Diagnostic assessment of human sperm parameters Flashcards
What is semen analysis and why is it done?
- Analysis of seminal fluid and sperm parameters as an indicator of male fertility potential.
- Usually the first diagnostic step in male fertility investigations.
What are the two ways of carrying out semen analysis?
- Manual semen analysis – done by lab practitioner (more common in clinical setting)
- Computer-assisted semen analysis (CASA) – camera attached to microscope and a computer
What is the normal volume of semen?
1.4-6.0ml
What is the normal appearance of semen?
Grey-opalescent appearance
When does the semen normally liquify?
- Around 30 minutes or less
- An abnormally long liquefaction time may be indicative of an infection e.g. bacterial prostatitis
What is the normal sperm concentration?
16 million/ml or more
What % of sperm usually have motility?
42% or more
What % of sperm usually have progressive motility?
30% or more
What % of sperm have normal form?
4% or more
What % of sperm usually have vitality?
54% or more
What is the normal pH of semen?
7.2-8.0
What is the concentration of leucocytes in the semen?
less than 1 million/ml
What are the 2 methods of measuring sperm volume?
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.
How is concentration and motility of sperm assessed?
• 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
What is it called when the semen has a concentration below the ref value?
Oligozoospermia
When should sperm motility be assesed?
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.
What are the four categories of sperm motility?
- Rapidly progressive motility
- Slowly progressive motility
- Non-progressive motility
- Immotility
What are sperm like in rapidly progressive motility?
- 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.
What are sperm like in slowly progressive motility?
- 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
What are sperm like in non-progressive motility?
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.
What are sperm like in immotility?
no movement
What is the term for when motility is below reference valus?
Asthenozoospermia
Which sperm are actually counted?
only spermatozoa with intact head and tail.
How can sperm motility be assessed?
- Assessed directly on the wet preparation – used commonly in clinics for diagnosing and treatment
- Using stains – can be toxic, so usually used in clinics that only diagnose
Describe a healthy sperm head?
- 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.
Describe a healthy sperm tail?
- 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.
What is the term for when the % of the semen is below the ref value for morphology?
Teratozoospermia
What is sperm vitality?
How many sperm are alive
How is sperm vitality determined?
Determined by assessing the membrane integrity of the spermatozoa - especially important for samples with low progressive motility.
When should the sperm vitality be assessed?
Assessed as soon as possible after liquefaction of the semen sample, preferably at 30 minutes, but no later than 1 hour post-ejaculation.
How is sperm vitality assessed?
- 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
What is the term for when the sperm vitality % is below the reference value?
Necrozoospermia
How is the semen pH assessed?
Standard pH strips used
Why is the semen pH important to asses?
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
When should the semen pH be assessed?
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).
How is the % of leucocytes assessed?
All round cells counted – if there’s too many round cells immunocytochemical staining is used to check for leucocytes
Why is assessing leucocytes important?
An increase in leucocytes could be indicative of an infection
