Which ultrasound?

Teresa • Due April 24th with #3! 1 boy 1 girl-tie breaker on the way! cloth diapering, baby wearing, cosleeping, homebirth Mama!
Im about 8+1 and going in for an ultrasound today due to disappearing symptoms. Well they were gone for a full week until yesterday I started feeling nauseous again. 
My question- expect vaginal and not abdominal, correct?
A bit nervous. Just need peace if mind.