Aspermia is the complete lack of semen

Semen

Semen is an organic fluid, also known as seminal fluid, that may contain spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize female ova...

 (not to be confused with azoospermia

Azoospermia

Azoospermia is the medical condition of a male not having any measurable level of sperm in his semen. It is associated with very low levels of fertility or even sterility, but many forms are amenable to medical treatment...

, the lack of sperm

Spermatozoon

A spermatozoon is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote...

 cells in the semen). Naturally, it is associated with infertility

Infertility

Infertility primarily refers to the biological inability of a person to contribute to conception. Infertility may also refer to the state of a woman who is unable to carry a pregnancy to full term...

.

One of the causes of aspermia is retrograde ejaculation

Retrograde ejaculation

In the human male reproductive system, retrograde ejaculation occurs when semen, which would normally be ejaculated via the urethra, is redirected to the urinary bladder. Normally, the sphincter of the bladder contracts before ejaculation forcing the semen to exit via the urethra, the path of least...

, which can be brought on by excessive drug use, or as a result of prostate

Prostate

The prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals....

 surgery.

Another cause of aspermia is ejaculatory duct obstruction

Ejaculatory duct obstruction

Ejaculatory duct obstruction is a congenital or acquired pathological condition which is characterized by the obstruction of one or both ejaculatory ducts. Thus, the efflux of semen is not possible....

, which may result in a complete lack of or a very low-volume semen

Semen

Semen is an organic fluid, also known as seminal fluid, that may contain spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize female ova...

 (oligospermia

Oligospermia

Oligospermia, also oligozoospermia, refers to semen with a low concentration of sperm and is a common finding in male infertility. Often semen with a decreased sperm concentration may also show significant abnormalities in sperm morphology and motility...

), in which the semen contains only the secretion of accessory prostate

Prostate

The prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals....

 glands downstream to the orifice of the ejaculatory ducts.