Diagnosis and management of selective fetal growth restriction in monochorionic twin pregnancies: A cross-sectional international survey.

OBJECTIVE: To identify current practices in the management of selective fetal growth restriction (sFGR) in monochorionic diamniotic (MCDA) twin pregnancies. DESIGN: Cross-sectional survey. SETTING: International. POPULATION: Clinicians involved in the management of MCDA twin pregnancies with sFGR. METHODS: A structured, self-administered survey. MAIN OUTCOME MEASURES: Clinical practices and attitudes to diagnostic criteria and management strategies. RESULTS: Overall, 62.8% (113/180) of clinicians completed the survey; of which, 66.4% (75/113) of the respondents reported that they would use an estimated fetal weight (EFW) of <10th centile for the smaller twin and an inter-twin EFW discordance of >25% for the diagnosis of sFGR. For early-onset type I sFGR, 79.8% (75/94) of respondents expressed that expectant management would be their routine practice. On the other hand, for early-onset type II and type III sFGR, 19.3% (17/88) and 35.7% (30/84) of respondents would manage these pregnancies expectantly, whereas 71.6% (63/88) and 57.1% (48/84) would refer these pregnancies to a fetal intervention centre or would offer fetal intervention for type II and type III cases, respectively. Moreover, 39.0% (16/41) of the respondents would consider fetoscopic laser surgery (FLS) for early-onset type I sFGR, whereas 41.5% (17/41) would offer either FLS or selective feticide, and 12.2% (5/41) would exclusively offer selective feticide. For early-onset type II and type III sFGR cases, 25.9% (21/81) and 31.4% (22/70) would exclusively offer FLS, respectively, whereas 33.3% (27/81) and 32.9% (23/70) would exclusively offer selective feticide. CONCLUSIONS: There is significant variation in clinician practices and attitudes towards the management of early-onset sFGR in MCDA twin pregnancies, especially for type II and type III cases, highlighting the need for high-level evidence to guide management.

The impact of late pregnancy dating on the detection of fetal growth restriction at term.

INTRODUCTION: The inaccuracy of late pregnancy dating is often discussed, and the impact on diagnosis of fetal growth restriction is a concern. However, the magnitude and direction of this effect has not previously been demonstrated. In this study, we aimed to investigate the effect of late pregnancy dating by head circumference on the detection of late onset growth restriction, compared to first trimester crown-rump length dating. MATERIAL AND METHODS: This was a cohort study of 14 013 pregnancies receiving obstetric care at a tertiary center over a three-year period. Universal scans were performed at 12 weeks, including crown-rump length; at 20 weeks including fetal biometry; and at 36 weeks, where biometry, umbilical artery doppler and cerebroplacental ratio were used to determine the incidence of fetal growth restriction according to the Delphi consensus. For the entire cohort, the gestational age was first calculated using T1 dating; and was then recalculated using head circumference at 20 weeks (T2 dating); and at 36 weeks (T3 dating). The incidence of fetal growth restriction following T2 and T3 dating was compared to T1 dating using four-by-four sensitivity tables. RESULTS: When the cohort was redated from T1 to T2, the median gestation at delivery changed from 40 + 0 to 40 + 2 weeks (p < 0.001). When the cohort was redated from T1 to T3, the median gestation at delivery changed from 40 + 0 to 40 + 3 weeks (p < 0.001). T2 dating resulted in fetal growth restriction sensitivity of 80.2% with positive predictive value of 78.8% compared to T1 dating. T3 dating resulted in sensitivity of 8.6% and positive predictive value of 27.7%, respectively. The sensitivity of abnormal CPR remained high despite T2 and T3 redating; 98.0% and 89.4%, respectively. CONCLUSIONS: Although dating at 11-14 weeks is recommended, late pregnancy dating is sometimes inevitable, and this can prolong the estimated due date by an average of two to three days. One in five pregnancies which would be classified as growth restricted if the pregnancy was dated in the first trimester, will be reclassified as nongrowth restricted following dating at 20 weeks, whereas nine out of 10 pregnancies will be reclassified as non-growth restricted with 36-week dating.

Early antenatal risk factors for births before arrival: An unmatched case-control study.

INTRODUCTION: Birth before arrival is associated with maternal morbidity and neonatal morbidity and mortality. Yet, timely risk stratification remains challenging. Our objective was to identify risk factors for birth before arrival which may be determined at the first antenatal appointment. MATERIAL AND METHODS: This was an unmatched case-control study involving 37 348 persons who gave birth at a minimum of 22+0 weeks' gestation over a 5-year period from January 2014 to October 2019 (IRAS project ID 222260; REC reference: 17/SC/0374). The setting was a large UK university hospital. Data obtained on maternal characteristics at booking was examined for association with birth before arrival using a stepwise multivariable logistic regression analysis. Data are presented as adjusted odds ratios with 95% confidence intervals. Area under the receiver-operator characteristic curves (C-statistic) were employed to enable discriminant analysis assessing the risk prediction of the booking data on the outcome. RESULTS: Multivariable analysis identified significant independent predictors of birth before arrival that were detectable at booking: parity, ethnicity, multiple deprivation, employment status, timing of booking, distance from home to the nearest maternity unit, and safeguarding concerns raised at booking by clinical staff. Our model demonstrated good discrimination for birth before arrival; together, the predictors accounted for 77% of the data variance (95% confidence interval 0.74-0.80). CONCLUSIONS: Information gathered routinely at booking may discriminate individuals at risk for birth before arrival. Better recognition of early factors may enable maternity staff to direct higher-risk women towards specialized care services at an early point in their pregnancy, enabling time for clinical and social interventions.

The impact of a universal late third-trimester scan for fetal growth restriction on perinatal outcomes in term singleton births: A prospective cohort study.

OBJECTIVE: To investigate perinatal mortality, morbidity and obstetric intervention following the introduction of a universal late third-trimester ultrasound scan for growth restriction. DESIGN: Prospective cohort study. SETTING: Oxfordshire (OUH), UK. POPULATION: Women with a non-anomalous singleton pregnancy undergoing pregnancy care and term delivery at OUH with an estimated due date (EDD) of birth between 1 January 2014 and 30 September 2019. METHODS: Universal ultrasound for fetal growth restriction between 35+0 and 36+6 weeks was introduced in 2016. The outcomes of the next 18 631 eligible term pregnancies were compared, adjusting for covariates and time, with the previous 18 636 who had clinically indicated ultrasounds only. 'Screen-positives' for growth restriction were managed according to a pre-determined protocol which included non-intervention for some small-for-gestational-age babies. MAIN OUTCOME MEASURES: Extended perinatal mortality, a composite of mortality or encephalopathy Grade II-III, and expedited birth. Other outcomes included composite adverse outcomes used elsewhere, detection of low birthweight and birth from 37+0 to 38+6 weeks. RESULTS: Extended perinatal deaths decreased 27% and severe morbidity decreased 33% but neither change was statistically significant (adjusted odd ratio [aOR] 0.53, 95% confidence interval [C1] 00.18-1.56 and aOR 0.71, 95% CI 0.31-1.63). Expedited births changed from 35.2% to 37.7% (aOR 0.99, 95% CI 0.92-1.06). Birthweight (<10th centile) detection using fetal biometry alone was 31.4% and rose to 40.5% if all abnormal scan parameters were used. CONCLUSION: Improvements in mortality and severe morbidity subsequent to introducing a universal ultrasound for growth restriction are encouraging but remain unclear. Little change in intervention is possible. The antenatal detection of low birthweight remains poor but improves where markers of growth restriction are used.

Do specific maternal sensations experienced in late pregnancy correlate to a breech presenting baby? Evaluation of a simple maternal questionnaire.

OBJECTIVES: To investigate the effectiveness of a structured questionnaire completed at 36 weeks gestation in predicting breech presentation. DESIGN: Questionnaire-based study. SETTING: Tertiary NHS Foundation Trust. PARTICIPANTS: Women attending for a universally offered 36-week fetal growth scan. INTERVENTION: Completion of a previously designed maternal questionnaire detailing sensation of fetal movements during the past week, immediately before a routine growth scan. RESULTS: Between September 01, 2018 and September 30, 2019, 2341 questionnaires were handed out and 2053 were returned. Analysis was performed in 1938 (94.4%) completed questionnaires. Recorded presentation was breech in 109 (5.6%), transverse/oblique in 15 (0.8%), and cephalic in 1814 (93.6%). Women "thinking their baby was breech" had a high positive likelihood ratio, at 11.8 (95% CI 7.4-19.1), but poor sensitivity (27.3%). "Feeling kicks low down or near the bladder" was sensitive for non-cephalic presentation (76.3%) but with poor specificity (48.9%). The questions "kicks low" ("no") (P = 0.013, aOR 2.18 [1.18-4.04]) and 'thinks cephalic ("no")' (P = 0.001, aOR 0.12 (0.04-0.43) were independent risk factors for a non-cephalic presentation. CONCLUSIONS: The questions posed in this questionnaire could aid the detection of breech presentation, but do not perform better than published data on palpation. Missing a breech presentation near term through palpation alone is well reported. Combining the concept of palpation to exclude breech presentation and these questions may help focus a clinician and improve both palpation skills and breech detection. As a minimum, a woman who believes her baby is breech should be taken seriously.

Prenatal diagnosis of PERCHING syndrome caused by homozygous loss of function variant in the KLHL7 gene.

AIMS: A couple were referred for prenatal genetic testing at 31 weeks' gestation due to the presence of mild polyhydramnios and multiple central nervous system (CNS) abnormalities, including borderline ventriculomegaly, possible delayed sulcation, an enlarged cisterna magna and a small area of calcification around the posterior horns. Testing was initiated to identify any underlying genetic cause. MATERIALS AND METHODS: Rapid trio exome sequencing (ES) was performed on DNA extracted from parental blood samples and amniotic fluid. RESULTS: A pathogenic homozygous nonsense variant in KLHL7 (NM_001031710.2) associated with PERCHING syndrome (#617055) was identified. CONCLUSION: Whilst there are detailed descriptions of the many postnatal phenotypes seen in these patients, there are few reports of features identified during pregnancy. This report is the first published prenatal diagnosis of PERCHING syndrome and provides further information on the associated fetal phenotypes.

Ultrasound predictors of adverse outcome in pregnancy complicated by pre-existing and gestational diabetes.

INTRODUCTION: Ultrasound assessment of fetuses subjected to hyperglycemia is recommended but, apart from increased size, little is known about its interpretation, and the identification of which large fetuses of diabetic pregnancy are at risk is unclear. Newer markers of adverse outcomes, abdominal circumference growth velocity and cerebro-placental ratio, help to predict risk in non-diabetic pregnancy. Our study aims to assess their role in pregnancies complicated by diabetes. MATERIAL AND METHODS: This is a retrospective analysis of a cohort of singleton, non-anomalous fetuses of women with pre-existing or gestational diabetes mellitus, and estimated fetal weight at the 10th centile or above. Gestational diabetes was diagnosed by selective screening of at risk groups. A universal ultrasound scan was offered at 20 and 36 weeks of gestation. Estimated fetal weight, abdominal circumference growth velocity, presence of polyhydramnios, and cerebro-placental ratio were evaluated at the 36-week scan. A composite adverse outcome was defined as the presence of one or more of perinatal death, arterial cord pH less than 7.1, admission to Neonatal Unit, 5-minute Apgar less than 7, severe hypoglycemia, or cesarean section for fetal compromise. A chi-squared test was used to test the association of estimated fetal weight at the 90th centile or above, polyhydramnios, abdominal circumference growth velocity at the 90th centile or above, and cerebro-placental ratio at the 5th centile or below with the composite outcome. Logistic regression was used to assess which ultrasound markers were independent risk factors. Odds ratios of composite adverse outcome with combinations of independent ultrasound markers were calculated. RESULTS: A total of 1044 pregnancies were included, comprising 87 women with pre-existing diabetes mellitus and 957 with gestational diabetes. Estimated fetal weight at the 90th centile or above, abdominal circumference growth velocity at the 90th centile or above, cerebro-placental ratio at the 5th centile or below, but not polyhydramnios, were significantly associated with adverse outcomes: odds ratios (95% confidence intervals) 1.85 (1.21-2.84), 1.54 (1.02-2.31), 1.92 (1.21-3.30), and 1.53 (0.79-2.99), respectively. Only estimated fetal weight at the 90th centile or above and cerebro-placental ratio at the 5th centile or below were independent risk factors. The greatest risk (odds ratio 6.85, 95% confidence interval 2.06-22.78) was found where both the estimated fetal weight is at the 90th centile or above and the cerebro-placental ratio is at the 5th centile or below. CONCLUSIONS: In diabetic pregnancies, a low cerebro-placental ratio, particularly in a macrosomic fetus, confers additional risk.

The impact of a routine late third trimester growth scan on the incidence, diagnosis, and management of breech presentation in Oxfordshire, UK: A cohort study.

BACKGROUND: Breech presentation at term contributes significantly to cesarean section (CS) rates worldwide. External cephalic version (ECV) is a safe procedure that reduces term breech presentation and associated CS. A principal barrier to ECV is failure to diagnose breech presentation. Failure to diagnose breech presentation also leads to emergency CS or unplanned vaginal breech birth. Recent evidence suggests that undiagnosed breech might be eliminated using a third trimester scan. Our aim was to evaluate the impact of introducing a routine 36-week scan on the incidence of breech presentation and of undiagnosed breech presentation. METHODS AND FINDINGS: We carried out a population-based cohort study of pregnant women in a single unit covering Oxfordshire, United Kingdom. All women delivering between 37+0 and 42+6 weeks gestational age, with a singleton, nonanomalous fetus over a 4-year period (01 October 2014 to 30 September 2018) were included. The mean maternal age was 31 years, mean BMI 26, 44% were nulliparous, and 21% were of non-white ethnicity. Comparisons between the 2 years before and after introduction of routine 36-week scan were made for 2 primary outcomes of (1) the incidence of breech presentation and (2) undiagnosed breech presentation. Secondary outcomes related to ECV, mode of birth, and perinatal outcomes. Relative risks (RRs) with 95% confidence intervals (CIs) are reported. A total of 27,825 pregnancies were analysed (14,444 before and 13,381 after). A scan after 35+0 weeks was performed in 5,578 (38.6%) before, and 13,251 (99.0%) after (p < 0.001). The incidence of breech presentation at birth did not change significantly (2.6% and 2.7%) (RR 1.02; 95% CI 0.89, 1.18; p = 0.76). The rate of undiagnosed breech before labour reduced, from 22.3% to 4.7% (RR 0.21; 95% CI 0.12, 0.36; p < 0.001). Vaginal breech birth rates fell from 10.3% to 5.3% (RR 0.51; 95% CI 0.30, 0.87; p = 0.01); nonsignificant increases in elective CS rates and decreases in emergency CS rates for breech babies were seen. Neonatal outcomes were not significantly altered. Study limitations include insufficient numbers to detect serious adverse outcomes, that we cannot exclude secular changes over time which may have influenced our results, and that these findings are most applicable where a comprehensive ECV service exists. CONCLUSIONS: In this study, a universal 36-week scan policy was associated with a reduction in the incidence but not elimination of undiagnosed term breech presentation. There was no reduction in the incidence of breech presentation at birth, despite a comprehensive ECV service.

Correction: The impact of a routine late third trimester growth scan on the incidence, diagnosis, and management of breech presentation in Oxfordshire, UK: A cohort study.

[This corrects the article DOI: 10.1371/journal.pmed.1003503.].

Emergency cervical cerclage in twin and singleton pregnancies with 0-mm cervical length or prolapsed membranes.

INTRODUCTION: Cervical cerclage is controversial in twin pregnancies, although recent data from the USA supports its use where "physical examination-indicated". Limited data exist, however, in the extreme situation of 0-mm ultrasound-measured cervical length or even prolapsed membranes. This research compares the success of emergency cervical cerclage in multiple and singleton pregnancies. MATERIAL AND METHODS: This is a retrospective cohort study of all such cerclages performed at a tertiary hospital over a 15-year period. "Emergency" was where transvaginal ultrasound-assessed cervical length was 0 mm, with amniotic membranes at or beyond the external cervical os. Exclusion criteria were clinical or biochemical evidence of infection, regular contractions, bleeding, ruptured membranes, or gestation beyond 24+0  weeks. The primary outcome, or "success", was defined as birth >27+6  weeks of gestation, with the neonate alive 28 days later with no markers of adverse outcome (seizures, periventricular leukomalacia, intracranial hemorrhage more than Grade 2, or necrotizing enterocolitis). Demographic and cerclage variables were assessed against the primary outcome. Variables correlated with success were analyzed between multiple and singleton pregnancies. Comparison of all adverse outcomes was then adjusted using logistic regression. RESULTS: A total of 135 pregnancies were included (107 singletons and 28 multiples [all twins]). Success was achieved in 79 (58.5%; 57.9% in singletons, 60.7% in twins). Nulliparity, in utero transfer, symptoms, prolapsed membranes, and dilation more than 3 cm were predictors of failure, but twin pregnancy was not. After controlling for potential confounding variables, there was no significant difference in measures of success between singleton and twin pregnancies, apart from higher rates of neonatal unit admission. CONCLUSIONS: Emergency cervical cerclage, even in extreme situations, is as effective in twin pregnancies as it is in singletons.

The impact of individual sonographer variation on the detection of small for gestational age fetuses using a third trimester growth scan.

OBJECTIVES: Detection of small for gestational age (SGA) fetuses in a third trimester ultrasound could be affected by variation in sonographer performance. METHODS: Retrospective analysis of all singleton, non-anomalous ultrasound examinations between 35+0 -36+6 weeks gestation, in a single institution where a universal 36-week scan is offered. Screen positive was defined as estimated fetal weight (EFW) <10th centile; SGA was birthweight <10th centile. Individual sonographers' distributions of head circumference (HC), abdominal circumference (AC) and femur length (FL) were used to assess sonographers' screen positive rate (SPR), detection rate (DR) and true positive rate (TPR). Univariate and multivariate regression analysis was performed to assess the association between the sonographers' mean and SD (SD) for HC, AC, FL and their SPR, DR and TPR. RESULTS: There were 27 sonographers performing more than 50 examinations per year, a total of 5691 scans. The mean incidence of SGA was 10.0%. For an overall SPR of 9.4%, the overall DR was 43.8% (95% CI: 39.6% - 48.1%) and the overall TPR was 46.5% (95% CI: 42.9% - 50.2%). Higher AC scatter (SD difference up to 11.6 mm) was associated with higher SPR (P = 0.001). Lower mean FL (difference up to 3.6 mm) was associated with higher SPR (P = 0.003) and higher DR (P = 0.002). As a result, DR varied amongst different sonographers between 14.3% and 85.7% and TPR varied between 8.3% and 100.0%. CONCLUSIONS: Monitoring of individual AC and FL distributions is a simple and effective tool for institutional quality assurance.

How often do we incidentally find a fetal abnormality at the routine third-trimester growth scan? A population-based study.

BACKGROUND: Third-trimester scans are increasingly used to try to prevent adverse outcomes associated with abnormalities of fetal growth. Unexpected fetal malformations detected at third-trimester growth scans are rarely reported. OBJECTIVE: To determine the incidence and type of fetal malformations detected in women attending a routine third-trimester growth scan. STUDY DESIGN: This was a population-based study of all women with singleton pregnancy attending antenatal care over a 2-year period in Oxfordshire, UK. Women who had a viable singleton pregnancy at dating scan were included. Women had standard obstetrical care including the offer of a routine dating scan and combined screening for trisomies; a routine anomaly scan at 18 to 22 weeks; and a routine third-trimester growth scan at 36 weeks. The third-trimester scan comprises assessment of fetal presentation, amniotic fluid, biometry, umbilical and middle cerebral artery Dopplers, but no formal anatomic assessment is undertaken. Scans are performed by certified sonographers or clinical fellows (n=54), and any suspected abnormalities are evaluated by a team of fetal medicine specialists. We assessed the frequency and type of incidental congenital malformations identified for the first time at this third-trimester scan. All babies were followed-up after birth for a minimum of 6 months. RESULTS: There were 15,244 women attending routine antenatal care. Anomalies were detected in 474 (3.1%) fetuses as follows: 103 (21.7%) were detected before the anomaly scan, 174 (36.7%) at the anomaly scan, 11 (2.3%) after the anomaly scan and before the third-trimester scan, 43 (9.1%) at the third-trimester scan and 143 (30.2%) after birth. The 43 abnormalities were found in a total of 13,023 women who had a 36 weeks scan, suggesting that in 1 out of 303 (95% confidence interval, 233-432) women attending such a scan, a new malformation was detected. Anomalies detected at the routine third-trimester scan were of the urinary tract (n=30), central nervous system (5), simple ovarian cysts (4), chromosomal (1), splenic cyst (1), skeletal dysplasia (1), and cutaneous lymphangioma (1). Most urinary tract anomalies were renal pelvic dilatation, which showed spontaneous resolution in 57% of the cases. CONCLUSION: When undertaking a program of routine third-trimester growth scans in women who have had previous screening scans, an unexpected congenital malformation is detected in approximately 1 in 300 women.

The outcomes of pregnancies with reduced fetal movements: A retrospective cohort study.

INTRODUCTION: The objective of this study was to examine the outcomes and interventions in pregnant women presenting with a perception of reduced fetal movements (RFM), and to determine if repeated episodes of RFM increase the risk of adverse outcomes. MATERIAL AND METHODS: This was a retrospective cohort study conducted in six NHS hospitals within the Thames Valley network region, UK and one neighboring hospital, an area with approximately 31 000 births annually. All women with a primary presentation of perceived RFM after 24 completed weeks of gestation during the month of October 2016 were included in the study. Prospective records in all units were examined and individual case-notes were reviewed. Pregnancy and neonatal outcomes and their relation with recurrent presentations with RFM were examined using relative risks with 95% CI. The main outcome measures are described. Neonatal outcomes measured were perinatal mortality, neonatal unit admission, abnormal cardiotocography at presentation, a composite severe morbidity outcome of Apgar <7 at 5 minutes or arterial pH <7.0 or encephalopathy, and birthweight. Pregnancy outcomes measured were induction of labor, cesarean section, admission and ultrasound usage rates. RESULTS: In all, 591 women presented with RFM during the month; using annual hospital birth figures, the incidence of RFM was estimated at 22.6% (range 14.9%-32.5%). More than 1 presentation of RFM occurred in 273 (46.2%). All 3 deaths (0.5%) were at the first presentation. More than 1 presentation was associated with higher induction rates (56.0% vs 31.9%), but no increase in any adverse outcomes including small-for-gestational-age. CONCLUSIONS: Reduced fetal movements, and recurrent episodes, are common, and lead to considerable resource usage and obstetric intervention. We found no evidence to suggest that recurrent episodes increase pregnancy risk.

Arteriovenous differences in cord blood gas analysis and the prediction of adverse neonatal outcome.

INTRODUCTION: The aim of this paper was to determine whether arteriovenous differences of pH and pCO2 are useful predictors of adverse neonatal outcome in acidemic neonates. MATERIAL AND METHODS: An established database of 8759 term, singleton, non-anomalous neonates with validated cord gases and outcomes [Encephalopathy (Grade 2/3), Apgar <7 at five minutes and composite neonatal outcomes of neurological and systemic involvement] was used. Analysis was of the cohort of the 520 acidemic (arterial pH <7.10) neonates. Chi-square tests with odds ratio (OR), 95% CI were calculated for dichotomous cut-offs of differences; hierarchical logistic regression was used to examine the predictive performance over and above arterial pH. RESULTS: Arteriovenous hydrogen ion concentration ([H+ ion]) differences do not predict neonatal outcomes except low Apgar scores, and large pCO2 differences are associated with worse neonatal outcomes. Nevertheless, neonates with large arteriovenous [H+ ion] and pCO2 differences have lower arterial pH values. Hierarchical regression demonstrates that arteriovenous pCO2 differences do not add predictive value beyond arterial pH and arteriovenous [H+ ion] adds only to the prediction of low Apgar scores. CONCLUSIONS: Arteriovenous differences of [H+ ion] and pCO2 are not useful independent predictors of adverse neonatal outcomes in acidemic neonates.

A reference range of fetal abdominal circumference growth velocity between 20 and 36 weeks' gestation.

OBJECTIVE: To create a single equation and reference range for abdominal circumference growth velocity (ACGV) between 20 and 36 weeks in singleton pregnancies. METHOD: Observational study of pregnant women having routine scans for abdominal circumference (AC) at 20 and 36 weeks' gestation. Exclusion criteria were multiple pregnancy, abnormal karyotype, major fetal abnormalities, and absent data on first-trimester dating. Scan image quality and AC measurement reliability were assessed according to INTERGROWTH-21st criteria. Regression models for the AC mean and standard deviation were fitted separately at 20 and 36 weeks, and z scores were calculated. Abdominal circumference growth velocity was defined as the z score difference between 20 and 36 weeks divided by the interval in days and multiplied by 100. RESULTS: The study population included 3334 fetuses. The equation for ACGV is (((AC36  - 53.090 - 1.081*GA36 )/(0.057638*GA36  + 0.622741)) - ((AC20  + 68.349 - 1.571*GA20 )/(0.06265*GA20  - 2.55361)))*100/(GA36  - GA20 ), where AC is expressed in millimeters and GA is gestational age in days. The 3rd, 5th, 10th, 50th, 90th, 95th, and 97th centiles are -1.8997, -1.6785, -1.3091, -0.0069, 1.3255, 1.7279, 1.9973, respectively. CONCLUSION: We have defined ACGV between 20 and 36 weeks, and we have established its reference range. Further studies are needed to evaluate the clinical significance of growth patterns in the tail ends of this distribution.

A technique for the estimation of fractional moving blood volume by using three-dimensional power Doppler US.

PURPOSE: To (a) demonstrate an image-processing method that can automatically measure the power Doppler signal in a three-dimensional ( 3D three-dimensional ) ultrasonographic (US) volume by using the location of organs within the image and (b) compare 3D three-dimensional fractional moving blood volume ( FMBV fractional moving blood volume ) results with commonly used, unstandardized measures of 3D three-dimensional power Doppler by using the human placenta as the organ of interest. MATERIALS AND METHODS: This is a retrospective study of scans obtained as part of a prospective study of imaging placental biomarkers with US, performed with ethical approval and written informed consent. One hundred forty-three consecutive female patients were examined by using an image-processing technique. Three-dimensional FMBV fractional moving blood volume was measured on the vasculature from the uteroplacental interface to a depth 5 mm into the placenta by using a normalization volume 10 mm outside the uteroplacental interface and compared against the Virtual Organ Computer-aided AnaLysis ( VOCAL Virtual Organ Computer-aided AnaLysis ; GE Healthcare, Milwaukee, Wis) vascularization flow index ( VFI vascularization flow index ). Intra- and interobserver variability was assessed in a subset of 18 volumes. Wilcoxon signed rank test and intraclass correlation coefficients were used to assess measurement repeatability. RESULTS: The mean 3D three-dimensional FMBV fractional moving blood volume value ± standard deviation was 11.78% ± 9.30 (range, 0.012%-44.16%). Mean VFI vascularization flow index was 2.26 ± 0.96 (range, 0.15-6.06). Linear regression of VFI vascularization flow index versus FMBV fractional moving blood volume produced an R(2) value of 0.211 and was significantly different in distribution (P < .001). Intraclass correlation coefficient analysis showed higher FMBV fractional moving blood volume values than VFI vascularization flow index for intra- and interobserver variability; intraobserver values were 0.95 for FMBV fractional moving blood volume (95% confidence interval [ CI confidence interval ]: 0.90, 0.98) versus 0.899 for VFI vascularization flow index (95% CI confidence interval : 0.78, 0.96), and interobserver values were 0.93 for FMBV fractional moving blood volume (95% CI confidence interval : 0.82, 0.97) versus 0.67 for VFI vascularization flow index (95% CI confidence interval : 0.32, 0.86). CONCLUSION: The extension of an existing two-dimensional standardized power Doppler measurement into 3D three-dimensional by using an image-processing technique was shown in an in utero placental study. Three-dimensional FMBV fractional moving blood volume and VFI vascularization flow index produced significantly different results. FMBV fractional moving blood volume performed better than VFI vascularization flow index in repeatability studies. Further studies are needed to assess accuracy against a reference standard.