Oligohydramnios or Anhydramnios and Ultrasonically Normal Renal Echotexture Secondary to Autosomal Recessive Renal Tubular Dysgenesis: An Important Consideration in the Prenatal Setting.

INTRODUCTION: Autosomal recessive renal tubular dysgenesis (ARRTD) is a rare disorder of renal tubular development. ARRTD is a severe condition with high risk of fetal demise and early neonatal death, with only limited case reports of survival over 2 years [Clin Kidney J. 2012 Feb 1;5(1):56-8]. Prenatal diagnosis of ARRTD is challenging, and diagnosis has only previously been confirmed after postnatal or post-mortem investigation. CASE: To the best of our knowledge, we describe the first reported case of utilizing targeted genetic testing on the chorionic villous sample (CVS) to identify a homozygous variant in the angiotensinogen (AGT) gene. DISCUSSION: By substantiating the diagnosis of ARRTD prenatally, we allow timely and appropriate counseling during pregnancy.

Shear wave elastography: the relationship of the cervical stiffness with gestational age and cervical length- a feasibility study.

OBJECTIVES: To standardize the measurement of shear wave elastography for assessment of cervical stiffness and its relationship with gestational age and cervical length. METHODS: A prospective cross-sectional study was conducted from September 2017 to March 2019. Data from 125 unselected women (at 11-13 + 6, 18-22 and 24-28 weeks' gestation) and 55 high-risk women were analyzed for the study. Six regions of interest were evaluated for cervical elastography in the mid-sagittal position by transvaginal ultrasound. Statistical analyses were performed using R statistical language in R-studio. Delivery outcomes were recorded for each patient. RESULTS: The shear wave elastography was feasible with good intraoperator and interoperator reproducibility. The endocervical canal and anterior lip internal position had the highest reproducibility (ICC-0.82, 0.75). Shear wave speed was significantly higher in all internal os regions than the external os. There was a statistically significant negative linear relationship of shear wave speed with the gestational age. There was a weak positive relationship between shear wave speed and cervical length. There was no difference between pregnancies with and without spontaneous preterm delivery in shear wave speed measurements and cervical length, although numbers were small for statistical analysis. The internal os of the large loop excision of the transformation zone group was stiffer than the normal population. CONCLUSION: Cervical elastography is feasible and effectively evaluates the tensile properties of the cervix during pregnancy. The most reproducible measurements were obtained at the anterior lip of the internal cervical os. Combining evaluation of cervical elasticity and length might further improve the identification of women at risk of preterm delivery. Currently, technical issues hinder the practical application of shear wave elastography in the clinical setting and require further research and development of the imaging modality.

A survey of current practice in reporting third trimester fetal biometry and Doppler in Australia and New Zealand.

INTRODUCTION: Inconsistent reporting practices in third trimester ultrasound, the choice of reference charts in particular, have the potential to misdiagnose abnormal fetal growth. But this may lead to unnecessary anxiety and confusion amongst patients and clinicians and ultimately influence clinical management. Therefore, we sought to determine the extent of variability in choice of fetal biometry and Doppler reference charts and reporting practices in Australia and New Zealand. METHODS: Clinicians performing and/or reporting obstetric ultrasound were invited to answer questions about fetal biometry and Doppler charts in a web-based survey. RESULTS: At least four population-based charts are in current use. The majority of respondents (78%) report the percentile for known gestational age (GA) alongside measurements and 63% using a cut-off of estimated fetal weight (EFW) < 10th percentile when reporting small for gestational age (SGA) and/or fetal growth restriction (FGR). The thresholds for the use of fetal and maternal Doppler in third trimester ultrasound varied in terms of the GA, EFW cut-off, and how measures were reported. The majority of respondents were not sure of which Doppler charts were used in their practice. CONCLUSION: This survey revealed inconsistencies in choice of reference chart and reporting practices. The potential for misdiagnosis of abnormal fetal growth remains a significant issue.

Prediction of Birth Weight and Neonatal Adiposity Using Ultrasound Assessment of Soft Tissue Parameters in Addition to Two-Dimensional Conventional Biometry.

INTRODUCTION: We aim to evaluate the supplementary predictive value of soft tissue markers, including fetal limb volumes, for fetal birth weight and fat tissue weight. METHODS: This is a prospective study of 60 patients undergoing term induction of labor. Ultrasound was performed 48 h before birth, and 2D sonographic measurements, subcutaneous tissue thickness, and 3D fetal limb volumes were taken. Birth weight and neonatal fat weight were assessed by plethysmography. Clinical data were collected. The relation between ultrasound and neonatal outcomes was assessed by univariate and multivariate predictive models. The estimated and actual birth weights were compared applying different published formulas, and systematic and random error were collected and compared. RESULTS: 3D fetal limb volumes showed a strong relation to birth weight, absolute weight, and relative fat weight. The Lee 6 formula performed better than either Hadlock 3 or Lee 3 with the lowest random error. Fractional limb volumes involve a highly reproducible technique, with excellent correlation (intra-class coefficient >0.90) for both inter- and intra-observer reliability. The prevalence of estimated EFW measures within 10% error from the actual birth weight was 71.7% with the Hadlock 3 model and 95.0% with the Lee 6 model (p = 0.09). CONCLUSION: Late assessment of 3D fetal limb volume in upper and lower extremities is not only useful for accurately predicting birth weight but is a useful marker for prediction of birth fat tissue weight.

Measured Hyperelastic Properties of Cervical Tissue with Shear-Wave Elastography.

The nonlinear mechanical behaviour of cervical tissue causes unpredictable changes in measured elastograms when pressure is applied. These uncontrolled variables prevent the reliable measurement of tissue elasticity in a clinical setting. Measuring the nonlinear properties of tissue is difficult due to the need for both shear modulus and strain to be taken simultaneously. A simulation-based method is proposed in this paper to resolve this. This study describes the nonlinear behaviour of cervical tissue using the hyperelastic material models of Demiray-Fung and Veronda-Westmann. Elastograms from 33 low-risk patients between 18 and 22 weeks gestation were obtained. The average measured properties of the hyperelastic material models are: Demiray-Fung-A1α = 2.07 (1.65-2.58) kPa, α = 6.74 (4.07-19.55); Veronda-Westmann-C1C2 = 4.12 (3.24-5.04) kPa, C2 = 4.86 (2.86-14.28). The Demiray-Fung and Veronda-Westmann models performed similarly in fitting to the elastograms with an average root mean square deviation of 0.41 and 0.47 ms-1, respectively. The use of hyperelastic material models to calibrate shear-wave speed measurements improved the consistency of measurements. This method could be applied in a large-scale clinical setting but requires updated models and higher data resolution.

Prospective Validation of First-Trimester Ultrasound Characteristics as Predictive Tools for Twin-Twin Transfusion Syndrome and Selective Intrauterine Growth Restriction in Monochorionic Diamniotic Twin Pregnancies.

OBJECTIVE: Monochorionic diamniotic (MCDA) twins are at increased risk of adverse outcome due to unequal placental sharing and placental vascular communications between the fetal circulations. Most centres perform ultrasound examination every 2-3 weeks to identify these complications. Identifying a high-risk cohort of MCDA twins in the first trimester would allow more efficient surveillance. We have attempted to validate first-trimester ultrasound characteristics as predictive tools for twin-twin transfusion syndrome (TTTS) and selective intrauterine growth restriction (sIUGR) in MCDA twins. MATERIAL AND METHODS: This is a prospective cohort study including MCDA twins enrolled at the time of first-trimester combined screening. Differences in crown-rump length (CRL), nuchal translucency (NT) thickness, ductus venosus pulsatility index for veins (DV PIV), presence or absence of tricuspid regurgitation and right ventricular E/A ratio were assessed. Receiver operating characteristic (ROC) curves were used to assess the potential value of these measures as predictive tools for identifying a cohort of MCDA pregnancies at high risk of adverse pregnancy outcome. RESULTS: Sixty-five MCDA pregnancies were included in the analysis. Nine (14%) developed TTTS, 17 (26%) developed sIUGR. The best predictive marker for TTTS was NT discordance of ≥20% (ROC AUC = 0.79; 95% CI 0.59-0.99). Combining measures did not improve performance (AUC = 0.80; 95% CI 0.62-0.99). CONCLUSION: NT discordance was the most effective characteristic at predicting TTTS but still had a relatively poor positive predictive value (36%). Intertwin differences in CRL, DV PIV and E/A ratio were not predictive of subsequent pregnancy complications. None of these characteristics have sufficient efficacy to be used to triage MCDA twin pregnancies ongoing obstetric surveillance.

Fly Thru imaging: Feasibility study and comparison with outpatient hysteroscopy.

BACKGROUND: In the investigation of abnormal uterine bleeding, hysteroscopy with endometrial biopsy is considered the gold standard. Fly Thru™ imaging is a new application used to generate virtual hysteroscopy clips. AIMS: We aimed to investigate the feasibility and diagnostic accuracy of sonohysterogram with virtual hysteroscopy as an alternative to outpatient diagnostic hysteroscopy. MATERIALS AND METHODS: Two separate cohorts of women were recruited. The first cohort was to assess feasibility of the application. The second cohort included women recruited to undergo a sonohysterogram, with virtual hysteroscopy, prior to their scheduled outpatient hysteroscopy. Pain scores were recorded after each procedure. RESULTS: Sixteen women were recruited to the feasibility cohort and virtual hysteroscopy post-processing was successfully applied in 14/16 (88%). Clips were produced in less than one minute in 12/16 (75%). Both tubal ostia were identified in 12/16 (75%). Twenty-nine women were enrolled in the correlation cohort with two women excluded as they did not proceed to hysteroscopy according to study protocol. Virtual hysteroscopy, successfully generated in 23/27 women (85%), detected all intra-cavitary pathologies (9/27) detected on outpatient hysteroscopy. Tubal ostia were visualised less often with virtual hysteroscopy (37%) when compared with outpatient hysteroscopy (74%). Sonohysterogram with virtual hysteroscopy was associated with less pain with a median difference in pain score of 2 (interquartile range 1.0-4.0, P < 0.0001). CONCLUSIONS: Sonohysterogram with virtual hysteroscopy is feasible; however, the addition of virtual hysteroscopy to sonohysterogram alone has limited value. Larger studies are required to determine whether it can be used as a diagnostic alternative to outpatient hysteroscopy.

Early fetal echocardiography: Experience of a tertiary diagnostic service.

BACKGROUND: There is a growing body of evidence that most of the major cardiac abnormalities can be diagnosed at 14-15 weeks of gestation. We present our experience of early fetal echocardiography. MATERIALS AND METHODS: This is a retrospective cohort study of women referred for early fetal echocardiography at 13-16 weeks of gestation at Royal Prince Alfred Hospital and Sydney Ultrasound for Women between August 2011 and March 2014. Findings of early fetal echocardiography, details of subsequent ultrasound examinations and pregnancy outcome were recorded. RESULTS: Early fetal echocardiography was performed in 400 euploid fetuses at a mean gestational age of 15(+2)  weeks. 85% of women were referred for increased nuchal translucency. 383/400 (96%) women had both normal early and late fetal echocardiograms 15/400 (3.7%) were found to have a cardiac defect at early fetal echocardiography, including 14 major and one minor abnormality. Two additional minor cardiac defects were diagnosed at later antenatal ultrasounds. One case, defined as being normal antenatally, was found to have a minor cardiac abnormality post-natally. Eight (57%) women whose fetus had a major cardiac defect chose to terminate the pregnancy. In the pregnancies that continued, the sensitivity and specificity for major cardiac defects was 100%, 95% CI (0.98-1.00). CONCLUSION: Early fetal echocardiography is feasible and highly sensitive and specific in experienced hands. The high specificity facilitates early reassurance of those women assessed at increased risk for fetal cardiac malformations.

Ultrasound assessment of cervical length at 18-21 weeks' gestation in an Australian obstetric population: comparison of transabdominal and transvaginal approaches.

BACKGROUND: Using a fixed cut-off of ≤25 mm, ultrasound assessment of cervical length during the 18-23 week anomaly scan has been shown to identify approximately 50% of pregnancies that would deliver prior to 34 weeks. AIM: To determine whether a policy of reverting to transvaginal cervical assessment only if the cervix appears short (≤25 mm) on transabdominal assessment affects the efficiency of screening. METHODS: Women with a singleton pregnancy that presented for a routine anomaly scan had their cervical length assessed transabdominally, initially with the maternal bladder full (TABF) and then empty (TABE). Cervical length was then assessed transvaginally (TV). RESULTS: One hundred and ninety-eight women agreed to participate in the study. Identification of the internal and external cervical os was possible during TABF, TABE and TV sonography in 97.0, 82.8 and 100%, respectively. Compared with TV sonography, TABF overestimates cervical length (6.1 mm difference in median values; P < 0.01). There was no significant difference between TV and TABE. However, TABE assessment was not possible in one in six women. If TABF sonography was to be used as a screening tool and using ≤25 mm as the critical cut-off, the sensitivity and specificity was 15.4 and 93.2%, respectively. CONCLUSION: This study has shown that assessment of cervical length using a TA approach is only routinely possible when the bladder is full. However, measurements are significantly overestimated. Therefore, we feel that TV assessment of cervical length is the preferred method of reliable cervical assessment. As such, all women should be offered a TV assessment of cervical length at the time of the fetal anomaly ultrasound as a screening test for preterm birth.

First trimester ultrasound assessment for fetal aneuploidy.

Screening tests for trisomy 21 have gradually become more refined and now involve complex statistical models that combine demographic, biophysical, and biochemical parameters to produce individualized risk estimates for pregnant women. An understanding of the evolution of the principles, methods, and statistical techniques applied to Down syndrome screening is valuable as these processes can be transferred to other, more prevalent, adverse pregnancy outcomes. First trimester ultrasound forms the foundation of this process.

Simplifying ultrasound assessment of the fetal heart: Incorporating the complete Three Vessel View into routine screening.

Introduction: As our experience and ultrasound resolution have improved significantly in last 30 years it is possible to detect most of the major cardiac abnormalities prenatally with high degree of accuracy. Method: Current screening techniques have poor detection rate for congenital heart diseases (CHD) and nearly half of the major cardiac abnormalities mainly of Great Arteries goes unrecognised. A high detection rate for major CHDs can be achieved in a screening setting by improving techniques of routine screening in the low risk population. Conclusion: This article summarises the alternative strategies to examine the outflow tracts and Great Arteries, its correct interpretation and examples of abnormal views.

Increased nuchal translucency and congenital heart disease.

Sonographic assessment of fetal nuchal translucency (NT) thickness is the cornerstone of screening for chromosomal abnormality at 11-13(+6) weeks gestation. This marker was first recognized in pregnancies being karyotyped for advanced maternal age, but its underlying pathophysiology remains to be fully determined. Although increased NT is clearly associated with changes in both lymphatic and cardiac development, neither is an obvious causative agent. The association with cardiac defects has now being subjected to a significant amount of research, with a large body of evidence showing that this marker is also a screening tool for major cardiac defects - although it performs more modestly than for chromosomal abnormality. The field continues to change rapidly. Recent evidence that uses a combination of increased NT, tricuspid regurgitation and abnormal flow in the 'a' wave of the ductus venosus can provide an effective screening strategy to predict many major cardiac defects at this early stage of pregnancy.

Normal ranges for fetal nasal bone length determined by ultrasound at 18-20 weeks of gestation in a multiethnic Australian population.

OBJECTIVE: Absence or hypoplasia of the nasal bone is commonly reported in Down syndrome fetuses. We define normal ranges and the 2.5th centile for fetal nasal bone length (NBL) in a multiethnic Australian population at 18-20 weeks of gestation. METHODS: A prospective cohort study of women attending for a routine anomaly scan. Ethnicity of the patient and their partner was recorded, and the nasal bone was measured three times. Two methods of nasal bone assessment were used to define normal ranges: a single (first) measurement and the mean value of three measurements. Mixed-effects regression models were employed to account for interoperator differences treating sonographers as random effects. Nonparametric methods were used to define the 2.5th centile for gestational age. RESULTS: A total of 1199 women were included with a mean gestational age 19.1 (SD 0.4; range 18-20) weeks. There is significant linear relationship between NBL and gestational age (P<0.001). The mean of three nasal bone measurements had a smaller standard deviation than single nasal bone measurements. Nonparametric assessment was used to define the 2.5th centile, which is 4.4 mm at 18 weeks and 5.0 mm at 20 weeks of gestation. CONCLUSIONS: This study provides a reference range for fetal NBL at 18-20 weeks of gestation in an unselected multiethnic Australian population. Whilst NBL increases linearly from 18 to 20 weeks, the data are not normally distributed and nonparametric techniques are required to define the 2.5th centile. The mixed-effects model also accounts for variation in sonographer measurements.

A prospective cross-sectional study to define racial variation in fetal nasal bone length through ultrasound assessment at 18-20 weeks' gestation.

OBJECTIVE: An absent or short nasal bone is highly predictive of Down syndrome in Caucasian populations, but Asians may have shorter nasal bones - increasing the false positive rate of screening. We examine differences in nasal bone length (NBL) in Caucasian and Asian populations. METHODS: This prospective cohort study involved pregnant women attending for their routine anomaly scan at 18-20 weeks' gestation. Ethnicity of the patient and their partner was recorded, and the nasal bone was measured three times. Mean NBL was calculated and used to investigate the effect of ethnicity first with a simple linear regression model and second with a mixed-effects regression model that accounted for variability of measurement between sonographers. RESULTS: A total of 1087 families were involved in the study, including 592 (54%) Caucasians, 214 (20%) East Asians, 110 (10%) South Asians and 171 (16%) West Asians. Twenty-three sonographers performed the scans with an average of 19 scans each. There is no significant difference in NBL between Caucasian and Asian populations. The mixed-effects model shows that accounting for sonographer variation is important, with 6.7% of the total variance in measurement being related to this random effect. CONCLUSIONS: There is no significant difference in NBL between Caucasian and Asian populations. It is reasonable to use criteria established in a Caucasian population to define the characteristics of an absent/short nasal bone in Asian fetuses. This finding also removes difficulties in counselling mixed race couples.

RBC motion and the basis of ultrasound Doppler instrumentation.

Ultrasonography has become one of the most popular techniques for noninvasive body assessment. The advent of sophisticated Doppler imaging has added an "information about blood flow" dimension. However, searching for complex details, despite enhanced system design and capabilities, place an increased demand on the operator. Examination technique and equipment settings are potential sources of error and therefore to obtain and interpret Doppler indices well it is essential to understand the physics of the Doppler principle and the dynamics of blood flow.