Updated: NOVEMBER 21, 2016
Dilation is the process where orifices of the body that are ordinarily closed are opened. The cervix, the vagina, and the anus, are the most common orifices referred to when discussing dilation. Dilation may occur during sexual arousal or activity or in a medical setting. It may occur involuntarily or through the penetration of a foreign body such as a speculum.
More About Dilation
The process of dilation occurs in a range of settings. The cervix dilates during childbirth to allow the safe passage of a baby into the world. Before dilation, the cervix is closed to keep the baby safe in the uterus. Dilation begins near the end of a pregnancy with most of the process occurring at the onset of active labor. The cervix dilates to approximately the same size as a baby's head.
A medical professional uses a speculum to dilate the vagina during an OB/GYN exam. The vagina or anus also dilates during sexual activity to prepare itself for penetration.
While the dilation of the vagina is generally involuntary, people who suffer from a disorder such as vaginismus may find that their vagina remains closed even at times of sexual arousal. Vaginal dilators of various sizes may be useful in helping these women develop better control of their bodies and learn to dilate their body when they want to. In a similar way, people may use butt plugs or dildos to dilate their anus to make anal sex more comfortable.