First-trimester, three-dimensional transvaginal ultrasound volumetry in normal pregnancies and spontaneous miscarriages (original) (raw)
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Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology, 2011
ObjectivesThere 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.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.MethodsThis 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.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.ResultsOf 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.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.ConclusionsThese 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.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.
Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology, 2011
ObjectivesWe studied changes in mean gestational sac diameter (MSD) and embryonic crown–rump length (CRL) in intrauterine pregnancies of uncertain viability (IPUVs). We aimed to establish cut-off values for MSD and CRL growth that could be definitively associated with either viability or miscarriage, and to establish the relationship between growth in MSD and appearance of embryonic structures in the gestational sac.We studied changes in mean gestational sac diameter (MSD) and embryonic crown–rump length (CRL) in intrauterine pregnancies of uncertain viability (IPUVs). We aimed to establish cut-off values for MSD and CRL growth that could be definitively associated with either viability or miscarriage, and to establish the relationship between growth in MSD and appearance of embryonic structures in the gestational sac.MethodsOne thousand and sixty consecutive IPUVs were recruited prospectively from four London University hospitals: 462 with no yolk sac or embryo, 419 with a yolk sac but no embryo, and 179 with an embryo but no heartbeat visible. IPUV was defined as an empty gestational sac with or without a yolk sac but no embryo seen with MSD < 20 or < 30 mm (depending on center) or an embryo with no heartbeat and CRL < 6 mm or < 8 mm (depending on center). Scans were repeated 7–14 days later. The endpoint was viability at first-trimester screening ultrasonography between 11 and 14 weeks. Change in MSD and CRL between the first and second scans of each pregnancy was compared with respect to viability and appearance of embryonic structures using the two-sample t-test.One thousand and sixty consecutive IPUVs were recruited prospectively from four London University hospitals: 462 with no yolk sac or embryo, 419 with a yolk sac but no embryo, and 179 with an embryo but no heartbeat visible. IPUV was defined as an empty gestational sac with or without a yolk sac but no embryo seen with MSD < 20 or < 30 mm (depending on center) or an embryo with no heartbeat and CRL < 6 mm or < 8 mm (depending on center). Scans were repeated 7–14 days later. The endpoint was viability at first-trimester screening ultrasonography between 11 and 14 weeks. Change in MSD and CRL between the first and second scans of each pregnancy was compared with respect to viability and appearance of embryonic structures using the two-sample t-test.ResultsThe study included 359 pregnancies in which a gestational sac with or without embryo was identified at the follow-up scan 7–14 days later. Of these, 192 were viable and 167 non-viable at the 11–14-week scan. MSD growth was significantly higher in viable than non-viable pregnancies (mean 1.003 vs. 0.503 mm/day; P < 0.001, 95% CI of difference 0.403–0.596). A difference in CRL growth was found between the two groups (mean 0.673 vs. 0.148 mm/day; P < 0.001, 95% CI of difference 0.345–0.703). MSD growth of 0.6 mm/day was associated with a specificity for diagnosing miscarriage of 90.1%, a sensitivity of 61.7% and 19 false-positive test results. A cut-off of CRL growth rate of 0.2 mm/day gave a sensitivity of 76.3% and there were no false-positive test results for miscarriage. On repeat scan the failure of either a yolk sac or embryo to be visualized was always associated with miscarriage.The study included 359 pregnancies in which a gestational sac with or without embryo was identified at the follow-up scan 7–14 days later. Of these, 192 were viable and 167 non-viable at the 11–14-week scan. MSD growth was significantly higher in viable than non-viable pregnancies (mean 1.003 vs. 0.503 mm/day; P < 0.001, 95% CI of difference 0.403–0.596). A difference in CRL growth was found between the two groups (mean 0.673 vs. 0.148 mm/day; P < 0.001, 95% CI of difference 0.345–0.703). MSD growth of 0.6 mm/day was associated with a specificity for diagnosing miscarriage of 90.1%, a sensitivity of 61.7% and 19 false-positive test results. A cut-off of CRL growth rate of 0.2 mm/day gave a sensitivity of 76.3% and there were no false-positive test results for miscarriage. On repeat scan the failure of either a yolk sac or embryo to be visualized was always associated with miscarriage.ConclusionThere is an overlap in MSD growth rates between viable and non-viable IPUV. No cut-off exists for MSD growth below which a viable pregnancy could be safely excluded. A cut-off value for CRL growth of 0.2 mm/day was always associated with miscarriage. These data suggest that criteria to diagnose miscarriage based on growth in MSD and CRL are potentially unsafe. However, finding an empty gestational sac on two scans more than 7 days apart is highly likely to indicate miscarriage, irrespective of growth. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.There is an overlap in MSD growth rates between viable and non-viable IPUV. No cut-off exists for MSD growth below which a viable pregnancy could be safely excluded. A cut-off value for CRL growth of 0.2 mm/day was always associated with miscarriage. These data suggest that criteria to diagnose miscarriage based on growth in MSD and CRL are potentially unsafe. However, finding an empty gestational sac on two scans more than 7 days apart is highly likely to indicate miscarriage, irrespective of growth. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Journal of Clinical Ultrasound, 2012
Purpose. To determine whether gestational sac volume (GSV) or amniotic sac volume (ASV) and/or the difference between them can predict abortion in women with first-trimester threatened abortion. Methods. Ninety patients between 6 and 12 weeks of gestation presenting with vaginal bleeding were studied. Seventy-six delivered after 24 weeks of gestation (group A) and 14 aborted before 20 weeks of gestation (group B). All patients had a singleton viable pregnancy demonstrated by transvaginal ultrasound. Gestational sac and amniotic sac volumes were measured in all the patients using three-dimensional transvaginal ultrasound with Virtual Organ Computer-aided Analysis software, and the gestational sac volume 2 amniotic sac volume (GSV 2 ASV) was calculated. Results. The groups did not differ in terms of age, parity, number of previous abortions, or term deliveries. The GSV (group A: mean 32.0 6 27.7 cm 3 ; group B: 26.7 6 29.1 cm 3) and the ASV (group A: 21.1 6 25.5 cm 3 ; group B: 20.6 6 26.0 cm 3) were not statistically different, while the GSV 2 ASV was significantly smaller in group B (aborting before week 20) (group A
Expert Review of Obstetrics & Gynecology, 2012
First-trimester prediction of intrauterine growth restriction (IUGR), preeclampsia (PE), birthweight, aneuploidy, miscarriage, complications in multiple pregnancies and homozygous a 0-thalassemia is a challenging and emerging field. Placenta volumes (PV) and embryo volume/fetal volume ratios are correlated with crown-rump length (CRL) or gestational age. Measurement of PV or placental quotient (PV/CRL ratio) is an early method to identify impaired trophoblast invasion and predict subsequent development of IUGR or PE. In early-onset IUGR caused by triploidy, or trisomy 13 or 18, a larger deficit in fetal volume than CRL is observed. Fetal and placental volume measurements may be applied to predict other conditions such as aneuploidy, miscarriage or stillbirth. Standardization of the 3D volumetric methodology is needed to improve reproducibility of measurement. Further studies are required to determine the use of first-trimester volumetry alone or in combination with Doppler ultrasound and other parameters to achieve the best predictive models for IUGR and PE.
BMC Pregnancy and Childbirth, 2012
Background: First trimester growth restriction is associated with an increased risk of adverse birth outcomes (preterm birth, low birth weight and small for gestational age at birth). The differences between normal and abnormal growth in early pregnancy are small if the fetal size is measured by the crown-rump-length. Three-dimensional ultrasound volume measurements might give more information about fetal development than two-dimensional ultrasound measurements. Detection of the fetus with a small fetal volume might result in earlier detection of high risk pregnancies and a better selection of high risk pregnancies. Methods: A prospective cohort study, performed at the Máxima Medical Centre, in Eindhoven-Veldhoven, the Netherlands. During the routine first trimester scan with nuchal translucency measurement 500 fetal volumes will be obtained. The gestational age is based on the first day of the last menstrual period in a regular menstrual cycle and by the crown-rumplength. The acquired datasets are collected and stored on a hard disk for offline processing and volume calculation. The investigator who performs the volume measurements is blinded for the results of the first trimester scan. The manual mode will be used to outline the Region Of Interest, the fetal head and rump, in all cross sections. The fetal volumes are calculated with a rotational step of 9°. First, the relation between fetal volume and gestational age, for a set of participants with normal pregnancies (training set), will be assessed. This model will then be used to determine expected values of fetal volume for a normal pregnancy, which will be referred to as expected normal values. Secondly, for a new set of participants with normal pregnancies and a set of participants with complicated pregnancies (together defined as validation set), the observed fetal volumes (FV observed) are compared with their expected normal values (FV expected) and expressed as a percentage of the expected normal value. The mean difference in percentage error between the set of normal versus complicated pregnancies will then be compared using the independent-samples t-test. Finally, logistic regression analysis will be applied to the validation set of participants to analyze the possibility of predicting the pregnancy outcome after fetal volume calculation in the first trimester, using this percentage error. Discussion: After this study it is clear whether FV measurement in the first trimester can detect high risk pregnancies. If it is possible to detect these pregnancies, more intensive follow up in these pregnancies might result in fewer complicated pregnancies and fewer fetal morbidities.
Ultrasound in Obstetrics and Gynecology, 2007
Objective To identify ultrasound measurements that are the best predictors of the presence of retained products of conception (RPOC) within the uterine cavity in women with clinical diagnosis of incomplete miscarriage. Methods This was a prospective observational study, set in a dedicated early pregnancy assessment unit in a London teaching hospital. Endometrial thickness and the volume of suspected retained products of conception were measured by transvaginal ultrasound scan preoperatively. Indications for surgical intervention were heavy vaginal bleeding or continuous bleeding lasting > 7 days. The main outcome measure was histological evidence of chorionic villi in surgical specimens. Results Among the patients, 109 (85%) had evidence of chorionic villi on histology, whilst decidua was only found in the remaining 19 (15%). There was no identifiable cutoff for endometrial thickness or volume that could be used to differentiate between retained products of conception and decidua. Conclusion Measurements of endometrial thickness or volume on ultrasound scan are not good tests for diagnosing an incomplete miscarriage.
The application of first-trimester volumetry in predicting pregnancy complications
Journal of Basic and Clinical Reproductive Sciences, 2014
The application of first trimester volumetry in predicting pregnancy complications is a promising and interesting field in Obstetrics and Radiology. This was a descriptive review of first trimester volumetry in predicting pregnancy complications over a period of 6 months (January 1 st , 2013 to June 30 th , 2013). A search of literature on first trimester volumetry published in English was conducted. Relevant materials on first trimester volumetry were selected. Placenta volumes (PV) and embryo volume/fetal volume ratios in the first trimester are correlated with crown rump length (CRL) or gestational age (GA). Measurement of PV or placental quotient (PV/CRL ratio) is an early assessment to identify impaired trophoblast invasion and predict subsequent development of intrauterine growth restriction (IUGR) or pre-eclampsia (PE). In early onset IUGR due to triploidy, or trisomy 13 or 18, a larger deficit in fetal volume is observed compared to CRL. In obstetric sonography, standardization of the 3D volumetric methodology is needed to improve reproducibility of measurement. The accuracy of these measurements is uncertain and current applicability to practice is not fully accepted, therefore, the current methods are yet to be standardized and general applicability is uncertain. Volumetry holds a good promise as an extra method for predicting IUGR, PE, aneuploidy, miscarriages, or stillbirth but lack of standardization currently limits its applicability.
Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology, 2011
ObjectivesTo assess intra- and interobserver agreement of routinely performed measurements—crown–rump length (CRL) and mean gestational sac diameter (MSD)—for assessing the likelihood of miscarriage in the first trimester of pregnancy using transvaginal sonography.To assess intra- and interobserver agreement of routinely performed measurements—crown–rump length (CRL) and mean gestational sac diameter (MSD)—for assessing the likelihood of miscarriage in the first trimester of pregnancy using transvaginal sonography.MethodsA cross-sectional study of CRL and gestational sac measurements in first-trimester pregnancies was conducted in a fetal medicine referral center with a predominantly Caucasian population. Gestational age ranged from 6 to 9 weeks. All patients underwent a transvaginal ultrasound examination using a high-resolution ultrasound machine. Two measurements of CRL and measurements of three diameters of the gestational sac were obtained by two observers. Agreement within and between observers for CRL and between observers for MSD was analyzed using 95% prediction intervals, Bland–Altman plots with 95% limits of agreement and the intraclass correlation coefficient (ICC).A cross-sectional study of CRL and gestational sac measurements in first-trimester pregnancies was conducted in a fetal medicine referral center with a predominantly Caucasian population. Gestational age ranged from 6 to 9 weeks. All patients underwent a transvaginal ultrasound examination using a high-resolution ultrasound machine. Two measurements of CRL and measurements of three diameters of the gestational sac were obtained by two observers. Agreement within and between observers for CRL and between observers for MSD was analyzed using 95% prediction intervals, Bland–Altman plots with 95% limits of agreement and the intraclass correlation coefficient (ICC).ResultsIn total 54 patients were included in the study, with measurements obtained by both observers in 44 of these. Intra- and interobserver ICCs were high for CRL measurements, with values of 0.992 and 0.993 for intraobserver agreement and 0.993 for interobserver agreement. For the MSD, the interobserver ICC was 0.952. Limits of agreement were ± 8.91 and ± 11.37% for intraobserver agreement of CRL and ± 14.64% for interobserver agreement of CRL. For MSD, the interobserver limits of agreement were ± 18.78%. For an MSD measurement of 20 mm by the first observer, the prediction interval for the second observer was 16.8–24.5 mm. For a CRL measurement of 6 mm, the prediction interval for the second observer was 5.4–6.7 mm.In total 54 patients were included in the study, with measurements obtained by both observers in 44 of these. Intra- and interobserver ICCs were high for CRL measurements, with values of 0.992 and 0.993 for intraobserver agreement and 0.993 for interobserver agreement. For the MSD, the interobserver ICC was 0.952. Limits of agreement were ± 8.91 and ± 11.37% for intraobserver agreement of CRL and ± 14.64% for interobserver agreement of CRL. For MSD, the interobserver limits of agreement were ± 18.78%. For an MSD measurement of 20 mm by the first observer, the prediction interval for the second observer was 16.8–24.5 mm. For a CRL measurement of 6 mm, the prediction interval for the second observer was 5.4–6.7 mm.ConclusionFor dating purposes, there is reasonable reproducibility of CRL measurements using transvaginal ultrasonography at 6–9 weeks' gestation. When diagnosing miscarriage based on measurements of CRL care must be taken for values close to any decision boundary. The higher interobserver variability that we observed for MSD has implications for the diagnosis of miscarriage based on this measurement in the absence of a visible embryo or yolk sac. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.For dating purposes, there is reasonable reproducibility of CRL measurements using transvaginal ultrasonography at 6–9 weeks' gestation. When diagnosing miscarriage based on measurements of CRL care must be taken for values close to any decision boundary. The higher interobserver variability that we observed for MSD has implications for the diagnosis of miscarriage based on this measurement in the absence of a visible embryo or yolk sac. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Ultrasound in Obstetrics and Gynecology, 2003
Objective This was a prospective observational cohort study to evaluate the outcome and prognostic criteria of pregnancies with first-trimester bleeding and a gestational sac ≤ 16 mm without a demonstrable embryo. Methods Criteria for admission into the study included: (1) first-trimester bleeding; (2) a transvaginal scan performed upon admission demonstrating a single intrauterine gestational sac with a mean diameter ≤ 16 mm and without a demonstrable embryo. The outcome variable was miscarriage, defined as pregnancy loss prior to 22 weeks. The following explanatory variables were considered: maternal age, menstrual age, size of the gestational sac, presence or absence of the yolk sac and subchorionic hematoma, and β-human chorionic gonadotropin levels. The relationship of these variables with pregnancy failure was analyzed by stepwise logistic regression. Results Of 50 patients, 32 (64%) underwent miscarriage. The receiver-operating characteristics (ROC) curve of the size of the gestational sac demonstrated a high level of statistical significance (area under the ROC curve 0.9080, P < 0.000001) and stepwise logistic regression revealed that this was the only variable independently correlated with the subsequent occurrence of miscarriage. Discussion It is commonly accepted that in pregnant patients with first-trimester bleeding, demonstration by transvaginal ultrasound of an intrauterine gestational sac ≤ 16 mm without an embryo may be compatible with a viable pregnancy. Our results suggest that in general this finding is associated with a poor outcome, with miscarriage occurring in two-thirds of patients. When the sac is small for gestational age, the risk of miscarriage is greatly increased. In the present series, a gestational sac diameter less than − 1.34 standard deviations of the mean was associated with pregnancy failure in over 90% of cases.