How Frequently Does Transsexualism Occur? by Lynn Conway Updated version of 12-17-02. Original article was posted on the web on January 30, 2001. In this investigative report we calculate an approximate value of the lower bound of the prevalence of male-to-female (MtF) transsexualism in the United States, based on estimates of the numbers of sex reassignment surgeries performed on U.S. residents during the past four decades.