When placed in the closed cervix, a osmotic dilator absorbs
moisture from the tissues surrounding the cervix and swells, opening the cervix
slowly and with little discomfort. Two common types of osmotic dilators are a
laminaria, a small tube made of dried seaweed, and
synthetic dilator, a man-made sterile, dry
Unless a woman is in labor before childbirth, the cervical
opening is very narrow. An osmotic dilator is commonly used to gently open the
cervix before a gynecologic procedure that requires the cervix to be open,
allowing access to the uterus and fallopian tubes. Cervical dilation reduces
the risk of injury to the cervix during such a procedure.
the cervical dilation with laminaria occurs in the first 6 hours. But maximum
dilation usually occurs 12 to 24 hours after the laminaria is placed. This means
that laminaria placement may be done the day before a procedure. Osmotic
dilators may be sequentially added to or replaced to increase the cervical
A synthetic dilator opens the cervix in less time and can
be used several hours before a procedure.
Sarah Marshall, MD - Family Medicine & Rebecca H. Allen, MD, MPH - Obstetrics and Gynecology & Kirtly Jones, MD - Obstetrics and Gynecology
How this information was developed to help you make better health decisions.