Caitlyn Jenner says she has undergone genital surgery, two years after the Olympic-winning decathlete announced she had transitioned to a woman.

Jenner, 67, one of the most-high profile American transgender woman, says in an upcoming memoir that she had the surgery in January, and that she decided to go public "so all of you can stop staring."

"You want to know, so now you know. Which is why this is the first time, and the last time, I will ever speak of it," Jenner wrote in leaked excerpts of her memoir "The Secrets of My Life."

The excerpts were published by RadarOnline on Monday ahead of the April 25 publication of the memoir. Grand Central Publishing said on Tuesday it did not wish to discuss the contents ahead of the publication date and Jenner's representative had no comment.

Jenner announced her new identity in an April 2015 TV interview and announced her change of name from Bruce to Caitlyn in a July 2015 Vanity Fair cover shoot. Jenner, the step-father of reality stars Kim, Kourtney and Khloe Kardashian, later had her own TV reality show which documented her transition.

According to the excerpts, Jenner said the surgery, which is costly and complex, was successful and that she feels "not only wonderful but liberated."

She said having a penis had "no special gifts or use for me... I just want to have all the right parts. I am also tired of tucking the damn thing in all the time."

Many transgender people share Jenner's distress over being asked intrusive questions about their genitals, although most forgo gender reassignment surgery, citing the high cost.

Only 11% of transgender women had their testicles removed and 12% underwent vaginoplasty, according to a 2016 U.S. survey by the National Center for Transgender Equality.