Gestational sac volume measured by three-dimensional ultrasound at 11 to 13 + 6 weeks of gestation: relation to chromosomal defects

Subchorionic Hematoma Volume Measured by Virtual Organ Computer-Aided Analysis in the Prediction of First-Trimester Pregnancy Outcome

ABSTRACT

This study aimed to assess the association of subchorionic hematoma (SCH) size measured by virtual organ computer-aided analysis (VOCAL) with the first-trimester pregnancy outcome. A total of 139 first-trimester pregnancies from 6 to 12 weeks of gestational age with SCH were included. The circumference, area, and volume of the SCH (Cs, As, and 3DVs) and gestational sac (Cg, Ag, and 3DVg) were automatically calculated by VOCAL. Interobserver agreement was assessed with the intraclass correlation coefficient and Bland-Altman plot. Odds ratios for the clinical and ultrasound characteristics of adverse pregnancy outcomes were estimated by univariate or multivariable logistic regression. There was high interobserver agreement in VOCAL measurements of the SCH and gestational sac (intraclass correlation coefficients, >0.900). By univariate regression analysis, women with adverse pregnancy outcomes were more likely to have vaginal bleeding, a larger As and 3DVs, and higher Cs/Cg, As/Ag, and 3DVs/3DVg ratios (all P < 0.05). In the multivariable regression analysis, a higher 3DVs/3DVg ratio of SCH (odds ratio, 1.034; 95% confidence interval [CI], 1.015-1.053; P = 0.000) and vaginal heavy bleeding had a significant positive relationship with the risk of adverse pregnancy outcomes (odds ratio, 7.846; 95% CI, 1.104-55.737; P = 0.039) remained associated with an increased risk of adverse pregnancy outcomes. With 11.87% as the cutoff, the receiver operating characteristic curve yielded a good predictive performance (area under the curve, 0.713) and high sensitivity (91.18%). The measurements of SCH by VOCAL provide high reliability for estimating the total hematoma burden in first-trimester pregnant patients. A greater volume proportion (3DVs/3DVg) of SCH worsens the pregnancy outcome, and a greater risk of adverse pregnancy outcome also associated with the severity of vaginal bleeding.

Amniotic Fluid INSL3 Measured During the Critical Time Window in Human Pregnancy Relates to Cryptorchidism, Hypospadias, and Phthalate Load: A Large Case-Control Study

The period of the first to second trimester transition in human pregnancy represents a sensitive window for fetal organogenesis, particularly in regard to the development of the male reproductive system. This is a time of relative analytical inaccessibility. We have used a large national biobank of amniotic fluid samples collected at routine amniocentesis to determine the impacts of exogenous endocrine disruptor load on specific fetal biomarkers at this critical time. While adrenal and testicular steroids are highly correlated, they are also mostly positively influenced by increasing phthalate load, represented by the metabolites 7cx-MMeHP and 5cx-MEPP, by perfluorooctane sulfonate (PFOS) exposure, and by smoking, suggesting an adrenal stress response. In contrast, the testis specific biomarkers insulin-like peptide 3 (INSL3) and androstenedione are negatively impacted by the phthalate endocrine disruptors. Using a case-control design, we show that cryptorchidism and hypospadias are both significantly associated with increased amniotic concentration of INSL3 during gestational weeks 13-16, and some, though not all steroid biomarkers. Cases are also linked to a specifically increased variance in the Leydig cell biomarker INSL3 compared to controls, an effect exacerbated by maternal smoking. No influence of phthalate metabolites or PFOS was evident on the distribution of cases and controls. Considering that several animal and human studies have shown a negative impact of phthalate load on fetal and cord blood INSL3, respectively, the present results suggest that such endocrine disruptors may rather be altering the relative dynamics of testicular development and consequent hormone production, leading to a desynchronization of tissue organization during fetal development. Being born small for gestational age appears not to impact on the testicular biomarker INSL3 in second trimester amniotic fluid.

Sonographic Measurement of Cervical Volume in Pregnant Women at High Risk of Preterm Birth Using a Geometric Formula for a Frustum Versus 3-Dimensional Automated Virtual Organ Computer-Aided Analysis

OBJECTIVES

To compare cervical volume measurements by 3-dimensional (3D) sonography using Virtual Organ computer-aided analysis (VOCAL; GE Healthcare, Milwaukee, WI) versus a manual method using a geometric formula for a frustum.

METHODS

We included 142 asymptomatic pregnant women at 16 to 24 weeks gestation at high risk for preterm birth. With a Voluson 730 Expert system (GE Healthcare), they underwent 2-dimensional (2D) transvaginal sonographic cervical length measurements and 3D cervical volume acquisition. The stored volumes were processed by VOCAL on a surface tablet. Cervical volume was manually calculated from the 2D images by using the formula V = 1/3 × π × h × (r1²  + r2²  + r1 × r2), where V represents cervical volume; π was approximated as 3.14159; h, cervical length; r1, radius at the internal os; and r2, radius at the external os.

RESULTS

Cervical volume was lower when obtained manually than by VOCAL, with a coefficient of variation of 30%, a mean difference of 10.1 ± 14.9 cm³ (P < .0001), and a poor interclass correlation coefficient of 0.62 (95% confidence interval [CI], 0.31 to 0.78). Both methods had good reproducibility; however, VOCAL had wider limits of agreement. A positive correlation was found between both methods (r = 0.63; P < .0001). No correlation was found between cervical length by 2D transvaginal ultrasound and cervical volume by the VOCAL technique (r = 0.06; 95% CI, -0.10 to 0.22) or cervical volume by the manual method (r = 0.2; 95% CI, 0.08 to 0.39).

CONCLUSIONS

The cervix represents a frustum (truncated cone, r1 is not equal to r2) in shape rather than a cylinder. Both methods are reproducible; VOCAL is less reliable but provides higher values of cervical volume.

First trimester pregnancy volumes and subsequent small for gestational age fetuses

OBJECTIVE

To examine whether in the first trimester, placental, gestational sac and fetal volumes are different in pregnancies that result in small for gestational age (SGA) compared to average for gestational age (AGA) neonates.

METHODS

Case-control study comparing first trimester 3D volumes of the placenta, the fetus and the gestational sac between SGA and AGA pregnancies. 3D volumes were acquired for quality assurance and documentation. Pregnancy volumes were calculated by the virtual organ computer-aided analysis technique. Linear regression analysis was used to compute a normal range for the placental, gestational sac and fetal volume based on the crown rump length (CRL) in AGA pregnancies. Multiple regression analysis was used to examine significant influencing covariates. A Student's t test was used to compare the difference between the SGA and AGA group.

RESULTS

The study population consisted of 19 first trimester pregnancies with subsequent SGA neonates and 105 control pregnancies. In the AGA group, all pregnancy volumes were significantly dependent on the CRL. After controlling the CRL effect, the placental, gestational sac and fetal volumes were not significantly different between the SGA and AGA group.

CONCLUSION

First trimester 3D pregnancy volume measurements are not different in SGA or AGA pregnancies.

Gestational sac fluid volume measurements in virtual reality

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSION

New charts for first-trimester GSFV were constructed using VR. These growth charts could be promising tools for studying normal and abnormal embryonic development.

Sonographic markers of aneuploidies at 6-10 weeks of gestation

OBJECTIVES

To determine if sonographic features of live embryos at 6-10 weeks' gestation are altered in aneuploidies.

METHODS

Embryonic crown rump length (CRL), embryonic heart rate, gestational sac diameter (GSD) and yolk sac diameter (YSD) were measured by transvaginal sonography in 5603 live embryos from singleton pregnancies at 6-10 weeks' gestation. The measurements were expressed as differences from the expected normal mean for CRL (delta values) and median delta values in the aneuploid cases were compared to the euploid group.

RESULTS

5393 pregnancies resulted in the live birth of phenotypically normal neonates and these cases constituted the euploid group. In 55 cases there was subsequent prenatal diagnosis of aneuploidies (trisomy 21, n=28; trisomy 18, n=10; trisomy 13, n=10; triploidy, n=4; Turner syndrome, n=3). The median and interquartile range (IQR) of delta embryonic heart rate in trisomy 18 was -19.44 (-23.77 to -7.20)bpm and in trisomy 13 it was 11.12 (7.25 to 20.39)bpm, which were significantly lower and higher, respectively, than in euploid embryos (median -0.05, IQR -6.18 to 6.21bpm). The median delta YSD in trisomy 21 was higher than in euploid fetuses (median 0.56, IQR 0.23 to 0.79 and median -0.17, IQR -3.11 to 2.82 mm). There were no other significant differences in measurements between the groups.

CONCLUSION

At 6-10 weeks' gestation there are sonographically detectable differences between euploid and trisomic embryos.

Prenatal sonographic features of fetuses in trisomy 13 pregnancies. IV

Prenatal ultrasound is a powerful tool to detect structural abnormalities associated with the fetuses in trisomy 13 pregnancies. This article provides a comprehensive review of the prenatal sonographic markers of trisomy 13 in the first trimester, including fetal nuchal translucency thickness, fetal heart rate, fetal nasal bone, fetal tricuspid regurgitation, ductus venous flow, fetal crown-rump length, fetal trunk and head volume, fetal frontomaxillary facial angle, gestational sac volume and umbilical cord diameter, along with biochemical markers such as maternal serum free beta-human chorionic gonadotropin, maternal serum pregnancy-associated plasma protein-A, maternal serum placental growth factor, and the fetal and total cell-free DNA concentration in the maternal circulation.

Comparison of inter- and intraobserver agreement and reliability between three different types of placental volume measurement technique (XI VOCAL, VOCAL and multiplanar) and validity in the in-vitro setting

OBJECTIVES

To compare XI VOCAL (eXtended Imaging Virtual Organ Computer-aided AnaLysis) for three-dimensional (3D) ultrasound volumetry of the placenta and of phantom objects with a rotational method using VOCAL and with the multiplanar method.

METHODS

We acquired 3D volume datasets from 32 fetuses at 11-14 weeks' gestation. Placental volume was calculated twice by each of two observers using XI VOCAL (with 5, 10, 15 and 20 slices), multiplanar (1-mm interval) and VOCAL (with 12 degrees, 18 degrees and 30 degrees rotation) methods. In addition, validity was assessed using the in-vitro setting with three phantom objects of known volume.

RESULTS

Both inter- and intraobserver reliabilities were very high for all three methods. There was no systematic bias between any two methods except between XI VOCAL (10 slices) and the multiplanar (1-mm interval) method, with a smaller volume using the former method. The limits of agreement were wide between any two of the three methods. In the in-vitro setting, there was a trend towards less valid measurements with the XI VOCAL technique and fewer slices. With the same number of steps, measurements made with VOCAL (12 degrees and 18 degrees) were more valid than were those made with XI VOCAL (15 and 10 slices, respectively).

CONCLUSION

XI VOCAL cannot be used interchangeably with VOCAL or multiplanar techniques in measuring placental volume at 11-14 weeks' gestation.

A novel technique for the semi-automated measurement of embryo volume: an intraobserver reliability study

The aim was to assess intraobserver reliability of a new semi-automated technique of embryo volumetry. Power calculations suggested 46 subjects with viable, singleton pregnancies were required for reliability analysis. Crown rump length (CRL) of each embryo was analyzed using 2-D and a 3-D dataset acquired using transvaginal ultrasound. Virtual organ computer-aided analysis (VOCAL) was used to calculate volume of gestation sac (GSV) and yolk sac (YSV) and SonoAVC (sonography-based automated volume count) was used to quantify fluid volume (FV). Embryo volume was calculated by subtracting FV and YSV from GSV. Each dataset was measured twice. Reliability was assessed using Bland-Altman plots and intraclass correlation coefficients (ICCs). Fifty-two datasets were analyzed. Median embryo volume was 1.8 cm(3) (0.1 to 8.1 cm(3)); median gestational age 7 + 4 weeks; median CRL 13 mm (2 to 29 mm). Mean difference of embryo volume measurements was 0.1cm(3) (limits of agreement [LOA] -0.3 to 0.4 cm(3)); multiples of mean (MoM) 0.38; mean difference of CRL measurements 0.3 mm (LOA -1.4 to 2.0 mm), MoM = 0.26. ICC for embryo volume was 0.999 (95%CI 0.998 to 0.999), confirming excellent intraobserver agreement. ICC for CRL was 0.996 (95%CI 0.991 to 0.998). Regression analysis showed good correlation between embryo volume and CRL (R(2) = 0.60). The new semi-automated 3-D technique provides reliable measures of embryo volume. Further work is required to assess the validity of this technique.

Gestational sac volume: comparison between SonoAVC and VOCAL measurements at 11 + 0 to 13 + 6 weeks of gestation

OBJECTIVES

To assess the novel three-dimensional (3D) tool, Sonography-based Automated Volume Count (SonoAVC) in the calculation of gestational sac volume at 11 + 0 to 13 + 6 weeks of gestation, to correlate the measurements with those obtained using Virtual Organ Computed-aided AnaLysis (VOCAL) and to study the reproducibility of SonoAVC volume calculation of this irregularly shaped structure.

METHODS

We acquired 3D volumes of the uterus in 65 pregnancies at 11 + 0 to 13 + 6 weeks of gestation. We performed volume calculation of the gestational sac, excluding the fetus and the placenta, using VOCAL with 15 degrees 12-step rotation. We then repeated the calculation with three different SonoAVC settings and compared both techniques. In 30 cases we assessed the reproducibility of the SonoAVC volume calculations.

RESULTS

In 95% of cases it was possible to calculate the gestational sac volume with SonoAVC. This volume increased with advancing gestation and the volumes were expressed as delta values to compare the measurements made with VOCAL and the three different SonoAVC settings. There was no difference between delta values of gestational sac volume calculated using VOCAL and SonoAVC with high and medium growth settings. Reproducibility analysis showed good results.

CONCLUSION

Gestational sac volume calculation is feasible with SonoAVC in most cases and does not differ from that performed using VOCAL. High and medium growth SonoAVC settings seem to be more accurate for gestational sac volume calculation, although larger studies are required for standardization of the technique. The reproducibility analysis showed similar results to those previously published.

Comparison of inter- and intraobserver agreement between three types of fetal volume measurement technique (XI VOCAL, VOCAL and multiplanar)

OBJECTIVES

To compare the new XI VOCAL (eXtended Imaging Virtual Organ Computer-aided Analysis) for three-dimensional (3D) ultrasound measurement of fetal volume with the conventional multiplanar technique and a rotational method using VOCAL.

METHODS

We acquired 3D volume datasets from 30 fetuses at 11-14 weeks of gestation using a commercially available ultrasound system. Fetal volume was calculated using XI VOCAL (with 5, 10, 15 and 20 slices), multiplanar (1-mm interval) and VOCAL (with 12 degrees, 18 degrees and 30 degrees rotation) techniques. The level of agreement for interobserver and intraobserver variability was determined and evaluated for all methods and reliability was assessed.

RESULTS

Fetal volume measurements obtained using XI VOCAL (10 slices) showed good correlation with those obtained using VOCAL (18 degrees) (r = 0.940, P = 0.076; intraclass correlation coefficient (ICC), 0.962 (95% CI, 0.920-0.982), P = 0.182), and XI VOCAL (15 slices) showed good correlation with VOCAL (12 degrees ) (r = 0.961, P = 0.092; ICC, 0.979 (95% CI, 0.957-0.990), P = 0.190). The mean difference between paired measurements by the XI VOCAL (10 slices) and VOCAL (18 degrees ) methods was 1.00 mL, while that by the XI VOCAL (15 slices) and VOCAL (12 degrees) methods was 0.90 mL. 95% limits of agreement were - 2.80 to 4.80 between XI VOCAL (10 slices) and VOCAL (18 degrees) and - 1.90 to 3.70 between XI VOCAL (15 slices) and VOCAL (12 degrees). There was a small difference in the time required to complete the fetal volume measurement between XI VOCAL and VOCAL when a similar number of slices or rotational steps was used (P < 0.05), XI VOCAL taking less time.

CONCLUSION

XI VOCAL (with 10, 15 and 20 slices) can be used interchangeably with the multiplanar technique (1-mm interval) for the measurement of fetal volume. XI VOCAL (10 slices) and VOCAL (18 degrees) can be used interchangeably, as can XI VOCAL (15 slices) and VOCAL (12 degrees), for the measurement of fetal volume.

Three-dimensional ultrasound in prenatal diagnosis

PURPOSE OF REVIEW

Several technological advances have greatly improved three-dimensional sonography, which have improved acquisition and display capabilities. This review describes these technical changes as well as current applications of 3D sonography in prenatal diagnosis.

RECENT FINDINGS

Recently published papers have emphasized the potential of getting a precise 'any plane of choice' from a three-dimensional volume, as a new way of scanning, based on the off-line analysis of a volume dataset. Surface mode has been used to demonstrate malformations and genetic diseases. The maximum rendering mode, which highlights bones, has great potential for imaging the nasal bones and the frontal bones with the metopic suture. Organ volume can be measured, but the utility of this in clinical practice remains to be determined. Three-dimensional ultrasound needs to be standardized.

SUMMARY

Three-dimensional ultrasonography is the most rapidly developing technique in fetal imaging. New features will permit the transition from the era of 'sonography in two-dimensional planes' to 'volume ultrasound'.

Three-dimensional sonographic volumetry of the gestational sac and the amniotic sac in the first trimester

OBJECTIVE

The purpose of this study was to measure the volumes of the gestational sac and amniotic sac in normal pregnancies during the first trimester with 3-dimensional sonography to prepare nomograms.

METHODS

One hundred fifty-one patients between 6 and 12 weeks' gestation were studied. Nine aborted and were excluded, leaving 142 patients for evaluation. Inclusion criteria were a singleton viable pregnancy shown by transvaginal sonography and continuation of the pregnancy beyond 24 weeks. Women with known thrombophilia or fetal malformations were excluded. In all patients, gestational sac and amniotic sac volumes were measured by 3-dimensional transvaginal sonography with virtual organ computer-aided analysis software.

RESULTS

The mean gestational sac volume was 20.35 mL (range, 0.7-113 mL) and correlated closely with the gestational age (GA) (r2 = 0.769; P << .001) and crown-rump length (CRL) (r2 = 0.823; P << .001). The mean amniotic sac volume was 3.69 mL (range, 0.01-92.1 mL) and also had a strong correlation with the GA (r2 = 0.869; P << .001) and CRL (r2 = 0.919; P << .001).

CONCLUSIONS

Gestational sac and amniotic sac volumes show excellent correlation with the GA and CRL and hence may be used for determining the GA. Larger studies are needed to determine the importance of these volumes in predicting normal pregnancy outcomes and whether these volumes can be used in the management of pregnancies at risk for abortion.

How useful is 3D and 4D ultrasound in perinatal medicine?

AIM

The purpose of this paper is to review and analyze the published literature on the use of three-dimensional (3DUS) and four-dimensional (4DUS) ultrasound in perinatal medicine.

METHODS

We systematically searched Medline through PubMED (January 2000-January 2006), including EMBASE/Excerpta Medica database as well as the Cochrane Database of Systematic Reviews. The search terms used to identify clinical application of 3DUS and 4DUS studies in perinatal medicine were technical development, special features, and recommendation for fetal imaging, research on 3DUS or 4DUS, and the usage of invasive 3DUS or 4DUS procedures. The reference bibliographies of relevant books were also manually searched for supplementary citations. Inclusion criteria were as follows: (1) studies related to the use of 3DUS or 4DUS in perinatal medicine; (2) full text were available in English; (3) publication format of original scientific articles, case reports, editorials or literature reviews and chapters in the books.

RESULTS

Five hundred and seventy-five articles were identified, and among those, 438 were relevant to this review.

CONCLUSIONS

3DUS and 4DUS provided additional information for the diagnosis of facial anomalies, evaluation of neural tube defects, and skeletal malformations. Additional research is needed to determine the clinical utility of 3DUS and 4DUS for the diagnosis of congenital heart disease, central nervous system (CNS) anomalies and detection of fetal neurodevelopmental impairment assessed by abnormal behavior in high-risk fetuses.

Three and four-dimensional ultrasound in obstetrics and gynecology

PURPOSE OF REVIEW

Developments in ultrasound in general, but even more so in three-dimensional ultrasound, parallel the growth in computing power and speed of computer technology. It is not surprising, therefore, that three-dimensional ultrasound technology is constantly evolving at a fast pace. The purpose of this article is to provide enhanced diagnostic capabilities for the obstetrical and gynecologic provider.

RECENT FINDINGS

The most recent advances in three-dimensional ultrasound have to do with two main features. First, an increasingly fast acquisition speed, enabling quick sequences of fast moving organs such as the heart to be captured. Second, the increasing number of different display modalities, making understanding and analysis of normal anatomy and pathology easier for clinicians.

SUMMARY

This article highlights a selected number of clinical situations in which three-dimensional ultrasound meaningfully enhances the contribution of this fast evolving diagnostic imaging tool.

Quantitative and morphological assessment of early gestational sacs using three-dimensional ultrasonography

OBJECTIVE

Our main objective was to determine the value of three-dimensional ultrasonography (3DUS) and Virtual Organ Computer-aided AnaLysis (VOCAL) in the evaluation of gestational sac volume and morphology during early pregnancy.

METHODS

Twenty-eight normal early pregnancies were scanned approximately every 2 weeks using transabdominal (TAS) and transvaginal (TVS) sonography. The VOCAL technique was used to create computerized surface models to classify gestational sac shapes as discoid or ellipsoid. Serial sac volume changes were analyzed using repeated measures ANOVA. Bland-Altman plots determined examiner bias and limits of agreement (LOA) for sac volume measurements. Gestational sac volumes were compared between the two-dimensional (2D) ellipsoid and VOCAL techniques. Differences between volume measurements were tested using the two-tailed paired t-test with statistical significance at the P < 0.05 level.

RESULTS

Each subject was examined at a mean +/- SD menstrual age of 7.9 +/- 0.6 weeks (Scan 1), 9.9 +/- 0.6 weeks (Scan 2), and 11.9 +/- 0.6 weeks (Scan 3). Sac volumes significantly increased over time from 22 +/- 11 mL at Scan 1, to 57 +/- 21 mL at Scan 2 and 116 +/- 35 mL at Scan 3 (P < 0.001). Predominant sac shapes were classified as ellipsoid (76.2%) or discoid (23.8%). Additional descriptors included: concave (60.7%), irregular (53.6%), or smooth (7.1%), with 19% of the overall group having more than one additional shape attribute. Clinically acceptable volume measurement bias and agreement were found for the following comparisons: (1) TAS versus TVS; (2) interobserver volume measurements; and (3) intraobserver volume measurements. The VOCAL technique yielded slightly greater sac volumes (64 +/- 45.4 mL) when compared to the 2D ellipsoid model (48.6 +/- 36.8 mL) (28.9 +/- 24.3% (95% limit of agreement range, - 18.7 to 76.5%), P < 0.001).

CONCLUSIONS

Reproducible sac volume measurements can be obtained using VOCAL with either TAS or TVS. Early gestational sacs variably appear as discoid or ellipsoid structures with a concave indentation from the placenta. Sac volumes can be underestimated if an ellipsoid shape is assumed. Morphological and quantitative analysis of the gestational sac may provide baseline parameters for studying patients at risk for early pregnancy failure.

Three- and 4-dimensional ultrasound in obstetric practice: does it help?

OBJECTIVE

The purpose of this article was to review the published literature on 3-dimensional ultrasound (3DUS) and 4-dimensional ultrasound (4DUS) in obstetrics and determine whether 3DUS adds diagnostic information to what is currently provided by 2-dimensional ultrasound (2DUS) and, if so, in what areas.

METHODS

A PubMed search was conducted for articles reporting on the use of 3DUS or 4DUS in obstetrics. Seven-hundred six articles were identified, and among those, 525 were actually related to the subject of this review. Articles describing technical developments, clinical studies, reviews, editorials, and studies on fetal behavior or maternal-fetal bonding were reviewed.

RESULTS

Three-dimensional ultrasound provides additional diagnostic information for the diagnosis of facial anomalies, especially facial clefts. There is also evidence that 3DUS provides additional diagnostic information in neural tube defects and skeletal malformations. Large studies comparing 2DUS and 3DUS for the diagnosis of congenital anomalies have not provided conclusive results. Preliminary evidence suggests that sonographic tomography may decrease the examination time of the obstetric ultrasound examination, with minimal impact on the visualization rates of anatomic structures.

CONCLUSIONS

Three-dimensional ultrasound provides additional diagnostic information for the diagnosis of facial anomalies, evaluation of neural tube defects, and skeletal malformations. Additional research is needed to determine the clinical role of 3DUS and 4DUS for the diagnosis of congenital heart disease and central nervous system anomalies. Future studies should determine whether the information contained in the volume data set, by itself, is sufficient to evaluate fetal biometric measurements and diagnose congenital anomalies.

Fetal trunk and head volume measured by three-dimensional ultrasound at 11 + 0 to 13 + 6 weeks of gestation in chromosomally normal pregnancies

OBJECTIVE

To establish the relationship between fetal trunk and head volume measured by three-dimensional (3D) ultrasound and gestational age at 11 + 0 to 13 + 6 weeks of gestation.

METHODS

The fetal trunk and head volume were measured using 3D ultrasound in 417 chromosomally normal fetuses from singleton pregnancies at 11 + 0 to 13 + 6 (median, 12 + 0) weeks of gestation. Regression analysis was used to determine the significance of the association between fetal volume and gestational age. The Bland-Altman analysis was used to compare the measurement agreement and bias for a single examiner and between different examiners.

RESULTS

The fetal trunk and head volume increased linearly with gestation from a mean of 5.8 mL at 11 + 0 weeks to 33.3 mL at 13 + 6 weeks and 1 SD was 4.4 mL. There was also a significant linear association between fetal volume and crown-rump length (CRL), from a mean of 5.1 mL at a CRL of 45 mm to 37.5 mL at a CRL of 84 mm and 1 SD was 2.7 mL. However, within this gestational range, a doubling in CRL, from a mean of 48 mm at 11 + 0 weeks to 79 mm at 13 + 6 weeks, was associated with a 5-6-fold increase in fetal volume. The mean difference in fetal volume between paired measurements by the same sonographer was -0.87 mL (95% limits of agreement, -2.31 to 4.05 mL) and the mean difference between paired measurements by two sonographers was -1.09 mL (-5.49 to 3.32 mL).

CONCLUSIONS

3D ultrasound can provide a reproducible measurement of the fetal trunk and head volume in early pregnancy. At between 11 + 0 and 13 + 6 weeks there is a 5-6-fold increase in fetal volume but only a doubling in CRL.

Placental volume measured by three-dimensional ultrasound at 11 to 13 + 6 weeks of gestation: relation to chromosomal defects

OBJECTIVE

To determine the potential value of measuring the placental volume at 11 to 13 + 6 weeks of gestation in screening for chromosomal defects.

METHODS

The placental volume was measured using three-dimensional ultrasound in 500 consecutive singleton pregnancies immediately before chorionic villus sampling for fetal karyotyping at 11 to 13 + 6 (median, 12) weeks of gestation.

RESULTS

The fetal karyotype was normal in 417 pregnancies and abnormal in 83. In the chromosomally normal group the mean placental volume increased significantly with gestation from a mean of 51 mL (5th and 95th centiles: 31.2 and 82.4 mL) at 11 weeks to 91 mL (5th and 95th centiles: 55.7 and 147.2 mL) at 13 + 6 weeks. In the chromosomally abnormal group the mean placental volume for gestational age was not significantly different from normal in trisomy 21 and Turner syndrome, but it was smaller in trisomies 13 and 18.

CONCLUSIONS

The measurement of the placental volume at 11 to 13 + 6 weeks of gestation is unlikely to be a useful predictor of the major chromosomal defects. In trisomies 13 and 18 the small placental volume may be due to early-onset fetal growth restriction, which could be the consequence of impaired placental function.