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Updated: 20-July-2024
Introduction
Teratozoospermia, also called teratospermia, is a condition characterized by low numbers of sperm with normal morphology. Specifically when less than 4% of sperm in a semen sample has normal morphology.
Or in other words, more than 96% of sperm display abnormal morphology (defects in the head, middle piece of tail of the sperm cell). These defects hinder the sperm from fertilizing the egg and is one of the main causes of male infertility.
Evidently, teratozoospermia is categorised into 2 types:
- Polymorphic
- Monomorphic
Polymorphic teratozoospermia is when the majority of the ejaculate contains spermatozoa with more than one type of abnormality. This is common as men get older and the processes of spermiogenesis and sperm maturation deteriorate.
Source: Kleshchev M, et al. (2023)
Monomorphic teratozoospermia is when most sperm cells display only one unique abnormality. Usually caused by a genetic defect. Examples of monomorphic teratozoospermia are globozoospermia and macrocephalic sperm head syndrome, also called macrozoospermia. However both these conditions are very rare and believed to affect less than 1% of infertile men.
Globozoospermia is characterised by round-headed spermatozoa with an absent acrosome, an aberrant nuclear membrane and midpiece defects.
Macrocephalic sperm head syndrome is defined as the presence of a very high percentage of spermatozoa with enlarged heads and multiple flagella.
Overall teratozoospermia is a serious condition which affects a males ability to conceive naturally. In fact, on average, only 1 in 20 males with teratozoospermia will get their partner pregnant within 12 months, according to the WHO reference values for human semen.
By this same reference, high numbers of sperm with abnormal morphology is actually quite normal among the male population.
In fact, 1 in 4 males produce semen samples with at least 90% or more sperm displaying abnormal morphology.
However, the majority of these males will manage to successfully get their partner pregnant within 12 months.
These statistics highlight the limitations that normal sperm morphology has on the likelihood of pregnancy among couples trying to conceive naturally. Which means there is likely to be other factors hindering a couple’s fertility than just strictly teratozoospermia.1
Symptoms of Teratozoospermia
The symptoms of low sperm morphology are similar to men diagnosed with oligospermia or asthenospermia. The primary symptom is the inability to conceive a child despite 1 year of frequent and unprotected intercourse.
Other related symptoms may include:
- Erectile dysfunction or low sex drive
- Pelvic or urinary pain
- Changes in body hair indicating hormonal abnormality 2
Diagnosis of Teratozoospermia
Diagnosis of teratozoospermia is normally made at least 1 year after a couple have been unable to conceive despite frequent and unprotected intercourse.
At this stage, it is advised that both partners consult a Doctor since the inability to conceive frequently occurs due to a combination of issues arising from both male and female partners.
For males, the European Academy of Andrology recommends doctors perform the following:
- General physical examination to assess for signs of hypogonadism.
- Physical examination of the scrotum to assess; the volume and consistency of the testicles and epididymis, the total or partial absence of deferent ducts, the presence of varicoceles.
- Two semen analyses (3 months apart) according to the WHO guidelines.
Semen samples can be collected in the clinic or at home following 2 to 7 days of sexual abstinence. However, if collected at home, the sample should be kept at room temperature and delivered to the laboratory immediately.
Men are diagnosed with isolated teratozoospermia if there is < 4% morphologically normal sperm, and all other parameters are normal.
The test should then be repeated after 3 months to confirm any abnormal values. Preferably at the same laboratory by the same technician, observing 2 or more smears (i.e. microscope slides) to minimize interobserver and intersample variability.3,4
Laboratory Assessment
During assessment, the 3 main parts of human sperm (head, neck, tail) are carefully observed under a microscope with the help of hematoxylin and eosin staining.
Head
A normal head should be:
- Smooth and oval
- 5-6 microns in length
- 2.5 to 3.5 microns in width
- 40-70% of the head covered by the acrosome
- No large vacuoles, and ≤ 2 small vacuoles, in the acrosomal region covering < 20% of the sperm head
A large or several vacuoles indicates significant DNA damage.
Source: Pastuszek E, et al. (2017)
Neck (middle piece)
The area between the head and the tail, which is slightly wider than the base of the tail and about the same length as the sperm head. It contains the mitochondria, which generates the ATP required for the sperm’s movement.
Tail (flagellum)
The tail is approximately 10 times the head length and is made up of the same structural molecules involved in spermatogenesis (during mitosis and meiosis). Therefore, an abnormal tail can occur from the incorrect distribution of chromosomes.
At least 200 sperm cells are evaluated during this assessment, to minimise any sampling errors, and a percentage of normal sperm cells calculated.
The sample is considered to be normal if at least 4% of sperm do not show any visible defects.
Source: World Health Organization, (2021)
Additional Tests
After semen analyses, your doctor might recommend additional tests to determine or rule out potential causes of teratozoospermia.
These additional tests may include:
- Scrotal ultrasound to look at the testicles and surrounding tissues.
- Blood tests to:
i) Check the hormones secreted by the testicles and pituitary gland.
ii) Perform karyotyping (genetic tests). - Other less commonly used tests:
i) Biopsy of the testicles to determine if there is normal production of sperm.
ii) Anti-sperm antibody tests to check if the immune system is attacking the sperm cells.
iii) Specialised sperm function test to determine the attaching potential of the sperm cells.
Risks associated with Teratozoospermia
Men suffering from abnormal sperm parameters are susceptible to further issues such as:
- Stress, loss of self-esteem and relationship issues due to difficulties trying to conceive.
- Increased risk of cancer.
CANCER
Several studies to date have found an association between abnormal semen analysis, including poor morphology, and a higher risk of cancer. Although the exact reason for this link has yet to be identified infertile men should consult their Doctor to discuss long-term monitoring strategies.5,6,7
Causes of Teratozoospermia
Possible causes of teratozoospermia (0-4% normal sperm morphology) include genetic defects, hormonal imbalance, varicoceles, infection, obesity, smoking, drugs, alcohol, chemicals and heavy metals.
Fortunately, the majority of teratozoospermia cases is not caused by genetic defects. Only the rare monomorphic teratozoospermia condition is strictly linked to genetic defects.
This means for the majority of males, diagnosed with teratozoospermia, sperm quality should improve after intervention.
DOES CAFFEINE AFFECT SPERM MORPHOLOGY
In a systematic review containing 19,967 males, normal consumption of caffeine has no significant effect on sperm morphology.8
However, excess consumption of caffeine (4 or more cups of coffee per day) significantly increases the percentage of abnormal sperm morphology, and leads to decreased implantation rates in subfertile males undergoing ICSI treatment.9
Treatment of Teratozoospermia
Treating teratozoospermia is a step-by-step process. The first step towards treatment is diagnosing and understanding the exact cause of teratozoospermia in your individual case.
Once a diagnosis has been made, your Doctor will recommend one (or a combination) of the following treatment options for teratozoospermia:
- Expectant management
- Lifestyle modification
- Medication
- Surgery
- Supplements
- Assisted Reproductive Technology
References
- Pelzman D L and Sandlow J I, (2024). Sperm morphology: Evaluating its clinical relevance in contemporary fertility practice. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11194684/ ↩︎
- Yu X, et al. (2022). Sexual dysfunction is more common among men who have high sperm DNA fragmentation or teratozoopermia. https://www.nature.com/articles/s41598-022-27006-z ↩︎
- van den Hoven L, et al. (2024). Evaluation of structural problems in the application of strict criteria for sperm morphology assessment. https://onlinelibrary.wiley.com/doi/10.1111/andr.13684 ↩︎
- Dubin J M and Halpern J A, (2022). Rethinking the role of sperm morphology in clinical practice. https://www.fertstertreports.org/article/S2666-3341(22)00033-2/fulltext ↩︎
- Hanson H A, et al. (2016). Subfertility increases risk of testicular cancer: evidence from population-based semen samples. https://www.fertstert.org/article/S0015-0282(15)02038-5/fulltext ↩︎
- Eisenberg M L, et al. (2015). Increased Risk of Cancer in Infertile Men: Analysis of U.S. Claims Data. https://www.auajournals.org/doi/10.1016/j.juro.2014.11.080 ↩︎
- Jacobsen R, et al. (2000). Risk of testicular cancer in men with abnormal semen characteristics: cohort study. https://www.bmj.com/content/321/7264/789 ↩︎
- Ricci E, et al. (2017). Coffee and caffeine intake and male infertility: a systematic review. https://nutritionj.biomedcentral.com/articles/10.1186/s12937-017-0257-2 ↩︎
- Karmon A E, et al. (2017). Male caffeine and alcohol intake in relation to semen parameters and in vitro fertilization outcomes among fertility patients. https://onlinelibrary.wiley.com/doi/10.1111/andr.12310 ↩︎
