Pregnant. Was Taking Ortho Evra. Doctor Told It Could Be Lump Also. Can This Happen?

My daughter was using ortho evra for awhile and missed out on two patches. She has taken a pregnancy test and its positive. She went to see the doctor and they took a blood test and said she was pregnant of about 5 or 6 weeks or that maybe it's just a lump. So I'm wondering can she test positive and have only a lump in her stomach. I've had kids of my own and never heard of that. Now they are doing an ultra sound to see if there is actually a baby there or not. How can that be. How can she test positive, be pregnant and yet not have a baby inside. I don't understand. In French they say that it might me a "false baby" a lump or something. She has all of the symptoms and she gained 9 pounds. So how is it that the doctor says it might just be a lump. A mother in law who is worries. Pls help.