Many women lose one or two or even more babies to second trimester miscarriage before their doctor will diagnose them with incompetent cervix. This is so sad!! I have an incompetent cervix and I want you to know something about them so you don't have to have those multiple losses if you suffer from it.
An incompetent cervix is a cervix that can not hold up the weight of a baby. It most commonly shows up in the middle of the second trimester, but that is not always true and it is important that you understand that. With my first child, my water broke and cervix began opening at 35 weeks. With my second, it was about 24-26 weeks, and with my third, 13 weeks! All over the place. So how can you know if incompetent cervix is your problem??
If you are showing cervical funneling (shown on transvaginal ultrasound), cervical shortening, cervical ripening (softening), dilating or effacement before the end weeks of pregnancy without having significant preterm labor, you may have an incompetent cervix. It is hard to tell whether it is your cervix or preterm labor because the cervical opening can provoke preterm labor. There is no real test for this.
Some doctors advocate a wait and see approach. Unfortunately, cervical change can happen very, very quickly and I know moms who appeared to be fine at their appointment and then lost their babies two or three days later. No thanks.
I think it is much better, if IC (incompetent cervix) is a possibility, to do a cerclage anyway. It should be done before 17 weeks and the earlier, the less likely you will have complications or infections. It is a simple, no problem stitching of the cervix and I would a whole lot rather have an unnecessary one than lose a child.
Sometimes, though, the opening is found too late to do a cerclage - it wouldn't be safe for the baby. At that point, there is still much that can be done: a Smith-Hodge pessary, anti-tocolytics (anti-labor drugs like nefedipine or terbutaline), and complete bedrest in the Trendelenburg position (lifting the foot of the bed a few inches). I was too late to get a cerclage with our second child, but with the help of these things was able to get him to 37 weeks anyway. It's much, much easier with a cerclage, but don't despair!
I highly recommend the IC Forum at Healing Our Broken Hearts for support and encouragement if you think you might have this problem!