Few words on an imaging or exam report create more quiet worry than the ones involving the scrotum. Varicocele and hydrocele are two of the most common, and they turn up often enough that most men who encounter these terms have never heard them before. Both describe a change in the structures surrounding the testicle rather than in the testicle itself, and in the large majority of cases, both are benign.
Still, “usually benign” is not the same as “never worth attention.” A varicocele has a well-documented association with fertility, and there is one specific pattern that leads clinicians to look a little further. Understanding the difference between these two findings, and knowing which questions to ask, turns a confusing term on a report into something manageable.
A varicocele is an enlargement of the network of veins that carries blood away from the testicle, known as the pampiniform plexus. When the small valves inside those veins stop closing properly, blood pools and the vessels widen, much the same way a varicose vein develops in the leg. Men who can feel one often describe the sensation as a soft bag of worms sitting above or behind the testicle, more noticeable when standing and less noticeable when lying down.
Varicoceles are common. Roughly 15% of men have one, and about 85% of those occur on the left side. The left-sided pattern reflects anatomy rather than anything gone wrong: the left testicular vein drains at a sharper angle into the left renal vein, while the right drains more directly into the vena cava. Many men live with a varicocele for decades without noticing it. When symptoms do appear, they tend to be a dull ache or a feeling of heaviness that builds through the day or after long periods on your feet.
On ultrasound, radiologists commonly grade varicoceles using the Sarteschi classification, a five-point scale based on how much blood flows backward and under what conditions. Grade I describes reflux visible only during a Valsalva maneuver while standing; Grade V describes reflux present even at rest. Grade V is the one most consistently associated with reduced testicular size, which is part of why the grading matters.
A hydrocele is a collection of clear fluid that gathers between the two thin layers of the tunica vaginalis, the sac that wraps around the testicle. Because the fluid is transparent, a hydrocele classically transilluminates during a physical exam, meaning light passes through it when a small light is held against the scrotum. The typical presentation is a soft, painless swelling that grows slowly enough that many men cannot say when it began.
Hydroceles affect roughly 1% of men over the age of 40. They come in two forms. A communicating hydrocele occurs when the passage between the abdomen and the scrotum, called the processus vaginalis, never fully closed, allowing fluid to move back and forth. These change in size through the day and are most often seen in infants. A noncommunicating hydrocele is a closed pocket of fluid, usually acquired later in life after inflammation, injury, infection, or for no identifiable reason at all. That is the form most adult men encounter.
The simplest way to hold the distinction is by what is inside. A varicocele contains blood sitting in dilated veins. A hydrocele contains clear fluid sitting in a sac. That single difference explains most of what follows.
Because a varicocele is venous, it responds to gravity and pressure. It often becomes more prominent when you stand and softens when you lie down, and it enlarges when you bear down. A hydrocele generally does not behave that way; it stays roughly the same regardless of position. A varicocele can be associated with reduced fertility, while a hydrocele generally is not unless it becomes large enough to cause discomfort or to make examining the testicle difficult. Both are usually painless, and neither is a form of cancer, though both can occasionally coexist with conditions that do need attention, which is why a physical exam is rarely the end of the conversation.
The clearest reason a varicocele gets attention is fertility. While around 15% of men in the general population have one, varicoceles are found in roughly 40% of men evaluated for infertility. That association is well established, though it is important to read it carefully: most men with a varicocele father children without difficulty. The finding raises a question rather than delivering an answer, and a urologist is the right person to help sort out whether it is contributing to anything in an individual case.
The second reason is testicular size. When a varicocele is associated with a measurably smaller testicle on the affected side, particularly in adolescents and younger men, that changes the calculus and may prompt a discussion about repair. Higher-grade varicoceles are more likely to show this pattern.
Hydroceles are usually a comfort question rather than a health question. A small one that causes no symptoms is often simply monitored. A larger one may become heavy or awkward, and some men choose to have it drained or repaired for that reason alone. The one clinical concern worth noting is that a large hydrocele can obscure the testicle underneath it during a physical exam, which is one of the reasons imaging is often used rather than relying on examination alone.
There is a specific situation that changes how clinicians think about a varicocele. A varicocele that appears only on the right side is uncommon, accounting for something in the range of 5% of cases. A varicocele that appears suddenly in an older man, or one that does not soften when he lies down, is likewise unusual.
Those patterns can occasionally reflect something in the abdomen pressing on the veins that drain the testicle, such as a mass in the retroperitoneum affecting the vena cava or the renal vein. This is uncommon, and the great majority of right-sided varicoceles turn out to be an anatomical variation and nothing more. But it is the reason a clinician may recommend imaging of the abdomen rather than the scrotum alone. It is a good example of how a finding in one part of the body can be a reason to look at another.
For the scrotum itself, ultrasound with Doppler is the first-line test, performed both standing and lying down and with a Valsalva maneuver. It is quick, inexpensive, and well suited to imaging superficial structures and blood flow. A whole-body MRI is not a substitute for that examination, and it would be misleading to suggest otherwise.
What comprehensive imaging contributes is the surrounding context. A whole-body MRI covers the abdomen, retroperitoneum, kidneys, and pelvis without ionizing radiation and without contrast dye, which is precisely the territory a clinician would want to review if an unusual varicocele pattern raised a question. It also builds a personal baseline, so that a change identified years from now can be compared against what your anatomy actually looked like before.
Findings like these are also a reminder that scans frequently reveal things nobody was looking for. Most of them are harmless. Understanding how incidental findings are interpreted and followed up makes the experience of reading a report far less unsettling, and it is worth knowing before you ever see one.
If you have been told you have a varicocele or a hydrocele, the most useful next step is a conversation with a urologist, supported by a dedicated scrotal ultrasound. Neither finding is a reason for alarm, and both are well understood.
For men who want a broader view of their health, comprehensive imaging offers a way to establish a personal baseline and understand what is happening across the body before symptoms appear. Our team, led by Medical Director Edward M. Tavel Jr., MD, is happy to walk you through what a scan covers and what it does not. You can review common questions about scanning or reach out to schedule a conversation at your convenience.
Frequently asked questions
Is a varicocele dangerous?
In itself, no. A varicocele is a dilated group of veins, not a tumor, and it does not become cancerous. The reasons it gets attention are its association with fertility and, in some cases, with reduced testicular size. A new or isolated right-sided varicocele is the one presentation that typically prompts additional imaging.
Can a varicocele or hydrocele go away on its own?
Varicoceles do not generally resolve without treatment, though they often remain stable for many years. Communicating hydroceles in infants frequently close on their own during the first year of life. Adult noncommunicating hydroceles usually persist, and treatment is elective and based on symptoms.
How is the difference between them diagnosed?
A physical exam often distinguishes the two, since a hydrocele transilluminates and a varicocele changes with position. Scrotal ultrasound with Doppler confirms the diagnosis, measures the veins, assesses blood flow, and evaluates the testicle underneath a hydrocele that may be difficult to examine by hand.
Does a varicocele always need to be repaired?
No. Repair is typically considered when there is pain that does not respond to conservative measures, documented infertility with abnormal semen parameters, or measurable testicular size difference in a younger patient. Many varicoceles are simply monitored. That decision belongs with a urologist.
Would a whole-body MRI show a varicocele or hydrocele?
Larger fluid collections and prominent dilated veins can be visible on MRI, but ultrasound remains the appropriate test for evaluating the scrotum. The value of comprehensive MRI in this context is its view of the abdomen and retroperitoneum, which is where a clinician would look if an unusual varicocele pattern needed explanation.
