Crown-rump Length Measurements Research Articles

Impact of bias in crown–rump length measurement at first‐trimester screening for trisomy 21

To assess the repeatability of crown-rump length (CRL) measurement and examine the effect of its over- and underestimation on first-trimester combined screening. Intra- and interoperator repeatability of CRL measurement at 11-13 weeks of gestation was assessed in 124 cases by two operators. Raw data were transformed into gestational age and intra- and interoperator repeatability was evaluated by within-operator standard deviation (SD) and the SD of differences in measurements between both operators. Modeling techniques were used to assess the impact of CRL measurement error on general population screening and on the operator-specific screening performance. The impact of errors in CRL measurement were investigated by simulating fetal nuchal translucency (NT) measurements and multiple of the median (MoM) values for pregnancy-associated plasma protein A (PAPP-A) and free β-human chorionic gonadotropin (β-hCG) for 500 000 euploid and 500 000 trisomy 21 pregnancies at 12 weeks and 9 weeks of gestation, and adding to or subtracting from each CRL value up to 10 mm and recalculating patient-specific risks. Within-operator SD of the CRL measurement was 1.27 days of gestation. The SD of the differences in CRL measurement between operators was 1.37 days of gestation. Both intra- and interoperator 95% limits of agreement were around ± 5 mm. In general population-based screening, a CRL measurement error SD of 5 mm accounts for an estimated 5% of the SD of log MoM PAPP-A and less than 1% of the SD of log MoM free β-hCG. Modeling the effect of removing this measurement error on overall screening performance showed a minimal impact. For a risk cut-off of 1 in 100, the benefit in terms of overall screening performance would be an increase in detection rate of about 1% and a reduction in false-positive rate of less than 0.1%. With regard to the operator-specific screening performance, a consistent 5-mm underestimation of CRL reduces the detection rate from 84% to 79% and the false-positive rate from 2.4% to 1.2%. With a consistent 5-mm overestimation the rates would be 88% and 5.6%, respectively. The impact of the interoperator variability in CRL measurement on patient-specific risk needs to be taken into account when interpreting first-trimester screening results. A systematic under- or overestimation of CRL should be avoided.

Can discordance in CRL at the first trimester predict birth weight discordance in twin pregnancies?

To examine the correlation between measurements of crown rump length (CRL), nuchal translucency (NT), and birth weight in dichorionic (DC) and monochorionic (MC) twin pregnancies. A retrospective analysis was performed on all twin term pregnancies delivered between 2001 and 2007 at the McGill University Health Center. Data collected included maternal age, CRL and NT measurement, results of glucose challenge test, birth weight and length, gestational age at delivery, and fetal gender. The study population comprised 792 fetuses: 94 MC/DA and 698 DC/DA. Maternal age, gestational age at delivery, birth weight, and birth length were all significantly higher for the DC group. Male fetuses had significantly higher NT and higher birth weight than female fetuses. Discordance in CRL was found to correlate with discordance in birth weight in the entire study population (P<0.0001, R=0.25), in the DC twins (P<0.0001, R=0.275), but not in MC twins (R=0.10, P=0.33). CRL discordance above the 90th percentile (>12%) predicted 14/40 pregnancies with birth weight discordance above the 90th percentile (>24%) [P<0.001, LR=4.1 (2.6-6.2)]. CRL discordance above the 95th percentile (>16%) predicted 5/21 pregnancies with birth weight discordance above the 95th percentile (>30%) [P<0.001, LR=5.5 (2.6-10.4)]. NT discordance was correlated with CRL discordance (R=0.15, P<0.0001), but not with birth weight, regardless of chorionicity or gender. In twin pregnancies, CRL discordance in first trimester can predict discordance of more than 25% in neonatal birth weight.

Yolk sac number does not predict reliably amnionicity in monochorionic twin pregnancies: a case of a monochorionic monoamniotic twin pregnancy with two distinct yolk sacs on early first‐trimester ultrasound

The dramatic increase in multiple births over the past 30 years has made multiple pregnancy one of the most common high-risk conditions encountered by obstetricians. In North America, the rate of multiple pregnancy has increased by 50–70% and this is largely attributed to advanced reproductive technologies1, 2. In monochorionic multiple gestations the determination of amnionicity is technically difficult to perform based both on the relatively late appearance of the amnion on ultrasound, typically between 8 and 10 weeks, along with the thin nature of the membrane. Previous studies have suggested that on early first-trimester ultrasound, monochorionic monoamniotic (MCMA) twin pregnancies can be reliably characterized by the presence of a single yolk sac and monochorionic diamniotic (MCDA) twins can be reliably characterized by the identification of two yolk sacs3. Accurate and early prenatal ultrasound diagnosis of amnionicity, along with enhanced prenatal/neonatal care, has been shown to decrease the mortality rates of MCMA twins from 50% to 10–20% in more recent years2. Recently, the accuracy of using yolk sac number as a means of predicting amnionicity has been challenged4-6. In a recent series of 22 cases of monochorionic multiple gestations, Shen et al.4 revealed that 85% of the 20 cases of MCDA gestations had two yolk sacs and that 15% were characterized by only a single yolk sac; a single case of MCMA was identified in this series and one yolk sac was seen. In 2010, three cases of MCMA twins characterized by the presence of two yolk sacs on first-trimester ultrasound were reported5, 6. Here, we present a fourth case of MCMA twins in which early first-trimester ultrasound demonstrated the presence of two yolks sacs with confirmed monoamnionicity in the late first trimester. A 31-year-old G1P0 Caucasian woman presented at a private fertility clinic for intrauterine insemination with donor sperm for social reasons. A transvaginal ultrasound examination (E8, GE Medical Systems, Zipf, Austria) was performed at 7 + 0 weeks for confirmation of intrauterine pregnancy. The 7-week ultrasound clearly demonstrated two distinct fetal poles and two separate yolk sacs. The crown–rump length measurements, of 7.6 mm and 7.9 mm, were consistent with the expected size for each fetal pole, and cardiac activity was present in both. The pregnancy was considered to be MCDA twin gestation at this point in time, based on the presence of two yolk sacs (Figure 1). At 9 + 2 weeks a single amniotic sac was observed with the absence of a dividing intergestational membrane (Figure 2). At 12 + 2 weeks of gestation, ultrasound demonstrated the absence of a dividing membrane between the fetuses (Figure 3). Power Doppler at this time revealed umbilical cord entanglement, confirming the diagnosis of a MCMA twin gestation (Figure 4). Transvaginal ultrasound at 7 weeks' gestation demonstrated two yolk sacs in a monochorionic twin pregnancy. Repeat transvaginal ultrasound at 9 + 2 weeks revealed a single amniotic sac and the absence of an intergestational membrane. Transvaginal ultrasound at 12 + 2 weeks demonstrated the absence of a dividing membrane. Transvaginal ultrasound at 12 + 2 weeks verified umbilical cord entanglement. This case highlights the close proximity in the sequence of development of the yolk sac and amnion and emphasizes our lack of understanding of the temporal differentiation of these structures. The almost simultaneous development of the yolk sac and amnion could explain these most recent findings that yolk sac number does not always correlate with amnionicity in monochorionic gestations. Yolk sac number should no longer be considered a reliable means of diagnosing amnionicity on early first-trimester ultrasound. The consequent clinical implications are an enhanced focus on the diagnosis of amnionicity based on the presence or absence of the intergestational amnion and the visualization of umbilical cord entanglement7, 8.

Is there a correlation between birth weights and first-trimester crown-rump length growth velocity?

Objective: To test the hypothesis that small- or large-for-gestational-age (SGA or LGA) newborns have anomalous crown-rump length (CRL) growth rates in the first trimester. Methods: Prospective observational study. Women in the first trimester presenting to the Early Pregnancy Unit, between November 2006 and December 2010, underwent transvaginal scan. Women with viable singleton pregnancies in the first trimester who had at least two CRL measurements > 5 mm, recorded at least 2 weeks apart, and also had birth weight data available were included in the final analysis. Birth weight percentiles were calculated and adjusted for gestational age and gender. SGA was equivalent to < 10th centile and LGA was equivalent to > 90th centile. Correlation analysis was performed between birthweight percentiles and first-trimester CRL growth-rate coefficients. In addition, we estimated early fetal growth rates (EFGR) by calculating the Δ CRL/Δ time (mm/day) to see if these differed according to the birth-weight percentiles. Results: A total of 107 women had complete data. The mean maternal characteristics were age 27.5 ± 6 years, weight 87 ± 29 kg and height 163 ± 8 cm. The mean birth weight and gestational age at delivery were 3405 g (SD = 597) and 269 days (SD = 13), respectively. The proportions of SGA and LGA were 7.5% and 18.7%, respectively. There were no significant correlations between birth-weight percentiles and any of the CRL growth rates. There were also no significant differences in the mean CRL velocities when comparing the SGA and LGA newborns birth weights. EFGR for SGA and LGA newborns were 1.34 mm/day (SD = 0.17) and 1.32 mm/day (SD = 0.24), respectively (p > 0.05). Conclusions: Newborns who are found to be SGA or LGA at delivery do not appear to have anomalous CRL growth patterns in the first trimester. The EFGR also did not correlate with birth-weight percentiles.

Three‐dimensional ultrasound is an accurate and reproducible technique for fetal crown‐rump length measurement

The aim of the study was to evaluate the accuracy and reproducibility of fetal crown-rump length (CRL) measurement using three-dimensional ultrasound (3DUS). We included a series of women with singleton pregnancy at 6-13 + 6 weeks. Following CRL measurement by the two-dimensional ultrasound (2DUS), a 3DUS volume was acquired. On the reconstructed midsagittal plane, CRL was measured twice by an operator and once by another. The correlation between CRL measured by 3DUS and 2DUS, as well as the intraobserver and interobserver agreement, was then calculated. Furthermore, the agreement between 2DUS and 3DUS CRL measurements together with intraobserver and interobserver agreement was calculated separately for the groups with a midsagittal acquisition plane (MSAP) and non-midsagittal acquisition plane (NMSAP). Overall, 137 pregnancies were included in the analysis. CRL measurements performed using 3DUS showed excellent correlation with 2DUS [intraclass correlation coefficient (ICC) = 0.992]. In addition, the 3DUS showed a high intraobserver and interobserver agreement (ICC = 0.999 and 0.993, respectively). Finally, when we divided the acquired volumes according to the plane of acquisition, excellent 2DUS-3DUS, as well as intraobserver and interobserver agreement, was maintained for both MSAP and NMSAP. 3DUS is a highly accurate and reproducible tool for fetal CRL measurement regardless of the fetal position at the time of 3D volume acquisition.

Limitations of Current Definitions of Miscarriage Using Mean Gestational Sac Diameter and Crown-Rump Length Measurements

Objectives There is significant variation in cut-off values for mean gestational sac diameter (MSD) and embryo crown–rump length (CRL) used to define miscarriage, values suggested in the literature ranging from 13 to 25 mm for MSD and from 3 to 8 mm for CRL. We aimed to define the false-positive rate (FPR) for the diagnosis of miscarriage associated with different CRL and MSD measurements with or without a yolk sac in a large study population of patients attending early pregnancy clinics. We also aimed to define cut-off values for CRL and MSD that, on the basis of a single measurement, can definitively diagnose a miscarriage and so exclude possible inadvertent termination of pregnancy. Methods This was an observational cross-sectional study. Data were collected prospectively according to a predefined protocol. Intrauterine pregnancy of uncertain viability (IPUV) was defined as an empty gestational sac or sac with a yolk sac but no embryo seen with MSD < 20 or < 30 mm or an embryo with an absent heartbeat and CRL < 6 mm or < 8 mm. We recruited to the study 1060 consecutive women with IPUV. The endpoint was presence or absence of a viable pregnancy at the time of first-trimester screening ultrasonography between 11 and 14 weeks. The sensitivity, specificity, positive and negative predictive values were calculated for potential cut-off values to define miscarriage from MSD 8 to 30 mm with or without a yolk sac and from CRL 3 to 8 mm. Results Of the 1060 women with a diagnosis of IPUV, 473 remained viable and 587 were non-viable by the time of the 11–14-week scan. In the absence of both embryo and yolk sac, the FPR for miscarriage was 4.4% when an MSD cut-off of 16 mm was used and 0.5% for a cut-off of 20 mm. There were no false-positive test results for miscarriage when a cut-off of MSD ≥ 21 mm was used. If a yolk sac was present but an embryo was not, the FPR for miscarriage was 2.6% for an MSD cut-off of 16 mm and 0.4% for a cut-off of 20 mm, with no false-positive results when a cut-off of MSD ≥ 21 mm was used. When an embryo was visible with an absent heartbeat, using a CRL cut-off of 4 mm the FPR for miscarriage was 8.3%, and for a CRL cut-off of 5 mm it was also 8.3%. There were no false-positive results using a CRL cut-off of ≥ 5.3 mm. Conclusions These data show that some current definitions used to diagnose miscarriage are potentially unsafe. Current national guidelines should be reviewed to avoid inadvertent termination of wanted pregnancies. An MSD cut-off of > 25 mm and a CRL cut-off of > 7 mm could be introduced to minimize the risk of a false-positive diagnosis of miscarriage. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.

Re: Limitations of current definitions of miscarriage using mean gestational sac diameter and crown–rump length measurements: a multicenter observational study

Re: Limitations of current definitions of miscarriage using mean gestational sac diameter and crown–rump length measurements: a multicenter observational study

Re: Limitations of current definitions of miscarriage using mean gestational sac diameter and crown–rump length measurements: a multicenter observational study

Re: Limitations of current definitions of miscarriage using mean gestational sac diameter and crown–rump length measurements: a multicenter observational study

Ultrasound Evidence of Early Fetal Growth Restriction after Maternal Malaria Infection

BackgroundIntermittent preventive treatment (IPT), the main strategy to prevent malaria and reduce anaemia and low birthweight, focuses on the second half of pregnancy. However, intrauterine growth restriction may occur earlier in pregnancy. The aim of this study was to measure the effects of malaria in the first half of pregnancy by comparing the fetal biparietal diameter (BPD) of infected and uninfected women whose pregnancies had been accurately dated by crown rump length (CRL) before 14 weeks of gestation.Methodology/Principal FindingsIn 3,779 women living on the Thai-Myanmar border who delivered a normal singleton live born baby between 2001–10 and who had gestational age estimated by CRL measurement <14 weeks, the observed and expected BPD z-scores (<24 weeks) in pregnancies that were (n = 336) and were not (n = 3,443) complicated by malaria between the two scans were compared. The mean (standard deviation) fetal BPD z-scores in women with Plasmodium (P) falciparum and/or P.vivax malaria infections were significantly lower than in non-infected pregnancies; −0.57 (1.13) versus −0.10 (1.17), p<0.001. Even a single or an asymptomatic malaria episode resulted in a significantly lower z-score. Fetal female sex (p<0.001) and low body mass index (p = 0.01) were also independently associated with a smaller BPD in multivariate analysis.Conclusions/SignificanceDespite early treatment in all positive women, one or more (a)symptomatic P.falciparum or P.vivax malaria infections in the first half of pregnancy result in a smaller than expected mid-trimester fetal head diameter. Strategies to prevent malaria in pregnancy should include early pregnancy.

Determination of Fetal Age by Ultrasonography in St. Kitts Green Monkeys

Ultrasound assessments of fetal growth have been used in other species of primates to estimate fetal age, but there are no published morphometrics for the St. Kitts green monkey (Chlorocebus sabaeus), a species that has been important for studies of transplantation of fetal tissue into the brain as potential treatment for degenerative disease. Previous studies with other primate species have used relatively small numbers of pregnancies, measured repeatedly, to derive regressions for predicting fetal age from ultrasound studies. The present study derives data from 967 pregnancies, collected over a 9-year period, for predicting fetal age from ultrasound measurements of crown rump length, biparietal diameter, head circumference, abdominal circumference, and femur length in the St. Kitts green monkey. Linear and polynomial regressions were determined from pregnancies dated from a 3- to 4-day breeding period and confirmed in a second, independent group of pregnant monkeys with more extended breeding times to determine their accuracy for predicting fetal age. Although similar to morphometrics reported in other monkey species, there were some significant differences. These data will improve the estimates of fetal ages in previously published studies of St. Kitts green monkeys and provide more precise estimates of fetal age in studies of fetal development, genomics, and reproductive toxicology.

Accuracy of emergency physicians using ultrasound measurement of crown-rump length to estimate gestational age in pregnant females

Study objectiveThe objective of this study is to evaluate the accuracy of emergency providers (EPs) of various levels of training in determination of gestational age (GA) in pregnant patients using bedside ultrasound measurement of crown-rump length (CRL). MethodsWe conducted a prospective, cross-sectional, observational study of patients in obstetrical care at an urban county hospital. We enrolled a convenience sample of women at 6 to 14 weeks gestation as estimated by last menstrual period. Emergency providers used ultrasound to measure the CRL. Repeat CRL measurements were performed by either an obstetrical ultrasound technician or senior obstetrician and used as the criterion standard for true GA (TGA). ResultsOne hundred five patients were evaluated by 20 providers of various levels of training. The average time required to complete the CRL measurement was 85 seconds. When CRL measurements performed by EPs were compared with the TGAs, the average correlation was 0.935 (0.911-0.959). Using standard accepted variance for CRL measurements at different GAs according to the obstetrics literature (±3 days for 42-70 days and ±5 days for 70-90 days), correlation between EP ultrasound and measured TGA was 0.947 (0.927-0.967). ConclusionsEmergency providers can quickly and accurately determine GA in first-trimester pregnancies using bedside ultrasound to calculate the CRL. Emergency providers should consider using ultrasound to calculate the CRL in patients with first-trimester bleeding or pain because this estimated GA may serve as a valuable data point for the future care of that pregnancy.

Limitations of current definitions of miscarriage using mean gestational sac diameter and crown–rump length measurements: a multicenter observational study

Limitations of current definitions of miscarriage using mean gestational sac diameter and crown–rump length measurements: a multicenter observational study

21st World Congress on Ultrasound in Obstetrics and Gynecology, 18-22 September 2011, Los Angeles, USA: presentations and awards

21st World Congress on Ultrasound in Obstetrics and Gynecology, 18-22 September 2011, Los Angeles, USA: presentations and awards

Yolk Sac Diameter in Early Pregnancy in Maternal Diabetes Mellitus

Aims: To investigate the possible association between maternal diabetes mellitus and increased yolk sac diameter (YSD). Methods: We searched the Early Pregnancy Unit database to identify singleton pregnancies with measurements of embryonic crown-rump length (CRL) and YSD at 6–10 weeks of gestation and subsequent delivery of phenotypically normal neonates. We compared the YSD in patients with pre-gestational and gestational diabetes with those who were unaffected by diabetes. Results: A total of 3,686 cases were identified including 43 (1.2%) with type 1 diabetes, 31 (0.8%) with type 2 diabetes and 71 (1.9%) who subsequently developed gestational diabetes. The measured YSD in both the diabetic and non-diabetic groups were expressed as differences from the expected normal mean for CRL (Δ values). There were no significant differences in ΔYSD between the groups. The median (IQR) ΔYSD was 0.01 (–0.33 to 0.37) mm in the unaffected group, 0.01 (–0.35 to 0.51) mm in type 1 diabetes, –0.02 (–3.44 to 0.27) mm in type 2 diabetes and 0.01 (–0.28 to 0.35) mm in gestational diabetes. Conclusion: After exclusion of miscarriages and embryopathies, pre-gestational and gestational diabetes are not associated with altered YSD.

Evaluation of fetal nuchal translucency in 98 pregnancies at risk for severe spinal muscular atrophy: possible relevance of the SMN2 copy number

Objective: To study fetal nuchal translucency (NT) thickness as a possible early marker in fetuses at risk for severe spinal muscular atrophy (SMA). To investigate the significance of the survival motor neuron (SMN) 2 gene copy number in affected fetuses. Methods: We performed 2D-ultrasound in 98 pregnancies at risk for SMA, all of which underwent prenatal molecular testing of the SMN1 gene. Crown-rump length (CRL) and NT measurements were obtained in all cases before chorionic villus sampling. Fetuses were diagnosed as healthy, carriers or affected according to the SMN1 molecular testing results. SMN2 copies were also tested in all affected fetuses. Results: Nineteen fetuses were predicted to be affected due to the absence of the SMN1 gene, 18 of which had two SMN2 copies. Mean CRL and NT values did not differ between healthy, carrier and affected fetuses. In the remaining affected case who had only one SMN2 copy, the ultrasound examination showed a NT value of 4.98 mm and findings compatible with hypoplastic left heart. Conclusions: Most affected SMA fetuses have normal NT values. Our findings support the idea that SMN2 copy number in SMA fetuses is relevant for the development of congenital heart defects and increased NT values.

Gestational sac fluid volume measurements in virtual reality

To evaluate a virtual reality (VR) application for gestational sac fluid volume (GSFV) measurements in first-trimester pregnancies and to study the correlation between different embryonic growth parameters. This was a prospective cohort study analyzing 180 three-dimensional (3D) ultrasound scans of 42 healthy women, performed between 5 + 5 and 12 + 6 weeks' gestational age (GA). The 3D datasets were transferred to the I-Space immersive VR system. The V-Scope application was used to create a 'hologram' of the ultrasound image, allowing depth perception and interaction with the rendered objects. Volumes were measured semi-automatically using a segmentation algorithm. In addition to the GSFV, the total gestational sac volume (GSV) and its diameter (GSD) were measured. The GSV was also calculated using the ellipsoid formula. Previously obtained measurements of embryonic volume and crown-rump length (CRL) were included in the study. The outcomes were analyzed using repeated-measures analysis of variance. The GSFV was measured in 78 scans, and varied from 434 to 81 491 mm(3). A positive correlation between GSFV and GA, CRL and GSD was found. Comparison of the GSD formula constructed in our study in relation to GA with a formula that is commonly used clinically showed an increasing difference with increasing GA either side of 8 + 5 weeks. The GSFV/embryonic volume ratio showed a decrease with GA. The GSV calculated using the ellipsoid formula was on average 19.8% larger compared with the GSV measured in VR. New charts for first-trimester GSFV were constructed using VR. These growth charts could be promising tools for studying normal and abnormal embryonic development.

Limitations of current definitions of miscarriage using mean gestational sac diameter and crown–rump length measurements: a multicenter observational study

There is significant variation in cut-off values for mean gestational sac diameter (MSD) and embryo crown-rump length (CRL) used to define miscarriage, values suggested in the literature ranging from 13 to 25 mm for MSD and from 3 to 8 mm for CRL. We aimed to define the false-positive rate (FPR) for the diagnosis of miscarriage associated with different CRL and MSD measurements with or without a yolk sac in a large study population of patients attending early pregnancy clinics. We also aimed to define cut-off values for CRL and MSD that, on the basis of a single measurement, can definitively diagnose a miscarriage and so exclude possible inadvertent termination of pregnancy. This was an observational cross-sectional study. Data were collected prospectively according to a predefined protocol. Intrauterine pregnancy of uncertain viability (IPUV) was defined as an empty gestational sac or sac with a yolk sac but no embryo seen with MSD < 20 or < 30 mm or an embryo with an absent heartbeat and CRL < 6 mm or < 8 mm. We recruited to the study 1060 consecutive women with IPUV. The endpoint was presence or absence of a viable pregnancy at the time of first-trimester screening ultrasonography between 11 and 14 weeks. The sensitivity, specificity, positive and negative predictive values were calculated for potential cut-off values to define miscarriage from MSD 8 to 30 mm with or without a yolk sac and from CRL 3 to 8 mm. Of the 1060 women with a diagnosis of IPUV, 473 remained viable and 587 were non-viable by the time of the 11-14-week scan. In the absence of both embryo and yolk sac, the FPR for miscarriage was 4.4% when an MSD cut-off of 16 mm was used and 0.5% for a cut-off of 20 mm. There were no false-positive test results for miscarriage when a cut-off of MSD ≥ 21 mm was used. If a yolk sac was present but an embryo was not, the FPR for miscarriage was 2.6% for an MSD cut-off of 16 mm and 0.4% for a cut-off of 20 mm, with no false-positive results when a cut-off of MSD ≥ 21 mm was used. When an embryo was visible with an absent heartbeat, using a CRL cut-off of 4 mm the FPR for miscarriage was 8.3%, and for a CRL cut-off of 5 mm it was also 8.3%. There were no false-positive results using a CRL cut-off of ≥ 5.3 mm. These data show that some current definitions used to diagnose miscarriage are potentially unsafe. Current national guidelines should be reviewed to avoid inadvertent termination of wanted pregnancies. An MSD cut-off of > 25 mm and a CRL cut-off of > 7 mm could be introduced to minimize the risk of a false-positive diagnosis of miscarriage.

51 Accuracy of Emergency Physicians Using Ultrasound Measurement of Crown-Rump Length to Estimate Gestational Age in Pregnant Females

51 Accuracy of Emergency Physicians Using Ultrasound Measurement of Crown-Rump Length to Estimate Gestational Age in Pregnant Females

OP11.07: Practical biometry ratios of first trimester screening

We aimed to determine some practical contributive biometry ratios of the first trimester screening in order to note measurements more properly and recognise abnormal or mistaken measurements simultaneously. All medical records of singleton pregnancies whose 110–136 week gestational fetal screening was done between 2004–2010, were evaluated retrospectively. All singleton pregnancies with detected/suspicious anatomical or genetic fetal anomalies, any systemic disease, biochemical abnormalities, familial genetic diseases were excluded. The ratios of the measurements of biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL) and crown rump length (CRL) of included fetuses, to each other were calculated. The mean and standard deviations of the ratios were determined for each gestational weeks of 11 0–11 6, 12 0–12 6 and 13 0–13 6. A total of 1615 singleton pregnancies were included in the data analyses according to exclusion and inclusion criteria. Mean maternal age was 29.5 ± 4.6 years. Mean gestational age of the fetuses was 12.6 ± 0.6 weeks. Mean and standard deviation of the ratios are as follows; CRL/BPD: 3.0 ± 0.2; AC/BPD: 3.0 ± 0.2; CRL/AC: 1.0 ± 0.1; CRL/HC: 0.8 ± 0.1; CRL/FL: 8.8 ± 1.6; BPD/FL: 2.9 ± 0.6; AC/FL: 8.9 ± 1.6; HC/FL: 11.1 ± 2.2 and HC/AC: 1.3 ± 0.1. Among these ratios the standard deviation was small in the ratios of CRL/BPD, AC/BPD, CRL/AC, CRL/HC and HC/AC. Mean values of the ratios according to each gestational week are shown in the table. The ratios of CRL/BPD; AC/BPD and CRL/AC seems to be more practical to be used in the first trimester fetal ultrasonography practice to check for abnormal or mistaken measurements simultaneously. OP11.07: Table 1. Biometry Ratios

OP11.08: Nuchal translucency qualitative quality control in France. The CFEF (College Français d'Echographie Fœtale) five years experience

Methods: All medical records of singleton pregnancies whose 110–136 week gestational fetal screening was done between 2004–2010, were evaluated retrospectively. All singleton pregnancies with detected/suspicious anatomical or genetic fetal anomalies, any systemic disease, biochemical abnormalities, familial genetic diseases were excluded. The ratios of the measurements of biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL) and crown rump length (CRL) of included fetuses, to each other were calculated. The mean and standard deviations of the ratios were determined for each gestational weeks of 11 0–11 6, 12 0–12 6 and 13 0–13 6. Results: A total of 1615 singleton pregnancies were included in the data analyses according to exclusion and inclusion criteria. Mean maternal age was 29.5 ± 4.6 years. Mean gestational age of the fetuses was 12.6 ± 0.6 weeks. Mean and standard deviation of the ratios are as follows; CRL/BPD: 3.0 ± 0.2; AC/BPD: 3.0 ± 0.2; CRL/AC: 1.0 ± 0.1; CRL/HC: 0.8 ± 0.1; CRL/FL: 8.8 ± 1.6; BPD/FL: 2.9 ± 0.6; AC/FL: 8.9 ± 1.6; HC/FL: 11.1 ± 2.2 and HC/AC: 1.3 ± 0.1. Among these ratios the standard deviation was small in the ratios of CRL/BPD, AC/BPD, CRL/AC, CRL/HC and HC/AC. Mean values of the ratios according to each gestational week are shown in the table. Conclusions: The ratios of CRL/BPD; AC/BPD and CRL/AC seems to be more practical to be used in the first trimester fetal ultrasonography practice to check for abnormal or mistaken measurements simultaneously.