As a part of your fertility diagnostic testing, you or your partner, may be asked to take a sperm analysis test to rule out or diagnose male factor infertility and measure the sperms quality. 

Sperm quality refers to the sperm’s ability to fertilise an egg. This ability is determined by two interconnected factors: sperm motility and sperm morphology. The health of the DNA carried by the sperm is also extremely important.

The sperm analysis test explained:

When performing a sperm analysis we look at the following key parameters to determine the quality of the sperm: 

  1. Volume: 1.5ml to 4.5ml
  2. Count: minimum 15million/ml 
  3. Concentration: minimum 39 million/ml
  4. Motility: ideally 40-50% (minimum 32%)
  5. Morphology: minimum 4% normal
Reference Values: WHO 2010Lower limit (5th percentile)Median (50th percentile) Upper limit (95th percentile)
Volume (ml)1.53.76.8
Sperm concentration/ml (x106)1573213
Total sperm number (x106/ejaculation)39255802
Total motility (a & b%)406178
Progressive motility (a%)325572
Normal Morphology (%)41544
Reference Values – WHO 2010

What is Sperm motility?

Sperm motility refers to the ability of the sperm to “swim” to an egg. Progressive motility is the best type of movement noted during a semen analysis and means that the sperm are moving forward in straight lines, as opposed to in small tight circles or along highly erratic paths.

The lower limit for sperm motility is 40% of both progressive + non-progressive aka “twitching” sperm.

What is Sperm morphology?

Sperm morphology refers to the way the sperm looks – it’s appearance. A morphologically normal sperm should have:

  • A long tail: made of protein fibers that contract to propel the sperm through the seminal fluid. Up until very recently it was thought that sperm moved forward due to the lashing movement of their tail. Last year a breakthrough study revealed that the tail of a sperm actually only flagellates on one side, causing a rotating “corkscrew” pattern, so sperm  actually “spin” towards the egg!  
  • A mid-piece: which contains mitochondria (energy producing organelles) to power the sperm’s movement.
  • A nicely shaped head: made of a fatty acid membrane which stores the nucleus (which contains the sperm’s genetic information (DNA)) & cytoplasm: a thick solution that fills cells and is made of water, salts & protein. At the tip of the head is the “acrosome”: a structure bound to the sperm membrane in its own fatty acid layer, which contains digesting enzymes that enable the sperm to break down the zona pellucida (outer glycoprotein layer) in order to enter the egg for fertilisation. 

The lower limit for normal sperm morphology is 4% according to WHO statistics, though some clinics use 2% as their barometer – if your clinic does use the latter and dismisses these results as problematic, seek the second opinion of a urologist specializing in fertility. 

What should my Total sperm count be?

The total number of sperm is considered the total number of sperm in a particular quantity of semen, the fluid that carries sperm out of the penis. 

A high sperm count isn’t helpful to fertility if most of the sperm have abnormal morphology or can’t swim properly. Similarly sperm with textbook morphology may carry abnormal DNA.

The lower limit for total sperm count is 39million per ejaculation.

What is Sperm Concentration?

Sperm concentration refers to the total number of sperm per milliliter (ml) of ejaculate.

The lower limit for sperm concentration is 15 million per ml.

Sperm count and sperm quality (morphology and motility) can be tested with a semen analysis. A routine semen analysis however cannot assess the genetic health of sperm. 

What is Sperm DNA Fragmentation?

The sperm DNA carries all the instructions for the development of the embryo. Any damage to this DNA may interfere with the sperm’s ability to fertilise an egg correctly or develop into a healthy developing embryo. Genetic integrity is thought to be one of the most important factors for male fertility. Our DNA is contained in structures called chromosomes. Our cells usually contain 46 chromosomes but sex cells or gametes, i.e., the sperm and egg, contain just 23. When the egg and sperm combine, they produce an embryo with 46 chromosomes in each cell. 

Sperm DNA fragmentation happens when there is a change in the strands of DNA contained within the nucleus of the sperm. This could be a deletion, a break or a separation in the DNA strands and can occur at any point during the sperm’s life: whilst its being made in the testis (during spermatogenesis), during its time stored in the epididymis before ejaculation or even after ejaculation. 

A specialist test is required to assess the level of DNA fragmentation within a sperm sample. The following tests can be offered:

  • sperm chromatin structure assay (SCSA) – the most commonly used test (industry standard)
  • sperm chromatin dispersion test (SCD)
  • transferase-mediated terminal uridine nick-end labelling (TUNEL)
  • Comet Assay test

Risk factors for sperm DNA fragmentation: 

  • Paternal age
  • Smoking
  • Illness or infection (e.g., covid-19)
  • Cancer treatment (e.g., chemotherapy)
  • Chemical, radiation or toxin exposure