 Some sources may use the terms "dilation and evacuation" or "suction" "dilation and curettage" to refer to vacuum aspiration, although those terms are normally used to refer to distinct procedures.Vacuuming as a means of removing the uterine contents, rather than the previous use of a hard metal curette, was pioneered in 1958 by Drs Wu Yuantai and Wu Xianzhen in China, but their paper was only translated into English on the fiftieth anniversary of the study that "ultimately led to the technique becoming the world’s most common and safest obstetric procedure".In Canada, the method was pioneered and improved on by Henry Morgentaler, achieving a complication rate of 0.48% and no deaths in over 5,000 cases.