Effacement is simply your cervix getting softer. Normally, it's about as hard as the tip of your nose. When it's effaced, it's about as soft as your lips. Your mucus plug will be released when you start to dialate. It's attached to the inside edge of your cervix and when your cervix starts opening up, it detaches and falls out.
Also, dialation, effacement, and presence of mucus plug are not indicitive of impending labor. Many women will dialate at the end of their pregnancy and stay pregnant for weeks with their provider telling them it'll come any day. Others can be closed up tight and posterior and have their babies within hours. Vaginal checks do nothing to truly measure how close to or how far into labor you are. There are other, more reliable, signs as to the progression of labor. I would stop all vaginal checks now, let baby come on it's schedule, and stop risking the introduction of infection to the uterus.
at 4:49 PM on Jun. 3, 2010