditional method of emotional support.
During the appointment, the clinician asks about the timing of the pain, exercise habits, injuries, urinary symptoms, and sexual health. The examination is performed while he is standing. When he bears down, the veins become easier to feel. They shrink when he lies down. The testicles are normal in size and firmness, and no hard mass is present.
The pattern is consistent with a clinical varicocele. The patient leaves relieved that the finding is usually benign, but also better informed about which changes would require follow-up.
The Fertility Workup Surprise
Consider a 33-year-old man and his partner who have been trying to conceive for more than a year. He has never experienced scrotal pain and has not noticed swelling. During the fertility evaluation, a urologist identifies enlarged veins on the left side during a standing examination.
A semen analysis shows reduced sperm concentration and movement. A second sample is collected because semen parameters can fluctuate. The repeat test remains abnormal. Hormone tests and a detailed medical history help rule out additional contributors, including testosterone use, previous infections, heat exposure, and genetic or hormonal conditions.
The diagnosis creates mixed emotions. There is relief in finding a potentially relevant factor, but also frustration because a varicocele does not explain every case of infertility and does not guarantee a particular outcome. The clinician discusses the findings in the context of both partners rather than treating the enlarged veins as the sole villain in the story.
This experience highlights why diagnosis involves more than spotting a vein on ultrasound. The physical examination, repeated semen testing, reproductive goals, partner evaluation, and overall health all influence what happens next.
The Teenager With Uneven Testicular Growth
In another common scenario, a 15-year-old is found to have a left-sided varicocele during a sports physical. He has no pain and had never noticed it. Understandably, the phrase “enlarged scrotal veins” does not improve anyone’s afternoon.
A pediatric urologist measures both testicles and explains that natural asymmetry is common. Because one side appears slightly smaller, the clinician recommends observation and repeat measurement rather than an immediate procedure.
Several months later, the difference is reassessed. Ultrasound may be used if physical measurements are uncertain or if objective documentation is needed. The teenager and his parents learn that the goal is not to react dramatically to a single measurement. Growth patterns, persistent asymmetry, discomfort, and age-appropriate fertility considerations matter more than one snapshot.
Regular follow-up also gives the teenager an opportunity to ask questions privately. Concerns about body image, sexual development, and future fertility may be harder to discuss than the physical symptoms themselves. A calm, factual conversation can prevent years of unnecessary anxiety.
The Emotional Side of Getting Diagnosed
Scrotal symptoms often create disproportionate worry because people may fear cancer, infertility, surgery, or changes in sexual function. Embarrassment can delay care, even though clinicians evaluate groin and testicular conditions routinely.
The physical examination is generally brief. Ultrasound, when needed, is noninvasive and does not use ionizing radiation. Patients may feel awkward, but the medical team’s focus is anatomy and blood flow, not judgment.
A useful approach is to write down when symptoms occur, which activities aggravate them, whether lying down provides relief, and when the lump was first noticed. People seeking fertility evaluation should bring information about medications, supplements, testosterone products, previous pregnancies, surgeries, infections, and relevant medical conditions.
Receiving a varicocele diagnosis does not automatically mean treatment is required. It also does not mean infertility is inevitable. The diagnosis is a starting point for understanding symptoms and testicular function, not a forecast carved in stone.
Conclusion
A varicocele is an enlargement of the veins surrounding a testicle, most often on the left side. It generally develops because blood does not drain efficiently through the testicular veins. Many people have no symptoms, while others experience a dull ache, heaviness, visible twisted veins, testicular size differences, or fertility problems.
Diagnosis usually begins with a standing and lying physical examination, often including the Valsalva maneuver. Doppler ultrasound can clarify uncertain findings, evaluate blood flow, measure the testicles, and rule out other causes of scrotal swelling. Semen analysis and hormone testing may be appropriate when fertility or testicular function is a concern.
Most importantly, do not assume every scrotal lump is a varicocele. New swelling, a hard testicular mass, or persistent discomfort should be assessed by a healthcare professional. Sudden severe pain requires emergency evaluation because testicular torsion and other urgent conditions cannot wait for a convenient calendar opening.
Medical note: This article provides general educational information and is not a substitute for an examination, diagnosis, or personalized advice from a licensed healthcare professional.
