Total Normal Motile Count

Total Normal Motile Count

04:56 7th April 2013 | Motile Sperm

Sperm Count Normal Motile Sperms Fallopian Tubes IVF Fertilisation Chromosomal Abnormalities Klinefelters Syndrome Undescended Testes Normal Sperm Production Dilatation Infertility Semen Parameters

The importance of sperm count is explained in the concept of the total normal motile count. This is the total amount of sperms that are normal and also motile that is available to fertilise the eggs. There is evidence that following intercourse only about 15% of the total normal motile sperms get to the site of fertilisation of the egg in the fallopian tubes. We also know from our experience with IVF that we need approximately 200,000 sperms around each egg to assure fertilisation of the egg. A sperm sample with a density of 20million, motility of 50%(10million) and normal forms of 15% delivers a total normal motile count (TNMC) of 1,5000,000. If only 15% reaches the site of fertilisation then we will expect 225,000 sperms around the egg at the site of fertilisation.
This phenomenon explains the difficulties of achieving fertilisation with low sperm counts as there just is not enough sperm around the eggs to achieve fertilisation.

There are many reasons why a man may have low sperm count.

  • He could be born with it as is seen with chromosomal abnormalities such as Klinefelters syndrome;
  • It could be due to childhood factors such as undescended testes (where the testes do not descend into the scrotum for effective sperm production)
  • It could be due to childhood infections such as mumps which is known to be associated with inflammation and damage to the testes.
  • It could be due to acquired causes such as damage to the testes or ducts following infection.
  • It could be due to normal factors such as excess or under production of the hormones necessary for normal sperm production.
  • It could be due to abnormalities within the testes such as dilatation of the veins around the testes (varicocoeles) which could cause changes in the temperature around the testes and affect sperm production.

There are many theories about causes of infertility but the unfortunate fact is that for most men with abnormal semen parameters we are not able to effectively improve the sperm count in a way that will lead to pregnancy.

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