Ultrasound dating accuracy first trimester

Enugu State is one of the five states in the southeast geopolitical zone of Nigeria, and its capital city is Enugu. It has an average annual temperature of The state covers a land area of approximately 8, The Enugu State University Teaching Hospital, Parklane, is a state-owned teaching hospital located in the center of the Enugu metropolis.

Both centers provide antenatal and postnatal care services to pregnant women in Enugu State. The commonest indication for induction of labor in the two hospitals and in our environment is prolonged pregnancy. This was a cross-sectional study of consecutive pregnant women attending for antenatal care at the antenatal clinics of the University of Nigeria Teaching Hospital, Ituku-Ozalla, Enugu, and the Enugu State University Teaching Hospital, Parklane, from January 1, to March 31, Every singleton pregnant woman due for a routine delivery planning discussion at a gestational age of 36 weeks and beyond was eligible for the study.

Exclusion criteria included uncertainty of date, presence of contraindications to vaginal delivery, irregular menstrual cycle prepregnancy, use of hormonal contraceptives prior to pregnancy, or bleeding during pregnancy. After individual counseling of eligible participants, pretested structured questionnaires were administered to consecutive consenting women by trained medical interns.

Introduction

Ethical clearance for the study was obtained from the institutional review board of the University of Nigeria Teaching Hospital, Enugu. Data collected included the sociodemographic characteristics of the respondents age, marital status, tribe, level of education, occupation, parity , opinions and preferences regarding LMP and ultrasound scan dates, and their attitudes toward postdatism and induction of labor in relation to estimated dates. The primary outcome measure was willingness to accept induction of labor at an LMP-derived gestational age of 40 weeks plus 10 days when late pregnancy ultrasound scan-derived gestational age was less than 40 weeks plus 10 days.

The first trimester was defined as a gestational age of 1—13 weeks, the second trimester as 14—27 weeks, and the third trimester as 28—42 weeks.

Further, the early second trimester was defined as a gestational age of 15—22 weeks and the late second trimester as 23—27 weeks. Frequency tables were generated for relevant variables. A P -value of less than 0. A total of questionnaires were administered, but only were completed correctly, giving a response rate of The mean age of the respondents was Most of the women Four hundred and thirty-one respondents The majority of respondents were multiparous Further details of the sociodemographic characteristics of the respondents are shown in Table 1.

The mean gestational age at recruitment and antenatal booking for respondents was One hundred and sixty-seven One hundred and ninety-one The remaining eight women 1. On the other hand, All the women who responded positively Likewise, all the women who responded negatively Characteristics of respondents versus acceptance of labor induction for postdatism using menstrual dating.

OR, odds ratio; CI, confidence interval. This study demonstrates that pregnant women in Enugu, Nigeria, have poor knowledge of the limits of accuracy of late pregnancy ultrasound scan in estimating the delivery date.

This poor knowledge invariably translated into the observed perception of respondents toward induction of labor for postdatism, as more than half of the women This attitude poses a great challenge to perinatal care in our environment because an ultrasound scan is usually carried out in the third trimester when the margin of error is up to 3 weeks. Late booking for antenatal care might have strongly contributed to the poor uptake 7. The recent proliferation of ultrasound scan services in our environment came with a wave of optimism that ultrasound scanning could accurately determine all aspects of fetal well-being, hence only the well-educated or informed could question or resist its results.

This misconception is further worsened by uncontrolled purchasing and use of ultrasound scanning machines by poorly trained personnel who advertise themselves as sonologists or sonographers. Accordingly, in creating recommendations and the associated summary table, single-point cutoffs were chosen based on expert review. Because this practice assumes a regular menstrual cycle of 28 days, with ovulation occurring on the 14th day after the beginning of the menstrual cycle, this practice does not account for inaccurate recall of the LMP, irregularities in cycle length, or variability in the timing of ovulation.

It has been reported that approximately one half of women accurately recall their LMP 2—4. Accurate determination of gestational age can positively affect pregnancy outcomes.

For instance, one study found a reduction in the need for postterm inductions in a group of women randomized to receive routine first-trimester ultrasonography compared with women who received only second-trimester ultrasonography 5. A Cochrane review concluded that ultrasonography can reduce the need for postterm induction and lead to earlier detection of multiple gestations 6. Because decisions to change the EDD significantly affect pregnancy management, their implications should be discussed with patients and recorded in the medical record. Measurements of the CRL are more accurate the earlier in the first trimester that ultrasonography is performed 11, 15— 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, 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.

For instance, the EDD for a pregnancy that resulted from in vitro fertilization should be assigned using the age of the embryo and the date of transfer. 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.

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. 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.

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. For the purposes of research and surveillance, the best obstetric estimate, rather than estimates based on the LMP alone, should be used as the measure for gestational age. 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.

What types of ultrasound are there?

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. Methods for estimating the due date. Estimation of first trimester, it is no need to delivery, the accuracy. Of bleeding in the baby's due date pregnancy dating, and then when for post-term. In the gold standard for predicting due date by last menstrual and so.

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