Female ejaculation (colloquially known as squirting or gushing) refers to the expulsion of noticeable amounts of clear fluid, always from the urethra during sexual stimulation at or near orgasm.

Female ejaculation is accomplished by stimulation of the g-spot (the urethral sponge, named after Dr. Ernst Gräfenberg), an area on the front vaginal wall. More rarely, it can be accomplished through external stimulation of the clitoris alone, the internal tissue of the clitoris then contracting and stimulating the urethral tissue.

Female ejaculation is not a new concept. The Greek philosopher Aristotle noted its existence, Galen (2nd century) described the female prostate, the Italian anatomist Renaldus Columbus referred to female ejaculate while he was explaining the function of the clitoris and in the 17th century, the Dutch anatomist Regnier de Graaf wrote a book about female anatomy and spoke of female fluid "rushing out" and "coming in one gush" during sexual excitement.

Up until the 1980s female ejaculation was largely ignored by the medical community. At that time the subject resurfaced with the bestselling book "The G-Spot" by Drs. Ladas, Whipple and Perry. The book not only addressed the validity of the g-spot but brought female ejaculation to the forefront of women's sexual health inside the medical community.

While many in the medical and scientific communities are now acknowledging the existence of female ejaculation, there remains a large void when it comes to solid scientific data explaining the process of ejaculation in females or the source of the fluid itself.

Studies have been done by Dr. Beverly Whipple, Dr. John Perry, Dr. Gary Schuback, Dr. Milan Zaviacic and Dr. Cabello Santamaria but their findings are limited. While current information offers no solid information about the source of the fluid, chemical analysis performed on the fluid by a number of teams has revealed that it is not urine (the levels of creatinine and urea are too low).

There have been a number of studies done on the fluid expelled during female ejaculation to determine the chemical makeup. Through chemical analysis the expelled fluid has been found to contain the following:

• glucose (a natural sugar) and fructose (another natural sugar, also found in the prostatic fluid of semen)
• prostate-specific antigen (PSA), the fluid produced by males which forms the base of male ejaculate, produced by the prostate gland, and in females, believed to be generated by Skene's glands
• very low levels of creatinine and urea (the two primary chemical markers of urine, found in high levels in pre- and post-ejaculatory urinalysis).

In 1988, Milan Zaviacic, M.D., Ph.D., head of the Institute of Pathology, Comenius University Bratislava, published a study of five women who were patients at a fertility department of a hospital of gynecology and obstetrics. Total samples from one of the participants and one of four samples from a second participant were collected in the laboratory. The rest were collected at the homes of the women and transported to the laboratory in ice. In four of the five cases, the samples were analyzed within three hours of collection, with the fifth subject’s specimens analyzed three months after collection. The results in all five cases showed a higher concentration of fructose in the ejaculate sample than in the urine sample.

In 1997 Dr. F Cabello Santamaria analyzed urine for PSA using Microparticle Enzyme Immunoassay and found that 75 percent of the samples showed a concentration of PSA in post-orgasmic urine samples which was not present in pre-orgasmic urine samples. The fluid collected at the point of orgasm (distinct from the urine samples) showed the presence of PSA in 100 percent of samples.

In 2002, Emanuele Jannini of L'Aquila University in Italy offered one explanation for this phenomenon, as well as for the frequent denials of its existence:

Skene's gland openings are usually the size of pinholes, and vary in size from one woman to another, to the point where they appear to be missing entirely in some women. If Skene's glands are the cause of female ejaculation, this may explain the observed absence of this phenomenon in many women.

Retrograde ejaculation, where the fluid travels up the urethra towards the bladder could also possibly account for the absence otherwise observed.

Women do not have an exact equivalent of the male prostate gland, an essential part of the male reproductive system. They do, however, have structures which are homologous to the male prostate, this meaning that they have developed from the same embryonic tissue. (The testicles of the male and the ovaries of the female are also homologous.) These are called para-urethral glands or Skene’s glands – although the term ‘Skene’s glands’ is often reserved for the two para-urethral glands closest to the opening of the urethra. They are there because, for the first weeks in development, the male and female embryo are not yet differentiated.

The size and structure of the para-urethral glands varies relatively considerably, it seems, from woman to woman. The fluid they produce is similar to that produced by the male prostate and, as in the male, passes into the urethra – and in some cases may pass into the vagina. The glands fill with fluid during sexual arousal and may be felt through the vaginal wall. The swelling of the tissue surrounding the urethra may be a combination of the glands filling with fluid and of the swelling of the woman’s erectile tissue, the corpus spongiosum, which latter, in the male, gives a man his erection. Swelling of the non-visible part of the clitoris will also be evident.

It is, it seems, the rhythmic contractions of pelvic muscle during orgasm which expel the accumulated fluid as at least one constituent of female ejaculation. The amount of fluid released can be considerable, through repeated filling and emptying of the glands during orgasm.