Varicocele thrombosis is a rare condition in which a cluster of dilated veins in the scrotum develops a blood clot. Treatment options range from anti-inflammatory medications to surgery.

A varicocele is a collection of veins in the scrotum that are unusually dilated or swollen, not unlike varicose veins that can develop in the legs. Varicocele thrombosis is the clinical term for a blood clot that develops in one of those veins.

Varicocele thrombosis can lead to swelling and pain, usually on one side of the scrotum. Doctors may treat it conservatively or, if the condition is severe, with surgery to remove part of the affected vein.

Clots can develop in arteries and veins throughout the body. They may be small and dissolve before they become problematic, or they may become life threatening, depending on their size and location.

The network of veins in the scrotum is known as the pampiniform plexus. These veins carry blood from the testis and epididymis, a duct that carries sperm, within the scrotum back toward the heart. When a cluster of these veins becomes unusually enlarged (dilated), it’s called a varicocele.

Research suggests that about 15% to 20% of adult males have a varicocele. Often, the condition exists without causing any symptoms or the person even knowing about it.

However, in rare cases, it can turn into varicocele thrombosis. This happens when a blood clot develops in the dilated veins.

If a clot forms in a varicocele, blood flow back to the heart is blocked or reduced, often leading to swelling and other symptoms.

A 2025 case report suggested that there have been only around 20 cases of spontaneous varicocele thrombosis reported in medical literature. Spontaneous varicocele thrombosis is when it occurs without a known cause.

Scrotal pain is often the first symptom of varicocele thrombosis. The pain is usually on the left side of the scrotum due to the arrangement of arteries and veins within the scrotum. However, it may also occur on the right side in rare cases.

The condition may also cause swelling in the scrotum. In addition, you may feel the varicocele if the section of affected veins is large enough. The clump of veins may feel like a small lump of worms or spaghetti.

Possible causes of varicocele thrombosis include:

  • trauma
  • hypercoagulable state (increased tendency to form blood clots)
  • vigorous activity
  • infections
  • very long flights
  • drugs

Additional risk factors include tumors of the genital and urinary tract.

In some cases, varicocele thrombosis may happen after an operation. Spontaneous varicocele thrombosis occurs with no identifiable trigger.

A physical examination of the scrotum, as well as the penis and lower abdomen, can help narrow the likely cause of symptoms and rule out other potential causes.

However, imaging is usually necessary to formally diagnose varicocele thrombosis. Ultrasound can help with diagnosing varicocele thrombosis.

Once a healthcare professional has diagnosed varicocele thrombosis, they may begin with anticoagulation therapy. This helps reduce the likelihood of further clots forming.

You usually only take oral anticoagulant medications for a limited time, as they can increase the risk of bleeding complications while they help prevent existing clots from growing larger. The hope with a conservative approach is that the clot will shrink and eventually dissolve into the bloodstream, allowing typical circulation to resume.

A 2018 report suggests that, if someone’s condition doesn’t respond to medications, they may benefit from a varicocelectomy. This is surgery to remove all or a portion of the varicocele.

Without treatment, varicoceles and varicocele thrombosis can lead to pain and infertility. However, if conservative treatment relieves symptoms and helps restore circulation to and from the scrotum, the outlook is very promising.

If surgical repair of the varicocele is necessary, the outlook is also encouraging. A 2022 article that looked at people who had embolization for pain suggests that more than 90% experienced pain relief.

Varicocele thrombosis is a rare condition that happens when a blood clot forms in dilated veins in the scrotum. It can cause symptoms such as pain and swelling. Pain usually develops on the left side, though it may occur on the right side in rare cases.

Anticoagulants can help treat the condition, though surgery to remove the varicocele may be necessary. A healthcare professional can provide more information about the treatment they recommend based on individual circumstances.

It’s important to seek a medical evaluation promptly if you experience pain, swelling, or other symptoms involving the scrotum.