Definition - What does Sperm Morphology mean?
Sperm morphology refers to the size and shape of sperm. Sperm morphology is measured during a semen analysis, which is typically performed on men undergoing fertility testing. All men produce some degree of abnormal sperm, it is the ratio of abnormal to normal sperm that has the potential to impact fertility.
A morphology value of under 4% is typically considered abnormal. This means that having at least 4% of sperm a normal shape is less likely to impact fertility.
FertilitySmarts explains Sperm Morphology
Sperm morphology is one element measured during a semen analysis, along with sperm count, concentration, motility and the volume of fluid. It is determined by examining semen under a microscope and the percentage of normal sperm is estimated. Krugar criteria
A typical sperm is shaped similar to tadpole:
- An oval-shaped head
- A defined cap on the top of the head (acrosome)
- Neck with no abnormalities
- Midpeice with no abnormalities
- Long tail with no abnormalities
Abnormalities can include deformations of the neck, tail, or midsection of the sperm. Examples include a misshapen head or a split tail. These defects can impact the ability of sperm to locate and fertilize an egg.
Abnormal sperm can still fertilize an egg. One study found that 22.9% of men with 0% morphology were actually able to conceive naturally, compared to 55.6% of the control group with normal morphology. Additionally, the mishappen structure does not mean that there are problems with the genetic material inside.
- Men with a complete absence of normal sperm morphology exhibit high rates of success without assisted reproduction. (2017).
- Sperm Morphology (Shape): Does It Affect Fertility?. (2014).