To evaluate a specimen, a microscope slide is prepared with a very thin coating of semen. The slide is stained to make the sperm clearly visible, and then at least 200 hundred sperm are viewed under high magnification and individually scored as either normal or abnormal based on their shape. The percentage of normally shaped sperm is then calculated.
Morphology is assessed using one of two sets of characteristics: Kruger or World Health Organization (WHO). Kruger criteria are stricter and consider small irregularities as abnormal. WHO criteria are more lenient and therefore do not classify as many sperm as abnormal. Most clinics today are moving toward the Kruger strict criterion which is more predictive of egg fertilization success.
More recent research led to a change in 2010 in the interpretation of sperm morphology. Prior to that time, a higher percentage of normal sperm was required for a sample to be considered normal. Specifically, at least 14% of the sperm in the ejaculate had to be normal in order to have a good prognosis for fertilization. Now, the World Health Organization has adopted a new cut-off. Only 4% of the ejaculate needs to be of normal shape for the sample to be considered fertile.
So what impact does abnormal morphology (teratospermia) have on fertility?
It is possible for an abnormally shaped sperm to fertilize an egg. However, some studies have shown that having higher amounts of abnormally shaped sperm is associated with difficulty in achieving pregnancy. It is unclear if this is due to the shape of the sperm itself, or by another reason that causes the sperm to be shaped differently and also causes infertility problems. In addition, men who have poor morphology often have other irregularities too, including low sperm count and/or motility.
The next question is whether there is anything that can be done to improve morphology?
There are three main causes of this problem:
- A genetic trait
- Exposure to toxic chemicals
- Increased testicular temperature
Men can be exposed to toxic chemicals either at work or in the home. If your occupation exposes you to toxins (such as automotive paint shops), you need to follow all safety guidelines. Even some household items such as cleaning supplies or pesticides can cause problems with sperm morphology when used without proper ventilation. You should always use protective masks, gloves and clothing when using these chemicals.
Wearing tight-fitting clothing (like jockey shorts) around the clock can increase scrotal temperature to a point where sperm morphology could be affected. Even sitting at a desk for a prolonged period of time can keep the testicles drawn up close to the body which can result in an increased temperature. It is best to get up and walk around periodically to avoid this situation.
Some medications, such as antidepressants, can also have an effect on sperm morphology. You should review any medications you are taking with your fertility specialist. Lastly, improving your lifestyle may also help. When trying to achieve a pregnancy, you should avoid smoking and/or recreational drugs, and limit the use of alcohol. Dietary supplements have not been shown to have a positive effect on sperm morphology, but some fertility specialists do recommend a daily multivitamin to improve your overall well-being including reproductive health.
Poor sperm morphology, however, by no means eliminates your chances for successfully achieving pregnancy. Recent studies, in fact, suggest that below normal sperm morphology has less of an impact on the success of intrauterine insemination (IUI). This is likely due to the number of sperm used in an insemination. It is common to place 10 million or more sperm in the uterus when performing an IUI, so even if a significant percent are abnormal in shape there are still plenty of normally shaped sperm available to get the job done. If inseminations are not successful, then in vitro fertilization (IVF) may be necessary. The good news then is that a technique called ICSI (Intracytoplasmic Sperm Injection) can be used to inject good quality, normal-shaped sperm into the eggs to achieve fertilization.
So, if your sperm morphology results are not what you expected, don’t be discouraged! There are ways to overcome this setback and still achieve your ultimate goal of parenthood.