not been confirmed or substantiated in larger studies from Europe. If this is extremely painful please let us know. Further developments in doppler ultrasound technology in recent years have enabled a great expansion in its application in Obstetrics, particularly in the area of assessing and monitoring the well-being of the fetus, its progression in the face of intrauterine growth restriction, and the diagnosis. If the scan date differs from your period dates, the scan date will be used. A second scan is performed at 18 to 20 weeks mainly to look for congenital malformations, when the fetus is large enough for an accurate survey of the fetal anatomy. It's amazing to see the little blob with a heartbeat that will soon become your baby. Mar 10 Gray JAM, Ward. Determination of gestational age and assessment of fetal size. Usually a vaginal scan is also performed. It may show a very minor problem, or something that may get better on its own. One should not dwell too much on the definitions or guidelines for a level II ultrasound scan. ( Table ) An important point to note is that when the due date has been set by an accurately measured CRL, it should not be changed by a subsequent scan.