Safe use of Doppler ultrasound during the 11 to 13 + 6-week scan: is it possible?

Learning deep architectures for the interpretation of first-trimester fetal echocardiography (LIFE) - a study protocol for developing an automated intelligent decision support system for early fetal echocardiography

BACKGROUND

Congenital Heart Disease represents the most frequent fetal malformation. The lack of prenatal identification of congenital heart defects can have adverse consequences for the neonate, while a correct prenatal diagnosis of specific cardiac anomalies improves neonatal care neurologic and surgery outcomes. Sonographers perform prenatal diagnosis manually during the first or second-trimester scan, but the reported detection rates are low. This project's primary objective is to develop an Intelligent Decision Support System that uses two-dimensional video files of cardiac sweeps obtained during the standard first-trimester fetal echocardiography (FE) to signal the presence/absence of previously learned key features.

METHODS

The cross-sectional study will be divided into a training part of the machine learning approaches and the testing phase on previously unseen frames and eventually on actual video scans. Pregnant women in their 12-13 + 6 weeks of gestation admitted for routine first-trimester anomaly scan will be consecutively included in a two-year study, depending on the availability of the experienced sonographers in early fetal cardiac imaging involved in this research. The Data Science / IT department (DSIT) will process the key planes identified by the sonographers in the two- dimensional heart cine loop sweeps: four-chamber view, left and right ventricular outflow tracts, three vessels, and trachea view. The frames will be grouped into the classes representing the plane views, and then different state-of-the- art deep-learning (DL) pre-trained algorithms will be tested on the data set. The sonographers will validate all the intermediary findings at the frame level and the meaningfulness of the video labeling.

DISCUSSION

FE is feasible and efficient during the first trimester. Still, the continuous training process is impaired by the lack of specialists or their limited availability. Therefore, in our study design, the sonographer benefits from a second opinion provided by the developed software, which may be very helpful, especially if a more experienced colleague is unavailable. In addition, the software may be implemented on the ultrasound device so that the process could take place during the live examination.

TRIAL REGISTRATION

The study is registered under the name "Learning deep architectures for the Interpretation of Fetal Echocardiography (LIFE)", project number 408PED/2020, project code PN-III-P2-2.1-PED-2019.

TRIAL REGISTRATION

ClinicalTrials.gov , unique identifying number NCT05090306, date of registration 30.10.2020.

First Trimester Tricuspid Regurgitation: Clinical Significance

Tricuspid regurgitation is a cardiac valvular anomaly that consists of the return of blood to the right atrium during systole due to incomplete valve closure. This structure can be visualized on ultrasound between 11 and 14 weeks of gestation in most cases. Despite being a common finding, even in healthy fetuses, the presence of tricuspid regurgitation may be associated with chromosomal and structural abnormalities. The evaluation of tricuspid flow and the presence of regurgitation on first-trimester ultrasound has shown promising results regarding its role in the early detection of aneuploidies, congenital heart defects, and other adverse perinatal outcomes. This review article aims to demonstrate the importance of tricuspid regurgitation as a secondary marker, and consequently, significant benefits of its early detection when added to the combined first-trimester screening. Its value will be discussed, namely its sensitivity and specificity, alone and together with other current markers in the fetal assessment performed in the first-trimester ultrasound.

The diagnostic value of the early extended fetal heart examination at 13 to 14 weeks gestational age in a high-risk population

BACKGROUND

Congenital heart disease (CHD) is the most common congenital malformation that affects high-risk populations. A more definite heart diagnosis in the first trimester should be provided to guide clinical treatment. The study aim was to evaluate the diagnostic precision of the early extended fetal heart examination (EFHE) that includes abdominal situs view, four-chamber view (4CV), left ventricular outflow tract view (LVOT), right ventricular outflow tract view (RVOT), 3-vessel and tracheal view (3VT), ductal arch view, and the aortic arch view in the detection of CHD at the gestational age (GA) 13 to 14 weeks in a population with high risks.

METHODS

This study was a diagnostic test study. EFHE was performed by transabdominal sonography in women at GA 13 to 14 weeks with singleton pregnancies who were at high risk for CHD. The risk of CHD was determined by family history of CHD, rubella infection, metabolic disorders, exposure to teratogens, conception by in-vitro fertilization (IVF), increased nuchal translucency (NT) thickness, abnormal obstetric ultrasound, etc. The operator had more than 5 years of experience in first-trimester scans and fetal echocardiography. Early scans were compared with a fetal echocardiography in the second trimester (16-24 weeks).

RESULTS

EFHE was performed, and the pregnancy outcomes were obtained in 234 single pregnancies with a high risk of CHD. The average crown-rump length (CRL) was (76.17±7.09) mm. CHD was diagnosed in 43 cases by EFHE; 10 of these cases were misdiagnosed, and 2 cases were missed. Four cases were inconsistent in the main diagnosis of CHD. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and kappa coefficient (Ko) value of EFHE in diagnosing CHD by type and severity was 84.6% [95% confidence interval (CI), 69.5-94.1%], 96.9% (95% CI, 93.4-98.9%), 84.6% (95% CI, 69.5-94.1%), 96.9% (95% CI, 93.4-98.9%), and 0.82 (P<0.001), respectively.

CONCLUSIONS

EFHE can work as a diagnose examination for most major CHD cases at GA 13 to 14 weeks by an experienced operator; Therefore, this diagnostic system for fetal CHD may be applied in the first trimester. The study has been registered in the Chinese Clinical Trial Registry (www.chictr.org.cn). The registration number is ChiCTR2000038451.

In vitro characterisation of ultrasound-induced heating effects in the mother and fetus: A clinical perspective

INTRODUCTION

The quantification of heating effects during exposure to ultrasound is usually based on laboratory experiments in water and is assessed using extrapolated parameters such as the thermal index. In our study, we have measured the temperature increase directly in a simulator of the maternal-fetal environment, the 'ISUOG Phantom', using clinically relevant ultrasound scanners, transducers and exposure conditions.

METHODS

The study was carried out using an instrumented phantom designed to represent the pregnant maternal abdomen and which enabled temperature recordings at positions in tissue mimics which represented the skin surface, sub-surface, amniotic fluid and fetal bone interface. We tested four different transducers on a commercial diagnostic scanner. The effects of scan duration, presence of a circulating fluid, pre-set and power were recorded.

RESULTS

The highest temperature increase was always at the transducer-skin interface, where temperature increases between 1.4°C and 9.5°C were observed; lower temperature rises, between 0.1°C and 1.0°C, were observed deeper in tissue and at the bone interface. Doppler modes generated the highest temperature increases. Most of the heating occurred in the first 3 minutes of exposure, with the presence of a circulating fluid having a limited effect. The power setting affected the maximum temperature increase proportionally, with peak temperature increasing from 4.3°C to 6.7°C when power was increased from 63% to 100%.

CONCLUSIONS

Although this phantom provides a crude mimic of the in vivo conditions, the overall results showed good repeatability and agreement with previously published experiments. All studies showed that the temperature rises observed fell within the recommendations of international regulatory bodies. However, it is important that the operator should be aware of factors affecting the temperature increase.

Hydrophone Spatial Averaging Correction for Acoustic Exposure Measurements From Arrays-Part I: Theory and Impact on Diagnostic Safety Indexes

This article reports underestimation of mechanical index (MI) and nonscanned thermal index for bone near focus (TIB) due to hydrophone spatial averaging effects that occur during acoustic output measurements for clinical linear and phased arrays. TIB is the appropriate version of thermal index (TI) for fetal imaging after ten weeks from the last menstrual period according to the American Institute of Ultrasound in Medicine (AIUM). Spatial averaging is particularly troublesome for highly focused beams and nonlinear, nonscanned modes such as acoustic radiation force impulse (ARFI) and pulsed Doppler. MI and variants of TI (e.g., TIB), which are displayed in real-time during imaging, are often not corrected for hydrophone spatial averaging because a standardized method for doing so does not exist for linear and phased arrays. A novel analytic inverse-filter method to correct for spatial averaging for pressure waves from linear and phased arrays is derived in this article (Part I) and experimentally validated in a companion article (Part II). A simulation was developed to estimate potential spatial-averaging errors for typical clinical ultrasound imaging systems based on the theoretical inverse filter and specifications for 124 scanner/transducer combinations from the U.S. Food and Drug Administration (FDA) 510(k) database from 2015 to 2019. Specifications included center frequency, aperture size, acoustic output parameters, hydrophone geometrical sensitive element diameter, etc. Correction for hydrophone spatial averaging using the inverse filter suggests that maximally achievable values for MI, TIB, thermal dose ( t ₄₃ ), and spatial-peak-temporal-average intensity ( [Formula: see text]) for typical clinical systems are potentially higher than uncorrected values by (means ± standard deviations) 9% ± 4% (ARFI MI), 19% ± 15% (ARFI TIB), 50% ± 41% (ARFI t ₄₃ ), 43% ± 39% (ARFI [Formula: see text]), 7% ± 5% (pulsed Doppler MI), 15% ± 11% (pulsed Doppler TIB), 42% ± 31% (pulsed Doppler t ₄₃ ), and 33% ± 27% (pulsed Doppler [Formula: see text]). These values correspond to frequencies of 3.2 ± 1.3 (ARFI) and 4.1 ± 1.4 MHz (pulsed Doppler), and the model predicts that they would increase with frequency. Inverse filtering for hydrophone spatial averaging significantly improves the accuracy of estimates of MI, TIB, t ₄₃ , and [Formula: see text] for ARFI and pulsed Doppler signals.

Application of the Electronic Nose in Predicting Preeclampsia in High-risk Pregnancies. Pilot Study

BACKGROUND

Preeclampsia is a syndrome that affects 2-8 % of pregnancies worldwide and is the leading cause of maternal death. Therefore, early detection is crucial to identify women who require clinical monitoring during pregnancy and to evaluate new preventive therapies before clinical symptoms occur.

METHODS

The chemical fingerprints of the urine from three study groups pregnant with Preeclampsia, Healthy Pregnant (HP) and pregnant at High Risk of Preeclampsia (HRP) were evaluated using an electronic nose and the data obtained were subjected to principal component analysis (PCA), Canonical Analysis of Principal Coordinates (CAP), Partial Least Squares - Discriminant Analysis (PLS-DA) and ROC curves to determine the diagnostic power of the test.

RESULTS

A separation was found between the patients with preeclampsia and HP explaining 99% of the variability of the data. Subsequently, a CAP was obtained with a correct classification of 100%, and the PLS-DA was obtained an accuracy of 88%. With the results of axis CAP1, a ROC curve was performed resulting in a sensitivity of 100% and a specificity of 95.5%. Based on the CAP model it was found that 36% (n=9) of the HRP patients would develop preeclampsia based on the metabolites found in urine.

CONCLUSION

metabolomics can be used as a tool for early detection of preeclampsia in high-risk pregnant women, using portable olfactory technology.

Color Doppler ultrasound of spiral artery blood flow in mid first trimester (4-8 weeks) in cases of threatened abortion and in normal pregnancies

Introduction

The aim of the study was to evaluate and compare the spiral artery flow in mid first trimester (4–8 weeks) in cases of threatened abortion and in normal pregnancies.

Material and methods

Spiral artery was sonographically evaluated in 50 patients comprising two groups of 25 women each. The first group included patients presenting with threatened miscarriage (vaginal bleeding/spotting with or without abdominal pain). The second group comprised of females who had no complications, but had no desire to continue the pregnancy. Spiral artery flow velocity measurements were performed using Color Doppler (Pulsatility Indices, Resistive Indices and Systolic/diastolic values) in mid first trimester (between 4–8 weeks of gestation), each measurement was performed twice. Statistical analysis was performed using Statistical package for social sciences software. Values were rounded off to two digits after decimal point.

Results

Significant differences were noted in the spiral artery Doppler values in the two groups. In particular, the Resistive Indices was higher in cases of women with threatened miscarriage. The difference in Pulsatility Indices was also statistically significant between the two groups.

Conclusion

Doppler values of spiral artery may be used as a useful parameter in assessing the prognosis in cases presenting with threatened miscarriage.

Ultrasound biosafety: Knowledge and opinions of health practitioners who perform obstetric scans in South Africa

BACKGROUND

Diagnostic ultrasound is generally considered as a safe test in pregnancy. To date there is no evidence that ultrasound has caused harm to the developing foetus. However, with the number of obstetric scans on the rise and the steep increase in acoustic output achieved by modern machines, the lack of evidence of absolute safety remains a concern. Acoustic output is under the direct control of the operator and is therefore the operator's responsibility to keep the intensity as low as reasonably achievable. A situation analysis in the South African context was deemed necessary to determine end user knowledge and opinions on safe antenatal ultrasound practice.

AIM

The aim of this quantitative descriptive, cross-sectional study was to evaluate the knowledge and practice of health practitioners who perform antenatal scans regarding safety aspects of diagnostic ultrasound.

SETTING

A self-administered questionnaire was distributed at two national congresses, hosted by the South African Society of Ultrasound and Obstetrics (SASUOG) and South African Society of Obstetricians (SASOG) committees.

METHOD

Quota non-probability sampling allowed for the identification of professional categories capable of providing information relevant to the study objectives. The sample represented a population with experience in obstetric ultrasound.

RESULTS

Compared to international studies, South African end users demonstrated better knowledge of safety indices than their international counterparts. It is, however, discouraging that end users still demonstrate insufficient knowledge regarding factors contributing to adverse biological effects.

CONCLUSION

With room for improvement, an effort should be made to comply with international standards through increased training efforts and raising awareness.

Screening performance of congenital heart defects in first trimester using simple cardiac scan, nuchal translucency, abnormal ductus venosus blood flow and tricuspid regurgitation

OBJECTIVE

The objective of this study was to analyze if the addition of simple cardiac scan in cases with increased nuchal translucency (NT) and/or abnormal ductus venosus (DV) blood flow, and/or tricuspid regurgitation (TCR) can improve detection of congenital heart defects (CHD) in chromosomally normal fetuses without non-cardiac defects at 11-13 + 6 gestational weeks in a population of singleton pregnancies.

METHODS

During the 10 years period, all singleton pregnancies at 11-13 + 6 weeks were routinely scanned for NT, DV blood flow and TCR assessment and, if a single of these parameters was abnormal, simple cardiac scan with 2D gray scale and color and/or directional power Doppler in 4-chamber (4-CV) and 3 vessel and trachea views (3VTV) was performed.

RESULTS

The sensitivity and specificity of NT ≥ 95th + DV R/A a-wave + TCR in detecting CHD were 77% and 97%, respectively, and of simple cardiac scan, 67% and 98%, respectively. Area under the curve of receiver operating characteristic curve of NT ≥ 95th + DV R/A a-wave + TCR was 0.838, and of NT ≥ 95th + DV R/A a-wave + TCR + simple cardiac scan was 0.915.

CONCLUSIONS

In chromosomally normal fetuses without non-cardiac anomalies, addition of simple cardiac scan to the combined first trimester screening parameters improves detection of major CHD during first trimester.

Can Ultrasound in Early Gestation Improve Visualization of Fetal Cardiac Structures in Obese Pregnant Women?

OBJECTIVES

To determine whether ultrasound (US) imaging of obese pregnant women in early gestation improves fetal cardiac visualization.

METHODS

We report a prospective longitudinal trial comparing late first- and early second-trimester US to traditional second-trimester US for fetal cardiac screening in maternal obesity. All study participants received US for fetal cardiac screening at a gestational age of 13 weeks to 15 weeks 6 days using a transvaginal or transabdominal approach (UST1). All patients also underwent a traditional transabdominal examination at 20 to 22 weeks (UST2). If UST2 failed to complete the cardiac visualization, a follow up examination (second UST2) was performed 2 to 4 weeks later. Imaging was considered complete if the visceral situs, 4 chambers, outflow tracts, and 3 vessels were visualized. The completion rates between UST1 and UST2 were the primary outcomes. A power analysis (85%) and sample size calculation (n = 145) were performed.

RESULTS

A total of 152 pregnancies met study criteria. Completion rates of cardiac screening were 77% for UST1 and 70% for UST2 (P = .143). This comparison reached statistical significance in patients with a body mass index of greater than 40 kg/m² (UST1 [69%] versus UST2 [38%]; P = .001). Sixty-two percent of patients with a body mass index of greater than 40 kg/m² required second UST2. The highest fetal cardiac screening completion rate was achieved when UST1 was combined with UST2 (96.1%). In 1 fetus, congenital heart disease was detected at UST1 and later confirmed.

CONCLUSIONS

This study represents the largest prospective trial assessing early-gestation US for fetal cardiac screening in the setting of maternal obesity. In obese pregnancies, the addition of early-gestation US to the 20- to 22-week US substantially improves the visualization of fetal cardiac anatomy.

[Doppler Sonography during Pregnancy - DEGUM Quality Standards and Clinical Applications]

Doppler sonography is widely established in prenatal medicine and obstetrics and is commonly used in screening for aneuploidy and preeclampsia during the first trimester. More importantly, during the 2nd and 3 rd trimester, it is used in the assessment of fetal health as well as the surveillance of underlying fetal conditions such as IUGR and anemia. Correct use of the method is vital for correct data interpretation and the inferred clinical decision process. Therefore, we aim to provide all users of doppler sonography with a guide for meeting the required quality standards. These quality standards will further be the basis of DEGUM-certified training courses. In the first part, we will introduce the technical principles of the method and potential error sources, vascular disciplines to which the method can be applied, analysis of the spectral curves, patient safety and the needed requirements for successful certification.

Early fetal ultrasound screening for major congenital heart defects without Doppler

OBJECTIVE

Congenital heart defects are the most common major structural fetal abnormalities. Color flow mapping has played a dominant role in the detection of abnormalities during the first trimester, regardless of the International Society of Ultrasound in Obstetrics and Gynecology warning on the use of Doppler during early pregnancy. The aim of our study was to investigate the use of transvaginal two-dimensional sonography without Doppler for assessing the four-chamber view and the outflow tract view of fetuses at 11-13 weeks of gestation for cardiac screening of major congenital heart defects.

STUDY DESIGN

This was a prospective observational study conducted in the Fetal Medicine Unit of Cabueñes University Hospital, between May 2014 and August 2015. Only low risk-pregnancies were studied. All ultrasonographic examinations were performed by two experienced sonographers in maternal-fetal medicine. The combination of high-frequency transvaginal (nine MHz) and transabdominal (six MHz) ultrasonography transducers were used. An early cardiac screening was performed in 97% of cases. Statistical analysis was carried out using successive multivariate logistic regression models in order to investigate the effect of crown-rump length and body mass index on the probability of visualizing the four-chamber view and/or the outflow tract view.

RESULTS

663 low-risk pregnant women were included. Regarding the transvaginal approach, neither the crown-rump length nor the body mass index had a statistically significant relationship on the probability of visualization of the four-chamber view and outflow tract view. For the transabdominal approach, the crown-rump length and the body mass index presented a statistically significant effect on the visualization of the four-chamber view and the outflow tract view. Using the transvaginal approach: the success rate of performing a four-chamber view was 89.4% and 82.4% for the outflow tract view. Using the transabdominal approach: the success rate of performing a four-chamber view was 77.8% and 61.5% for the outflow tract view. Four major congenital heart defects were diagnosed, and the prenatal ultrasonagraphic diagnosis was confirmed for all cases.

CONCLUSIONS

Routine first-trimester ultrasonagraphy without Doppler, when performed by experienced sonographers, can effectively identify major congenital heart defects. Additional multicenter well designed studies should clarify the feasibility of this approach.

Sonographic Development of the Pericallosal Vascularization in the First and Early Second Trimester of Pregnancy

BACKGROUND AND PURPOSE

Anomalies of the corpus callosum are rare. Routine scanning in midtrimester of the pregnancy often fails to identify defective development. The purpose of the study was to identify the pericallosal artery and all its main branching arteries during early gestation from the first trimester onward, to measure the length of the pericallosal artery during its development, and to establish a normal vascular map for each week of development.

MATERIALS AND METHODS

We performed a single-center prospective, longitudinal clinical study in 15 patients between 11 and 22 weeks of gestation. The origin and course of the different blood vessels were identified.

RESULTS

There was a linear association among gestational age, the biparietal diameter, and the length of the pericallosal artery. The curvature of the developing pericallosal artery increases linearly with the gestational age and biparietal diameter, and 4 variations of branching of the callosomarginal artery were observed.

CONCLUSIONS

The pericallosal artery and its branches can be identified and measured from 11 weeks on, and the pericallosal artery takes its characteristic course. A defective course or an abnormal biometry of the pericallosal artery could be an early sonographic marker of abnormal development of the corpus callosum.

Contemporary best practice urolithiasis in pregnancy

Urolithiasis is the most common nonobstetric complication in the gravid patient. The experience can provoke undue stress for the mother, fetus, and management team. The physiologic changes of pregnancy render the physical exam and imaging studies less reliable than in the typical patient. Diagnosis is further complicated by the need for careful selection of imaging modality in order to maximize diagnostic utility and minimize obstetric risk to the mother and ionizing radiation exposure to the fetus. Ultrasound remains the first-line diagnostic imaging modality in this group, but other options are available if results are inconclusive. A trial of conservative management is uniformly recommended. In patients who fail spontaneous stone passage, treatment may be temporizing or definitive. While temporizing treatments have classically been deemed the gold standard, ureteroscopic stone removal is now acknowledged as a safe and highly effective definitive treatment approach. Ultimately, a multidisciplinary, team-based approach involving the patient, her obstetrician, urologist, radiologist, and anesthesiologist is needed to devise a maximally beneficial management plan.

Are There Head Volume Alterations at 11 to 14 Weeks in Fetuses with Congenital Heart Defects? A First Trimester Case Series

Objective This study aims to assess head volume (HV) alterations at 11 to 14 weeks in fetuses with congenital heart defects (CHD). Methods A retrospective case-control study on 100 normal and 26 CHD fetuses was conducted. The fetuses had a first trimester scan with volume data sets stored from which HV was calculated. The mean HV and HV as a function of crown-rump length (CRL) in normal fetuses were compared with established normograms. Mean HV, HV as a function of CRL, and HV/CRL were compared between normal and CHD fetuses. Nonparametric Kruskal-Wallis H test was used with p < 0.05 considered significant. Results Overall, 83 normal and 19 CHD fetuses were included. The mean HV and HV as a function of CRL in the normal fetuses were comparable to what has been established (p = 0.451 and 0.801, respectively). The mean HV was statistically smaller in fetuses with CHD, particularly those with hypoplastic left heart (HLH): 10.7 mL in HLH versus 13.0 mL in normal fetuses (p = 0.043). The HV/CRL was statistically smaller in fetuses with CHD (p = 0.01). Conclusion Despite the small sample size, our case series suggests that alterations in HV may potentially be apparent as early as 11 to 14 weeks in CHD fetuses, particularly those with HLH. Larger prospective studies are needed to validate our findings.

Atrial dominance in the human embryonic heart: a study of cardiac function at 6-10 weeks of gestation

OBJECTIVE

To investigate the difference in forces developed by atrial and ventricular myocardium during contraction in human embryos using a novel method.

METHODS

This was a cross-sectional study of 115 pregnancies examined at 6-10 weeks of gestation. Ventricular inflow and outflow velocities were obtained by Doppler echocardiography and the relative force development was evaluated by calculating the ratio between atrial and ventricular ejection force (EF).

RESULTS

Data from 97 embryos with monophasic ventricular filling were analyzed. Both inflow and outflow cardiac velocities increased with advancing gestational age (P < 0.001). The mean peak inflow velocity (31.7 ± 10.2 cm/s) was significantly higher (P < 0.0001) than the outflow velocity (19.6 ± 6.1 cm/s). The EFinflow /EFoutflow ratio was more than 1.0 in all but four (96%) cases.

CONCLUSION

Our study indicates the possibility of atrial dominance in the embryonic period of heart development, which may have clinical implications, as deviations from this normal pattern may indicate human embryonic cardiac dysfunction.

Is it Worth to Evaluate the Fetal Heart With Color Doppler Scan at 11 to 13+6 Weeks?

This study was conducted to try to achieve the success rate to detect fetal cardiac malformations and/or tricuspid regurgitation with color Doppler during first trimester ultrasound scan within a short period (less than 3 minutes) in a general low-risk population. For this purpose, we started a prospective study, evaluating 240 consecutive single pregnancies, by a single examiner, during the first trimester ultrasound scan (crown to rump length between 45 and 84 mm) using a Voluson E8 system (GE Healthcare, Zipf, Austria) with a 2- to 8-MHz RAB 4-8-D transabdominal probe. Pulsed-wave and color Doppler flow mapping was used to assess the blood flow through the tricuspid valve. In addition, color Doppler was used to evaluate the 4-chamber view, the great vessels ("V sign"), and the right subclavian artery. Blood flow in the tricuspid valve could be examined in 206 cases (85.8%). Of these, tricuspid regurgitation was detected in 17 cases (7.1%) with both pulsed-wave and color Doppler. The 4-chamber view, the V sign, and the right subclavian artery could be evaluated in 188 cases (78.3%). One case of aberrant right subclavian artery and 2 suspicious of cardiac malformations were detected. In our opinion, using color Doppler during first trimester ultrasound scan, even for a short period (<3 minutes), probably adds important information about the fetal heart.

Safety Indices during Fetal Echocardiography at the Time of First-Trimester Scan Are Machine Dependent

The aim of our study was to evaluate the thermal index (TI) and mechanical index (MI), during the assessment of the fetal heart at the time of first-trimester scan, with different ultrasound machines. This was part of an observational study conducted in patients undergoing routine first-trimester screening. Cases were examined with Voluson E8 or 730Pro scanners using 2–8 MHz transabdominal probes. TI and MI were retrieved from the saved displays while in gray mode, color flow mapping and pulsed-wave (PW) Doppler examinations of the fetal heart and also from the ductus venosus (DV) assessment. We evaluated 552 fetal cardiac examinations, 303 (55%) performed with Voluson E8 and 249 (45%) with Voluson 730Pro ultrasound machines. The gray-scale exam of the heart and the PW Doppler DV assessment had TI values significantly lower for the Voluson E8 group (median, 0.04 vs. 0.2 and 0.1 vs. 0.2, respectively). The MI values from gray-scale and color flow mapping of the heart were significantly lower (median, 0.6 vs, 1.2 and 0.7 vs. 1) and for PW Doppler exam of the tricuspid flow were significantly higher (median 0.4 vs. 0.2) in the Voluson E8 group. The TI values from Doppler examinations of the heart, either color flow or PW imaging and MI values from DV assessment were not significantly different between the two groups. A different (newer) generation of ultrasound equipment provides lower or at least the same safety indices for most of the first-trimester heart examinations.

Acoustic output measured by thermal and mechanical indices during fetal echocardiography at the time of the first trimester scan

We measured acoustic output, expressed as the thermal index (TI) and mechanical index (MI), during fetal echocardiography at the time of the first trimester scan. TI and MI were retrieved from the saved displays during gray-mode, high-definition color flow Doppler and pulsed-wave Doppler (tricuspid flow) ultrasound examinations of the fetal heart and from the ductus venosus assessment. A total of 399 fetal cardiac examinations were evaluated. There was a significant increase in TI values from B-mode studies (0.07 ± 0.04 [mean ± SD]) to color flow mapping (0.2 ± 0.0) and pulsed-wave Doppler studies (0.36 ± 0.05). The TI from ductus venosus assessment (0.1 ± 0.01) was significantly lower than those from Doppler examinations of the heart. MI values from B-mode scans (0.65 ± 0.12) and color flow mapping (0.71 ± 0.11) were comparable, although different, and both values were higher than those from pulsed-wave Doppler tricuspid evaluation (0.39 ± 0.03). There were no differences in MI values from power Doppler assessment between the tricuspid flow and ductus venosus. Safety indices were remarkably stable and were largely constant, especially for color Doppler (TI), tricuspid flow (MI) and ductus venosus assessment (TI, MI). We acquired satisfactory Doppler images and/or signals at acoustic levels that were lower than the actual recommendations and never reached a TI of 0.5.

First trimester trophoblast and placental bed vascular volume measurements in IVF or IVF/ICSI pregnancies

STUDY QUESTION

Are first trimester trophoblast volume (TV) and placental bed vascular volume (PBVV) different in IVF or IVF/ICSI pregnancies in comparison with spontaneously conceived pregnancies?

SUMMARY ANSWER

Any possible abnormal placentation in IVF or IVF/ICSI pregnancies in comparison with spontaneously conceived pregnancies is not detected by a difference in PBVV or TV at an early gestational age (GA).

WHAT IS KNOWN ALREADY

Assisted reproductive technology pregnancies have been associated with an increased risk of placenta-related adverse pregnancy outcomes. It is unclear whether these effects originate from infertility or from the technique itself.

STUDY DESIGN, SIZE, DURATION

We performed a retrospective cohort study in which 154 pregnant patients qualified for participation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Out of 154 pregnant patients, 84 conceived spontaneously and 70 conceived after IVF or IVF/ICSI. We determined the TV at 10 weeks GA by Virtual Organ Computer-aided AnaLysis measuring application and the PBVV at 12 weeks GA by the virtual reality operating system of BARCO I-Space in both subgroups. The investigators were blinded to the mode of conception during the measurements. Analysis was limited to singleton pregnancies with only one sac ever detectable.

MAIN RESULTS AND THE ROLE OF CHANCE

There were no differences in TV (mean 42.7, SD 15.9 versus mean 41.2, SD 13.9, P = 0.70) and PBVV (mean 27.6, SD 16.9 versus mean 24.8, SD 19.9, P = 0.20) between IVF or IVF/ICSI pregnancies and spontaneously conceived pregnancies. There was a significant correlation between TV and PBVV (rs = 0.283, P = 0.004).

LIMITATIONS, REASONS FOR CAUTION

The limitations of the present study concern the small size of the study groups.

WIDER IMPLICATIONS OF THE FINDINGS

IVF or IVF/ICSI does not seem to be associated with abnormal placentation.

STUDY FUNDING/COMPETING INTERESTS

This study was financially supported by the Erasmus Trustfonds, the Meindert de Hoop foundation and the Fonds NutsOhra. No competing interests are declared.

Do clinical practitioners seeking credentialing for nuchal translucency measurement demonstrate compliance with biosafety recommendations? Experience of the Nuchal Translucency Quality Review Program

OBJECTIVES

The purpose of this study was to evaluate compliance with the ALARA (as low as reasonably achievable) principle by practitioners seeking credentialing for nuchal translucency (NT) measurement between 11 and 14 weeks' gestation.

METHODS

Nuchal Translucency Quality Review Program credentialing requires quantitative scoring of 5 NT measurements from 5 different fetuses. Images submitted by 100 consecutive practitioners were retrospectively evaluated for the output display standard (ODS). The thermal index (TI) type (bone [TIb] or soft tissue [TIs]) and numeric value of the index were recorded. The TIb was considered the correct index for this study. Compliance with the numeric value was evaluated in several ways. Collectively, a TIb lower than 0.5 was considered optimal, lower than 0.7 compliant, and 1.0 or lower satisfactory.

RESULTS

An ODS was present in at least 1 image submitted by 77 practitioners. The TIb was used exclusively by 15 (19.5%), the TIs by 37 (48.1%), and 25 used a combination of the TIb and TIs. Only 4 of 77 providers (5%) used the correct TI type (TIb) at lower than 0.5 for all submitted images, 5 of 77 (6%) at lower than 0.7, and 9 of 77 (12%) at 1.0 or lower. A TI (TIb or TIs) higher than 1.0 was used by 15 of 77 providers (19.5%). Proficiency in NT measurement and educational background (physician or sonographer) did not influence compliance with ALARA.

CONCLUSIONS

Clinicians seeking credentialing in NT do not demonstrate compliance with the recommended use of the TIb in monitoring acoustic output.

Selection of the sub-noise gain level for acquisition of VOCAL data sets: a reliability study

This study was aimed at assessing the intra-observer and inter-observer repeatability of selecting the sub-noise gain (SNG) level when acquiring placental volumes with 3-D power Doppler for analysis using virtual organ computer-aided analysis (VOCAL). Sixty women with uncomplicated singleton pregnancies between 20 and 38 wk of gestation were recruited. Two women were excluded for flash artifact noted during image analysis. Two blinded observers independently adjusted gain to their perceived SNG level before acquiring a static 3-D volume of the placenta at the cord insertion; observers alternated after each acquisition until each had acquired two volumes. A single observer operated the probe at all times. During offline analysis, SNG levels were recorded and VOCAL indices were calculated. SNG exhibited excellent intra-observer and inter-observer reliability. Intra-observer intra-class correlation coefficients (95% confidence intervals) were 0.98 (0.97-0.99) and 0.98 (0.98-0.99) for observers 1 and 2, respectively. The inter-observer intra-class correlation coefficient was 0.96 (0.93-0.98). Despite its perceived inherent subjectivity, the excellent intra-class correlation coefficients obtained in this study support SNG as a promising tool for future research using 3-D power Doppler.

First trimester two- and four-dimensional cardiac scan: intra- and interobserver agreement, comparison between methods and benefits of color Doppler technique

OBJECTIVE

To evaluate intra- and interobserver agreement for first-trimester fetal cardiac structural assessment, using two-dimensional (2D) ultrasound (2D-US) and 4D-US (4D spatiotemporal image correlation (STIC) technology), to compare the methods and to assess the advantages of adding color Doppler to each technique.

METHODS

Digital videoclips (B-mode and color Doppler) and 4D-STIC volumes (gray-scale and color Doppler) from 632 pregnancies with normal fetal hearts were acquired and stored at the time of detailed first-trimester ultrasound examination. Later analysis on a randomized sample of 100 cases was performed, targeting 11 cardiac structures and features. We compared visualization of fetal heart parameters using 2D-US vs 4D-US and gray-scale vs color Doppler imaging.

RESULTS

STIC volumes were considered satisfactory (adequate visualization of at least 8/11 parameters) in 78% of cases and 2D-US acquisitions in 89% of cases. The intra- and interobserver agreement was good for both 2D and 4D methods (kappa > 0.6), and the percentage overall agreement was very high using both methods (95%). 2D- and 4D-US identification of the fetal cardiac parameters did not differ significantly. The differences between gray-scale and color Doppler imaging were statistically significant in identifying similar key cardiac parameters, for both 2D- and 4D-US (P < 0.05).

CONCLUSION

Both 2D and 4D methods for assessing first-trimester heart parameters are feasible and repeatable within and between observers. Color Doppler adds valuable information to both methods.

Cumulative sum plots and retrospective parameters in first-trimester ductus venosus quality assurance

OBJECTIVE

This study aimed to evaluate the application of two quality assurance methods to the ductus venosus pulsatility index (DVPI), as a first-trimester aneuploidy marker, including retrospective assessment of distribution parameters and cumulative sum (CUSUM) plots.

METHODS

The DVPI was measured in 14 444 singleton fetuses at 11+0 to 13+6 weeks in two Fetal Medicine centers during a 4-year period. Sonologist-specific quality assurance distribution parameters, previously described for nuchal translucency, were assessed: the median multiples of the median (MoM), the logarithmic standard deviation of DVPI MoMs and the weekly DVPI percent decrease. Quality assurance results were compared between median MoMs and MoM-based CUSUM plots.

RESULTS

When sonologist-specific DVPI distribution parameters were retrospectively applied for quality assurance, a 1.0 median MoM, a 0.1 median logarithmic standard deviation and a 3.4 median weekly DVPI drop percentage were observed. CUSUM plots showed good agreement with 0.9-1.1 MoMs range for median MoM, in the assessment of sonologist-specific performances.

CONCLUSION

Retrospective and prospective DVPI quality assurance methods appear to be applicable to DVPI at 11+0 to 13+6 weeks. Its use should be encouraged if DVPI is to be added to first-trimester Down syndrome or cardiac defects screening.

Utilization of antenatal ultrasound scan and implications for caesarean section: a cross-sectional study in rural Eastern China

Background

Antenatal ultrasound scan is a widely accepted component of antenatal care. Studies have looked at the relationship between ultrasound scanning and caesarean section (CS) in certain groups of women in China. However, there are limited data on the utilization of antenatal ultrasound scanning in the general population, including its association with CS. The purpose of this study is to describe the utilization of antenatal ultrasound screening in rural Eastern China and to explore the association between antenatal ultrasound scan and uptake of CS.

Methods

Based on a cluster randomized sample, a total of 2326 women with childbirth participated in the study. A household survey was conducted to collect socio-economic information, obstetric history and utilization of maternal health services.

Results

Coverage of antenatal care was 96.8% (2251/2326). During antenatal care, 96.1% (2164/2251) women received ultrasound screening and the reported average number was 2.55. 46.8% women received at least 3 ultrasound scans and the maximum number reached 11. The CS rate was found to be 54.8% (1275/2326). After adjusting for socio-demographic and clinical variables, it showed a statistically significant association between antenatal ultrasound scans and uptake of CS by multivariate logistic regression model. High husband education level, high maternal age, having previous adverse pregnant outcome and pregnancy complications during the index pregnancy were also found to be risk factors of choosing a CS.

Conclusions

A high use of antenatal ultrasound scan in rural Eastern China is found and is influenced by socio-demographic and clinical factors. Evidence-based guidelines for antenatal ultrasound scans need to be developed and disseminated to clinicians including physicians, nurses and sonographers. Guidance about the appropriate use of ultrasound scans should also be shared with women in order to discourage unreasonable expectations and demands. It is important to monitor the use of antenatal ultrasound scan as well as the indications for caesarean section in rural China.

Transvaginal 3-d power Doppler ultrasound evaluation of the fetal brain at 10-13 weeks' gestation

The objective of this study was to measure the fetal brain volume (FBV) and vascularization and blood flow using transvaginal 3-D power Doppler (3DPD) ultrasound late in the first trimester of pregnancy. 3DPD ultrasound examinations with the VOCAL imaging analysis program were performed on 36 normal fetuses from 10-13 weeks' gestation. FBV and 3DPD indices related to the fetal brain vascularization (vascularization index [VI], flow index [FI] and vascularization flow index [VFI]) were calculated in each fetus. Intra- and interclass correlation coefficients and intra- and interobserver agreements of measurements were assessed. FBV was curvilinearly correlated well with the gestational age (R2 = 0.861, p < 0.0001). All 3-D power Doppler indices (VI, FI and VFI) showed no change at 10-13 weeks' gestation. FBV and all 3-D power Doppler indices (VI, FI and VFI) showed a correlation > 0.82, with good intra- and interobserver agreement. Our findings suggest that 3-D ultrasound is a superior means of evaluating the FBV in utero, and that 3-D power Doppler ultrasound histogram analysis may provide new information on the assessment of fetal brain perfusion.

The Safe Use of Diagnostic Ultrasound in Obstetrics and Gynecology

The diagnostic ultrasound was considered safe after the intensity threshold was known and the output intensity (Ispta) was regulated to be less than 10 mW/cm2 in diagnostic devices in Japan, and diagnostic ultrasound was thought safe in USA when both thermal index (TI) and mechanical index were less than 1.0 in the obstetrical setting. Simple B-mode machine was not concerned from the thermal reason due to its extremely low ultrasound intensity, while the exposure was recommended within 30 minutes. Diagnostic ultrasound should be used after obstetrical setting in fetal study. The TI will be higher in febrile cases than nonfebrile, and the surface temperature of transvaginal scan (TVS) probe should be lower than 41°C. Simple three-dimensional or four-dimensional ultrasound imaging without pulsed Doppler studies will be as safe as Bmode when the study is within 30 minutes, because they are composed of simple B-mode images. The spectral Doppler study was not routinely used and its exposure should be short in 11 to 13 weeks of pregnancy in the statements of WFUMB and ISUOG, because experimentally early fetal animal tissue was sensitive to the studies. The use of diagnostic ultrasound should be limited for medical purposes, but not for the entertainment or keepsake of pregnancy.

How to cite this article

Maeda K, Kurjak A. The Safe Use of Diagnostic Ultrasound in Obstetrics and Gynecology. Donald School J Ultrasound Obstet Gynecol 2012;6(3):313-317.