New guidelines from the National Institute for Health and Care Excellence (NICE) now advise doctors to consider treating varicoceles in order to improve male fertility, a shift that could change how thousands of couples are assessed when they struggle to conceive.
The update, which came into effect in March 2026, overturns previous NICE guidance stating that treatment of the condition would not improve a couple’s chance of pregnancy. Clinicians are now instructed to “consider radiological or surgical treatment for individuals with male reproductive organs who have varicocele detected on clinical examination”.
What are varicoceles?
A varicocele is an abnormal enlargement of the veins within the scrotum — specifically the pampiniform plexus of the spermatic cord — and is often compared to varicose veins in the legs. Professor Suks Minhas, a urologist, describes it as “a collection of dilated veins around the testicle”. According to the National Institutes of Health, up to 40% of men with primary infertility have the condition, yet because infertility is still widely seen as a women’s issue, many cases go undiagnosed.
The condition is surprisingly common. Around 15-20% of all men have varicoceles, and the incidence rises after puberty. Among men attending fertility clinics, the figure jumps to between 35% and 50%. For men with secondary infertility — those who have previously fathered a child — prevalence can reach 69-81%. Age also plays a role: one study found a 48% prevalence in men over 40, with higher rates in older groups.
Most varicoceles occur on the left side — around 90% — due to the anatomy of the left testicular vein draining into the renal vein. A solitary right-sided varicocele is unusual and may warrant further investigation. Many men are asymptomatic; indeed, 80-90% of varicoceles cause no noticeable symptoms and are only discovered during routine physical exams or fertility investigations. When symptoms do appear, they typically include a dull or aching pain, a feeling of heaviness in the scrotum, swelling, or testicular atrophy. Larger varicoceles have been described as feeling like a “bag of worms” or twisted veins. Professor Minhas notes that “not all varicoceles cause harm or problems”, and the exact cause remains unknown — he calls them “one of the biggest conundrums in urological practice”. The condition is believed to result from faulty valves within the veins that regulate blood flow, causing pooling and dilation. In rare cases, a varicocele developing in older men may be linked to an underlying blockage in larger abdominal veins, potentially due to a tumour.
How varicoceles affect fertility
The impact of varicoceles on fertility is primarily driven by temperature. Professor Ramsay, a urologist with more than 30 years in the male fertility field, explains that the reason varicoceles matter is “heating the testicle”. Normally, the testicles sit in the scrotum because they need to be around 3°C below core body temperature for optimal sperm production. But when the veins around the testicle become dilated and distended, more blood pools in the area — and that blood comes from the abdomen, where it is warmer. This rise in local temperature interferes with sperm production and maturation.
The warming effect triggers a process called oxidative stress. Professor Ramsay describes this as certain chemicals entering the seminal fluid and reducing sperm quality. Elevated temperature and oxidative stress together impair sperm motility, morphology, and count. In laboratory tests, semen analysis after varicocele repair shows improvements in these parameters in 60-80% of men. However, not every varicocele causes infertility — some men with large varicoceles remain fertile while others with smaller ones do not, and researchers do not yet fully understand why.
Beyond sperm quality, varicoceles can also affect testosterone production. Larger varicoceles may disturb Leydig cell function in the testicles, which is responsible for producing the hormone. Some studies show a correlation between the presence of a varicocele and lower testosterone levels. Importantly, Professor Ramsay stresses that if the condition is treated, testosterone levels should return to normal. Varicoceles have also been linked to reduced testicular volume and atrophy, particularly when present for a long time.
Diagnosis typically begins with a physical examination by a doctor. Scrotal ultrasound is frequently used to confirm the presence of dilated veins, assess their size, and measure testicular size. Colour duplex ultrasound can evaluate blood flow. If infertility is a concern, semen analysis is standard, and blood tests to check hormone levels — including testosterone, FSH, LH, and prolactin — may also be performed.
Treatment and the new NICE guidelines
Varicoceles do not resolve on their own, so treatment is required to remove them. The updated NICE guidance represents a shift towards proactive management. The decision to treat is individualised and depends on symptoms, fertility goals, the partner’s fertility status, and the size or grade of the varicocele.
For asymptomatic or mildly uncomfortable varicoceles, conservative management such as supportive underwear or pain medication may be sufficient. But for those trying to conceive, NICE now explicitly recommends considering intervention. Two main treatment routes exist: surgery and radiological embolisation.
Surgical options include microsurgical varicocelectomy, which is considered the most precise approach and is often performed under general anaesthesia using a microscope to identify and tie off affected veins while preserving healthy tissue. It can be done as a day case. Open surgery and laparoscopic surgery are also available. On the radiological side, varicocele embolisation is a minimally invasive procedure in which a small catheter is inserted into a vein and coils or other agents are used to block abnormal blood flow in the affected veins. Professor Ramsay explains that this involves “putting a little tube into the veins and then injecting a plug to block the vein off”. When performed correctly, he says it is “almost as effective as surgery, but with fewer complications”. The procedure is done under local anaesthesia on an outpatient basis, with faster recovery than surgery.
Both surgical and embolisation procedures have high success rates — generally over 90% for successfully treating the varicocele itself. Recurrence rates vary, with embolisation showing lower recurrence in some studies compared to certain surgical techniques, although microsurgical methods tend to have lower complication and recurrence rates than traditional open surgery. Pregnancy rates after treatment vary, with some studies suggesting up to 50% or a 70% rate if semen parameters improve within three months after surgery. The exact benefit on overall pregnancy rates remains debated, but experts agree that for many men the intervention is worthwhile.
Professor Ramsay points out that the new NICE guidance could help couples who have not yet resorted to IVF. “If an individual has a big varicocele, and his female partner is 35 and not getting pregnant, there’s a strong argument to repair the varicocele and wait for the benefit, to potentially avoid IVF,” he says. He adds that there “aren’t many reasons for not treating a varicocele”. He warns that some fertility units, particularly those led by gynaecologists, may overlook the male partner’s condition. “If you’re going to a fertility unit to be seen by a gynaecologist, you must ask them whether or not they’ve considered if the man has a varicocele,” he urges. The NHS, he says, often defaults to IVF, calling that the treatment — “when in reality it’s not. It may be, when it works as a solution, but what about when it doesn’t?”