A pregnancy can be seen from as early as 6 weeks from the first day of your last period (LMP) and not the date of conception.
These appear white in the image, and soft tissues appear grey.
Fluids, such as the amniotic fluid surrounding your baby, appear black.
Most dating scans are done with a trans-abdominal transducer and a fullish bladder.
If the pregnancy is very early the gestation sac and fetus will not be big enough to see, so the transvaginal approach will give better pictures.
This is because the sound waves go through them with no echoes.
The person performing the scan (sonographer) will look at these different shades to interpret the images.
A registered nurse with more than 25 years of experience in oncology, labor/delivery, neonatal intensive care, infertility and ophthalmology, Sharon Perkins has also coauthored and edited numerous health books for the Wiley "Dummies" series.
Perkins also has extensive experience working in home health with medically fragile pediatric patients.
For transvaginal ultrasound you can have an empty bladder Dating scans are usually recommended if there is doubt about the validity of the last menstrual period.