Can I accompany my 17 year old to breast clinic?

My 17 year old has a breast lump and high platelet count. She's going for a scan at the breast clinic next week and the referrel letter says 'suspected cancer'. She's petrified and I'm worried she'll have to go in alone due to COVID? The nurse would not let me go with her for blood tests last week and I'm worried they'll make her do this alone as she's 17? Can I insist they let me in as she's technically still a child or will Covid override that?