Rob's condition was revealed when he underwent an MRI scan after complaining about blood in his urine.
He said: "The diagnosis came as a bombshell. I've never seen myself as anything but an ordinary bloke who has a normal sex life.
"I was shocked when the consultant said I had a fully functioning set of women's reproductive organs, and I was even having periods.
"It appears I could even potentially get pregnant."
When he was 18, Rob began noticing blood in his urine, but nothing was detected despite repeated tests and trips to his GP.
Doctors eventually began to suspect bladder cancer, but a biopsy came back clear. An MRI scan found he had a functioning uterus, ovaries and cervix.
It is possible Rob could produce eggs, and since he has a uterus it is conceivable he could even carry a baby.
But he said: "Much as I long to be a dad, even if this is possible it's not something I could ever do - it would just feel too weird."
Experts say about 120 babies a year are born in Britain with the same condition as Rob, but it is exceptionally rare for cases to be uncovered so late in life.
Intersex bodies
• Each foetus starts off with the potential to be a boy or girl.
• The default setting is female but if they have XY chromosomes then testes form, producing hormones that cause male genitalia to grow. This also triggers degeneration of internal female organs.
• But in rare cases, those with PMDS do not produce the hormone, or they fail to respond to it.
• Professor Richard Sharpe, who leads Edinburgh University's research team on male reproductive health, said: "This results in some female reproductive organs surviving, as well the growth of male genitalia. It is even more unusual for it not to be spotted until adulthood."
