The Journal of Maternal-Fetal & Neonatal Medicine

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Gestational age and fetal growth assessment among obstetricians Ricardo F. Sousa-Santos, Alfredo Mendes-Castro, Dânia Ferreira, Rui F. Miguelote, Ricardo J. Cruz-Correia & João F. M. A. L. Bernardes To cite this article: Ricardo F. Sousa-Santos, Alfredo Mendes-Castro, Dânia Ferreira, Rui F. Miguelote, Ricardo J. Cruz-Correia & João F. M. A. L. Bernardes (2015) Gestational age and fetal growth assessment among obstetricians, The Journal of Maternal-Fetal & Neonatal Medicine, 28:17, 2034-2039, DOI: 10.3109/14767058.2014.974541 To link to this article: http://dx.doi.org/10.3109/14767058.2014.974541

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http://informahealthcare.com/jmf ISSN: 1476-7058 (print), 1476-4954 (electronic) J Matern Fetal Neonatal Med, 2015; 28(17): 2034–2039 ! 2014 Informa UK Ltd. DOI: 10.3109/14767058.2014.974541

ORIGINAL ARTICLE

Gestational age and fetal growth assessment among obstetricians Ricardo F. Sousa-Santos1,2,3, Alfredo Mendes-Castro2,3, Daˆnia Ferreira1, Rui F. Miguelote1,4, Ricardo J. Cruz-Correia2,3, and Joa˜o F. M. A. L. Bernardes2,3

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1

Gynecology and Obstetrics Department, Centro Hospitalar do Alto Ave, Guimara˜es, Portugal, 2Center for Research in Health Technologies and Information Systems (CINTESIS), Al. Prof. Hernaˆni Monteiro, Porto, Portugal, 3Faculty of Medicine, University of Porto, Al. Prof. Hernaˆni Monteiro, Porto, Portugal, and 4Life and Health Sciences Research Institute (ICVS), Universidade do Minho, Campus de Gualtar, Braga, Portugal Abstract

Keywords

Objective: We aimed to characterize gestational age assessment and fetal growth evaluation among obstetricians. Methods: Observational, cross-sectional study. We applied a questionnaire to obstetrics specialists and residents, during a national congress on obstetrics. Results: Almost all 179 respondents correct gestational age in the first trimester by ultrasound, but 63% only if there is a difference of 2–9 days. Ultrasound at 11–13 weeks was considered more accurate than at 8–10 weeks by 81%, with a higher proportion of specialists choosing correctly the last answer (p ¼ 0.05). One-third of the respondents did not correctly point the error associated with the ultrasound estimation of fetal weight (EFW). Of the 88% who use a growth table, only 32% were able to identify it by publication/author. Ninety-eight percent identify fetal growth restriction risk (FGR) with centiles (10th in 76%) and 73% of doctors diagnose FGR without other pathological findings (10th in 49%). 44% finds that a low EFW centile maintenance (4th to 3rd) is more worrisome than the crossing of two quartiles (75th to 24th). Conclusions: The role of ultrasound in gestational age assessment and use of EFW use for FGR classification was disparate among participants. EFW and respective centiles may be over relied upon.

Birthweight, fetal development, prenatal, ultrasonography

Introduction Ultrasound has been steadily gaining relevance in obstetrics practice over the last few decades. It is widely used for prenatal evaluation of growth and anatomy, and most countries offer at least one mid trimester scan [1]. Fetal ultrasound scan main purposes are to determine gestational age (GA), assess growth, detect congenital malformations and identify multiple pregnancies, in order to optimize antenatal care to achieve the best possible outcomes for mother and fetus [1]. In Portugal, three ultrasounds are routinely performed throughout the pregnancy, per Servic¸o Nacional de Sau´de (SNS – National Health Service) policy [2]. The first is the 11–13 + 6/7 weeks scan, which in most regions integrates the combined screening for aneuploidies, the second one at 20–22 weeks, and a third scan at 30–32 weeks. There are good reasons to believe that training in obstetrics, and particularly in obstetric ultrasound, is good in Portugal, considering the six years of intensive basic resident training in obstetrics and gynecology, along with the good national

History Received 3 July 2014 Revised 1 October 2014 Accepted 6 October 2014 Published online 7 November 2014

maternal and perinatal indicators [3]. However, if the concepts and limitations behind its use are not fully understood, ultrasound may be over relied upon or misinterpreted. We aimed to characterize obstetricians’ current practice concerning pregnancy ultrasound dating and use of growth centiles for Fetal Growth Restriction (FGR) diagnosis as well as identify problems with the concepts pertaining to growth assessment.

Methods Study design Observational, cross-sectional study. Selection of study subjects We recruited a convenience sample of obstetrics specialists and residents attending a predefined plenary session on preterm labor of the major Portuguese National Congress on Obstetrics and Fetal Maternal Medicine. Data collection

Address for correspondence: Ricardo Filipe Sousa-Santos, CIDES, Faculdade de Medicina da Universidade do Porto, Al. Prof. Hernaˆni Monteiro, 4200-319 Porto, Portugal. Tel: +351936236997. E-mail: [email protected]

We developed a short anonymized semi-structured questionnaire for this purpose, designed to allow completion in under 4 minutes. The questionnaire comprised 8 questions: five

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multiple choice; one yes/no with multiple choice if yes; one yes/no, with open ended question if Yes. Age, sex, specialist/ resident status, as well as years as specialist were recorded. We distributed the questionnaire to all attendees in the selected session and collected them at its end. The purpose of the questionnaire and inclusion criteria were stated in the front page and reminded by one of the moderators of the session. Statistical analysis

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We analyzed data in IBM SPSS Statistics (Version 21.0; IBM Corp., Armonk, NY) and Excel 2013 (2013; Microsoft Corp., Redmond, WA). We used Fisher’s exact tests to compare groups. When we found statistical differences, we used z-tests to compare proportions in each answer.

Results We collected 179 valid questionnaires out of 240 delivered (75%). We have only considered questionnaires from obstetrics residents and specialists, as students and other professionals were also attending. Nineteen forms remained unreturned. Table 1 summarizes the sample characteristics. Tables 2–5 summarize the survey results. We compare answers from specialists and residents. Most respondents (81%) chose CRL at 11–13 weeks as more accurate than CRL/embryo length at 8–10 weeks for GA Table 1. Sample characterization. Specialists Number of answers (% total) Age – Median (range) Gender distribution – % female Number of years as specialist – Median

103 (58%)

Residents 76 (42%)

Total 179

50 (32–67) 78%

28 (26–35) 86%

37(26–67) 82%

16

NA

NA

NA: Not Applicable

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determination (Table 2). Specialists correctly chose more often the later (p ¼ 0.051). Almost all doctors correct GA based on first trimester scan, of which 63% do it only if there is a ‘‘significant difference’’. This difference ranged from 2 to 9 days, with a median and mode of seven days. The majority of respondents use a combination of Head Circunference (HC), Biparietal Diameter (BPD), Abdominal Circunference (AC) and Femur Length (FL) for the estimation of fetal weight (EFW) in the third trimester (Table 3). Only 68% of respondents correctly pointed the EFW error as ±15% for two standard deviations (SD), and 19% of residents as well as 11% of specialists believe this error to be 5%. Of the 88% of clinicians who use a growth centiles table, 45% were not able to identify the reference and 24% identified it by pointing its source. In this context, ‘‘Williams (textbook)’’ was coded as Alexander et al. [4], ‘‘Astraia Software’’ was coded as Yudkin et al. [5] (only four answers written with the word ‘‘Yudkin’’) and ‘‘Viewpoint software’’ was coded as Hadlock et al. [6] (Table 4). Although it is possible to change references in the aforementioned ultrasound reporting software, to the authors’ knowledge, after contacts with most Portuguese sites, Astraia and Viewpoint software distributors, these are the only tables in use for birthweight centiles in Portugal. Almost all clinicians use growth centiles to identify fetuses at risk of FGR (Table 4). Specialists selected a significantly higher proportion of 5th (27% versus 12%) and 3rd (5% versus 0%) centiles than residents. In fetuses with normal anatomy and Doppler velocimetry, 73% of respondents would use exclusively EFW centiles to diagnose FGR (Table 5). Of those who had selected the 10th centile in the previous question, 61% also selected this reference in the diagnosis of FGR, while 29% changed it to 5th centile and 9% to 3rd centile. Of those who had selected 5th centile, 91% (20) maintained it. Those who had selected the 3rd centile kept this option. In question 8 (Table 5), doctors were mostly divided between two troubling progression scenarios: 75th to 24th and 4th to 3rd centile over the same 6 weeks period.

Table 2. Results from questions 1–2 (pregnancy dating). Obstetricians

Residents

1. Which do you consider the most accurate method for determination or correction of gestational age by ultrasound? (Assume optimal conditions and technique in each determination) a. Embryonic length/CRL between the 8th and 10th weeks 24 (24.2%) 9 (11.8%) b. CRL between the 11th and 13th weeks 74 (74.7%) 67 (88.2%) c. Biparietal Diameter (BPD) at 20 weeks 0 0 d. Mean of biometric measurements between the 20th and 22nd weeks 1 (1%) 0 p value (Fisher’s exact) 0.051 2. In a pregnant woman with regular menses (28 days) and known last menstrual period: (Assume optimal conditions and technique in each determination) a. I don’t change GA based on ultrasound 2 (2.1%) 0 b. I always correct the GA based on the 1st trimester ultrasound (until 13 weeks) 31 (33%) 29 (39.2%) c. I correct the GA based on the 1st trimester ultrasound, but only if there 61 (64.9%) 45 (60.8%) is a significant difference d. I always update the GA performed on the last ultrasound performed at each trimester 0 0 p value (Fisher’s exact) 0.449 If applicable, correct answers are in bold. *Denotes significant difference in proportions at the 0.05 level (z-test).

Total

33 (18.9%)* 141 (80.6%)* 0 1 (0.6%)

2 (1.2%) 60 (35.7%) 106 (63.1%) 0

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Table 3. Results from questions 3–4 (Ultrasound estimation of fetal weight).

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Obstetricians

Residents

Total

3. Which biometric variables do you regularly use to estimate fetal weight in the 3rd trimester? a. BPD + FL 1 (1%) 0 1 (0.6%) b. AC + FL 3 (3%) 3 (4%) 6 (3.4%) c. HC + BPD + AC + FL 84 (84.8%) 67 (89.3%) 151 (86.8%) d. OFD + BPD + AC + FL 9 (9.1%) 5 (6.7%) 14 (8%) e. Other 2 (2%) 0 2 (1.1%) p value (Fisher’s exact) 0.757 4. The ultrasound estimate of fetal weight (in the third trimester) has an error which, to accommodate for 95% of determinations, is: a. Less than 100 g 0 1 (1.4%) 1 (0.6%) b. Less than 200 g 12 (12.1%) 11 (14.9%) 23 (13.3%) c.±5% of estimate 11 (11.1%) 14 (18.9%) 25 (14.5%) d. ±15% of estimate 71 (71.7%) 47 (63.5%) 118 (68.2%) e. I don’t know 5 (5.1%) 1 (1.4%) 6 (3.5%) p value (Fisher’s exact) 0.240 If applicable, right answers are in bold.; BPD: Biparietal Diameter; HC: Head Circunference; FL: Femur Length; AC: Abdominal Circunference; OFD: Occiput Frontal Diameter

Table 4. Results from questions 5–7 (centiles and SGA classification). Obstetricians

Residents

Total

5. Do you use a table or chart of reference values to assess fetal growth (to calculate centiles for each GA)? a. No 14 (14.1%) 7 (9.5%) 21 (12.1%) b. Yes 85 (85.9%) 67 (90.5%) 152 (87.9%) p value (Fisher’s exact)

0.481

If Yes, which one? (open ended question) Hadlock et al. [6] 23 (27.1%) 21 (31.3%) 44 (28.9%) Yudkin et al. [5] 20 (23.5%) 17 (25.4%) 37 (24.3 %) Lubchenco et al. [23] 2 (2.4%) 0 2 (1.3%) Alexander et al. [4] 0 1 (1.5%) 1 (0.7%) Do not know/no answer 40 (47.1%) 28 (41.8%) 68 (44.7%) p value (Fisher’s exact) 0.611 6. Do you use growth centiles to identify fetuses at risk of Fetal Growth Restriction (e.g. for close surveillance or other studies, such as doppler velocimetry)? a. No 1 (1%) 2 (2.6%) 3 (1.7%) b. Yes 102 (99%) 74 (97.4%) 176 (98.3%) p value (Fisher’s exact) 0.575 If Yes, which one? a. 10th centile b. 5th centile c. 3rd centile d. 1st centile e. Other p value (Fisher’s exact)

65 (67%) 26 (26.8%) 5 (5.2%) 0 1 (1%)

64 (87.7%) 129 (75.9%)* 9 (12.3%) 35 (20.6%)* 0 5 (2.9%)* 0 0 0 1 (0.6%) 0.004

*Denotes significant difference in proportions at the 0.05 level (z-test)

Discussion The response rate is good and probably underestimated, as we distributed the questionnaire to all attendees, probably including other specialties, students and nurses. The sample demographics attests the broad interest in the meeting selected for this survey. There is a predominance of female doctors, especially among residents (86%), which seems to reflect the actual gender distribution of the specialty [7].

Routine early obstetric ultrasound (524 weeks) is associated with earlier detection of twin pregnancies, improved pregnancy dating and consequential reduced rates of labor induction for post-term pregnancy, accurate placental location determination, as well as higher rates of pregnancy termination for fetal anomalies when detection of these anomalies is a specific aim of the examination [8]. In Portugal, two ultrasounds are routinely performed until the 24th week. The first is the 11–13 + 6/7 weeks scan, which in most regions integrates the combined screening for aneuploidies, and is performed by obstetricians in departments specialized in obstetric ultrasound from SNS hospitals. An overwhelming proportion of respondents wrongly chooses the CRL at 11-13 weeks as more accurate for GA determination than CRL/embryo length at 8–10 weeks. Although small, there is a gain in accuracy in a shorter embryo [9]. A higher proportion of specialists choose the right answer (p ¼ 0.051), an expected trend because some of the residents may have had little ultrasound experience at this time and ultrasound is a tool that may be taught, but practice will improve dexterity and empirical knowledge. The same is true among specialists, as many probably do not dedicate themselves to ultrasound. The error associated with GA determination throughout pregnancy is roughly ±8% for two SD, whether by CRL (in the first trimester) [9,10] or by combined HC, BPD, AC and FL in the second and third trimesters (the four parameter equations achieve the highest accuracy in these trimesters, if we exclude BPD until 20 weeks) [11,12]. In the first trimester, embryo/fetus growth is not yet significantly affected by the environment or genetics, and its measurements relate more closely to the actual GA [10]. The earlier the ultrasound, with an appropriate CRL measurement, the more accurate the GA determination, with smaller 95% confidence interval (CI) for the estimate, in days. With CRL, the limited embryo movement allows for even lower intra and inter-observer variability [13]. In fact, fetal movement may be one of the reasons BPD formulas have been shown more consistent (smaller CI – less random errors) than CRL formulas at 12–14 weeks [10] and until 20 weeks [14]. The fact that an earlier measurement of CRL is slightly better for pregnancy dating does not warrant, nevertheless, this ultrasound in the absence of an obstetrical reason. The 11–13 + 6/7 weeks scan is perfectly adequate for this purpose. However, when it is performed, it should be considered for pregnancy dating, as in the case of unknown/unreliable dates which undergo dating for scheduling aneuploidy screening, or unexpected early ultrasound (CRL545 mm) in this context. Almost all respondents correct GA based on ultrasound, even with certain last menstrual period (LMP). However, only 36% always correct dates based on CRL, while the rest only does it if there is a significant difference, the wide majority of which with discrepancies of a week or more. At 12 weeks GA, this approximately matches the 2 SD (95% CI) of estimated GA, as follows: ±4 days at 7 weeks; ±5 days at 9 weeks; ±6.7 days at 12 weeks; ±7.8 days at 14 weeks [9]. LMP estimates of gestation are associated with random errors, as well as a systematic tendency to overstate its duration [15]. Ultrasound in the first half of pregnancy tends to be more accurate predicting the actual delivery date [8,14], although a combination algorithm (correction when difference 

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Table 5. Results from questions 7–8 (centiles and FGR classification). Obstetricians

Residents

Total

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7. On fetuses with normal anatomy and Doppler velocimetry, do you diagnose Intrauterine Growth Restriction based solely on fetal growth centiles? a. No 29 (28.7%) 19 (25.7%) 48 (27.4%) b. Yes 72 (71.3%) 55 (74.3%) 127 (72.6%) p value (Fisher’s exact) 0.733 If Yes, which one? a. 10th centile 28 (41.2%) 31 (58.5%) 59 (48.8%) b. 5th centile 33 (48.5%) 16 (30.2%) 49 (40.5%) c. 3rd centile 7 (10.3%) 5 (9.4%) 12 (9.9%) d. 1st centile 0 0 0 e. Other centile 0 1 (1.9%) 1 (0.8%) p value (Fisher’s exact) 0.096 8. Which of the following would you consider more troubling, in a healthy pregnant woman, without other clinical or ultrasound abnormalities? (Assume optimal technique and conditions and the same operator) a. 75th centile at 30w; 24th centile at 36w 48 (50.5%) 40 (57.1%) 88 (53.3%) b. 8th centile at 30w; 6th centile at 36w 0 1 (1.4%) 1 (0.6%) c. 50th centile at 30w; 83rd centile at 36w 4 (4.2%) 0 4 (2.4%) d. 4th centile at 30w; 3rd centile at 36w 43 (45.3%) 29 (41.4%) 72 (43.6%) p value (Fisher’s exact) 0.162

7days) yielded marginally better delivery date prediction than ultrasound alone in a study [15]. Ultrasound between 11 and 14 weeks, on the other hand, tends to slightly overestimate actual gestational age from In Vitro Fertilization (IVF) pregnancies by 1.3 days (mean difference), and has a mean random error for singletons of 2.4 days (1 SD) [16]. First trimester ultrasound, versus second trimester, has also been found to reduce the rate of post term induction [17], by more accurately changing dates in women with delay of ovulation [8]. Therefore, in a woman with regular menses and known LMP, it may be reasonable to correct the GA if the difference from CRL dating is more than 6 days at 12 weeks (the most chosen option), but it is also valid, and globally less prone to errors, to always change it, or to change it using a smaller difference. Ultrasound in the second half of pregnancy can diagnose important placental anomalies (e.g. Placenta accreta, Placenta praevia), fetal malpresentation, disorders of amniotic fluid volume (oligohydramnios, polyhydramnios), and impaired/ excessive fetal growth. However, a Cochrane systematic review found no evidence of improved outcomes, either maternal or fetal, from screening low risk or unselected populations for these conditions, and it may confer a small increase in caesarean section rates [18]. This is a controversial matter, but it is standard practice in Portugal to screen all pregnancies by ultrasound also in the third trimester [2]. Nearly all respondents routinely use a four parameter equation to estimate fetal weight, from the mid-trimester onward, as described by Hadlock [11]. However, one-third of respondents did not know the error associated with the EFW. A systematic review reported that all studies of EFW by US report 95% confidence intervals that exceed ±14% (two SD) of birth weight [19], which means that a fetus with 3000 g would yield, with 95% confidence, an estimate between 2580 g and 3420 g, regardless of the formula used. This has not significantly improved over the last three decades, despite multiple published formulas, vastly improved ultrasound 2D performance and the attempt to introduce 3D in this setting [19,20]. Despite the deliberate wide gap among options, the

correct 15% option was not chosen by more than one-third of doctors, and this may have an impact on decisions based on this estimate, such as FGR or macrossomy diagnosis and further related obstetric interventions (such as pregnancy termination or elective cesarean section). This apparent overreliance in EFW may be exacerbated by the fact that, while almost all doctors use centile tables to identify fetuses at risk of FGR, only 55% recalled the reference or source used for this purpose (Table 4), and only 32% were able to identify the author. These tables have an effect on the sensibility and specificity of abnormal growth diagnosis [21], which is why its choice is important. As an example, Yudkin’s [22] and Lubchenco’s [23] references have been shown to have a sensitivity of, respectively, 38% and 14% to detect a fetus below the 10th centile at 39 completed weeks, in a Portuguese sample [24]. Lubchenco’s chart, although a landmark paper, has several bias that preclude its contemporary use. Hadlock was, by far, the most recalled author for a table, which was unexpected (for Portugal) by the authors. The second most chosen author, Yudkin et al. [22], was mostly remembered as ‘‘Astraia software’’ (and thus, most doctors who did remember a name wrote ‘‘Hadlock’’). This may correspond to confusion between Hadlock’s formula for EFW [11] (extensively utilized in Portugal) and Hadlock’s sonographic reference for fetal weight [6]. One of the most utilized ultrasound reporting software in SNS requires an option on the formula to calculate EFW (among those are Hadlock’s formulae), but will retrieve a centile (based on this EFW) from a reference not explicitly shown or selected (in Portugal, Yudkin et al. [22]). This means a centile will be provided after selecting a formula for EFW (Hadlock’s in most instances). Moreover, the references utilized by respondents are not customizable, except for fetal sex (in the case of Yudkin’s [22]). Almost all participants use centiles to identify fetuses at risk of FGR. The centiles used for this purpose were disparate among participants, and were significantly different between specialists and residents, with the latter selecting more often the 10% lighter fetuses for close monitoring. Concerning the

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diagnosis of FGR, almost a third of clinicians do not rely exclusively on EFW centiles to diagnose FGR. Those who do, tend to select lower figures, but 48% use the same 10th centile. Fetuses bellow the 10th centile are commonly referred to as Small for Gestational Age (SGA) [25], and this is the definition adopted by the Royal College of Obstetricians and Gynecologists (RCOG) in their updated guideline ‘‘The Investigation and Management of the Small–for–Gestational– Age Fetus’’ [26]. This guideline reserves FGR for fetuses that are not constitutionally small. It also uses the 3rd centile for classification of severe SGA. The American College of Obstetricians and Gynecologists (ACOG), in their Practice Bulletin No 134 [27], makes a very different use of the terminology, using FGR for fetuses bellow the 10th centile for EFW and SGA for newborns bellow the 10th centile for GA at birth. We adopt the former definition in this paper. Some, but not all, SGA will be FGR, and while the SGA group is at an increased risk of adverse outcomes, most of these events are concentrated in the growth restricted group [26]. Data from the PORTO study has shown 72% of fetuses below the 10th centile for EFW had normal perinatal outcomes. Those bellow the 3rd centile or those with a combination of EFW below the 10th centile and abnormal Uterine Artery (UA) Doppler, were strongly and most consistently associated with adverse perinatal outcomes (6.2%) and included all deaths, compared with a composite morbidity rate of 2% in the 3rd–10th centile group. Many doctors in our sample will not differentiate SGA from FGR and will use the same centile to describe both growth restricted and constitutionally small fetuses, in line with the ACOG paper. A survey in Ireland has shown similar results concerning the use of specific centiles to define SGA and FGR, with spread over a range of centiles and other ultrasound findings [28]. Specifically, use of EFW centiles alone in classification of FGR was very similar. Despite the recommended definitions in guidelines, both RCOG and ACOG acknowledge the use of other centile definitions for SGA/FGR classifications [26,27]. Question number 8 (Table 5) was the most skipped by doctors (7.8%, others 0-6.1%). The percentage of clinicians that chose option ‘‘d.’’ over ‘‘a.’’ depicts the importance attributed to the centile number, caused by practical definitions of FGR that fail to address the wider and more correct definition: failure to reach growth potential [29]. The six weeks interval between ultrasounds allows for sound clinical interpretation (a minimum of 3 weeks would be adequate [30]). With no other clinical or ultrasound features, valid scenarios are debatable for each of these answers. It is important to consider, however, that the relative velocity of growth is very different in the fetuses from scenarios ‘‘d.’’ and ‘‘a.’’: while the smaller one continues to grow as expected, the larger is not, crossing 50% of observations for the expected EFW at 36 weeks. The difficulty in establishing a prognosis regarding these fetuses, which does not abide to static definitions of ‘‘normal weight’’, may be lessened by the utilization of customized centiles [31]; as recommended by the RCOG [26], although the ACOG states that its use has not been shown to improve outcomes [27]. Nonetheless, it is of note that the reference used for classification of fetuses that are SGA, FGR, or even macrosomic is too often overlooked

J Matern Fetal Neonatal Med, 2015; 28(17): 2034–2039

when we discuss these issues. Even papers that depend on the definition of centiles often do not specify the adopted reference for EFW (or references). As examples, the PORTO [32] study refers ‘‘conventional population–based growth standards’’ and a questionnaire in Ireland, on the definition and management of FGR [28] fails to inquire which references doctors use, apart from if they are customizable. The questionnaire used in this study was simple and quick, allowing for a good response rate, while covering a broad range of growth related issues, in and heterogeneous audience including residents as well as ultrasound experts, in aspects pertinent to all trainees and specialists. The downside was a lack of finer detail and clarification of answers, which was a tradeoff the authors considered advantageous.

Conclusion There is an interdependence in the matters discussed here, which is sometimes difficult to ascertain. A correct pregnancy dating, correct intervals and technique of EFW, as well as good knowledge of ultrasound limitations have to be linked with sound clinical judgment, in order to improve decisions. There are differences in these important matters, in current practices and opinions of experienced obstetricians and obstetrics residents alike, as there are in the literature. It is important to debate and find a common set of definitions to ease this dilemma.

Acknowledgements The authors would like to thank professor Nuno Montenegro, for his suggestions and assistance and to Sociedade Portuguesa de Medicina Materno Fetal for providing assistance with the optimal conditions for the survey.

Declaration of interest The authors state no conflicts of interest. The authors would like to thank Federac¸a˜o das Sociedades Portuguesas de Obstetrı´cia e Ginecologia for financial support.

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DOI: 10.3109/14767058.2014.974541

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Gestational age and fetal growth assessment among obstetricians.

We aimed to characterize gestational age assessment and fetal growth evaluation among obstetricians...
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