What is teratozoospermia? Its causes, diagnosis and treatment

By (embryologist), (gynecologist), (embryologist) and (biochemist).
Last Update: 09/30/2022

Teratozoospermia, sometimes called teratospermia, is defined as abnormal sperm morphology. It is a sperm disorder that causes males affected to produced abnormally shaped sperm.

The pregnancy rate in males affected by teratozoospermia depends on the grade of severity. It is considered a cause of male infertility, and its causes are varied or even unknown.

There exist various treatment options to have a baby with abnormal sperm morphology. The chances of success depend on the remaining sperm parameters, as teratozoospermia may be combined with other pathologies, like sperm count or sperm motility.

Provided below is an index with the 9 points we are going to expand on in this article.


Teratozoospermia is the medical term used to refer to abnormal sperm morphology, caused by either defects in the head, midpiece, and/or tail. According to the criteria published in 2010 by the World Health Organization (WHO), a man has teratozoospermia when more than 96% of the sperms he produces are abnormally shaped.

Although the World Health Organization (WHO) has published an update of the Laboratory Manual for Semen Examination and Processing in 2021 (the sixth edition), the most common practice is to continue to follow the criteria of the fifth edition (2010).

If at least 4% of sperms have a normal shape, the male is considered fertile and able to make a woman naturally.

Teratozoospermia according to Kruger's criteria

Some laboratories use the Kruger's strict criteria to evaluate a semen sample as well as those of the WHO.

According to Kruger's strict criteria, teratozoospermia is present when more than 85% of spermatozoa have an abnormal shape. This criteria is far stricter than the ones published by the WHO.

In other words, the borderline to consider whether a man has teratozoospermia is set at a minumum of 15% of spermatozoa with normal forms instead of 4%, which is the percent currently established by the WHO.

Unless otherwise specified in your semen analysis report, it is according tp the critieria set by the WHO's 2010 and not that of Kruger.

What causes teratozoospermia

Teratozoospermia is associated with male infertility in all cases, as it means that sperm are unable to get to the egg due to their abnormal shape.

The causes of abnormal sperm morphology are varied and in most cases difficult to determine. The following are the most common ones:

  • Genetic traits
  • Cancer treatments (chemotherapy and radiotherapy)
  • Bacterial infections in sperm and orchitis
  • Testicular trauma
  • Testicular disorders, like varicocele
  • Fever
  • Diabetes mellitus (DM) or meningitis
  • Tobacco, alcohol and street drug use
  • Unhealthy habits: unbalanced diet, exposure to toxic substances, too tight clothes, etc.

The good news is that teratozoospermia can be cured in some of these cases. For example, if caused by fever, infections, or stress, the man is likely to start producing normal sperm again once these conditions disappear. If the cause is associated with unhealthy habits, picking up healthier habits such as following a balanced diet, quitting smoking, etc. can improve sperm quality.

You can read more about this in the following article: What are the causes of teratozoospermia?


When a man has teratozoospermia he will not feel any pain. Therefore, the way to diagnose this seminal alteration is by means of a seminogram. In this study a specialist will study the shape of the spermatozoa in the andrology laboratory.

To do this, the specialist will stain a drop of semen and observe the morphology of the stained spermatozoa under the microscope. The most common way to stain spermatozoa is using methylene blue dye.

Generally, 200 spermatozoa are studied to get a representative sample and work out the percentage of abnormal spermatozoa.

A spermatozoon is normal when it has an oval-shaped head and an acrosome inside. The neck or midpiece is slightly thicker than the tail and, finally, the tail is elongated and uncoiled.

If you are interested and want to read more detailed information, you can visit this link: How can teratozoospermia be diagnosed?

What different types of teratospermia are there?

Defects in the morphology of sperm can be classified into different types depending on their location - head, midpiece, and/or tail. However, before diagnosing teratozoospermia, all abnormalities are taken into consideration.

After examining sperm morphology with a semen analysis, it is possible for the specialist to determine the type of teratozoospermia and its grade of severity. For this purpose, the Kruger criteria are used and teratospermia is classified into three grades:

Mild teratozoospermia
Between 10% and 14% of sperm have a normal morphology.
Moderate teratozoospermia
The percentage of sperm with normal morphology ranges between 5% and 9%.
Severe teratozoospermia
Normal morphology is present in less than 5% of sperm.

As mentioned earlier, the criteria used to diagnose teratozoospermia are the ones published by the OMS. In other words, this classification has fallen into disuse. However, it is still possible to find them in the results of some sperm analyses.

For more information on this, we encourage you to read the following article: Teratozoospermia types - mild, moderate and severe.

Teratozoospermia index

This measurement is used to identify the number of defects present in each sperm cell. It is possible for a sperm to have an anomaly in just one part, or in multiple areas.

To calculate the teratozoospermia index (TZI), we use the following formula: TZI = ( c + p + q ) / x, where each variable means:

  • c = head defects
  • p = midpiece defects
  • q = tail defects
  • x = total number of abnormal sperm

The TZI score should be interpreted as follows:

  • TZI close to 1: One part affected
  • TZI close to 2: Two parts affected
  • TZI close to 3: Head, midpiece and tail affected

It should be noted that all three types can be found in a semen sample, that is, with sperm cells that have defects in one, two or all three parts. The TZI indicates which type is the most frequent one.

How to achieve pregnancy

A man with teratozoospermia can achieve a natural pregnancy as long as the remaining sperm parameters, particularly the sperm count and sperm motility, are normal.

Nevertheless, when a couple is trying to conceive but pregnancy it not happening,  men can follow a series of medical tips in an attempt to improve the morphology of their sperm.

On the other hand, if teratozoospermia has a genetic origin or is present from birth (congenital), finding a treatment option that works may be harder.

Natural treatments for teratospermia

First of all, men with teratozoospermia should change their lifestyle and quit unhealthy habits for their organism, such as cigarette smoking or alcoholic drinks.

Following a balanced diet is always key when it comes to improving one's fertility. Particularly, foods rich in antioxidants and essential amino acids like L-carnitine, which boosts sperm quality.

Oily fish is rich in omega-3 fatty acids as well, which is greatly beneficial for the reproductive health of males.

Also, all these vitamins and nutrients can be taken in the form of vitamin supplements like maca root powder or supplements containing vitamin E, which functions as a powerful antioxidant.

You can find more advice and recommendations in this article: TTreatment of teratozoospermia.

Assisted reproduction with teratozoospermia

Men with mild teratozoospermia who are unable to conceive a child should resort to assisted reproduction. In these cases, artificial insemination (AI), also known as intrauterine insemination (IUI) will be possible as long as the concentration and motility of the sperm are not altered.

IUI will be the first option to consider if the woman has no fertility problems and the only cause that prevents gestation is teratozoospermia.

On the other hand, in cases of moderate or severe teratozoospermia, or other alterations that cause sterility, it will be necessary to perform IVF-ICSI. This is an in vitro fertilization technique in which intracytoplasmic sperm injection is used to achieve fertilization of the eggs.

Finally, there exists a cutting-edge technique that is similar to ICSI. It is called IMSI (intracytoplasmic morphologically selected sperm injection), and involves the use of a high magnification light microscopy imaging method to see sperm morphology in detail.

If you need to undergo IVF to become a mother, we recommend that you generate your Fertility Report now. In 3 simple steps, it will show you a list of clinics that fit your preferences and meet our strict quality criteria. Moreover, you will receive a report via email with useful tips to visit a fertility clinic for the first time.

The microscope used in IMSI to select the best spermatozoon includes a lens for high magnification, which allows the specialist to see the potential defects that are present in each sperm cell in full detail.

More information on assisted reproduction with IMSI can be found in this article:Read: What Is Intracytoplasmic Morphologically Selected Sperm Injection (IMSI)?

FAQs from users

What is the cause of teratozoospermia?

By Jon Ander Agirregoikoa M.D. (gynecologist).

Teratozoospermia is an abnormality affecting male semen in which most sperm are abnormally shaped.

Because of their poor morphology, sperm cannot fertilize the egg and cause sterility.

The causes of teratozoospermia are:

  • Genetic alterations
  • Chemotherapy and radiation therapy
  • Seminal infections and orchitis
  • Testicular trauma
  • Varicocele
  • Fever
  • Diabetes Mellitus and meningitis
  • Tobacco, alcohol, drugs
  • Bad eating habits, toxic, tight clothing...

There are some causes that can be solved (fever, quitting tobacco, healthy habits...) so that the problem in some cases would be reversible.

Can leucospermia cause teratospermia and male sterility?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

Leucospermia, also called leucocytopermia, is the appearance of leukocytes in semen at a concentration greater than 1 million per milliliter. The cause of this seminal disease is an infection in the male reproductive tract that must be treated with antibiotics since it can affect spermatogenesis and cause alterations such as oligospermia or teratozoospermia.

Should I use donor sperm if I have teratozoospermia?

By Elena Lobo González MA (embryologist).

In principle, we should not resort directly to a treatment with donor sperm without first trying in vitro fertilization techniques with your own sperm.

However, if it is a severe teratozoospermia or if gestation is not achieved using the patient's own sperm, the alternative would be to opt for donor sperm.
Read more

What characteristics does a normal sperm have?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

According to the World Health Organization (WHO), the characteristics that should present the ideal sperm, that is, with an excellent morphology are the following:

  • Oval head and regular contour
  • Single straight tail
  • Fixed nucleus
  • Transparent color

In principle, all sperm that meet these requirements have the capacity to fertilize the egg and lead to a viable pregnancy.

What are the consequences of having abnormal sperm in your semen?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

The main consequence of teratozoospermia is the male infertility it causes, since amorphous sperm are not able to fertilize the egg or even present alterations in their DNA.
Read more

Can abnormal sperm morphology cause miscarriage?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

In principle, poor sperm morphology doesn't lead to miscarriage once the egg has been fertilized and the embryo has attached to the womb. Another case would be that the sperm also contain genetic mutations as well as the abnormal morphology, which could lead to miscarriage.

How can I improve amorphous sperm in semen?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

In the first place and as long as the cause of teratozoospermia is not a specific pathology, the male should follow some guidelines to modify his lifestyle, which may be interfering negatively in his reproductive state. Some men who give up habits such as tobacco or alcohol and follow a healthy diet see an improvement in their seminal quality after about 3 months.

Are teratozoospermia and necrozoospermia the same?

By Marta Barranquero Gómez B.Sc., M.Sc. (embryologist).

The answer is no. Teratozoospermia and necrozoospermia are seminal alterations, but each refers to a spermatic parameter.

On the one hand, teratozoospermia is an alteration in sperm morphology. In contrast, necrozoospermia refers to problems in the vitality of sperm, that is, when there are a lot of dead sperm in the ejaculate.

There are other sperm disorders that can cause male infertility or at least complicate the TTC journey. Click here to learn more: Sperm Disorders that Cause Male Infertility.

A semen analysis is a method used by all andrology laboratories to evaluate sperm quality. To learn how it works and how to interpret the results, please click here: What Is a Semen Analysis Report? – Purpose, Preparation & Cost.

We make a great effort to provide you with the highest quality information.

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Auger J, Jouannet P, Eustache F. Another look at human sperm morphology. Hum Reprod. 2016;31(1):10-23 (View)

De Braekeleer M, Nguyen MH, Morel F, Perrin A. Genetic aspects of monomorphic teratozoospermia: a review. J Assist Reprod Genet. 2015;32(4):615-23 (View)

El Khattabi L, Dupont C, Sermondade N, Hugues JN, Poncelet C, Porcher R, Cedrin-Durnerin I, Lévy R, Sifer C. Is intracytoplasmic morphologically selected sperm injection effective in patients with infertility related to teratozoospermia or repeated implantation failure? Fertil Steril. 2013;100(1):62-8 (View)

French DB, Sabanegh ES Jr, Goldfarb J, Desai N. Does severe teratozoospermia affect blastocyst formation, live birth rate, and other clinical outcome parameters in ICSI cycles? Fertil Steril. 2010;93(4):1097-103 (View)

Lee RK, Hou JW, Ho HY, et al. Sperm morphology analysis using strict criteria as a prognostic factor in intrauterine insemination. Int J Androl. 2002; 25: 277-80. (View)

Marchini M, Ruspa M, Baglioni A, Piffaretti-Yanez A, Campana A, Balerna M. Poor reproductive prognosis in severe teratozoospermia with a predominant sperm anomaly. Andrologia. 1989;21(5):468-75.

Shabtaie SA, Gerkowicz SA, Kohn TP, Ramasamy R. Role of Abnormal Sperm Morphology in Predicting Pregnancy Outcomes. Curr Urol Rep. 2016;17(9):67.

World Health Organization (WHO) (2010). WHO laboratory Manual for the examination of human semen and sperm-cervical mucus interaction. Cambridge Academic Press.

FAQs from users: 'Why does teratozoospermia cause fertility problems?', 'What is the cause of teratozoospermia?', 'Can leucospermia cause teratospermia and male sterility?', 'Should I use donor sperm if I have teratozoospermia?', 'What characteristics does a normal sperm have?', 'What are the consequences of having abnormal sperm in your semen?', 'Can abnormal sperm morphology cause miscarriage?', 'What does 0 morphology mean?', 'How can I improve amorphous sperm in semen?', 'What does teratozoospermia actually mean?' and 'Are teratozoospermia and necrozoospermia the same?'.

Read more

Authors and contributors

 Elena Lobo González
Elena Lobo González
Elena Lobo has a degree in Biology from the University of Seville and a Master's Degree in Assisted Human Reproduction from the University of Seville, also in collaboration with Ginemed. More information about Elena Lobo González
collegiate number: 003575
 Jon Ander  Agirregoikoa
Jon Ander Agirregoikoa
Graduated in medicine from the "Pays Basque" University, with a specialization in obstetrics and gynaecology. He has several years of experience in the field of assisted human reproduction and is co-director and co-founder of the ART clinics. He also combines his medical activity with teaching at the "Pays Basque" University. More information about Jon Ander Agirregoikoa
License: 014809788
 Marta Barranquero Gómez
Marta Barranquero Gómez
B.Sc., M.Sc.
Graduated in Biochemistry and Biomedical Sciences by the University of Valencia (UV) and specialized in Assisted Reproduction by the University of Alcalá de Henares (UAH) in collaboration with Ginefiv and in Clinical Genetics by the University of Alcalá de Henares (UAH). More information about Marta Barranquero Gómez
License: 3316-CV
Adapted into english by:
 Michelle Lorraine Embleton
Michelle Lorraine Embleton
B.Sc. Ph.D.
PhD in Biochemistry, University of Bristol, UK, specialising in DNA : protein intereactions. BSc honours degree in Molecular Biology, Univerisity of Bristol. Translation and editing of scientific and medical literature.
More information about Michelle Lorraine Embleton

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