Anejaculation is the pathological inability to ejaculate in males, with (orgasmic) or without (anorgasmic) orgasm. It is caused by failure of emission of semen from the prostate and seminal ducts into the urethra. In the older man, prostate cancer is the diagnosis of exclusion.

Ejaculation is mediated by the sympathetic nervous system. Causes of anejaculation include spinal cord injury, cauda equina lesions, multiple sclerosis, Parkinson's disease, diabetes mellitus, medication (antihypertensive, antipsychotic, antidepressants, alcohol) and surgery (aortoiliac surgery, retro peritoneal lymph node dissection, colorectal resection). The thoracolumbar sympathetic nerves cause contraction of the smooth muscles of the prostate, seminal vesicles and vas deferens leading to emission of seminal fluid into the urethra. These nerves are prone to injury during AAA (abdominal aortic aneurysma) repair, especially when undertaken as an emergency. Aortoiliac surgery can also lead to damage of the superior hypogastric plexus and result in erectile dysfunction. 

There are two kinds of anejaculation, one is situational and the second one is total.

In situational anejaculation, men are able to ejaculate during masturbation, or have nocturnal emissions, but there is problem with ejaculation during sexual activity. Men can be in able to ejaculation with specific partner or in specific type of sexual activity. 

Total or complete anejaculation is divided into orgasmic and anorgasmic anejaculation. In orgasmic, men are able to achieve orgasm, but there is no semen. It can be caused by blockage of ejaculatory nerves or there can be some obstruction in ejaculatory ducts. On the other hand, in anorgasmic anejaculation, men are not able to have orgasm in any way of sexual arousal, even while they masturbate. 

Anejaculation may be associated with several diseases including: 

Idiopathic male infertility

Unexplained male infertility (UMI) is a diagnosis reserved for men in whom routine semen analyses results are within normal values and physical as well as endocrine abnormalities were ruled out.

Possible factors that might explain the difficulties to conceive in UMI include the presence of antisperm antibodies, sperm DNA damage, elevated levels of reactive oxygen species (ROS), and sperm dysfunction. A further possibility to consider is unexplained female factor infertility and coital factors such as inappropriate timing of intercourse (not within the female fertile window), erectile dysfunction or anejaculation.

Ejaculatory disorders

Anejaculation, especially the orgasmic variant, is usually indistinguishable from retrograde ejaculation (when semen, which would, in most cases, be ejaculated via the urethra, is redirected to the urinary bladder). However, a negative urinalysis measuring no abnormal presence of spermatozoa in the urine will eliminate a retrograde ejaculation diagnosis. Thus, if the affected man has the sensations and involuntary muscle-contractions of an orgasm but no or very low-volume semen, ejaculatory duct obstruction is another possible underlying pathology of anejaculation.

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