Cervical Effacement and Dilatation
What are effacement and dilatation?
As labor nears,
the
cervix begins to thin or stretch (efface) and open
(dilate) to prepare for the passage of the baby through the birth canal
(vagina). How fast the cervix thins and opens varies from woman to woman. In
some women, the cervix may efface and dilate slowly over a period of weeks. A
first-time mother often will not dilate until active labor begins.
Late in your pregnancy, your health professional may manually check
(wearing sterile gloves) how much your cervix has effaced and dilated.
Effacement
As the baby's head drops
down into the pelvis, it pushes against the cervix and causes the cervix to
relax and thin out, or efface.
See a picture of
cervical effacement.
Throughout your pregnancy, your cervix has
been closed and protected by a plug of mucus. When the cervix effaces, the
mucus plug is loosened and passes out of the vagina. The mucus may be tinged
with blood. This passage of the mucus plug is called "show" or "bloody show." You may or may not notice when the mucus
plug passes.
Effacement is described as a percentage. For
example, if your cervix is not effaced at all, it is 0% effaced. If the cervix
has completely thinned, it is 100% effaced.
Dilatation
After the cervix begins to efface, it
will also begin to open (cervical dilatation).
Cervical
dilatation is expressed in centimeters from 0 to 10. Zero means that the cervix
is closed, and 10 means that it is completely dilated.
Credits
|
Author
|
Sandy Jocoy, RN |
|
Editor
|
Kathleen M. Ariss, MS |
|
Associate Editor
|
Pat Truman, MATC |
|
Primary Medical Reviewer
|
Kathleen Romito, MD - Family Medicine |
|
Primary Medical Reviewer
|
Sarah Marshall, MD - Family Medicine |
|
Specialist Medical Reviewer
|
Kirtly Jones, MD - Obstetrics and Gynecology |
|
Last Updated
|
December 4, 2009 |
Last Updated:
December 4, 2009
