David R. Knowles, M.D., is a urologist who wrote about sexual dysfunction issues for HealthCentral. He graduated from the College of Physicians and Surgeons of Columbia University. His residency training at New York Presbyterian Hospital included training at the New York Center for Human Sexuality. He is board certified in adult and pediatric urology by the American Board of Urology. His is a general adult and pediatric urologist at Advanced Urologic Surgeons in Mount Vernon, Illinois.