Diagnostic assessment of human sperm parameters

Question 1

What is semen analysis and why is it done?

Answer 1

• Analysis of seminal fluid and sperm parameters as an indicator of male fertility potential.
• Usually the first diagnostic step in male fertility investigations.

Question 2

What are the two ways of carrying out semen analysis?

Answer 2

• Manual semen analysis – done by lab practitioner (more common in clinical setting)
• Computer-assisted semen analysis (CASA) – camera attached to microscope and a computer

Question 3

What is the normal volume of semen?

Answer 3

1.4-6.0ml

Question 4

What is the normal appearance of semen?

Answer 4

Grey-opalescent appearance

Question 5

When does the semen normally liquify?

Answer 5

• Around 30 minutes or less

- An abnormally long liquefaction time may be indicative of an infection e.g. bacterial prostatitis

Question 6

What is the normal sperm concentration?

Answer 6

16 million/ml or more

Question 7

What % of sperm usually have motility?

Answer 7

42% or more

Question 8

What % of sperm usually have progressive motility?

Answer 8

30% or more

Question 9

What % of sperm have normal form?

Answer 9

4% or more

Question 10

What % of sperm usually have vitality?

Answer 10

54% or more

Question 11

What is the normal pH of semen?

Answer 11

7.2-8.0

Question 12

What is the concentration of leucocytes in the semen?

Answer 12

less than 1 million/ml

Question 13

What are the 2 methods of measuring sperm volume?

Answer 13

Direct volume measurement:

• commonly used in diagnostic setting
• Volume (ml) measured directly using serological pipette

Volume from weight:

• Weighing sample pots before and after sample production.
• Difference = sample volume.
• Studies have shown weight to be an accurate index of volume.

Question 14

How is concentration and motility of sperm assessed?

Answer 14

• Haemocytometers used
• Sperm concentration = quantity of sperm present in a sample.
• Measured in millions per ml.
• Determined using a counting chamber: there’s 2 types
o Neubauer haemocytometer
o Makler counting chamber

Question 15

What is it called when the semen has a concentration below the ref value?

Answer 15

Oligozoospermia

Question 16

When should sperm motility be assesed?

Answer 16

Sperm motility within semen should be assessed as soon as possible after liquefaction of the sample, within 1 hour following ejaculation, to limit the deleterious effects of dehydration, pH or changes in temperature on motility.

Question 17

What are the four categories of sperm motility?

Answer 17

1. Rapidly progressive motility
2. Slowly progressive motility
3. Non-progressive motility
4. Immotility

Question 18

What are sperm like in rapidly progressive motility?

Answer 18

• spermatozoa moving actively, either linearly or in a large circle
• covering a distance, from the starting point to the end point, of at least 25 μm (or ½ tail length) in one second.

Question 19

What are sperm like in slowly progressive motility?

Answer 19

• spermatozoa moving actively, either linearly or in a large circle
• covering a distance, from the starting point to the end point, of 5 to < 25 μm (or at least one head length to less than ½ tail length) in one second

Question 20

What are sperm like in non-progressive motility?

Answer 20

all other patterns of motility with an absence of progression, e.g. swimming in small circles, the flagellar force hardly displacing the head, or when only a flagellar beat can be observed.

Question 21

What are sperm like in immotility?

Answer 21

no movement

Question 22

What is the term for when motility is below reference valus?

Answer 22

Asthenozoospermia

Question 23

Which sperm are actually counted?

Answer 23

only spermatozoa with intact head and tail.

Question 24

How can sperm motility be assessed?

Answer 24

1. Assessed directly on the wet preparation – used commonly in clinics for diagnosing and treatment
2. Using stains – can be toxic, so usually used in clinics that only diagnose

Question 25

Describe a healthy sperm head?

Answer 25

• Smooth, regularly contoured and generally oval in shape.
• Well-defined acrosomal region comprising 40–70% of the head area.
• Acrosomal region should contain no large vacuoles, and not more than two small vacuoles, which should not occupy more than 20% of the sperm head.
• The post-acrosomal region should not contain any vacuoles.

Question 26

Describe a healthy sperm tail?

Answer 26

• Slender, regular midpiece about the same length as the sperm head.
• The major axis of the midpiece should be aligned with the major axis of the sperm head.
• Residual cytoplasm is considered an anomaly only when in excess i.e. when it exceeds one third of the sperm head size.
• The principal piece should be thinner than the midpiece and around 10 times the head length. It may be looped back on itself provided there is no sharp angle indicative of a flagellar break.

Question 27

What is the term for when the % of the semen is below the ref value for morphology?

Answer 27

Teratozoospermia

Question 28

What is sperm vitality?

Answer 28

How many sperm are alive

Question 29

How is sperm vitality determined?

Answer 29

Determined by assessing the membrane integrity of the spermatozoa - especially important for samples with low progressive motility.

Question 30

When should the sperm vitality be assessed?

Answer 30

Assessed as soon as possible after liquefaction of the semen sample, preferably at 30 minutes, but no later than 1 hour post-ejaculation.

Question 31

How is sperm vitality assessed?

Answer 31

• Dye exclusion (Eosin-Nigrosin) - Damaged plasma membranes, such as those found in dead cells, allow entry of membrane-impermeant stains.
• Hypo-osmotic swelling test - Only spermatozoa with intact membranes (live cells) will swell in hypotonic solutions

Question 32

What is the term for when the sperm vitality % is below the reference value?

Answer 32

Necrozoospermia

Question 33

How is the semen pH assessed?

Answer 33

Standard pH strips used

Question 34

Why is the semen pH important to asses?

Answer 34

The pH of semen reflects the balance between the pH values of the different accessory gland secretions, mainly the alkaline seminal vesicular secretion and the acidic prostatic secretion

Question 35

When should the semen pH be assessed?

Answer 35

Assessed as soon as possible after liquefaction of the semen sample, preferably at 30 minutes, but no later than 1 hour post-ejaculation (loss of CO2).

Question 36

How is the % of leucocytes assessed?

Answer 36

All round cells counted – if there’s too many round cells immunocytochemical staining is used to check for leucocytes

Question 37

Why is assessing leucocytes important?

Answer 37

An increase in leucocytes could be indicative of an infection