Sertoli Cell-Only Syndrome: Causes, Symptoms & Treatment for SCO Syndrome

Man in suit holding a question mark over his groin - Sertoli cell-only syndrome

What Is Sertolli Cell-Only Syndrome?

Sertoli cell-only syndrome, or SCO syndrome, is a type of male infertility where the seminiferous tubules within the testicles contain only Sertoli cells (which nurture immature sperm), but no germ cells (that later develop into sperm). As a result, no sperm cells are present within the seminiferous tubules.

Most men are diagnosed with SCO syndrome during adulthood when infertility testing shows they do not produce sperm, a condition called azoospermia.

Although the presence of other signs and symptoms is uncommon, there may be an underlying cause the for the condition, for example Klinefelter syndrome.

In the majority of instances, the exact cause of Sertoli cell-only syndrome is not known. However, it is believed that genetic abnormalities may be the cause in some cases. Other causes include:

  • Exposure to toxins or chemicals and toxins
  • Having had radiation treatments
  • Groin injuries

A testicular biopsy is used to confirm a diagnosis for Sertolli cell-only syndrome. To date, there is no way to effectively treat the condition. However, some men may benefit from the use of assisted reproductive technology as a way to still have children.

Signs and Symptoms

Sertoli cell-only syndrome is primarily characterized by the absence of sperm cell production (azoospermia). Some men with SCO syndrome may have testicles that are smaller than normal.

In some circumstances, Sertoli cell-only syndrome may be due to another underlying condition. Men in these cases could potentially experience other symptoms. For instance, some men diagnosed with SCO syndrome can later on develop Klinefelter Syndrome, which is another cause of male infertility.


Although Sertoli-cell-only syndrome can be caused by a number of factors, the causes for the majority of cases are due to undetermined reasons. However, some potential causes for SCO syndrome include the following:

  • Genetic factors
  • Hormonal imbalance
  • Exposure to toxins
  • Radiation treatment
  • Injury to the scrotum/testicles
  • Previous infection involving the testicles

Genetic Causes

Sometimes, Sertoli-cell-only syndrome occur due to a genetic mutation. Sertoli cell-only syndrome could be caused by deletions of genetic information in certain regions of the Y-chromosome.

If a man has SCO syndrome due to a genetic mutation, it isn’t likely that it was passed down from a parent. A man’s Y chromosome is inherited from his father, and most genetic causes of Sertoli-cell-only syndrome can be traced back to mutations of the Y chromosome.

Therefore, it is not likely that a man would inherit the cause of Sertoli cell-only syndrome. If the father had this mutation, he would not have been able to have children in the first place (barring the use of assisted reproductive technology).

However, sometimes SCO syndrome can be caused by a genetic mutation of another chromosome. In these types of situations, Sertoli cell-only syndrome could be passed down from one generation to the next.


Sertoli cell-only syndrome is a condition that is usually suspected in men who have infertility despite having normal testosterone levels. Tests are used to confirm the diagnosis in order to find evidence of azoospermia (lack of sperm production) and elevated follicle-stimulating hormone (FSH) levels.

A biopsy of the testicles is typically used in order to show conclusive evidence of no sperm production, thus confirming the diagnosis.


There is no effective treatment currently available for Sertoli-cell-only syndrome. Sometimes, men with SCO syndrome may have very low levels of sperm production, rather than no sperm production. In these cases, a procedure known as testicular sperm extraction (TESE) can be performed so that sperm can be retrieved from the testicles.

Afterwards, the sperm can be directly injected into a woman’s egg through a procedure called intracytoplasmic sperm injection (ICSI).

This procedure has a low success rate for men with SCO syndrome, however. Only around 13% of men with this condition who use this technique end up successfully having a child. Many men with Sertoli-cell-only syndrome have no sperm cells at all, and the procedure’s success is dependent upon the presence of sperm cells in the testicles.

In situations where TESE/ICSI is utilized, it is recommended to first have genetic testing done to learn more about a possibility of passing the condition on to the children.


There are several options available to men with Sertoli-cell-only syndrome who want to have children. Besides using assisted the reproductive techniques mentioned previously, they can consider adopting a child or have their partner’s eggs fertilized through a sperm donor.

Additionally, there is evidence that men with SCO syndrome have a greater than 10% chance of developing testicular cancer at some point during their lifetime. Discussing this risk with your doctor is important, as well as the methods used to screen for testicular cancer, like physical exams, ultrasound, or MRIs.

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