Retrograde ejaculation occurs when semen, which would, in most cases, 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 resistance. When the bladder sphincter does not function properly, retrograde ejaculation may occur
During a male orgasm, sperm are released from the epididymis and travel via small tubes called the vas deferens. The sperm mix with seminal fluid in the seminal vesicles, prostate fluid from the prostate gland, and lubricants from the bulbourethral gland. During climax, muscles at the end of the bladder neck tighten to prevent retrograde flow of semen.
In retrograde ejaculation, these bladder neck muscles are either very weak or the nerves controlling the muscles have become damaged.
A malfunctioning bladder sphincter, leading to retrograde ejaculation, may be a result either of:
- Autonomic nervous system dysfunction. (Dysautonomia)
- Operation on the prostate. It is a common complication of transurethral resection of the prostate, a procedure in which prostate tissue is removed, slice by slice, through a resectoscope passed along the urethra.
- a retroperitoneal lymph node dissection for testicular cancer if nerve pathways to the bladder sphincter are damaged, with the resulting retrograde ejaculation being either temporary or permanent.
- Surgery on the bladder neck accounted for about ten percent of the cases of retrograde ejaculation or anejaculation reported in a literature review.
- due to a common side effect of medications, such as tamsulosin, that are used to relax the muscles of the urinary tract, treating conditions such as benign prostatic hyperplasia. By relaxing the bladder sphincter muscle, the likelihood of retrograde ejaculation is increased.
- medications that mostly cause it are antidepressant and antipsychotic medication, as well as NRIs such as atomoxetine; patients experiencing this phenomenon tend to quit the medications.
Retrograde ejaculation can also be a complication of diabetes, especially in cases of diabetics with long term poor blood sugar control. This is due to neuropathy of the bladder sphincter.