This instrument is designed to dilate the uterine orifice gently. What sets it apart is the gradual thickening over several centimetres. In other tools, such as the Hegar rod, the increase in diameter is much more abrupt. This gradual widening produces dilation in a more gentle way.
A dilator is on display in the museum as a hands-on exhibit.
The Denniston Dilator is produced in various sizes and sold in packages of five. Normally, only two of the smaller sizes are used. Our specimen (size 12) illustrates the dilator’s function well, though it is much larger than the ones actually in use.
This dilator was developed by American gynaecologist George Denniston.