Accuracy of dating pregnancy by ultrasound 100percent dating site in usa
Traditional obstetric sonograms are done by placing a transducer on the abdomen of the pregnant woman.One variant, a transvaginal sonography, is done with a probe placed in the woman's vagina.Transvaginal scans usually provide clearer pictures during early pregnancy and in obese women.Also used is Doppler sonography which detects the heartbeat of the fetus.Not useful for dating, the abdominal circumference of the fetus may also be measured.This gives an estimate of the weight and size of the fetus and is important when doing serial ultrasounds to monitor fetal growth.Ultrasound scans offer an alternative method of estimating gestational age.
Dating is more accurate when done earlier in the pregnancy; if a later scan gives a different estimate of gestational age, the estimated age is not normally changed but rather it is assumed the fetus is not growing at the expected rate.
Doppler sonography can be used to evaluate the pulsations in the fetal heart and bloods vessels for signs of abnormalities.
A gestational sac can be reliably seen on transvaginal ultrasound by 5 weeks gestational age (approximately 3 weeks after ovulation).
Research shows that routine obstetric ultrasound before 24 weeks gestational age can significantly reduce the risk of failing to recognize multiple gestations and can improve pregnancy dating to reduce the risk of labor induction for post-dates pregnancy.
There is no difference, however, in perinatal death or poor outcomes for babies.
The International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) recommends that pregnant women have routine obstetric ultrasounds between 18 weeks and 22 weeks gestational age (the anatomy scan) in order to confirm pregnancy timing, to measure the fetus so that growth abnormalities can be recognized quickly later in pregnancy, and to assess for congenital malformations and multiple pregnancies (i.e. Additionally, the ISUOG recommends that pregnant women have obstetric ultrasounds between 11 weeks and 13 weeks 6 days gestational age in countries with resources to perform them (the nucal scan).