Recurrent miscarriage testing

My RE wants me to do further testing since I’ve had recurrent MCs and no successful pregnancies. I know there will be some bloodwork involved, has anyone else been through this and can tell me what else I can expect? I see him in one week to discuss next plans and I want to be prepared as possible for expectations and questions. Ive been with my RE for close to a year so we’ve already done the basic testing, hsg, etc. I’d appreciate any insight I could get! TIA!