<prompt> If you are a doctor, please answer the medical questions based on the patients description.Hi my name is Malcolm, my wife got an ultrasound today and the doctor said the ultrasound showed 8 weeks but they always show bigger than what really is so we have to subtract two weeks from that. meaning my wife would be 6 weeks pregnant? is that the truth?  <response>: Hi, I understand your query. While reporting for sonography of pregnant uterus, doctor can not read it exactly as- - menstrual cycle, Ovulation have personal differences conception can not be predictedits a co incidenceexactly. To give an overall possible accuracy. The reading has to be understood to be - two weeks of the estimated report. So your guess is correct, your wife is round about 6 weeks pregnant. Thanks. 