Dating scan russiandatingspace
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.Traditional obstetric sonograms are done by placing a transducer on the abdomen of the pregnant woman.One variant, transvaginal sonography, is done with a probe placed in the woman's vagina.Not useful for dating, the abdominal circumference of the fetus may also be measured.
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.
The embryo should be seen by the time the gestational sac measures 20 mm, about five-and-a-half weeks.
The heartbeat is usually seen on transvaginal ultrasound by the time the embryo measures 5 mm, but may not be visible until the embryo reaches 7 mm, around 7 weeks' gestational age.
The procedure is a standard part of prenatal care in many countries, as it can provide a variety of information about the health of the mother, the timing and progress of the pregnancy, and the health and development of the embryo or fetus.
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 (twins, etc).The Late Dating Scan is a reassurance scan that takes place in the first couple of weeks of the second trimester.