Second trimester ultrasound dating
The measurement used for dating should be the mean of three discrete CRL measurements when possible and should be obtained in a true midsagittal plane, with the genital tubercle and fetal spine longitudinally in view and the maximum length from cranium to caudal rump measured as a straight line 8, It is good for parents to keep in mind that the pregnancy ultrasound is primarily a medical examination, assessing your baby for significant problems that can sometimes occur.
Your bladder should not be so full that it causes pain.
Measurements of the CRL are more accurate the earlier in the first trimester that ultrasonography is performed 11, 15— While we had second trimester ultrasound dating less power in these analyses, the findings in both sets of multivariable analyses persisted data not shown.
Underestimation of gestational age by conventional crown—rump length dating curves. A comparison of recalled date of last menstrual period with prospectively recorded dates.
Neonatal complications of term pregnancies: Sonographic prediction of gestational age: A prospective cross-validation of established dating formulae in in-vitro fertilized pregnancies. While we searched the medical record for evidence of early ultrasound, it may be that some of these women experienced an early ultrasound elsewhere that did not make it into the record at UCSF.
Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. With poly-ovulation or incorrect recall, a woman may have actually ovulated earlier than predicted by the LMP, and is actually at a later gestational age than predicted. 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.
With oligo-ovulation or incorrect recall, a woman may have actually ovulated later than predicted by the LMP, and is second trimester ultrasound dating at an earlier gestational age than predicted.
Am J Obstet Gynecol ; The best fit curves represented linear equations: Generate a file for use with external citation management software. Standardization of sonar cephalometry and gestational age. Not all babies look exactly the same on ultrasound. In order to conduct such a study considerations would include the benefits to women of improved dating as well as the cost savings of less antenatal testing and labor inductions in those women who were improperly dated.
Last menstrual period versus ultrasound for pregnancy dating. Conclusion Our findings suggest that earlier obstetric ultrasound, which leads to better pregnancy dating, reduces the rate of estimated postterm pregnancies.
The sonographer will look at the position of the placenta in relation to the cervix. A small amount of ultrasound gel is placed on the end of this probe.
Sometimes a problem or change may be detected in your baby.
Most fibroids in pregnancy do not cause problems. Accurate determination of gestational age can positively affect pregnancy outcomes.