Sonogram question?

Well i went to my first ob appointment on 8/23 and they confirmed im pregnant and sent me down for a sonogram. They said i was 15 weeks and 4 days at that time. My next appointment is 9/19 and i was wondering if they will do a sonogram so now i can know the of the baby since ill be 19 weeks. and another thing dont they do test to check the spinal cord and everything on the baby?