Submitted by coral18 Mon 03/09/2009 – 12:56.
When is a pregnancy not a pregnancy? When it is a blighted ovum or a chemical pregnancy or ectopic. That’s why ultrasounds are helpful to make sure everything is ok. An early ultrasound looks for a few things: a series of measurements, including the size of the gestational sac, the size of the yolk sac, the length of the fetal pole, and the heart rate. The gestational sac first appears at about 4 weeks gestational age, and grows at a rate of about 1 mm a day through the 9th week of pregnancy. At 6 weeks, you might not be able to see a heartbeat or fetal sac and it is normal. However, your hCG levels should be increasing steadily.