The UN health agency estimates that 200 million women and girls have been subjected to FGM worldwide.
Victims are left to cope with a range of consequences from bleeding and pain while urinating, extreme discomfort during sex, fatal complications in childbirth and deep psychological trauma.
FGM is most prevalent in Africa -- where it is practiced in some 30 countries despite widespread criminalisation -- as well as pockets of Asia and the Middle East.
"Health workers are often unaware of the many negative health consequences of FGM and many remain inadequately trained to recognise and treat them properly," WHO said in a statement.
Victims therefore "may suffer needlessly", it added.
Underscoring the global spread of the problem, WHO's at-risk population specialist Lale Say said more than 500,000 women and girls in the United States have suffered from or face the threat of FGM, while some 66,000 women in Britain have been subjected to the practice.
With concrete data lacking, developing treatment guidelines was complicated, WHO experts said, and the agency's report notes that some of its recommendations are based on limited evidence.
The guidelines call for FGM sufferers to receive, when needed, psychological support and recommendations relating to obstertics.
One possible consequence of FGM is vaginal closure, which can lead to babies dying during delivery after getting "stuck" in the birth canal, Chou explained.
