Semen Analysis & Sperm DNA Fragmentation
The key tests used to assess male fertility — and how they are done
How a semen analysis is done
A semen analysis is the first and most important test of male fertility. It is simple, but a few practical points make the result reliable.
- Abstinence: avoid ejaculating for 2 to 5 days before the test — not less and not more, as both can affect the result.
- Collecting the sample: the sample is produced by masturbation into a sterile container provided by the clinic. It is important to collect the whole ejaculate, as the first part is the richest in sperm.
- Produced at the clinic: sperm must be examined very quickly, so the sample should be produced at the clinic to allow it to be analysed immediately.
- More than one test: because sperm production varies, at least two samples are needed, ideally around three months apart.
The laboratory measures the volume of semen, the number (concentration) of sperm, how well they move (motility) and their shape (morphology), and compares these against the current WHO reference values. Blood tests for hormones (FSH and testosterone) are often arranged alongside, and ideally should be undertaken in the morning with the results available prior to being seen in the clinic. If you have had tests taken before your appointment, please bring all of the results with you to the clinic, including any genetic tests, semen analyses, ultrasound scans and blood tests.
Sperm DNA fragmentation testing
A standard semen analysis tells us how many sperm there are, how they move and what they look like — but not whether the genetic material inside them is intact. Sperm DNA fragmentation testing measures breaks or damage in the sperm's DNA, often caused by oxidative stress.
High levels of DNA fragmentation have been linked to lower fertilisation and pregnancy rates, poorer embryo development, and a higher chance of miscarriage — sometimes even when the routine semen analysis appears normal.
When should it be used?
It is a selective test rather than a routine one. Mr Wiseman may recommend it when there is:
- Unexplained infertility, where standard tests are normal.
- Recurrent miscarriage.
- Repeated failed IVF or ICSI cycles.
The result can guide decisions about which sperm to use, to give a couple the best chance of a healthy pregnancy.
Other tests
Depending on your history and examination, a few further tests may be advised to establish the cause and guide treatment.
Genetic tests
Where the sperm count is very low or absent, genetic tests are important. These usually include a Karyotype (which looks at the chromosomes, for example to detect Klinefelter syndrome) and Y-chromosome microdeletion screening. If absence of the vas deferens is suspected, cystic fibrosis (CFTR) gene testing is arranged for you and your partner, with genetic counselling. These results help determine the likely cause, the chance of finding sperm, and any implications for your children.
Ultrasound scan of the testes
A scrotal ultrasound is a simple, painless scan that gives more detail about the testes and surrounding structures. It can confirm a varicocele (enlarged veins), assess the size and texture of the testes, and — importantly — pick up any lumps that need attention, such as a testicular tumour. It is often arranged as part of a thorough fertility assessment.
Frequently asked questions
How should I prepare for a semen analysis?
Abstain from ejaculation for 2 to 5 days beforehand (not less, not more). Collect the whole sample, by masturbation into a sterile container provided by the clinic, and make sure none is spilt. The sample should be produced at the clinic so it can be analysed immediately, as sperm must be examined very quickly.
Why do I need more than one semen test?
Sperm production naturally varies, and a single result can be misleading. At least two samples are recommended, ideally around three months apart, because sperm take roughly three months to develop — so this also allows any lifestyle changes or recovery from illness to show.
What is sperm DNA fragmentation?
A standard semen analysis counts sperm and looks at how they move and their shape, but it does not assess the genetic material inside them. Sperm DNA fragmentation testing measures breaks or damage in the DNA carried by the sperm, which can affect fertilisation, embryo development and the chance of miscarriage even when a routine semen analysis looks normal.
When is sperm DNA fragmentation testing useful?
It is most helpful in specific situations: unexplained infertility, recurrent miscarriage, and repeated failed IVF or ICSI. The result can guide decisions about which sperm to use.
Concerned about a test result?
Mr Wiseman offers a thorough assessment of your semen analysis and, where helpful, further tests such as sperm DNA fragmentation. Book a consultation to discuss your results.