Non-obstructive Azoospermia (NOA)
No sperm in the semen due to reduced production — and what can be done about it
Azoospermia means no sperm can be found in the semen. In non-obstructive azoospermia (NOA), the cause is reduced or absent sperm production within the testicles, rather than a blockage. It is one of the most challenging fertility diagnoses — but it is far from hopeless.
What causes non-obstructive azoospermia?
NOA reflects a problem with the testicle's ability to make sperm. Common contributing factors include:
- Genetic causes — such as Klinefelter syndrome (an extra X chromosome) or Y-chromosome microdeletions.
- Previous chemotherapy or radiotherapy — which can affect sperm production.
- Undescended testes or testicular injury/torsion earlier in life.
- Hormonal problems affecting the signals that drive sperm production.
- Unknown (idiopathic) — in many men no single cause is identified.
How NOA is diagnosed
The diagnosis is made carefully and without unnecessary surgery. Mr Wiseman uses a combination of:
- Two semen analyses, ideally at least three months apart, to confirm azoospermia.
- Blood tests — FSH and testosterone. In NOA the FSH is often raised and the testes may be smaller.
- Examination of the testes and the tubes that carry sperm.
- Genetic tests — a Karyotype and Y-chromosome microdeletion screen, which guide treatment and prognosis.
Treatment options
1. Optimising sperm production
Before any surgery, Mr Wiseman looks for anything that can be improved — addressing lifestyle factors, hormonal balance and general health. In selected men, medication such as clomiphene may be used to raise the testosterone level inside the testicle.
2. microTESE — microsurgical sperm retrieval
When sperm cannot be found in the semen, the best option is usually microTESE (microsurgical testicular sperm extraction). Using an operating microscope, the surgeon carefully searches the testicular tissue for the small areas most likely to contain sperm. Compared with older techniques, microTESE removes far less tissue, causes less damage, and offers higher retrieval rates. Mr Wiseman was the first surgeon to offer microTESE in the East of England.
Any sperm found are used with IVF and ICSI, where a single sperm is injected directly into an egg — so only a very small number of sperm are needed to give a couple the chance of a pregnancy.
What happens next
After your assessment, Mr Wiseman will explain your likely cause, your individual chance of finding sperm, and the next steps. Throughout, he works alongside the teams at Bourn Hall Clinic and Cambridge IVF so that your care is joined up from start to finish.
Frequently asked questions
Does azoospermia mean I can never be a biological father?
No. This is one of the most common and damaging myths. Even when no sperm appear in the semen, sperm can often be found within the testicle using microTESE and used with IVF/ICSI. A man with non-obstructive azoospermia may still become a biological father.
My FSH is high — does that mean no sperm will ever be found?
Not at all. A raised FSH points towards a production problem, but it does not predict whether sperm can be retrieved surgically. Men with high FSH, and even men with Klinefelter syndrome, can have sperm found at microTESE.
I had chemotherapy in the past — am I definitely sterile?
No. Some men recover sperm production after chemotherapy, and even when they do not, surgical sperm retrieval may still find sperm. This is always worth assessing rather than assuming.
What is the chance of finding sperm with microTESE?
It depends on the underlying cause, but sperm are found in a substantial proportion of men, even those previously told there was no hope. Mr Wiseman will discuss your individual likelihood after your assessment.
Talk to a specialist about NOA
Book a private consultation with Mr Oliver Wiseman, or arrange an NHS referral through your GP. Face-to-face, telephone and video appointments are available.