A sperm analysis is the study of a semen sample. It is the most important study for evaluating male fertility. It is carried out macroscopically and microscopically. It analyses parameters such as pH, volume, liquefaction, viscosity, count, motility, viability and morphology. In addition, a capacitation test is carried out, which allows us to know the number of sperm recovered after processing the sample.
The parameters studied and their reference values are as follows:
pH: The pH should be between 7.2 and 8.1, though there is no evidence that a value of more than 8.1 is negative. However, lower values may indicate genital infection.
Volume: Volume should be more than 2 ml. If a sample is less than 2 ml it is termed hypospermia. A lower volume may indicate an obstruction caused by genital infection, congenital alteration of the vasa deferentia, or retrograde ejaculation.
Liquefaction: When it is collected, the sample is in a state of coagulation, and must be liquefied to proceed to its analysis. Liquefaction occurs after 20-30 minutes. If this does not occur it may indicate a dysfunction in the prostate.
Viscosity: Once liquefied, the semen should be slightly more viscous than water. If the sample is highly viscous, it may be due to a prostate dysfunction, frequent ejaculation, and/or the psychological state of the patient. This increase in viscosity does not mean a direct cause of infertility, but may affect subsequent assessments of the seminogram such as its concentration and sperm motility.
Sperm count: Normal values should be above 20 million/ml. If the value is below this, the sample is classified according to the number of sperm as follows:
- Moderate oligozoospermia: between 10 and 20 million/ml
- Severe oligozoospermia: between 0.1 and 10 million/ml
- Cryptozoospermia: less than 0.1 million/ml
- Azoospermia: there is no sperm in the ejaculate
Motility: Motility is based on the observation of the sample through the microscope, and is classified as follows:
- Class a) Excellent. Fast displacement in straight lines. (Also classified as “+++”)
- Class b) Moderate. Moderate progressive speed in straight lines. (Also classified as “++”)
- Class c) Non progressive speed, in lines that are barely or not at all straight. (Also classified as “++”) or movement of the sperm with almost no displacement. (Also classified as “+”)
- Class d) Absence of motility
Viability or Vitality: Viability allows us to know the number of live sperm, even if they do not move. A dye is used to highlight the dead sperm. When the value is below 60%, it is referred to as a dead sperm (necrospermic) sample.
Morphology: The study of the shape of the sperm. This is carried out using Tygerberg’s strict criteria, in which a sample is considered to be morphologically normal when the number of normal sperm is the same or more than 4%.
This is the process where the seminal fluid is separated from the sperm. It is a process that occurs “in vivo”. In the lab, this technique allows us to separate the seminal fluid and also good quality sperm from bad quality sperm. It is a selection process. This way we will be able to see the number and motility of the sperm recovered, which will provide us with guidance, if necessary, with regard to the Assisted Reproduction technique to use.