Another scan with early loss?

Basically had a scan at 8 weeks no baby just a sac Measuring 6 weeks send home did hcg test didn’t rise much started bleeding.. they Booked in for another scan on Monday but why? Shall a ring them and tell them I’m bleeding will they still do the scan or want to wait till the bleeding stops I’m bleeding really heavy sorry tmi but its pouring out and I don’t really want to go for another vaginal scan while I’m going though this ?