William Aiken

In the male, orgasm and ejaculation is the culmination of rising sexual tension from sexual stimulation. Ejaculation almost invariably accompanies orgasm, but these are actually two separate physiologic processes which can be separated through training and practice.

Ejaculation refers to the expulsion of semen from the urethra at the time of peak sexual tension in which there are rhythmic muscular contractions of the pelvic floor and perineal muscles whereas orgasm refers to the subjective pleasurable sensations caused by these rhythmic muscular contractions.

Ejaculate or semen is composed of fluid from the prostate (25 per cent), seminal vesicles (70 per cent) and sperm from the testes (five per cent) ejaculation may seem like a short explosive phenomenon, it actually occurs in recognisable stages. The first stage is called the emission phase and is the phase in which sperm and seminal fluid is transported via the muscular contractions of the seminal vesicles, vas deferens and ejaculatory ducts to the urine passage at the level of the prostate. These contractions produce pleasurable sensations and a feeling of mounting sexual tension.

A recognisable second stage occurs where the prostatic urethra fills with semen under pressure enclosed by the closed sphincters (valves) of the bladder neck and urethra. This filling under pressure produces mounting sexual tension and intense pleasurable sensations along with a feeling of approaching inevitability of ejaculation.

The third and final phase which is called the expulsion phase is triggered by the pressure rise in the prostatic urethra beyond a certain threshold value which triggers the ejaculation reflex resulting in relaxing of the urethral sphincter or valve thereby allowing semen to flow down the urine passage around which involuntary muscular contractions result in the semen being ejected in a pulsatile manner. At this stage ejaculation could not be stopped even if the man wanted to. Semen is prevented from flowing backwards into the bladder by continued closure of the valve between the prostate and the bladder.

Flow of semen

There are a spectrum of disorders of ejaculation with premature ejaculation (PE) at one end and delayed ejaculation (DE) at the other. Retrograde ejaculation (RE), another ejaculatory disorder, refers to the backward flow of semen into the bladder during ejaculation instead of being propelled forwards. Anejaculation refers to a complete absence of ejaculation and is usually seen in nerve disorders such as spinal cord injury.

Premature ejaculation is by far the most common of the ejaculatory disorders, and is reported as occurring in up to one-third of all men. The vast majority of these men have lifelong or primary PE which means the problem exists from their very first sexual encounter. There is no universally accepted definition of PE, but it essentially refers to ejaculation occurring before, upon or shortly after penetration and before the man wants it to occur, resulting in significant distress to the man or his partner.

Based on studies in which self-professed men with PE were timed during sex it was determined that 90 per cent of men with this disorder ejaculate within one minute of penetration. Of these men, 12 per cent ejaculated prior to or upon penetration. Secondary or acquired PE is much less common and is usually due to inflammatory conditions affecting the genitourinary tract such as prostatitis. The cause of lifelong PE is controversial, but mounting evidence suggests that it may be due to an imbalance of certain types of nerve transmission receptors in the brain. Traditional theories postulated that it is a learnt behaviour from repeated episodes of hurried autoerotic or consensual sex. Perhaps these theories are not mutually exclusive.

(In part II, we will examine the available treatment options for PE and discuss delayed ejaculation and its treatment.)