When assessing sperm quality, the embryologist counts the number of sperm cells and evaluates the motility and morphology of the sperm. The good sperm cell looks normal with fast progressively forward movement. The raw semen sample contains many dead cells, making it difficult to assess sperm quality correctly.
After purification, the dead cells are removed, and only the best sperm with the highest fertilization capacity are left.
The number of fertile sperm is found by gradient centrifuging. The embryologist notes the number, morphology and motility of the sperm in the raw semen sample, and again after gradient centrifuging. If the total number of normally appearing sperm with good motility is below 5 million, the chances of conception by artificial insemination or IVF treatment are reduced. In this case we recommend IVF treatment with micro-insemination (ICSI).
When performing insemination treatment, the sperm must move their way from the uterus into the far end of the fallopian tubes where the egg is waiting to be fertilized. If no sperm are moving in a fast and progressive forward direction, they are not able to find out into the fallopian tubes and fertilize the egg.
In this case, IVF treatment with micro-insemination (ICSI) is preferable.
To fertilize the egg, the sperm must penetrate through the zona pellucida. This membrane or eggshell is not like the shell of a hen's egg. It resembles more a thick, dense knitting. Only sperm that look normal can get through this dense network. Therefore, an assessment of sperm morphology is very important when assessing a semen sample. Sperm with too small or too thick heads, dual head rudiments or double tails cannot penetrate the membrane and fertilize the egg.