Discrepancy between ultrasound dating chart

discrepancy between ultrasound dating chart

First trimester ultrasound dating calculator. Chamblis LR, et al. AJOG Wax. Ultrasound Dating – no clinically significant difference in CRL. How accurate are the menstrual and ultrasound pregnancy dating techniques? A Simple Solution to Dating Discrepancies: The Rule of Eights an experienced provider has a fairly consistent 8% margin of error at any gestation (Table 1). charts. In view of this, only dating tables are presented here. Fetal size can be assessed using makes little difference to the management of the pregnancy.

discrepancy between ultrasound dating chart

Mean sac diameter measurements are not recommended for estimating the due date. Dating changes for smaller discrepancies are appropriate based on how early in the first trimester the ultrasound examination was performed and clinical assessment of the reliability of the LMP date Table 1.

discrepancy between ultrasound dating chart

For example, for a day-5 embryo, the EDD would be days from the embryo replacement date. Likewise, the EDD for a day-3 embryo would be days from the embryo replacement date. Clinical Considerations in the Second Trimester Using a single ultrasound examination in the second trimester to assist in determining the gestational age enables simultaneous fetal anatomic evaluation.

With rare exception, if a first-trimester ultrasound examination was performed, especially one consistent with LMP dating, gestational age should not be adjusted based on a second-trimester ultrasound examination. Ultrasonography dating in the second trimester typically is based on regression formulas that incorporate variables such as the biparietal diameter and head circumference measured in transverse section of the head at the level of the thalami and cavum septi pellucidi; the cerebellar hemispheres should not be visible in this scanning plane the femur length measured with full length of the bone perpendicular to the ultrasound beam, excluding the distal femoral epiphysis the abdominal circumference measured in symmetrical, transverse round section at the skin line, with visualization of the vertebrae and in a plane with visualization of the stomach, umbilical vein, and portal sinus 8 Other biometric variables, such as additional long bones and the transverse cerebellar diameter, also can play a role.

Date changes for smaller discrepancies 10—14 days are appropriate based on how early in this second-trimester range the ultrasound examination was performed and on clinician assessment of LMP reliability.

Because of the risk of redating a small fetus that may be growth restricted, management decisions based on third-trimester ultrasonography alone are especially problematic; therefore, decisions need to be guided by careful consideration of the entire clinical picture and may require close surveillance, including repeat ultrasonography, to ensure appropriate interval growth.

The best available data support adjusting the EDD of a pregnancy if the first ultrasonography in the pregnancy is performed in the third trimester and suggests a discrepancy in gestational dating of more than 21 days. Conclusion Accurate dating of pregnancy is important to improve outcomes and is a research and public health imperative.

As soon as data from the LMP, the first accurate ultrasound examination, or both are obtained, the gestational age and the EDD should be determined, discussed with the patient, and documented clearly in the medical record.

Ultrasound Reference Chart Based on IVF Dates to Estimate Gestational Age at 6–9 weeks' Gestation

The American College of Obstetricians and Gynecologists, the American Institute of Ultrasound in Medicine, and the Society for Maternal—Fetal Medicine recognize the advantages of a single dating paradigm being used within and between institutions that provide obstetric care.

Table 1 provides guidelines for estimating the due date based on ultrasonography and the LMP in pregnancy, and provides single-point cutoffs and ranges based on available evidence and expert opinion. Fetal Imaging Workshop Invited Participants.

A comparison of recalled date of last menstrual period with prospectively recorded dates. J Womens Health Larchmt ; Comparison of pregnancy dating by last menstrual period, ultrasound scanning, and their combination. Am J Obstet Gynecol ; Last menstrual period versus ultrasound for pregnancy dating.

discrepancy between ultrasound dating chart

Int J Gynaecol Obstet ; First trimester ultrasound screening is effective in reducing postterm labor induction rates: Ultrasound for fetal assessment in early pregnancy. Cochrane Database of Systematic ReviewsIssue 7. Predicting delivery date by ultrasound and last menstrual period in early gestation.

New charts for ultrasound dating of pregnancy and assessment of fetal growth: Ultrasound Obstet Gynecol ; First- and second-trimester ultrasound assessment of gestational age. First- vs second-trimester ultrasound: Br J Obstet Gynaecol ; Gestational age in pregnancies conceived after in vitro fertilization: Ultrasound dating at 12—14 weeks of gestation.

A prospective cross-validation of established dating formulae in in-vitro fertilized pregnancies.

Methods for Estimating the Due Date - ACOG

Accuracy of gestational age estimation by means of fetal crown—rump length measurement. Estimation of gestational age by transvaginal sonographic measurement of greatest embryonic length in dated human embryos. Ultrasound Obstet Gynecol ;4: We assessed the ability of six commonly used reference charts to accurately date these pregnancies. Given all these charts showed inaccuracies in their ability to date these IVF pregnancies, we developed a new reference chart based on IVF dates in a singleton cohort.

These were identified from a total cohort of first trimester ultrasound reports of IVF and naturally conceived pregnancy scans.

Ultrasound Reference Chart Based on IVF Dates to Estimate Gestational Age at 6–9 weeks' Gestation

Pregnancies that resulted from frozen embryos transfer, complicated by fetal structural anomalies, delivered before 24 weeks, or had missing data were all excluded. Of our cohort of pregnancies, 84 were scanned twice, and 2 pregnancies were scanned three times, giving a total population size of In these pregnancies with multiple scans, all data were included in the analysis as discrete values.

discrepancy between ultrasound dating chart

We restricted our analysis to those who had fresh embryo transfer since we were concerned with the need to add the time from egg pickup to freezing, together with the time from subsequent thawing to transfer might introduce inaccuracies. We determined gestational age on the day of the ultrasound IVF dates by nominating the day of egg pickup and fertilisation as day 14 of gestation.

Gestational Age Determination by Ultrasound

We first compared IVF dates with estimated dates determined using six existing reference charts: Note that some charts did not have corresponding gestational ages for all measurements which accounts for the variability in sample size seen in the comparison of charts. Taking each twin as a discrete measurement, we determined the accuracy of all six existing reference charts and The Monash Chart in estimating gestational age.

We then applied all six existing reference charts and our chart to estimate gestational age of CRL measurements obtained from consecutive first-trimester singleton ultrasound scans pregnancies at 6—9 weeks of gestation. For this retrospective database study where we used de-identified data in aggregate, the ethics committee specifically approved our request not to obtain individual patient consent.

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