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  • Writer's pictureMaryam Rahbar

The basics of semen analysis: what you need to know about sperm and how it is tested



Infertility affects 1 in 7 couples worldwide with male infertility contributing to about half of these cases [1]. Throughout our lives, we have been taught that sperm and egg fuse together to make a baby. The sperm is half of the equation, so it's important to understand what sperm is and how it contributes to infertility through semen analysis testing. The team at Jack Fertility is focused on providing the right information to enhance your journey through understanding your fertility potential.

 

What is sperm made up of?


Sperm is made up of three parts, the head, the midpiece and the tail, all of which have their own function and role in aiding the sperm to reach the egg and fertilize it.

The anatomy of a sperm cell showing the position of the head, midpiece and tail
Sperm cell anatomy

  • The head of the sperm contains all the genetic material which will make up half of the genetics of the baby and contribute the X or Y chromosome which determines the sex of the baby. There are proteins that allow the sperm to break down the outer layers of the egg and deposit its genetic material. The head is the only region which enters the egg.

  • The midpiece of the sperm is where the sperm’s powerhouse is. This region contains the mitochondria which are responsible for producing the energy required for the sperm to move.


  • The tail of the sperm is the section which propels the sperm and allows it to move towards the egg.

 

Where is sperm produced?


Now that we know what the different parts of sperm are, let’s look into where sperm is produced.


Testicle anatomy showing the location of the epididymis and seminiferous tubules
Testicle anatomy

Sperm is continuously produced in the testicles within the seminiferous tubules, which are coiled tiny tubes inside the testis. On average, approximately 100 million sperm begin their maturation journey daily. The sperm cells undergo multiple division phases and maturation steps until they are capable of fertilization. The process of sperm production and maturation takes anywhere between 72 to 90 days which can vary slightly between individuals. Once the sperm cells have fully developed, they are stored in the epididymis. The sperm mixes with semen prior to ejaculation [2].


What is semen?


Semen is the fluid portion of the ejaculate which comes from the prostate glands and seminal vesicles. It provides nutrients and oxygen, while maintaining a balanced environment (temperature and pH) to provide an optimal medium for sperm to survive until it reaches the female reproductive tract and begins its swimming journey towards the egg. The average volume of semen is 1.5mL to 5mL [3].


How is sperm tested?


Semen analysis is the starting point for understanding and investigating male fertility and there are 5 key characteristics looked at: volume, count, motility, morphology and concentration. The semen sample is produced through masturbation and collected in a sterile collection cup. It is recommended to abstain from ejaculation for 2 to 5 days prior to sample production in order to obtain accurate results regarding sperm quality.


Typically, the sample is taken to a fertility clinic/laboratory within 1 hour of collection where it is tested. Sample collection can also be completed on-site at a clinic in a private room which can be embarrassing and daunting.


The sample is then analyzed using a microscope and the sperm parameters outlined below are investigated. The results are compared to an international guide provided by the World Health Organization (WHO). The main characteristics of sperm tested in a semen analysis are:


  • Semen volume, which is the amount of semen ejaculated. The lower value of the reference range is 1.5mL. The first fractions of the sample are sperm-rich so it is important to note whether portions of the sample were lost during collection [4].


  • Sperm count is the total number of sperm in the ejaculate. The lower value of the reference range for sperm count is 39 million [4].


  • Sperm motility investigates the ability of the sperm to move. The total motility is included in the report and can be broken down further according to how the sperm are moving. Progressive motility is the type of movement which propels the sperm in a forward direction, allowing the sperm to reach the egg. Non-progressive motility categorizes the sperm which are either moving slowly, in a non-forward direction or wiggling in place. According to the WHO guideline, the percentage of total motile sperm, irrespective of how the sperm moves, for a normal sample should be over 40% and progressive motility should be over 32%[4].


  • Sperm morphology refers to the sperm’s shape and structure looking at the head region, the midpiece, and the tail. The morphology can be broken down for each section of the sperm or can be provided as an overall percentage of normal morphology. According to WHO, there should be more than 4% normal sperm in a healthy sample [4].


  • Sperm concentration refers to how densely packed the sperm is in 1mL volume of semen. The lower value of the reference range is 15 million per 1 mL of semen. However, this is very low compared to the average sperm concentration which is 100 million so it would be worth discussing the results with a specialist if the concentration is below 30 million/mL [4].


  • Other characteristics which could also be noted are the pH of a sample, presence of white blood cells, time to liquefaction and viscosity [4].

It is recommended to have at least 2 semen samples analyzed to ensure the results are consistent and accurate [4]. The results of a semen analysis along with a general medical history can be used to determine fertility potential and may warrant additional testing to be performed.


Since the cycle of sperm production takes approximately 3 months, additional semen analysis tests may be required to test the effects of any changes in lifestyle, medication, or health status that may have an impact on the initial results. As an aside, Jack Fertility will be able to help track your fertility journey through multiple testing packages and in-depth results.


Other factors which may cause an abnormal semen analysis include: recent infection, genetic defects, hormonal imbalance, exposure to radiation, vasectomy, and varicocele, an enlargement of the veins within the loose bag of skin that holds the testicles aka the scrotum [5].


Globally, sperm counts have declined drastically in the past few decades and continue to decline further [6]. It is, therefore, crucial for male fertility to be on the forefronts of health care to increase awareness and remove the taboo/stigma associated with the topic.


Jack Fertility aims to provide a novel, easy-to-use semen analysis kit that allows you to take control of your fertility from home. If you're thinking about getting your sperm tested sign up for early access to our mail-in test.


Maryam Rahbar MSc DPhil (Pending, Oxon) is the Scientific Advisor of Jack Fertility


References


[1] Vander Borght, M. & Wyns, C. Fertility and infertility: Definition and epidemiology. Clin. Biochem. 62, 2–10 (2018).

[2] Alberts, B., Johnson, A. & Lewis, J. Sperm - Molecular Biology of the Cell - NCBI Bookshelf. Garland Sciences (2002). Available at: https://www.ncbi.nlm.nih.gov/books/NBK26914/.

[3] Chiu, Y. H. et al. What Does a Single Semen Sample Tell You? Implications for Male Factor Infertility Research. Am. J. Epidemiol. 186, 918 (2017).

[4] WHO. World Health Organization. WHO laboratory manual for the examination and processing of human semen. 6th ed. World Health Organization, Department of Reproductive Health and Research. Geneva, Switzerland. WHO Press (2021).

[5] Agarwal, A. et al. Male infertility. Lancet 397, 319–333 (2021).

[6] Levine, H. et al. Temporal trends in sperm count: a systematic review and meta-regression analysis. Hum. Reprod. Update 23, 646–659 (2017).



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