No sign of baby in womb

Patient: I am about 6-8 weeks pregnant an d already did the urine and the blood test. I went for a sc can on the 20th of Deceber2011 and for a second one on the 24th. The doctor could not find anything in the womb but did a urine test on both occasions, and it is positive. Is there something wrong that he can not see the baby.

Doctor: