###Human: Is it normal not to see the fetus but the gestational sac in early pregnancy? ###Assistant: Hello. In early pregnancy, by six weeks of gestation, the gestational sac is often not seen and only decidual reaction can be appreciated in the uterus, but as the hCG levels are doubling, there is definitely a viable ongoing pregnancy either inside or outside uterus, so a repeat ultrasound after two weeks shall establish the location and presence of a sac, considering that it would grow to a recognizable size in next two weeks. My concern with you is that you have been on the Adderall tablet, which is a pregnancy category C drug and not to be used before or during pregnancy as it has been known to cause congenital defects in fetuses.