Azoospermia is the complete absence of sperm in the seminal ejaculate. Azoospermia is uncommon but not rare, occurring in about 2% of men in the general population and 10-20% of men receiving care in infertility centers. Aspermia is an absence of ejaculate (semen). The finding of azoospermia often comes as a surprise for a couple since there often are no symptoms (there frequently is an ejaculate and a normal ejaculation process).
The approach to this difficult situation looks at categories of causes for azoospermia (such as pre testicular, testicular and post testicular), with the goal being to identify the treatable causes. In general, the pre and post testicular causes are more readily treatable than the testicular causes.
(1) Pre testicular azoospermia includes:
Ejaculatory dysfunctions, which may be due to such diverse issues as psychosexual dysfunction, prior urologic surgery, medications, and neurologic disease. Some of these are treatable.
Hormonal abnormalities such as hypogonadotropic hypogonadism (pituitary FSH and LH deficiency). This is often treatable. If a structural lesion or elevated prolactin concentration is discovered then these are treated. If there is destruction of the pituitary gland or a CNS-hypothalamic cause, then treatment with menotropins is often useful.
Anabolic steroid hormone abuse (such as for muscle building), which is associated with marked impairment of spermatogenesis that may recover once the drugs are stopped.
Hemochromatosis, which is a rare condition involved in azoospermia by means of iron overload of the pituitary gland occasionally causing isolated gonadotropin deficiency and possibly testicular atrophy.
(2) Testicular azoospermia includes:
Cryptorchidism (undescended testes), which is the most common congenital abnormality associated with azoospermia. The testes normally descend in the 8th month of gestation, with 3-4% of term male infants having cryptorchid testes at birth that will descend within the first year of life. The prevalence in adults is less than 1% in the general population but up to 6% in the infertile population. If the failure of descent is due to an obstruction then the prognosis in terms of fertility is much higher than if no obstruction is present. The degree of spermatogenic dysfunction is proportional to the duration of time the testes are outside the scrotum so most pediatric urologists suggest repair by the end of the second year of life. Cryptorchid testes have a greater chance of malignancy (cancer) and require appropriate followup with an urologist.
Androgen resistance syndromes due to the inability of cells to adequately respond to circulating androgens, either due to an androgen receptor deficiency or an androgen receptor dysfunction. This syndrome has a wide range in degrees of severity, with more severe forms resulting in azoospermia and less severe forms resulting in oligospermia. The most severe of these syndromes has been referred to as “testicular feminization” where the external genitalia are female.
5 alpha reductase deficiency, which is the enzyme that converts testosterone to dihydrotestosterone (its more active form for many cells in the body). A deficiency can result in azoospermia and is usually associated with multiple major congenital abnormalities of the reproductive tract.
Congenital anorchia (lack of testes) is a rare condition in which the testes are present and functioning at 8-14 weeks gestation (since the external and internal genitalia are male) and for some unknown reason are lost after this point in development.
Infection involving the testes (orchitis), including mumps (associated with a thickening and nodularity of the epididymis) and bacterial infections, which can result in azoospermia
Sertoli only syndrome, which is associated with relatively normal appearing seminiferous tubules except for an absence of germ cells from which spermatozoa are developed. It is postulated that this is due to abnormal migration of the germ cells in early embryonic life. This is associated with an increased FSH concentration, slightly decreased size of the testes, and a normal (or mildly suppressed) testosterone.
Vvascular insult with resulting spermatogenic arrest possibly due to trauma, torsion (twisting) or varicocele (uncommon cause of azoospermia). Occasionally, repair surgically can improve spermatogenesis.
Gonadotoxins including radiation, chemotherapy, excessive heat, and some medications
(3) Post testicular cause of azoospermia include:
Obstructive lesions of the epididymis, vas deferens or ejaculatory ducts. These may be associated with medical conditions such as cystic fibrosis.
Vasectomy with or without attempted reversal
Retrograde ejaculation with the seminal fluid traveling the path of least resistance, which is back into the bladder in certain postoperative conditions or with impaired nerve function.