I have had irregular contractions since 32 weeks with threatened preterm labour.
I started having bloody shows from Thursday after I started having irregular contractions during the day... I too was 80% effaced and 2 cms dilated. However, I have been regularly contracting since Thursday afternoon with contractions every 4 to 5 mins and I haven't dilated anymore. Nearly 7 days. So it really doesn't mean anything.
From what the obs have said over the last week is that it doesn't mean you will go into labour in an hour or in 3 weeks. It will happen when your body is ready... A bloody show is a good sign that things are moving but not a definate sign that labour is soon. It could be weeks away...
Or you will be like me and have an extremely prolonged latent phase.