Hi,
Welcome to the ehealthforum and I am really glad to help you out.
As your body prepares for birth, your cervix will begin to soften, open (dilate) and thin (efface).This progress is expressed in centimeters (cm) and percentages.Dilatation of the cervix is in cm and effacement in percentage. When you're ready to push your baby out, your cervix will be 10 cm dilated and 100 percent effaced.
Diarrhea along with 100% effacement means that labor is very close by. When you are 100% effaced or completely effaced, your cervix is paper-thin and labor is right around the corner.
I sincerely hope this information helps. Take care.