Causes of Male Infertility
By Dr. Kate Dudek
When a couple seek help for infertility, it is a common misconception that the female partner will be responsible for the issue. It is true that there are a wide range of conditions, both medical and environmental, that can impede a female’s ability to fall pregnant. However, in up to 50% of suspected infertility cases the male is also involved. In fact, 30% of the time the problem will be just down to the male. The good news is that many male-based problems can be easily diagnosed and treated, without the need to resort to challenging, invasive and costly Assisted Reproductive Techniques/Technologies (ART). The less positive news is that there remains a social stigma attached to male infertility and, that for as long as men refuse to acknowledge that the problem might lie with them, women will continue to undergo unnecessary procedures and infertility rates will not improve.
So, what are the major causes of infertility in males?
Abnormal sperm production
This is the largest contributor to male infertility. Low sperm count, or low sperm quality is thought to be involved in up to 90% of cases. Azoospermia occurs when semen analysis identifies no sperm cells. This can be non-obstructive, which is more common, or obstructive. Most cases of non-obstructive azoospermia occur due to testicular dysfunction, which usually results from developmental abnormalities, genetic mutations, trauma or tumour. The obstructive form is less common, affecting 15-20% of men with azoospermia. This occurs when there is obstruction of part of the male reproductive tract, usually the epididymis, the vas deferens or the ejaculatory duct. Other sperm disorders include low numbers (oligospermia), irregularly shaped sperm and sperm that moves the wrong way.
Alternative forms of testicular dysfunction which may cause impaired semen production include hypogonadism, which causes a disruption in the synthesis of male-specific hormones, called androgens; and cryptorchidism, a congenital abnormality of the male genitalia, more commonly known as undescended testes. Maldescended testes are normally treated during early childhood; however, do have a strong association with impaired semen in adulthood.
Genetic defects and chromosomal abnormalities
Several genetic mutations have been implemented in male infertility. Examples include, mutations of the AR gene, which cause androgen insensitivity; and deletions in the AZF region, which causes azoospermia because the genes located here play a key role in spermatogenesis.
All men who men who present with structural abnormalities of the vas deferens, the duct that carries sperm from the testes towards the penis, should be tested for mutations of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. If mutations are found, it would make them a carrier of cystic fibrosis. Their partner should also be tested because if she is a carrier too the chance of passing cystic fibrosis on to any offspring is 50%. Men with Cystic Fibrosis will have azoospermia; only 2-3% of these men will be fertile. More importantly, depending on the site of mutation in the CFTR gene, the condition can be life threatening, affecting the respiratory and digestive systems, causing a build up of thick mucus and hindering a patient’s ability to breathe and eat normally.
Men who have abnormal sperm might want to consider genetic counselling prior to attempting to conceive, as they will have a greater chance of passing on genetic mutations to their offspring, who may then suffer from fertility problems of their own. It is also advised that the female partner is screened as well in case she too is a carrier.
40% of infertile men will have varicoceles, which are enlarged veins in the scrotum. Men with a familial history of varicoceles are at greater risk of developing them, indicating a possible genetic component to the condition. They are particularly prevalent in men who have abnormal semen. They usually first appear during puberty and, if severe, can be treated with ligation using microscopic surgery (varicocelectomy).
Normal ejaculation is a three step process: Firstly the seminal fluid and sperm are transmitted into the prostatic urethra; then the bladder neck closes to prevent retrograde (backward) flow; finally, the seminal fluid is ejaculated in an antegrade (forward) direction. If this process is disrupted it gives rise to an ejaculation disorder:
Anejaculation. Absence of ejaculation; a complete lack of semen emission into the urethra.
Delayed ejaculation. Abnormal stimulation of the erect penis is required. Difficulty reaching orgasm.
Retrograde ejaculation. Semen passes backwards into the bladder.
These disorders occur in response to medications, psychological issues, nerve problems, dysfunction of the nervous system, or, in the case of retrograde ejaculation, bladder neck incompetence.
Anejaculation and retrograde ejaculation fall under the category of aspermia (dry ejaculate), whereby there is a complete lack of semen expulsion.
Anti-sperm antibodies may impair fertility. However, they are thought to play a greater role in female infertility, impeding the entry of sperm into the fallopian tube.
The environment, prior or current drug use (pharmaceutical or recreational) and a history of cancer (particularly those that affect the male reproductive organs) can also impair fertility. All of these factors highlight the need for a comprehensive medical evaluation during initial investigative diagnosis. A major challenge remains, because in up to 40% of infertility cases, no definitive cause will be identified. This is termed idiopathic male infertility.
The wide range of factors that can have a detrimental effect on male fertility highlights how important it is for couples to face any issues that they have conceiving together. Despite this, figures suggest that when couples first seek help for infertility, a male evaluation will not be performed in at least 18% of cases.
Katz, D J, et al. “Male Infertility - The Other Side of the Equation.” Australian Family Physician, vol. 46, no. 9, Sept. 2017, pp. 641–646.
Jungwirth A, et al. European Association of Urology (EAU) guidelines on male infertility. Arnhem, The Netherlands: European Association of Urology, 2015. Available at https://uroweb.org/wp-content/uploads/17-Male-Infertility_LR1.pdf [Accessed 31 March 2019].
“What Is Male Infertility?” Urology Care Foundation, www.urologyhealth.org/urologic-conditions/male-infertility.