Non-obstructive azoospermia is diagnosed in cases where no sperm cells can be found in the ejaculate, yet no evidence of a blockage can be seen. These cases are very challenging, as it is difficult to define the cause of infertility and recommend the next steps.
Sometimes, an analysis of a sample of testicular tissue can help provide answers. Under the microscope, an expert will be able to recognize certain conditions, including Sertoli-cell only (SCO), hypospermatogenesis, a maturation arrest (MA).
Sertoli-cell only
In the testis, the maturing sperm cells are located in tubules along with cells known as Sertoli cells. These Sertoli cells embrace the sperm as they develop, providing the environment and support needed.
In SCO, the tubules contain only Sertoli cells, rather than the expected Sertoli/sperm cell mix. This diagnosis can be confirmed under the microscope, as no sperm cells can be identified.
The cause of SCO is not always known, however, it is sometimes be associated with certain genetic mutations or caused by toxin exposure, radiation, or trauma. Men with SCO have normal testosterone levels but often have increased levels of FSH hormone.
Maturation Arrest
MA is a condition where the early sperm cells are unable to fully develop into mature cells. In the tissue sample, the examiner can observe many early-stage sperm cells, but cannot identify any fully developed sperm. If the arrest is uniform, then all the cells seen will have stopped developing at the same time point.
In some, MA has been linked to genetic changes. Particularly, if the failure occurs at an early stage, there is a higher chance that the MA is associated with genetic abnormalities. However, MA could also be caused by an outside factor such as chemotherapy, infection, drug use, alcohol consumption, or nutrition. It can also be associated with medical conditions such as undescended testes or varicoceles.
Depending on the cause, some cases of maturation arrest are reversible, and a successful future sperm retrieval is possible.
Hypospermatogenesis
Incomplete maturation arrest is known as hypospermatogenesis. In such cases, some cells are able to develop and mature sperm can be found within the testes. These cells can be retrieved surgically and used for IVF-ICSI.
