Can an internal ultrasound detect pregnancy before implantation?

From just over 5 weeks, see the associated website I had my first u/s done at less than five weeks I was probably 4.4 weeks, but all I showed was the yolk sac and the sac....no fetal pole or baby. == an internal ultrasound can detect a pregnancy much sooner than an external ultrasound, even if all it detects is a yolk sac.....there would not be a yolk sac if you were not pregnant.