The 5-1-1 rule, sometimes written as 5-5-1, is a rule of thumb for when labour is established enough to head to hospital: contractions coming every 5 minutes, each lasting about 1 minute, sustained for 1 hour. It is an American guideline and it is not the wording UK maternity units use, which more often ask you to call when contractions are regular, painful and coming about three times in every ten minutes.
Follow the instructions your own maternity unit has given you rather than a rule from the internet, and call them straight away, at any stage, if your waters break, you bleed, or your baby’s movements change. This is a labour question rather than a scan question, and we are not a maternity provider. What we can do late in pregnancy is a presentation scan to confirm which way up your baby is.