Hadlock dating criteria
Copyright December 2016 by the American College of Obstetricians and Gynecologists. No part of this publication may be reproduced, stored in a retrieval system, posted on the Internet, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission from the publisher. Received October 21, 2016 Accepted October 21, 2016 Obstetric ultrasound examinations are performed with a transabdominal, transvaginal, or transperineal approach.Requests for authorization to make photocopies should be directed to Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400. American College of Obstetricians and Gynecologists. Real-time ultrasonography is necessary to confirm fetal viability through observation of cardiac activity and active fetal movement.Gestational age (GA) refers to the length of pregnancy after the first day of the last menstrual period (LMP) and is usually expressed in weeks and days. Conceptional age (CA) is the true fetal age and refers to the length of pregnancy from the time of conception.This terminology does vary geographically and over time, and it may need clarification if not explicitly defined in relevant articles.
The accuracy of h CG measurement in determining the week since conception was more than 93%.
The first 2 are subject to considerable error and should only be used when ultrasonography facilities are not available.
The date of feeling the first fetal movements (quickening) is far too unreliable to be useful.
For example, antenatal test interpretation may be dependent on gestational age.
Specifically, the level of α-fetoprotein in both amniotic fluid and maternal serum is related to gestational age and when dates are inaccurate test results will be incorrect and misleading.