Scientists have pinned down the position of the fabled G spot and developed a simple test they claim can identify whether a woman has one.
The existence of the female erogenous zone, which is said to lead to very intense orgasms, has been controversial due to a lack of research.
The study, by an Italian team, is the first to uncover an anatomical difference between woman who say they have experienced vaginal orgasms involving a G-spot, and those who say they have not.
Ultrasound was used to scan the vaginal walls of the women, and an area of tissue was found to be thicker on the front side, between the vagina and the urethra, in those who had had the vaginal orgasms, which occur without stimulation of the clitoris.
The findings, published in the Journal of Sexual Medicine and reported in New Scientist, could help couples work out whether they should keep on searching for the pleasure centre, or give up.
"For the first time it is possible to determine by a simple, rapid and inexpensive method if a woman has a G spot or not," said team leader, Emmanuele Jannini, of the University of L'Aquila.
But Beverly Whipple, the American researcher whose team coined the term G spot and made it famous more than 25 years ago, challenged the conclusion that some women lacked a G spot.
"It is an intriguing study, but it doesn't necessarily mean that women who don't experience orgasm don't have any tissue there," Professor Whipple, of Rutgers University in New Jersey, told the magazine.
Her research has shown that all women describe some degree of sensitivity in the area, about a third of the way up the vagina.
She said the thicker tissue might have been found in all of the women in the Italian study if they had been stimulated before being given the ultrasound, because the area swelled in response to physical pressure.
Dr Jannini said it was not possible from his study, which involved 20 women, to estimate how many women have a G spot.
Only 30 per cent of women in some surveys report having orgasms through intercourse.
