Accuracy of pregnancy dating

Fortunately, gestational sac, yolk sac and embryo are surrounded by hyperechoic (brighter) body tissues.Traditional obstetric sonograms are done by placing a transducer on the abdomen of the pregnant woman.Sometimes a woman may be uncertain of the date of her last menstrual period, or there may be reason to suspect ovulation occurred significantly earlier or later than the fourteenth day of her cycle.

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In the past, the EDC was calculated by using Naegele's Rule, which determined the date by subtracting 3 months from the 1st day of the last period and then adding 7 days.With today's modern equipment, we can obtain very reliable images and measurements of even very early pregnancies, sometimes even seeing a heartbeat as early as 5-6 weeks!The most common misconception we encounter almost daily, has to do with how accurate ultrasounds are in fixing the EDC at different stages of pregnancy.There is no difference, however, in perinatal death or poor outcomes for babies.In normal state, each body tissue type, such as liver, spleen or kidney, has a unique echogenicity.

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