Talk to Gynecologist on Incompetent Cervix

I am 20 weeks pregnant. This is my second pregnancy. The previous one was miscarried at 18th week. It was due to the bursting of amniotic sac. I have cerclage during this pregnancy. Last night, mucous plug came out and pre term labour pains started. Now I am taking nefidil with few hours gap and pains have settled for now. There is a short cervix below 20mm and in scan some fluid shows in cervical canal I have had cervical cerclage what are the chances of my pregnancy survival?