Why does it usually occur on the left?

The left testicular vein drains into the left renal vein at a right angle and against a longer column of blood, so its valves are under more pressure and fail more often. Right-sided or sudden-onset varicoceles are less common and warrant assessment of the abdomen, because they can occasionally signal something pressing on the vein.

What is varicocele embolisation?

A catheter procedure that closes the leaking testicular vein from within. Through a single needle puncture at the groin or neck, under local anaesthesia with sedation, the refluxing vein is sealed with coils, sclerosant or both. Normal drainage routes take over. It is done as a day procedure, with no incision in the scrotum.

How does embolisation compare with surgery?

Both aim to stop reflux in the testicular vein. Embolisation avoids a groin or scrotal incision and a general anaesthetic, and most men return to normal activity within a day or two. Surgical ligation is an established alternative. Which is more appropriate depends on the anatomy shown on imaging and on the man's circumstances, and that comparison is part of the consultation.

Venous disease

Varicocele

Enlarged veins in the scrotum from a leaking gonadal vein — a dull ache, heaviness, or a finding during fertility assessment. Assessed and treated in Singapore.

Last reviewed 15 Sept 2026

Reviewed by Dr Tay Jia Sheng · Vascular, Endovascular & General Surgeon

What is a varicocele?

A varicocele is an enlargement of the veins that drain the testicle, within the scrotum — the same process as varicose veins in the leg, in a different place. The testicular (gonadal) vein carries blood upward against gravity; when its one-way valves fail, blood refluxes back down and pools in the network of veins around the testicle, which dilate. It is one of the conditions I assess and treat in Singapore.

Varicoceles are common, are found far more often on the left, and are frequently discovered by chance. Many cause no symptoms and need no treatment.

How it presents

A dull ache or a dragging heaviness in the scrotum, worse after standing, exertion or through the day, and eased by lying down
A visible or palpable swelling of the veins, classically described as a "bag of worms", more obvious when standing
A finding during fertility assessment — a varicocele can be associated with reduced semen quality
In adolescents, a difference in size between the two testicles

Why treat it

Treatment is not for every varicocele. It is worth considering when the varicocele is causing persistent discomfort, when it is associated with reduced semen parameters in a man seeking to conceive, or when a testicle is not growing normally in an adolescent. In those situations, stopping the reflux relieves the pressure on the testicle.

How I assess it

Assessment starts with examination — standing, and with a bearing-down manoeuvre that makes reflux more obvious — followed by scrotal duplex ultrasound, which confirms the diagnosis, measures the veins and demonstrates the reflux. Where embolisation is planned, imaging maps the gonadal vein and its drainage so the procedure can be planned precisely. Fertility questions are assessed alongside the relevant specialist. I read every scan and make every treatment decision myself.

Treatment options

Observation for varicoceles that cause no symptoms and no concern
Varicocele embolisation — closing the refluxing testicular vein from within through a catheter, with coils, sclerosant or both, as a day procedure under local anaesthesia with sedation. It uses the same technique as pelvic vein embolisation and leaves no incision in the scrotum
Surgical ligation — an established alternative, tying off the refluxing veins through a small incision, which may be preferred for some anatomies

The choice depends on the anatomy shown on imaging and on your circumstances, and is made with you at consultation.

When to see a doctor promptly

A varicocele that appears suddenly, that is on the right side only, or that does not settle when lying down should be assessed without delay, because it can occasionally indicate a problem higher up that is pressing on the vein. Scrotal pain that is severe or sudden is a separate emergency and needs same-day care.

Frequently asked questions

Is a varicocele dangerous?: Not in itself. Most cause no harm, and many need no treatment at all. Treatment is considered when the varicocele causes persistent discomfort, when it is associated with reduced semen quality in a man being assessed for fertility, or — less commonly — when a testicle has stopped growing normally in an adolescent.
Why does it usually occur on the left?: The left testicular vein drains into the left renal vein at a right angle and against a longer column of blood, so its valves are under more pressure and fail more often. Right-sided or sudden-onset varicoceles are less common and warrant assessment of the abdomen, because they can occasionally signal something pressing on the vein.
What is varicocele embolisation?: A catheter procedure that closes the leaking testicular vein from within. Through a single needle puncture at the groin or neck, under local anaesthesia with sedation, the refluxing vein is sealed with coils, sclerosant or both. Normal drainage routes take over. It is done as a day procedure, with no incision in the scrotum.
How does embolisation compare with surgery?: Both aim to stop reflux in the testicular vein. Embolisation avoids a groin or scrotal incision and a general anaesthetic, and most men return to normal activity within a day or two. Surgical ligation is an established alternative. Which is more appropriate depends on the anatomy shown on imaging and on the man's circumstances, and that comparison is part of the consultation.