Sperm Morphology: Abnormal Shape and Male Fertility
Sperm Morphology: What Abnormal Sperm Shape Means for Male Fertility
When a man has a semen analysis, the laboratory does more than count sperm and assess how they move.
It also examines their shape and structure.
This is known as sperm morphology.
Morphology is one of the three major components of semen assessment, alongside sperm concentration and motility.
A man may have a good sperm count and reasonable motility but still have abnormal sperm morphology.
However, an abnormal morphology result does not automatically mean that natural conception is impossible.
The result needs to be interpreted alongside the rest of the semen analysis and the clinical circumstances of both partners.
What Is Sperm Morphology?
Sperm morphology refers to the physical appearance and structure of sperm.
A sperm cell has three main structural components:
Head
Midpiece
Tail
The head contains the genetic material.
The midpiece provides energy needed for movement.
The tail allows the sperm to move.
A laboratory evaluates sperm under a microscope and determines whether their structure falls within the criteria used to classify normal morphology.
Why Is Sperm Shape Important?
Sperm need to perform several functions before fertilisation can occur.
They need to:
Survive in the reproductive tract
Move effectively
Reach the egg
Interact with the egg
Penetrate the egg
Deliver their genetic material
Abnormalities in sperm structure may interfere with some of these functions.
However, sperm morphology is only one part of the overall picture.
What Does Normal Sperm Morphology Mean?
Normal morphology does not mean that every sperm in the sample must look perfect.
In fact, when strict morphological criteria are used, only a relatively small proportion of sperm may meet all the criteria for normal morphology.
This is important because patients can become unnecessarily worried when they see a low percentage reported on their semen analysis.
The percentage needs to be interpreted according to the laboratory's reference criteria.
What Is Abnormal Sperm Morphology?
Abnormal morphology means that a greater proportion of sperm have structural characteristics outside the laboratory's normal criteria.
Abnormalities may involve:
The Head
The head may be:
Too large
Too small
Irregularly shaped
Abnormally formed
The Midpiece
The midpiece may have structural abnormalities or appear improperly attached to the head.
The Tail
The tail may be:
Short
Bent
Coiled
Multiple
Structurally abnormal
A single sperm can have more than one abnormal feature.
What Is Teratozoospermia?
Teratozoospermia is the medical term commonly used for abnormal sperm morphology.
It means that the proportion of sperm meeting normal morphological criteria is reduced.
Teratozoospermia can occur alone or together with other semen abnormalities.
For example:
Low count + abnormal morphology
Low motility + abnormal morphology
Low count + low motility + abnormal morphology
When several parameters are abnormal, the overall fertility assessment becomes particularly important.
Does Abnormal Morphology Mean Infertility?
No.
This is one of the most important points to understand.
A low morphology percentage does not by itself establish infertility.
Some men with abnormal morphology are still able to conceive naturally.
The significance depends on:
Sperm concentration
Motility
Total sperm number
Degree of morphological abnormality
Female partner's fertility
Duration of infertility
Other clinical factors
A fertility specialist should therefore avoid interpreting morphology in isolation.
Can Sperm Morphology Change Over Time?
Yes.
Semen parameters can vary between samples.
Morphology may be affected by factors such as:
Recent illness
Fever
Lifestyle
Smoking
Alcohol
Heat exposure
Varicocele
Testicular disease
Laboratory variation
This is one reason why a single abnormal semen analysis may sometimes need confirmation.
What Causes Abnormal Sperm Morphology?
There are many potential causes.
These may include:
Varicocele
Testicular disorders
Genetic abnormalities
Hormonal disorders
Infections
Oxidative stress
Smoking
Excessive alcohol use
Obesity
Heat exposure
Certain medications
Testosterone or anabolic steroid use
Age-related changes
Unknown causes
In some men, no specific cause can be identified.
Can Varicocele Cause Abnormal Sperm Morphology?
Yes.
A varicocele can affect multiple aspects of sperm quality, including morphology.
Potential mechanisms include:
Increased testicular temperature
Oxidative stress
Altered testicular blood flow
Impaired testicular function
However, having a varicocele does not automatically mean that treatment is required.
The decision should be based on the clinical examination, semen analysis and fertility goals.
Can Hormonal Problems Affect Sperm Morphology?
Yes.
Normal sperm development depends on coordinated hormonal stimulation.
Disorders involving FSH, LH and testosterone can interfere with spermatogenesis.
In men with certain hormonal conditions, appropriate treatment may improve sperm production and semen quality.
This is particularly relevant in conditions such as hypogonadotropic hypogonadism.
Can Testosterone Treatment Affect Sperm Morphology?
Testosterone therapy can suppress the hormonal signals required for sperm production.
When FSH and LH are suppressed, sperm production may decrease significantly.
This can lead to:
Low sperm count
Poor semen quality
Severe oligospermia
Azoospermia
Morphological abnormalities may occur alongside these changes.
Therefore, men who are trying to conceive should discuss testosterone treatment with a fertility specialist before starting or continuing it.
Can Smoking Affect Sperm Morphology?
Smoking has been associated with poorer semen quality.
It may affect:
Sperm concentration
Motility
Morphology
Sperm DNA integrity
Stopping smoking is therefore an important step for men who want to optimise reproductive health.
Can Alcohol Affect Sperm Morphology?
Excessive alcohol consumption may negatively affect reproductive health.
Heavy alcohol use can influence:
Testosterone production
Hormonal balance
Testicular function
Sperm production
Reducing excessive alcohol intake may therefore be beneficial as part of a broader fertility strategy.
Can Obesity Affect Sperm Morphology?
Obesity may be associated with changes in male reproductive function.
Possible mechanisms include:
Hormonal changes
Increased oxidative stress
Metabolic abnormalities
Increased scrotal temperature
For men who are overweight or obese, achieving a healthier weight may support overall reproductive health.
Can Fever Affect Sperm Morphology?
A significant fever can temporarily disrupt sperm production.
Because sperm development takes time, the effect of an illness may not appear immediately.
A semen analysis performed after a significant febrile illness may therefore show temporary abnormalities in:
Count
Motility
Morphology
If the result is abnormal, repeat testing may be appropriate.
Can Heat Affect Sperm Morphology?
The testicles need a temperature lower than core body temperature for normal spermatogenesis.
Repeated significant heat exposure may interfere with sperm development.
Potential sources include:
Hot tubs
Saunas
High-temperature workplaces
Prolonged heat exposure
However, heat is only one possible contributing factor and should not automatically be considered the primary cause.
Is Abnormal Morphology Related to Sperm DNA Damage?
There can be an association between abnormal semen quality and sperm DNA damage.
However, morphology and DNA fragmentation are not the same test.
A sperm can appear relatively normal under a microscope while carrying DNA damage.
Conversely, abnormal morphology does not automatically mean that significant DNA fragmentation is present.
When clinically appropriate, specialised sperm DNA testing may provide additional information.
What Tests Are Used to Assess Sperm Morphology?
The primary assessment is a semen analysis.
The laboratory examines sperm under a microscope and evaluates their structure using established criteria.
The report may provide a percentage of sperm classified as morphologically normal.
The result should be considered alongside:
Sperm concentration
Total sperm number
Motility
Semen volume
Should an Abnormal Morphology Result Be Repeated?
Sometimes.
Semen parameters can vary naturally between samples.
Repeat testing may be recommended when:
The result is significantly abnormal
Other semen parameters are also abnormal
The sample collection was incomplete
The patient recently had a fever or illness
The clinician needs to confirm persistent abnormality
The timing of repeat testing should be determined by the treating specialist.
Can Abnormal Morphology Be Improved?
Sometimes, depending on the cause.
Potentially treatable factors include:
Varicocele
Hormonal disorders
Certain infections
Medication-related suppression
Lifestyle factors
However, there is no universal treatment that guarantees an improvement in morphology.
The goal should be to identify and treat the underlying cause where possible.
Can Lifestyle Changes Improve Sperm Morphology?
Optimising general health may support sperm production.
Useful measures can include:
Stop smoking
Maintain a healthy weight
Exercise regularly
Limit excessive alcohol
Avoid unnecessary anabolic steroids
Manage underlying medical conditions
Avoid prolonged excessive heat exposure
Maintain good sleep habits
These measures should be viewed as part of a broader fertility strategy rather than a replacement for medical investigation.
Do Fertility Supplements Improve Sperm Morphology?
Many supplements are promoted as treatments for abnormal sperm morphology.
Some contain antioxidants or combinations of vitamins and minerals.
However, evidence varies between products and individual ingredients.
Supplements should not delay investigation for potentially treatable causes such as varicocele, hormonal disorders or testicular disease.
Can Men With Abnormal Morphology Conceive Naturally?
Yes.
Abnormal morphology alone does not mean that natural conception is impossible.
The probability depends on the complete reproductive picture.
For example, a man with:
Mildly abnormal morphology
Good sperm concentration
Good progressive motility
may have a very different fertility outlook from a man with:
Very low sperm count
Severe motility impairment
Markedly abnormal morphology
The complete semen analysis is therefore more meaningful than morphology alone.
Does Abnormal Morphology Require IVF?
Not necessarily.
Treatment decisions depend on the severity of the abnormality and the fertility status of both partners.
Depending on the circumstances, options may include:
Continuing natural conception
Treating an underlying cause
IUI
IVF
IVF with ICSI
ICSI may be considered when there are significant male-factor abnormalities because it allows an individual sperm to be selected and injected directly into the egg.
What Is the Role of ICSI in Abnormal Morphology?
Intracytoplasmic sperm injection (ICSI) involves injecting a selected sperm directly into an egg.
This can reduce the importance of some sperm-movement and sperm–egg interaction steps that occur during natural fertilisation.
However, ICSI is not automatically required for every man with abnormal morphology.
The decision should be based on the complete fertility assessment.
What If All Three Sperm Parameters Are Abnormal?
Sometimes a man may have abnormalities in:
Sperm concentration
Motility
Morphology
This combination is sometimes referred to as oligoasthenoteratozoospermia (OAT).
When all three major semen parameters are significantly abnormal, further investigation is particularly important.
The specialist may consider:
Hormonal testing
Genetic testing
Testicular assessment
Varicocele evaluation
Additional investigations
When Should Abnormal Morphology Be Investigated Further?
Further evaluation is particularly important when:
Morphology is severely abnormal
The abnormality persists
Sperm count is also low
Motility is also reduced
There is a history of testicular disease
There is a varicocele
Hormonal abnormalities are present
Pregnancy has not occurred despite appropriate attempts
The aim is to determine whether there is a treatable underlying cause.
Sperm Morphology vs Sperm Motility
These two parameters measure different things.
Sperm Morphology
How the sperm looks.
Sperm Motility
How the sperm moves.
A sperm may have normal morphology but poor motility.
Another sperm may move well but have an abnormal shape.
This is why both parameters are assessed during a complete semen analysis.
Sperm Morphology vs Sperm Count
Similarly:
Sperm Count
How many sperm are present.
Sperm Morphology
How many sperm have a structure classified as normal.
A high sperm count does not guarantee normal morphology.
Likewise, abnormal morphology does not necessarily mean that the sperm count is low.
What Happens After an Abnormal Morphology Result?
The next step depends on the complete semen analysis.
A typical pathway may be:
Semen analysis↓Assess count + motility + morphology↓Repeat testing when appropriate↓Medical history and physical examination↓Hormonal / genetic testing when indicated↓Identify possible underlying cause↓Treat reversible factors↓Consider natural conception or assisted reproduction
This approach is more useful than focusing on morphology alone.
Sperm Morphology and Male Fertility: Key Takeaway
Sperm morphology describes the physical structure of sperm and is an important part of semen analysis.
Abnormal morphology is common and does not automatically mean infertility.
Its significance depends on the rest of the semen profile and the fertility circumstances of both partners.
When morphology is significantly abnormal—especially when combined with low sperm count or poor motility—a specialist evaluation can help identify possible causes and determine whether treatment or assisted reproduction is appropriate.
Book a Male Fertility Consultation
If your semen analysis shows abnormal sperm morphology, poor sperm motility or a low sperm count, specialist assessment can help determine what the results mean and whether there is an underlying condition that can be treated.
Book a consultation with Professor Amr Raheem to discuss your semen analysis and male fertility treatment options.
References
European Society for Sexual Medicine (ESSM). 16th ESSM Congress Joint with the 12th EFS Congress – Final Programme, Istanbul, 2014. The programme contains scientific material relating to male infertility and reproductive medicine. ESSM 2014 Scientific Programme
European Association of Urology (EAU). EAU Guidelines on Sexual and Reproductive Health – Male Infertility. Guidance on semen analysis and the assessment of male infertility. EAU Male Infertility Guidelines
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