OAT Syndrome
(Oligoasthenoteratozoospermia)
Understanding abnormal semen analysis, male infertility and when varicocele treatment may help.
Understanding Low Sperm Count, Reduced Motility and Abnormal Sperm Morphology
OAT syndrome, or oligoasthenoteratozoospermia, is a term used when a semen analysis shows abnormalities in three sperm parameters at the same time:
Oligozoospermia — reduced sperm concentration
Asthenozoospermia — reduced sperm motility
Teratozoospermia — a lower proportion of sperm with normal morphology
Receiving an OAT result can be worrying, particularly when a couple is trying to conceive. However, OAT is a description of the semen analysis rather than a diagnosis of the underlying cause.
The next step is usually to confirm the findings and assess whether there is an identifiable or potentially treatable factor affecting sperm production or function.
Does OAT Mean That I Am Infertile?
Not necessarily.
A semen analysis provides information about sperm production and quality, but it cannot by itself determine whether natural conception is possible or impossible.
Semen parameters also vary naturally. Illness, fever, medications, lifestyle factors and the timing and collection of the sample can influence the result.
For this reason, when the first semen analysis is abnormal, a repeat semen analysis is often recommended before making treatment decisions.
The fertility assessment should also consider the couple as a whole, including the female partner’s age and fertility factors.
What Causes OAT Syndrome?
There is no single cause of OAT.
Some men have an identifiable condition affecting sperm production, while in others no definite cause is found despite appropriate investigation.
Possible contributing factors include:
Varicocele
A varicocele is an enlargement of the veins around the testicle. It is one of the more common potentially correctable findings in men being assessed for infertility.
A clinically significant varicocele may affect the environment around the testicle and interfere with normal sperm production.
Not every varicocele causes infertility, however, and not every man with OAT has a varicocele.
Hormonal Problems
Sperm production depends on signals between the brain and the testicles.
Abnormalities involving testosterone, follicle-stimulating hormone (FSH), luteinising hormone (LH) and other hormones may contribute to impaired sperm production.
Previous Testicular Problems
Previous testicular torsion, undescended testes, trauma, infection or surgery may affect testicular function and subsequent sperm production.
Genetic Factors
Genetic abnormalities can contribute to significantly impaired sperm production, particularly when the sperm concentration is very low.
Genetic testing is not required for every man with OAT. It is usually considered according to the severity of the abnormality and the clinical findings.
Medications and Lifestyle Factors
Certain medications and substances may affect sperm production. Smoking, obesity, excessive heat exposure and other lifestyle factors may also contribute.
Anabolic steroids or external testosterone are particularly important because they can suppress the hormonal signals required for sperm production.
Unexplained OAT
Sometimes, investigations do not identify a clear underlying cause. This is known as idiopathic male infertility.
How Is OAT Investigated?
The aim of assessment is not simply to confirm that the semen analysis is abnormal. It is to understand why the abnormalities may be present and whether anything potentially correctable can be identified.
Repeat Semen Analysis
Because semen parameters fluctuate, an abnormal semen analysis may need to be repeated.
The assessment considers sperm concentration, total sperm number, motility, morphology and other features of the sample rather than focusing on one number alone.
Medical and Fertility History
Important information may include:
How long the couple has been trying to conceive
Previous pregnancies
Childhood testicular problems
Previous infections or surgery
Current medications and supplements
Testosterone or anabolic steroid use
Smoking and lifestyle factors
Sexual and ejaculatory function
Examination of the Testicles
Physical examination can assess testicular size and consistency and look for abnormalities such as a clinical varicocele.
This distinction is important. A varicocele that can be detected during examination is not necessarily managed in the same way as a small varicocele identified only on ultrasound.
Hormonal Tests
Blood tests may be recommended, particularly when sperm concentration is significantly reduced or there are other clinical concerns.
These may include testosterone, FSH and LH, with additional tests depending on the individual situation.
Ultrasound and Further Investigations
Scrotal ultrasound is not required simply because OAT is present, but it may be useful when examination is uncertain or another testicular abnormality is suspected.
Men with severe abnormalities may require additional investigations, including genetic assessment in selected cases.
What Is the Relationship Between OAT and Varicocele?
Varicocele is particularly relevant because it is one of the potentially treatable conditions associated with impaired semen parameters.
The dilated veins of a varicocele can alter the environment around the testicle. Several mechanisms have been proposed, including increased scrotal temperature, oxidative stress and impaired testicular function.
This may affect:
Sperm concentration
Sperm motility
Sperm morphology
A man with OAT should therefore be examined for a clinically significant varicocele as part of an appropriate male fertility assessment.
However, finding OAT does not automatically mean that varicocele surgery is required.
Can Varicocelectomy Improve OAT?
In appropriately selected men, repairing a clinical varicocele may improve semen parameters.
Varicocelectomy involves interrupting the abnormal veins responsible for the varicocele while preserving important structures supplying and draining the testicle.
Microsurgical varicocelectomy uses magnification to help identify and preserve the testicular artery and lymphatic vessels while treating the abnormal veins.
Improvement after surgery is not immediate because sperm production takes time. Changes in semen parameters are generally assessed over the following months with repeat semen analyses.
Not every man will experience the same degree of improvement, and normalisation of all semen parameters cannot be guaranteed.
Who May Benefit From Varicocele Repair?
Varicocele repair may be considered when several factors occur together:
The couple is experiencing infertility
The man has abnormal semen parameters
A clinical or palpable varicocele is present
There is no major female fertility factor that would make waiting for improvement inappropriate
The decision also depends on the severity of the semen abnormalities, the female partner’s age and fertility assessment, how long the couple has been trying to conceive, and whether assisted reproductive treatment is already being considered.
Does Improving the Varicocele Guarantee Pregnancy?
No.
Pregnancy depends on many factors involving both partners.
Varicocele repair aims to improve the testicular environment and may improve semen parameters in selected men, but it cannot guarantee natural conception.
For some couples, improvement in semen quality may increase the possibility of natural conception. For others, assisted reproductive techniques such as intrauterine insemination (IUI), in-vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) may still be appropriate.
Male fertility treatment should therefore be considered alongside the fertility assessment of the female partner rather than in isolation.
What If There Is No Varicocele?
OAT does not always have a surgically correctable cause.
Management then depends on what the assessment identifies.
This may include addressing hormonal abnormalities, reviewing medications, stopping testosterone or anabolic steroids where appropriate, improving relevant lifestyle factors, treating other underlying conditions, or working with a fertility specialist when assisted reproduction is required.
The appropriate approach depends on the severity of the semen abnormalities and the couple’s overall fertility situation.
When Should I See a Urologist About an Abnormal Semen Analysis?
A urological assessment may be useful when:
A semen analysis shows OAT or another significant abnormality
Sperm concentration is particularly low
Abnormal results persist on repeat testing
A varicocele is suspected
There is testicular pain, swelling or a difference in testicular size
There is a history of undescended testis, torsion, testicular surgery or injury
There are concerns about testosterone or hormonal function
A couple has been having difficulty conceiving
The purpose of assessment is to determine whether there is an identifiable male factor and whether any part of it may be treatable.
Frequently Asked Questions
Is OAT syndrome the same as infertility?
No. OAT describes abnormalities in sperm concentration, motility and morphology. It may reduce the likelihood of conception, particularly when the abnormalities are severe, but a semen analysis alone cannot determine whether natural conception is impossible.
Can OAT improve naturally?
Semen parameters can change over time, particularly when there has been a temporary factor such as fever or illness. Where an underlying reversible factor is identified, addressing it may also improve semen quality. Persistent abnormalities should be appropriately assessed.
Can varicocele cause OAT?
A clinical varicocele can be associated with abnormalities in sperm concentration, motility and morphology. However, varicocele is only one possible cause of OAT, and the presence of OAT does not prove that a varicocele is responsible.
Does every man with OAT need varicocele surgery?
No. Varicocelectomy is considered when a clinically significant varicocele is present and the overall fertility situation makes treatment appropriate. Men without a clinical varicocele would not undergo varicocelectomy simply because their semen analysis shows OAT.
How long after varicocelectomy can sperm improve?
Sperm production occurs over several months, so improvement is not expected immediately after surgery. Follow-up semen analyses are generally performed over the following months to assess whether the parameters are changing.
Can severe OAT still be treated?
Severe OAT requires more detailed assessment because the underlying causes and fertility implications may differ from mild abnormalities. Depending on the findings, treatment may involve addressing a correctable male factor or considering assisted reproductive techniques with a fertility team.
Assessment for OAT Syndrome and Male Infertility
An abnormal semen analysis is the starting point rather than the final diagnosis.
Assessment can help determine whether there is an underlying hormonal, testicular, genetic or anatomical factor contributing to OAT and whether a potentially correctable condition such as a clinical varicocele is present.
Dr Roger Anthony Idi
Consultant Urologist
Prince Court Medical Centre, Kuala Lumpur
Related Reading
1. Microsurgical Varicocelectomy
How varicocele repair may improve sperm parameters in appropriately selected men.
2. Varicocele: Causes, Symptoms and Treatment
Understanding enlarged testicular veins and their possible effects on fertility.
3. Testicular Lump: Causes and When to Seek Assessment
Understanding testicular abnormalities that may require urological evaluation.