Ultrasound dating accuracy early
These include organizations such as the American College of Obstetricians and Gynecologists (ACOG), American Institute of Ultrasound in Medicine (AIUM), Australasian Society of Ultrasound in Medicine (ASUM), National Health Service (NHS) in the United Kingdom, and the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) (Table 1.3).
Guidelines typically describe the essential components of an obstetric ultrasound examination.
During the examination, the fetus is seen by abdominal ultrasound.
The fetus is now large enough for an accurate survey of the fetal anatomy.
Bethesda, MD: National Council on Radiation Protection and Measurements; 2002. Effective prenatal diagnosis relies on a high standard of imaging.
Several national and international bodies have described standards for imaging in the first, second, and third trimester of pregnancy.
It is particularly reassuring for women who have suffered a previous miscarriage or ectopic pregnancy.
Screening can also be used for prenatal sex discernment.■ There is no epidemiologic support for a causal relationship between diagnostic ultrasound during pregnancy and adverse biologic effects to the fetus observed for outputs under a spatial-peak temporal-average intensity of 94 m W/cm From Fowlkes JB; Bioeffects Committee of the American Institute of Ultrasound in Medicine. National Council on Radiation Protection and Measurements.American Institute of Ultrasound in Medicine consensus report on potential bioeffects of diagnostic ultrasound. Exposure Criteria for Medical Ultrasound, II: Criteria Based on All Known Mechanisms.amniocentesis, which can be done from about 14 weeks gestation, and usually up to about 20 weeks, and chorionic villus sampling, which can be done earlier (between 9.5 and 12.5 weeks gestation) but which may be slightly more risky to the fetus.
One study comparing transabdominal chorionic villus sampling with second trimester amniocentesis found no signiﬁcant difference in the total pregnancy loss between the two procedures.These dates are calculated from the first day of your last menstrual period.