Dating biometry during the first trimester: accuracy of an every-day practice

doi:10.1016/S0301-2115(99)00127-X

European Journal of Obstetrics & Gynecology and Reproductive Biology

Volume 88, Issue 1, January 2000, Pages 61-64

https://doi.org/10.1016/S0301-2115(99)00127-X Get rights and content

Abstract

Objective: The goal of this study was to determine the accuracy of an every-day practice for assessing gestational age by ultrasound measurement of the greatest embryonic length (GEL). Design: This retrospective study used measurements taken during the first trimester. Subjects: We considered all births in this hospital between 1 January 1992 and 31 December 1994 from pregnancies that began by an in-vitro fertilization procedure (IVF). We examined 143 consecutive files, containing 257 measurements made by 72 different operators. Methods: The precision of seven embryo growth curves was compared. We calculated for each curve its ability to predict (95% prediction interval) the date the pregnancy began, using these dated pregnancies. Result: For GEL measurements between 3 and 80 mm, which includes most of our population, Robinson and Wisser (2) were the most appropriate curves. The 95% prediction interval was 9.5 and 10.2 days respectively. Conclusion: Dating pregnancies in every-day practice with GEL is nearly as accurate as prospective studies with only one or two scanners.

Introduction

Among the indicators used to assess gestational age in the first trimester, the most precise is the measurement of the crown-rump length (CRL) [1], [2].

Precise knowledge of gestational age is important for many aspects of obstetric decision-making, including determining the exact risk of chromosomal anomalies during the first and second trimester with biological markers and interpreting biometric data during the second and third trimesters. It is one of the essential elements in deciding whether elective delivery or induction of labor is necessary. Finally, it is a prerequisite for defining when post-term pregnancy begins.

Exact gestational age calculated by ultrasound measurement of the crown-rump length has a prediction interval of two standard deviations (that is, of roughly 96%), from 9.4 to 16.0 days [1], [3], [4]. This interval is of the utmost importance for it defines our uncertainty. The goal of this pragmatic study is to evaluate, in our everyday practice, the accuracy for assessing gestational age based on crown-rump or greatest embryonic length (GEL). To do this, we studied the 95% prediction interval and the systematic error of curves for a GEL between 3 and 97 mm in a population for which we knew the exact date of conception, pregnancies obtained by in vitro fertilization (IVF).

Section snippets

Material and methods

This was a retrospective study of all women who underwent IVF and gave birth in our hospital between 1 January 1992 and 31 December 1994. It allowed us to consider dated human embryos.

Of 240 women, we considered 143, after excluding: triplet pregnancies (10 cases), because they have not been sufficiently studied in the literature, in utero fetal deaths and neonatal deaths (three cases), medically-indicated terminations of pregnancy, for fetal malformation or chromosomal anomaly (four cases), a

Results

The mean age of the women in our study population was 33.3±5.1 years. This pregnancy was the first for 37% of these patients, and it was the first delivery for 67%.

Characteristics of the newborn population are described in Table 1.

Fig. 1 shows the raw data with the reference curves of Robinson and Wisser (2).

Table 2 reports the 95% prediction intervals for all seven curves studied.

The 95% prediction interval, as a function of the GEL, is shown in Fig. 2 and Table 3. At between 10 and 80 mm, the

Discussion

The literature contains primarily are prospective studies [2], [3], [4], [5], [6], [7], [8], [9] performed by one or at least very few examiners in order to construct a curve. Our study, on the contrary, is retrospective and pragmatic, performed in a population setting. That is, we are evaluating the results of our daily practice, with 72 ultrasound operators. The goals thus cannot be the same. Previous authors constructed curves; we sought to measure our accuracy and discover which curve was

Conclusion

The performance of formulae for dating pregnancies in every-day practice with GEL is nearly as accurate as for prospective studies with only one or two scanners. In our maternity ward, we perform first trimester ultrasound at 12 or 13 weeks' gestation, that is, at a GEL of less than 80 mm. We therefore intend to use Wisser (2), which is the best compromise, as our reference curve.

Condensation

The goal of this study was to determine the accuracy of an every-day practice for assessing gestational age by ultrasound measurement of the greatest embryonic length (GEL) during the first trimester. We examined 143 consecutive files from pregnancies that began by an in-vitro fertilization procedure (IVF), containing 257 measurements made by 72 different operators. The precision of seven embryo growth curves was compared. We calculated for each curve its ability to predict (95% prediction

References (9)

F.P. Hadlock et al.
Estimating fetal age using multiple parameters: A prospective evaluation in a racially mixed population
Am J Obstet Gynecol
(1987)
A. Kustermann et al.
Transvaginal sonography for fetal measurement in early pregnancy
Br J Obstet Gynaecol.
(1992)
H.P. Robinson et al.
A critical evaluation of sonar 'crown-rump length' measurement
Br J Obstet Gynaecol.
(1975)
J. Wisser et al.
Estimation of gestational age by transvaginal sonographic measurement of greatest embyonic length in dated human embryos
Ultrasound Obstet Gynecol.
(1994)

There are more references available in the full text version of this article.

Cited by (19)

Role of ultrasound in elective abortions
2016, Journal de Gynecologie Obstetrique et Biologie de la Reproduction
La place de l’échographie dans le parcours de soins de l’interruption volontaire de grossesse (IVG) est fondamentale. Bien qu’elle puisse améliorer la qualité des soins au décours de l’IVG, elle ne doit pas constituer un frein à son accès. La place de l’échographie dans la datation de la grossesse et les alternatives possibles ont donc été étudiées. Une analyse de la littérature a ensuite été réalisée afin de déterminer sa place dans le suivi post-IVG. Lorsqu’une échographie est réalisée, l’estimation de la datation de la grossesse se fait par la mesure de la longueur cranio-caudale (LCC), définie par Robinson, ou par la mesure du diamètre bipariétal (BIP) définie par le Centre français d’échographie fœtale (CFEF) à partir de 11 SA (courbes de Robinson et CFEF) (grade B). De nouvelles courbes ont été actualisées dans l’étude INTERGROWTH. Au vu de la littérature, dans le contexte des demandes d’IVG, un delta de 5 jours est à prendre en compte notamment lorsque la datation de la grossesse évaluée sur la mesure de la LCC ou du BIP correspond à un terme proche de 14 SA (respectivement 80 mm et 27 mm) (accord professionnel). Ainsi la mesure échographique étant fiable à ± 5 jours lorsque les critères de réalisation sont respectés, l’IVG peut être réalisée lorsque les mesures de LCC et/ou de BIP sont respectivement inférieures ou égales à 90 mm et/ou 30 mm (courbes INTERGROWTH) (accord professionnel). Si la réalisation d’une échographie de datation doit être encouragée, pour les femmes déclarant bien connaître la date de leurs dernières règles et/ou la date du rapport sexuel à risque, et pour lesquelles un examen clinique par un professionnel de santé formé est possible, l’absence d’accès à l’échographie de routine ne devrait donc pas être un frein à la programmation de l’IVG demandée (accord professionnel). En cas de grossesse intra-utérine d’évolutivité incertaine, ou de grossesse de localisation indéterminée, sans symptômes particuliers, la patiente doit pouvoir bénéficier de la réalisation d’une échographie endovaginale pour augmenter la précision du diagnostic (grade B). Concernant le suivi post-IVG, les résultats de différentes études de la littérature permettent de ne pas recommander l’utilisation en routine de l’échographie lors de l’IVG instrumentale (accord professionnel). Si celle-ci est réalisée au décours immédiat de l’intervention un endomètre supérieur à 8 mm doit conduire à une réaspiration immédiate (grade B). L’étude échographique de l’endomètre quelques jours après une IVG instrumentale n’apparaît pas pertinente. En cas d’IVG médicamenteuse, la réalisation systématique d’une échographique post-IVG ne peut être recommandée en routine d’après l’analyse de la littérature (grade B). Si elle est pratiquée, l’échographie endovaginale après une IVG médicamenteuse devrait être réalisée à distance (après 15 jours) (accord professionnel). Lorsque l’examen échographique est effectué lors du suivi, son seul but devrait être de déterminer si le sac gestationnel est présent (accord professionnel). Enfin, si une échographie est réalisée dans le parcours d’une IVG, la réalisation d’un compte rendu doit être encouragée précisant les éventuelles anomalies gynécologiques retrouvées mais son absence ne doit pas retarder la programmation de l’IVG (accord professionnel).
Ultrasound plays a fundamental role in the management of elective abortions. Although it can improve the quality of post-abortion care, it must not be an obstacle to abortion access. We thus studied the role of ultrasound in pregnancy dating and possible alternatives and analyzed the literature to determine the role of ultrasound in post-abortion follow-up. During an ultrasound scan, the date of conception is estimated by measurement of the crown-rump length (CRL), defined by Robinson, or of the biparietal diameter (BPD), as defined by the French Center for Fetal Ultrasound (CFEF) after 11 weeks of gestation (Robinson and CFEF curves) (grade B). Updated curves have been developed in the INTERGROWTH study. In the context of abortion, the literature recommends the application of a safety margin of 5 days, especially when the CRL and/or BPD measurement indicates a term close to 14 weeks (that is equal or below 80 and 27 mm, respectively) (best practice agreement). Accordingly, with the ultrasound measurement reliable to ± 5 days when its performance meets the relevant criteria, an abortion can take place when the CRL measurement is less than 90 mm or the BPD less than 30 mm (INTERGROWTH curves) (best practice agreement). While a dating ultrasound should be encouraged, its absence is not an obstacle to scheduling an abortion for women who report that they know the date of their last menstrual period and/or of the at-risk sexual relations and for whom a clinical examination by a healthcare professional is possible (best practice agreement). In cases of intrauterine pregnancy of uncertain viability or of a pregnancy of unknown location, without any particular symptoms, the patient must be able to have a transvaginal ultrasound to increase the precision of the diagnosis (grade B). Various reviews of the literature on post-abortion follow-up indicate that the routine use of ultrasound during instrumental abortions should be avoided (best practice agreement). If it becomes clear immediately after the procedure that the endometrial thickness exceeds 8 mm, immediate reaspiration is necessary. Ultrasound examination of the endometrium several days after an instrumental elective abortion does not appear to be relevant (grade B). An analysis of the literature similarly shows that routine ultrasound scans after medical abortions should be avoided. If a transvaginal ultrasound is performed after a medical abortion, it should take place at least two weeks afterwards (best practice agreement). The only aim of an ultrasound examination during follow-up should be to determine whether a gestational sac is present (best practice agreement). Finally, if an ultrasound is performed at any point during pre- or post-abortion care, a report should be drafted, specifying any potential gynecologic abnormalities found, but its absence must not delay the scheduling of the abortion (best practice agreement).
Management of postterm pregnancies
2008, Revue Sage - Femme
Le terme classique d’une grossesse étant compris entre 37 et 42 semaines d’aménorrhée (SA) et les risques de mortalité et de morbidité périnatales augmentant progressivement durant cette période, il est difficile de décider du terme « idéal » au-delà duquel une intervention médicale (déclenchement du travail) apporte plus de bénéfices que de risques liés à l’évolution naturelle de la grossesse. Il existe cependant un niveau de preuve élevé en faveur du déclenchement du travail à partir de 41 SA, terme défini comme « dépassé », lorsque les conditions cervicales sont favorables (score de Bishop supérieur à 5) et de façon systématique à partir de 42 SA (diminution significative de la mortalité périnatale et risque de césarienne non augmenté par rapport à l’attente du travail spontané). Une surveillance rapprochée comportant une analyse du rythme cardiaque fœtal et l’évaluation échographique de la quantité de liquide amniotique est une alternative efficace lorsque les conditions d’accouchement ne sont pas réunies entre 41 et 42 SA ou lorsque la patiente ne souhaite pas de déclenchement.
The classic pregnancy term is between 37 and 42 weeks of gestation and the perinatal mortality and morbidity rates increasing progressively during this period, it is difficult to decide of an “ideal” term above which a medical intervention (induction of labour) brings more benefits than risks linked to the natural evolution of pregnancy. There is a good scientific evidence for the induction of labour from 41 weeks of gestation, defined like “postdating” term, when the cervical conditions are favourable (Bishop score > 5) and systematically from 42 weeks (significative reduction of perinatal mortality rate and not increased rate of cesarean delivery compared with expectant management). An intensive antenatal surveillance involving a nonstress test and an evaluation of amniotic fluid volume is an efficient alternative when the conditions of delivery are unfavourable between 41 and 42 weeks of gestation or when the woman does not wish induction.
Management of postterm pregnancies
2008, Journal de Gynecologie Obstetrique et Biologie de la Reproduction
Le terme classique d’une grossesse étant compris entre 37 et 42 semaines d’aménorrhée (SA) et les risques de mortalité et de morbidité périnatales augmentant progressivement durant cette période, il est difficile de décider du terme « idéal » au-delà duquel une intervention médicale (déclenchement du travail) apporte plus de bénéfices que de risques liés à l’évolution naturelle de la grossesse. Il existe cependant un niveau de preuve élevé en faveur du déclenchement du travail à partir de 41 SA, terme défini comme « dépassé », lorsque les conditions cervicales sont favorables (score de Bishop supérieur à 5) et de façon systématique à partir de 42 SA (diminution significative de la mortalité périnatale et risque de césarienne non augmenté par rapport à l’attente du travail spontané). Une surveillance rapprochée comportant une analyse du rythme cardiaque fœtal et l’évaluation échographique de la quantité de liquide amniotique est une alternative efficace lorsque les conditions d’accouchement ne sont pas réunies entre 41 et 42 SA ou lorsque la patiente ne souhaite pas de déclenchement.
The classic pregnancy term is between 37 and 42 weeks of gestation and the perinatal mortality and morbidity rates increasing progressively during this period, it is difficult to decide of an “ideal” term above which a medical intervention (induction of labour) brings more benefits than risks linked to the natural evolution of pregnancy. There is a good scientific evidence for the induction of labour from 41 weeks of gestation, defined like “postdating” term, when the cervical conditions are favourable (Bishop score > 5) and systematically from 42 weeks (significative reduction of perinatal mortality rate and not increased rate of cesarean delivery compared with expectant management). An intensive antenatal surveillance involving a nonstress test and an evaluation of amniotic fluid volume is an efficient alternative when the conditions of delivery are unfavourable between 41 and 42 weeks of gestation or when the woman does not wish induction.
ISUOG Practice Guidelines (updated): performance of 11–14-week ultrasound scan
2023, Ultrasound in Obstetrics and Gynecology
Influence of distribution of mother’s abdominal body fat on first trimester fetal growth
2020, Journal of Maternal-Fetal and Neonatal Medicine
Assessment of fetal development using cardiac valve intervals
2017, Frontiers in Physiology

View all citing articles on Scopus

View full text

Original ArticleDating biometry during the first trimester: accuracy of an every-day practice

Abstract

Introduction

Section snippets

Material and methods

Results

Discussion

Conclusion

Condensation

Am J Obstet Gynecol

Transvaginal sonography for fetal measurement in early pregnancy

Br J Obstet Gynaecol.

A critical evaluation of sonar 'crown-rump length' measurement

Br J Obstet Gynaecol.

Estimation of gestational age by transvaginal sonographic measurement of greatest embyonic length in dated human embryos

Ultrasound Obstet Gynecol.

Original Article
Dating biometry during the first trimester: accuracy of an every-day practice