Semen Analysis

sperm structureA semen analysis is the evaluation of a man’s semen, the sperm that is contained within it and its characteristics. It may be done to ascertain if a man is still fertile after having a vasectomy or to find out why a couple is having fertility difficulties.

It is also carried out prior to sperm donation, and also testing for Sexually Transmitted Infections (STI). Sometimes older men may request a semen analysis.

The parameters that are measured in an analysis include; volume, fructose level, sperm count, motility (movement of the sperm), morphology (form and structure of the sperm), and pH level.

The sperm count is the concentration of sperm in a man’s ejaculate, whilst total sperm count is the amount of sperm multiplied by the volume of a man’s ejaculate.

The easiest and most common way to collect a man’s ejaculate is for him to masturbate into a clean cup. Sometimes a man will prefer to use a collection condom. These condoms are made from polyurethane or silicon as a normal latex condom is harmful to sperm.

Semen can be directly collected from the epididymis if there is a suspected blockage in the vas deferens. The average sperm count is between 20 and 50 million per ml. It is best to do the analysis 30 to 60 minutes after collection.

Motility: Motility (movement) is measured and divided into four grades, these being;

  • Progressively Motile- these are strong sperm and swim fast in a straight line.
  • Non Linear – These sperm are also strong swimmers, but tend to swim in a curved line.
  • Sluggish – these sperm will move their tails as if swimming, but fail to move forward.
  • Immotile – these sperm fail to move at all.

A man can have a sperm count which far exceeds the recommended limit of sperm cells per ml, and still have poor quality because too few of them are motile. If 60% of sperm show good forward movement this is considered normal.

Morphology: The form and structure (morphology) of sperm is considered as a predictor of success in fertilization. Of all sperm, up to 10 % have defects which puts them at a disadvantage as far as fertilization is concerned.

Volume: An ejaculate volume of between 1.5 ml and 6.0 ml is considered a normal amount. It is best to ensure it has been at least 48 hours since the last ejaculation in order for a suitable sample to be taken.

Fructose: The normal level of fructose present in semen is considered within normal limits, if it is at least 3 mg/ml. If there is no fructose in the sample it could indicate a problem with the seminal vesicles e.g. a blockage.

pH: The pH scale ranges from 0 to 14 with 7 being neutral. The scale measures how acidic or basic (alkaline) a substance is. The normal range for ejaculate is between 7.1 and 7.8. If the ejaculate is below 7 it is acidic and if above it is alkaline. Any pH reading outside of the normal range is harmful to sperm and requires further detailed investigation.


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