What is vulvodynia and why can it make sex feel like 'serrated knives between your legs'?

A woman's experience of a rare condition that caused her vagina to feel like it was being cut by knives during sex has been turned into a play.

Actress Emily Francis heard on the radio the story of fashion stylist Callista Jane Wilson, who suffered from a rare form of vulvodynia. Francis based her new play, The Internet Was Made for Adults, on Wilson's story.

"I felt desperately sad listening to Callista's story. This problem with her vagina had destroyed her life. She'd lost her relationship, become depressed. It felt tragic," Francis, whose play is showing in London, told BBC News.

Wilson first experienced searing pain in her vagina at the age of 12 when she tried to insert a tampon.

"Where I thought it should go caused intense pain when I tried pushing. It felt like hitting a wall and having it bite you back," she wrote in a blogpost about her condition.

Recalling the experience of having sex at 16, she wrote: "I never imagined it would feel like serrated knives between my legs, like fresh rope burn, like a ring of fire that burned for days afterwards."

At the age of 20, she asked her doctor for help but when the examination showed her genitalia was healthy she was told that the pain was psychological and down to her Catholic upbringing.

Callista wrote how she distanced herself from others in order to avoid intimacy, would pretend to enjoy sex, and would use drink and drugs to help her body tune out the pain during intercourse.

After visiting 20 doctors she was finally told that she had congenital neuroproliferative vestibulodynia, a type of vulvodynia focused in the vestibule around the opening of the vagina.

Wilson underwent surgery to remove the painful tissue and was finally able to enjoy pain-free sex for the first time. She was 34.

What is vulvodynia?

The term is used to describe persistent, unexplained pain in the vulva, or the skin and lips surrounding the entrance to the vagina, according to the NHS.

What are the symptoms?

Symptoms include a soreness and burning sensations, which can be worsened by activities such as sex, inserting a tampon, or sitting. The pain may be localised to one area, such as in neuroproliferative vestibulodynia which affects the opening of the vagina. It can also affect the inner thighs and buttocks.

The NHS advises anyone who has persistent vulval pain to contact their doctor.

How is it treated?

It is unlikely that vulvodynia will go away on its own. As there are a number of reasons why the pain might occur, both physical and mental treatments can help.

Wearing cotton underwear and avoiding scented products such as feminine wipes and soaps can prevent pain. The NHS advises not ceasing sexual activities if possible as this may make the vulva more sensitive.

Antidepressants and anti-epilepsy medications are also sometimes prescribed, as well as physiotherapy and cognitive behavioural therapy depending on the cause of the pain. In rare cases, surgery can be used to remove the painful tissue, although the tissue may return.

Who is at risk?

People of all ages can experience vulvodynia and it often affects those who are otherwise in good general health. It is not contagious.