First ultra sound; abdominal or transvaginal?

Okay ladies, this is my first pregnancy that so fas has stuck (previously miscarriaged at 6 weeks before appt) and my very first doctors appointment is Wednesday morning. I'm estimated 7w and not sure what to expect.. I know both ultra sounds are available but does anyone know what week you would go from transvaginal to abdominal? 
I'm very excited and nervous but I'm looking forward to having some understanding when I go Wednesday!
Thank you!