A Hegar dilator, also known as a uterine dilator, is a medical instrument used by gynecologists to open (dilate) the cervix, the lower part of the uterus that connects to the vagina.
 
It is a smooth, rod-shaped instrument with rounded ends and comes in various sizes. Hegar dilators are typically made of stainless steel and are reusable after sterilization.
 
There are two main purposes for using a Hegar dilator:
To measure the dilation of the cervix: This is important for monitoring labor progress during childbirth or for determining if the cervix is dilated enough for certain gynecological procedures.
 
To induce cervical dilation: This may be necessary before performing procedures such as a uterine biopsy, endometrial ablation (removal of the lining of the uterus), or insertion of an intrauterine device (IUD).