Two disposable Karman aspiration cannulae, for vacuum abortion in first seven weeks of pregnancy, by Rocket of London, 1981

Disposable cannulae are tube-like instruments designed to be used in early abortions. Two are pictured here. In this case, the cannulae were to be used up to the seventh week of pregnancy. They are involved in the technique called vacuum aspiration, the most common form of abortion in early pregnancy. It involves the artificial dilation of the cervix, usually by manual techniques or drugs. This allows access to the uterus. A cannula is then inserted into the uterus which is attached, via tubing, to the aspirator. This acts as a suction pump. A vacuum is created once the syringe rod is pulled. The contents of the uterus are then extracted.