What is a varicocele?

Varicoceles are a collection of abnormally swollen veins in the scrotum. They are similar to varicose veins, which can develop in the legs and other places in the body.  

In particular, varicoceles involve dilation of the pampiniform plexus, which is a bundle of small veins located in the spermatic cord. The spermatic cord is a bundle of nerves, ducts, and blood vessels connecting the testicles to the abdominal cavity. Normally, blood drains from the testicles through the pampiniform plexus to the internal spermatic vein towards the heart; however, in a varicocele, the blood flows backwards towards the testicles.

An important function of the pampiniform plexus is to cool the testicles by giving off heat as blood is drained out of the scrotum. Spermatogenesis (creation of sperm) requires a cooler temperature than that of the rest of the body. When there is a varicocele, blood pools in the scrotum and this can increase scrotal temperature, leading to impairment or disruption in sperm production, which can impact fertility.ⁱ In children, varicocele can also prevent the testicle from developing normally, which can lead to testicular atrophy (shrinkage) and impaired sperm production from that testicle.

Doctors classify varicoceles into three gradesⁱⁱ:

Grade 1: the varicocele is only palpable with the Valsalva maneuver (closing the mouth and pinching the nose while attempting to forcefully blow out, which increases pressure in the abdomen and therefore on the testicular veins)

Grade 2: the varicocele is easily palpable while standing without the Valsalva maneuver

Grade 3: the varicocele is visible upon inspection of the scrotum.  Large grade 3 varicoceles may look like a “bag of worms” within the scrotum.ⁱⁱⁱ

Varicoceles are more likely to occur in older individuals and can get larger as a person gets older. Levinger et al (2007) completed a study of 504 men over the age of 30 and found that the prevalence of varicocele increased by about 10 percent with each decade of life, reaching 75 percent in those above 80 years old.^iv

Overall, varicoceles occur in 15 percent of men. They appear to be more prevalent among men with subfertility, affecting 35-50 percent of males with primary infertility (people who have never conceived) and 45-81 percent of males with secondary infertility (people who have had at least one previous conception).^v,vi

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What are the symptoms of a varicocele?

Varicoceles may cause pain in the testicles, typically described as dull, aching, or throbbing; testicular pain associated with varicoceles is rarely acute or stabbing. Some individuals may also notice a “heaviness” in the scrotum, which worsens with prolonged standing, exercise, or activity.^vii

However, varicoceles usually have no symptoms and are often diagnosed incidentally on physical examination or during a fertility evaluation.^viii

Varicoceles are found in the left testicle 80 to 90 percent of the time. If a left-sided varicocele is present, there is a 30-40 percent chance that a varicocele is present on the right side as well.^ix

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What causes varicoceles?

There are multiple potential causes of varicoceles. These include the following three most common causes of varicocele:^x,xi

1. All veins contain valves that prevent the backflow of blood. It is thought that the most common cause of varicocele is weakness or absence of these valves. If there are weak or absent valves, blood will drain towards the testicle with gravity instead of back towards the heart.

2. On the left side, the internal spermatic vein drains into the left renal vein. Sometimes, these veins come together at a sharp angle. This disrupts the blood flow in the veins and leads to an enlargement of the internal spermatic vein and pooling of blood in the scrotum.

3. Also on the left side, the internal spermatic vein can get caught between two other blood vessels, the aorta and the superior mesenteric artery. This compresses the internal spermatic vein and reduces blood flow out of the scrotum, causing abnormal enlargement of the scrotal veins. This is called the “nutcracker” effect.

Rarer causes of varicocele include a blood clot in the veins or a mass in or near the kidney leading to compression of veins. Genetics may play a role in the development of large varicoceles. A study by Griffiths et al (2018) found that compared to people with a grade 1 varicocele, people with a grade 2 or 3 varicocele were more likely to have a father with a varicocele.^xii

Males with a lower body mass index (BMI) may be at higher risk for more severe varicoceles. A 2021 meta-analysis of 11 studies found that BMI was higher in people with grade 1 varicoceles, compared to those with grade 2 and 3 varicoceles.^xiii

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How are varicoceles diagnosed?

Varicoceles are fairly common and are usually found incidentally on physical examination in adolescents, or during fertility evaluations. The standard diagnostic test for varicocele is a physical exam. The patient is instructed to stand and take a deep breath or perform the Valsalva maneuver while a doctor palpates the scrotum and testicles.^xiv  

In some circumstances (i.e., if the diagnosis of a varicocele is uncertain), a scrotal ultrasound is performed.^xv Ultrasound is the most commonly used imaging modality for varicocele.  Ultrasound may also identify “subclinical” varicoceles, which are varicoceles that cannot be detected on a physical exam. However, the current consensus is that subclinical varicoceles should not be treated, as they have not been shown to impact fertility.^xvi

Ultrasound imaging can also be used to determine the degree of backward blood flow, known clinically as reflux. The degree of reflux ranges from I-V, with Grade V being the most severe.^xvii

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How does a varicocele impact fertility?

As mentioned previously, the prevalence of varicocele in the general male population is 15 percent, but the prevalence is even higher among infertile men. Varicoceles develop in up to 50 percent of men with primary infertility and up to 81 percent with secondary infertility.^xviii These statistics are consistent with studies suggesting that varicoceles can have detrimental effects on sperm production, maturation, and transport.^xix

While the degree to which varicoceles impact fertility is uncertain, studies indicate that varicocele surgery can significantly improve natural pregnancy outcomes and reduce the need for assisted reproductive technologies (ART).  

A meta-analysis by Kim et al (2013) looked at 610 couples diagnosed with varicoceles and subfertility. Of those, 311 patients underwent surgical treatment of their varicocele and 299 received no varicocele treatment. The researchers found that the rate of natural pregnancy was 21.8 percent in the group that underwent varicocele surgery compared to 11.0 percent in the group that did not.^xx The researchers concluded that surgical repair of varicocele increased the odds of natural conception for patients with palpable varicocele and impaired semen quality.^xxi

Surgical varicocele repair has also been shown to improve intrauterine insemination (IUI) outcomes. In a study with 58 couples undergoing IUI, 34 men underwent varicocele treatment and 24 did not. The IUI pregnancy rate was 11.8 percent among the group who underwent surgical varicocele treatment, compared to 6.3 percent in the group that did not.^xxii

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What treatments exist for varicoceles and how successful are they?

Treatment of varicocele depends on the age of the patient, semen analysis parameters, desire for fertility and symptoms.^xxiii,xxiv

Among adolescents and children, treatment is somewhat controversial. In general, it is recommended that if a varicocele is diagnosed, treatment be considered if there is a difference in testicular size (i.e., smaller testicle on the side of the varicocele) or if the patient has an abnormal semen analysis. If the varicocele is asymptomatic and the testicles are of equal size, the varicocele can be monitored yearly or every two years with exam and semen analysis once the patient reaches adolescence.^xxv,xxvi

In the case of adults with varicocele, treatment is considered only when the varicocele is palpable; treatment of subclinical varicocele (varicocele seen only on ultrasound) has not been shown to improve fertility. Additionally, the following criteria should be met: ^{xxvii, xxviii}

1) the patient or couple has known infertility  

2) the female partner has normal fertility or correctable infertility

3) the male partner’s semen analysis is abnormal

Varicocele treatment can also be considered in patients with normal semen analyses if the patient has pain related to the varicocele. In this case, treatment is unlikely to improve fertility but may help with symptoms.  

Various techniques exist for the surgical repair of varicoceles, including open, microscopic or laparoscopic surgery, and radiologic embolization.^xxix,xxx In open and microscopic surgery, an incision is made in the lower abdomen, groin or upper scrotum and the swollen vessels are clipped or tied off. In laparoscopic surgery, a surgeon makes a few small incisions in the abdomen in order to tie off the spermatic veins where they enter the abdomen. Interventional radiologic embolization involves accessing the veins with a needle and injecting coils or glue to block off the vessels and direct flow away.  

A comprehensive discussion of each varicocele surgery technique and comparison of the different methods is beyond the scope of this article.  

Is varicocele curable without surgery?  

Varicoceles are not curable without surgery, but as noted above, treatment is only indicated if the varicocele is associated with infertility or pain.  

Pharmacological agents such as oral or topical medications can be used to treat the pain associated with varicoceles. Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil®, Motrin ®), scrotal elevation, and limiting physical activities can help alleviate testicular pain associated with a varicocele.^xxxi,xxxii

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What happens if a varicocele is left untreated?

In adults, an untreated varicocele is unlikely to cause permanent damage to the testicle. Among children and adolescents, an untreated varicocele can sometimes lead to impaired testicular development. A meta-analysis conducted by Nork et al (2014) found that varicoceles negatively affect sperm production and motility in young males aged 15-24, which can lead to male infertility. The authors suggest that treating varicoceles in this younger population may be beneficial in preserving testicular and sperm function, as well as future fertility.^xxxiii However, as previously noted, not all varicoceles lead to testicular dysfunction or infertility and treatment is typically directed towards children and adolescents with asymmetric testicular size or abnormal semen analysis parameters.

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What are the other risks or complications associated with varicoceles?

In addition to male infertility, other risks or complications associated with varicoceles include:  

• Scrotal and testicular pain  
• Swollen scrotum
• Slow testicular growth in children
• Decreased testosterone production

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Conclusion

Many men have varicoceles and never experience any symptoms or problems with their reproductive health. However, research does suggest that varicoceles are more prevalent in men with fertility issues.  

Men experiencing varicocele symptoms should talk to a healthcare provider. Treatment for problematic varicoceles is available and may also improve fertility and pregnancy outcomes.  

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