Short Cervix & Low Fluid: A Personal Journey & Management

Question
I was diagnosed with a short cervix (2.4) at 18 weeks and had preventative cerclage.  Had bi-weekly u/s to measure cervix and I was told bed rest but I continued to work (desk job).  At my 32 week check I was told I had low amniotic fluid (8.4).  After much research I found that I was actually on the low side of normal.  I had my last measurement at 34 weeks, I measured 1.8.  I scheduled my cerclage removal at 36 weeks.  At 35 week my baby was very active.  While resting on the couch my water broke and I gave birth to a health baby boy.  I never experienced any PTL symptoms.  My questions:  1) Could the high activity of my baby have caused my water to break?  Will I suffer from PROM in future pregnancies?  At my 34 week measurement the doctor said I had minimal change and expected me to go to at least 38 weeks.  Since my cerclage and cervix seemed to hold did I truely suffer from IC?  Or could I have just had a short but strong cervix to begin with?  I understand the true risk of IC is between weeks 18 - 26 since the baby is small enough to fit into the birth canal and put pressure on the cervix is this correct?  I know there are 2 different types of vaginal cerclages, I had the Macdonald cerclage.  Sorry I can't spell the name of the other cerclage - but I understand it is put higher on the cervix and is a bit stronger, is this true?   Would it be a better option to avoid months of bed rest?  Since I didn't have any PTL symptoms is it safe to assume I didn't have PTL?  Will I have these problems in future pregancies?

Thank you for taking the time to answer my questions.  My doctor has not been very helpful.  I would definately get a new ob if I decided to have another baby.  

Answer
There is no way to tell if you had true incompetent cervical os or merely a shortened cervix. In any case, a short cervix such as yours can easily lead to preterm labor and the MacDonald Cerclage was a prudent course of action. (We rarely perform the Shirodkar procedure which uses a mersilene suture and is placed higher. We do not remove the Shirodkar suture. I do not know why you had PROM. Perhaps there was a mild infection that caused rupture of fetal membranes. I doubt that the activity of the baby caused your water to break. Since  your cervix is not likely to increase in size, you will always have the risk of preterm labor. HOwever, you did very well and may never have PTL in the future.