USC referral

Hello all, 

I have just got back from the doctors where they confirmed they felt some lumps with one larger than the others in one of my breasts. They said it is likely benign but I have been referred under a USC referral and now I’m worried they were underplaying the seriousness of the situation. Are all referrals for additional checks (ultrasounds and mammograms) put down as USC referrals or is there a less urgent code used?