# Question about dilation



## mama_in_PA (Nov 30, 2007)

I've been told there's an "inner" and an "outer" cervix and that a woman can experience dilation of the "outer" cervix while the "inner" cervix is still closed. Which do you go by? If a woman's outer cervix were dilated to 4-5cm but the inner cervix only a finger tip, which measurement would she go by?

And how is effacement determined? Is it the thinning of the outer cervix, the inner cervix or both?


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## JamieCatheryn (Dec 31, 2005)

There is one cervix, but while it's not very effaced it could sorta funnel: open at the outer os not so much at the inner. Effacement would be of the whole thing, that's the thickness of it. If you're talking during labor, I'd count the inner as what matters since it all has to be open to get the baby out. Not that dilation matters than much, it gives some indication of progress but the rest of the cervix could open up out of the way quickly or slowly, you never know.


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## blissful_maia (Feb 17, 2005)

Think of your cervix as a cylinder with an opening at top and bottom (top = beside baby, bottom = end of vagina). During pregnancy, it's usually around 3-5 cm long, so effacement is determined by how much thinner it is. i.e. 1.5 cm would be around 50%. But it's very approximate/subjective. As for dilation, go with the inner os. The outer os can be quite stretchy, especially if it's not your first baby, and it's the os closer to the baby that needs to open to let him/her through. But of course, once you are mostly/fully effaced, the two openings sort of become one.

Clear as mud?


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## cocoanib (May 14, 2009)

Quote:


Originally Posted by *blissful_maia* 
Think of your cervix as a cylinder with an opening at top and bottom (top = beside baby, bottom = end of vagina). During pregnancy, it's usually around 3-5 cm long, so effacement is determined by how much thinner it is. i.e. 1.5 cm would be around 50%. But it's very approximate/subjective. As for dilation, go with the inner os. The outer os can be quite stretchy, especially if it's not your first baby, and it's the os closer to the baby that needs to open to let him/her through. But of course, once you are mostly/fully effaced, the two openings sort of become one.

Clear as mud?









Very good explanation, thanx!
I could never quite grasp the effacement part of things.


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## nashvillemidwife (Dec 2, 2007)

The dilation of the inner os is what really counts in assigning a measurement, but any change of any part of the cervix indicates progress.


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## mama_in_PA (Nov 30, 2007)

Thanks a lot. That really does help. I was 4-5cm dilated but it was the outer part and the inner part was only a finger-tip. Things seem to have progressed quite a bit further now so while the effacement hasn't changed much, I'm dilated to about 4cm. This is a relief since I was due yesterday.


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