Occipitofrontal Diameter Research Articles

Prenatal and postnatal growth: An ultrasound and clinical investigation

Background Understanding facial development requires sound knowledge of growth at different stages. Although studies in the past have established the relationship between prenatal and postnatal growth, little research has been done using noninvasive ultrasound. The purpose of this study is to evaluate correlation between prenatal and postnatal growths using ultrasound as a fetal growth assessment tool. Study Settings: It is a hospital-based study where prenatal growth is measured at different intervals of gestational period and compared with the growth at birth. Materials and Methods: Ten subjects with normal pregnancy were studied using ultrasound. Cephalocaudal growth gradient, body proportions of the fetus were assessed and compared at different stages. Growth was also evaluated at birth and compared with the predicted growth. Results The growth rate of estimated fetal weight is at maximum between the 28th and 32nd week of the fetal life (P ≤ 0.001). The growth rate of head circumference, occipitofrontal diameter, and femur length is maximum between the 20th and 28th week of the fetal life (P < 0.001). Cephalocaudal growth gradient decreases with increased age of the fetus. Conclusions Prenatal growth is correlated with postnatal growth. Ultrasound can be used as a tool for the measurement and prediction of prenatal and postnatal growths.

Accuracy of ultrasound scanning relative to reference tests for prenatal diagnosis of microcephaly in the context of Zika virus infection: a systematic review of diagnostic test accuracy

Objective: To assess the accuracy of ultrasound measurements of fetal biometric parameters for prenatal diagnosis of microcephaly in the context of Zika virus (ZIKV) infection. Methods: We searched MEDLINE, EMBASE, CINAHL, CDTA and other bibliographic databases for studies published until 3rd March 2016. We extracted the numbers of true positives, false positives, true negatives and false negatives and performed meta-analysis to estimate group sensitivity and specificity, where possible. Predictive values for ZIKVinfected pregnancies were extrapolated from those obtained for pregnancies unrelated to ZIKV. Results: Out of 111 eligible full texts, nine studies met our inclusion criteria. Pooled estimates from two studies showed that at 3, 4 and 5 standard deviations (SDs) < mean, sensitivities were 84%, 68% and 58% for head circumference (HC); 76%, 58% and 58% for occipito-frontal diameter (OFD); and 94%, 85% and 59% for biparietal diameter (BPD). Specificities at 3, 4 and 5 SDs below the mean were 70%, 91% and 97% for HC; 84%, 97% and 97% for OFD; and 16%, 46% and 80% for BPD. No study including ZIKV-infected pregnant women was identified. Extrapolated positive predictive values for ZIKV-infected pregnancies at 3, 4 and 5 SD < mean were 2.6%, 6.7% and 15.6% for HC; 4.3%, 15.6% and 15.6% for OFD; and 1.0%, 1.4% and 2.8% for BPD, respectively. Negative predictive values at 3, 4 and 5 SDs < mean were over 99% for HC, OFD, and BPD. Five out of seven studies with descriptive data reported high rates of false positives when ultrasound is applied for prenatal diagnosis of microcephaly. Conclusion: Prenatal ultrasound appears more accurate in detecting the absence of microcephaly than its presence.

National curves of foetal growth in singleton foetuses of Greek origin.

Foetal growth monitoring is an essential component of prenatal care with postnatal impact. The aim of the study was to construct reference ranges for foetal biometric parameters in Greek foetuses and to compare them with previously published models. Measurements from 1200 Greek foetuses were used to construct normal curves for biparietal diameter (BPD), occipitofrontal diameter (OFD), head circumference (HC), abdominal circumference (AC), femoral length (FL) and the BPD/FL ratio according to the methodology described by Royston and Wright (1998). The model was validated in a second group of 1200 different foetuses using analysis of the corresponding standardized residuals (z-scores). The z-scores which were derived by our model were compared to those calculated using previously published models from other populations. BPD, OFD, HC, AC, FL and the BPD/FL ratio are accurately described by simple quadratic equations (R(2) > 0·96 for most of the parameters tested). Statistically significant differences were observed for most of the z-scores when our models were compared to previously published models. Less than 10% of our foetuses were < 5th or > 95th centile of the latter models. About 10% of our foetuses were > 95th centile for FL and HC when the INTERGROWTH-21st formulas were used. We present national foetal biometric references. Using charts from other populations (including INTERGROWTH-21st) may be unrepresentative of local populations and lead to misclassification of foetal growth status.

Modification ultrasonic methods estimating expected fetal weight

Selection of the optimal tactics of pregnancy and childbirth greatly depends on the expected weight of the fetus. Frequency of perinatal mortality and morbidity increased in grоup with growth retardation and fetal macrosomia. The aim of the study was a modification of ultrasonic methods for determining the expected fetal weight. Materials and methods. On the basis of maternity hospitals Trans-Baikal Region in the years 2013-2015 was held retrospective and prospective analysis of 210 labor histories, which were divided into 3 equal groups: 1 group - pregnant women with a body mass index (BMI) for Quetelet less than 24, group 2 - with a BMI from 24 to 30, group 3 - with a BMI more than 30. In order to determine the expected fetal weight by ultrasonic methods used formula of Hadlock, Shephard and Demidov. The error in determining fetal weight standard methods more than 250 g, which identified the need to establish new precise formula. The increase in the error in determining fetal weight at border gestation due to the lack of assessment of fetal tissue density. On the basis of mathematical and 3d-modeling of the body’s volume, depending on its mass determined pattern change of the average density of fetal tissue, depending on the gestational age, which is expressed by the formula: ρ = 0,833 + 0,004475GA, where ρ - the average density of tissue, GA - gestational age. Through a comprehensive analysis of ultrasound data’s fetometry and medium-density tissue defined fetal weight formula: M = (0,2777 + 0,001492 × GA) × OFD × AC × (Fe + Ti + Hu + Ra), where GA - gestational age (weeks), AC - abdominal circumference (cm), OFD - occipitofrontal diameter (cm), Fe - femur’s length (cm), Ti - tibia’s length (cm), Hu - humerus’s length (cm), Ra - radius’s length (cm), 0.2777 and 0.001492 - digital prognostic factors. In calculating the weight of the fetus according to the proposed formula ultrasonic average error does not exceed 150 g. Thus, the method has a smaller error compared to the standard, and can be used to reliably determine fetal weight in II and III trimester of pregnancy.

Update Reference Charts: Fetal Biometry between the 15th and 20th Week of Gestation

Objective: The aim of this study was to derive reference charts between the 15th and 20th week of gestation for biparietal diameter (BPD), occipito-frontal diameter (OFD), head circumference (HC), abdominal circumference (AC) and femur length (FL) compared to commonly used curves and to evaluate the impact of maternal body mass index (BMI), ultrasound equipment, fetal gender and nicotine abuse. Methods: In a cross-sectional study of 4,265 low-risk pregnancies, biometric data were obtained between the 15th and 20th week of gestation. The statistical analysis included descriptive data, fitting regression curves for the 5th, 50th and 95th quantile as well as multivariate quantile regression analyses. Results: Reference curves for BPD, OFD, HC, AC and FL showed a linear increase between the 15th and 20th week of gestation. New equations and reference charts are presented in this study. In a comparison of influence factors sex, BMI and ultrasound systems have an impact. Conclusion: As a result of the study, we determined current growth curves for BPD, OFD, HC, AC and FL for both sexes as well as for males and females separately. The updated growth curves for all biometric parameters differ from the curves used commonly in the last two decades.

Head computed tomography: Dose output and relationship with anthropotechnical parameters

Background: The number of computed tomography (CT) centers and examinations in Nigeria has shown a steady increase. This will increase the collective dose and may potentially result in an increased incidence of cancer, hereditary diseases, and the possibility of mild deterministic effects. Objective: To determine radiation dose output and its relationship with anthropotechnical parameters. Methodology: A retrospective analyses of digital CT files. Effective dose was derived from the dose-length product and factor for examination of head CT (0.0023 mSv/mGy-cm). SPSS version 20.0 (SPSS Inc., Chicago, IL, USA) was used to analyze the data. Results: Files of 43 male and 42 female (n = 85) adult patients were analyzed. The mean (and 75 th percentile) of the CT dose index (CTDI), dose-length product (DLP), and effective dose in noncontrast examinations were 48 (59) mGy, 874 (1301) mGy-cm, and 1.8 (2.7) mSv, respectively. Contrast examinations yielded 54 (61) mGy, 1476 (2044) mGy-cm, and 3.1 (4.3) mSv, respectively. DLP showed a weak relationship with BPD (r = −0.220), age (r = 0.211), cephalic index (r = −0.186), height (r = 0.158), and gantry tilt (r = 0.154). There was no relationship with weight (r = 0.076), range (r = −0.073), occipitofrontal diameter (r = 0.037), and body mass index (r = −0.018). The correlations were neither statistically nor clinically significant. Conclusion: The CTDI is comparable with local values while the DLP is lower by a range of 5-31% but higher than foreign values by a range of 19-35%. Further optimization of CT radiation dose should be explored to eliminate the gulf between local and foreign dose outputs.

UTILIDAD DEL DIÁMETRO BIPARIETAL CORREGIDO PARA EL CÁLCULO DEL PESO FETAL DETERMINADO POR ULTRASONIDO

OBJETIVO: Analizar la utilidad del diámetro biparietal corregido para calcular el peso fetal, determinado por ultrasonido. DISEÑO: Estudio prospectivo. LUGAR: Hospital Cayetano Heredia, Piura, Perú. PACIENTES: Gestantes a término. INTERVENCIONES: Entre enero y mayo de 2006, se midió el diámetro biparietal (DBP), diámetro occipitofrontal (DOF), diámetro biparietal corregido (DBPc), longitud de fémur (LF) y perímetro abdominal (PA) en 50 gestantes. Se calculó el peso fetal, según Hadlock, en el primer grupo, utilizando el diámetro biparietal; y, en el segundo grupo, el diámetro biparietal corregido; se correlacionó ambos con el peso al nacer (PAN). El tiempo entre la ecografía y el parto fue menor de 72 horas. PRINCIPALES MEDIDAS DE RESULTADOS: Correlación de los diámetros biparietal y diámetro biparietal corregido fetales con el peso al nacer. RESULTADOS: La edad promedio de las gestantes fue 26,8 ± 6,4 años. Peso promedio al nacer de sus niños, 3 215 g. Utilizando el DBP, el peso promedio estimado fue 3 212 g, error porcentual 5,55%, error estándar 130 g y correlación 0,888. Usando el DBPc, el peso promedio estimado fue 3 320 g, error porcentual 5,85%, error estándar 127 g y correlación 0,858. CONCLUSIÓN: Para calcular el peso fetal por ecografía, no demostró utilidad usar el diámetro biparietal corregido en vez del diámetro biparietal, según la fórmula de Hadlock.

Effects of Serum 25-hydroxy-vitamin D and Fetal Bone Growth during Pregnancy.

BackgroundThis study was conducted to observe the prevalence of vitamin D deficiency during pregnancy and the effects of maternal 25-hydroxy-vitamin D (25-[OH]D) levels on fetal bone growth.MethodsFive hundred twenty-three Korean pregnant women were randomly recruited and serum 25-(OH)D level was measured. During pregnancy, fetal ultrasonography and serum 25-(OH)D measurements were carried out 3 times in 275 of 523 pregnant women. Fetal biparietal and occipitofrontal diameter, head and abdominal circumference, and femur and humerus length were measured through fetal ultrasonography.ResultsThe prevalence of vitamin D deficiency (25-[OH]D<20 ng/mL) based on the 1st serum measurement of 25-(OH)D was 88.9%. There was no association between maternal serum 25-(OH)D level and fetal bone growth. In 275 pregnant women who completed study design, the mean value of 25-(OH)D was 12.97±5.93, 19.12±9.82, and 19.60±9.98 ng/mL at 12 to 14, 20 to 22, and 32 to 34 weeks of pregnancy, respectively and there was an association between the difference of serum 25-(OH)D level between 12 to 14 and 20 to 22 weeks and growth velocity of fetal biparietal diameter between 20 to 22 and 32 to 34 weeks of pregnancy.ConclusionsThis study shows a high prevalence of vitamin D deficiency in Korean pregnant women and the change of serum 25-(OH)D levels is related with the growth of fetal biparietal diameter, however other parameters are not associated with serum 25-(OH)D levels.

International standards for fetal growth based on serial ultrasound measurements: the Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project

In 2006, WHO produced international growth standards for infants and children up to age 5 years on the basis of recommendations from a WHO expert committee. Using the same methods and conceptual approach, the Fetal Growth Longitudinal Study (FGLS), part of the INTERGROWTH-21(st) Project, aimed to develop international growth and size standards for fetuses. The multicentre, population-based FGLS assessed fetal growth in geographically defined urban populations in eight countries, in which most of the health and nutritional needs of mothers were met and adequate antenatal care was provided. We used ultrasound to take fetal anthropometric measurements prospectively from 14 weeks and 0 days of gestation until birth in a cohort of women with adequate health and nutritional status who were at low risk of intrauterine growth restriction. All women had a reliable estimate of gestational age confirmed by ultrasound measurement of fetal crown-rump length in the first trimester. The five primary ultrasound measures of fetal growth--head circumference, biparietal diameter, occipitofrontal diameter, abdominal circumference, and femur length--were obtained every 5 weeks (within 1 week either side) from 14 weeks to 42 weeks of gestation. The best fitting curves for the five measures were selected using second-degree fractional polynomials and further modelled in a multilevel framework to account for the longitudinal design of the study. We screened 13,108 women commencing antenatal care at less than 14 weeks and 0 days of gestation, of whom 4607 (35%) were eligible. 4321 (94%) eligible women had pregnancies without major complications and delivered live singletons without congenital malformations (the analysis population). We documented very low maternal and perinatal mortality and morbidity, confirming that the participants were at low risk of adverse outcomes. For each of the five fetal growth measures, the mean differences between the observed and smoothed centiles for the 3rd, 50th, and 97th centiles, respectively, were small: 2·25 mm (SD 3·0), 0·02 mm (3·0), and -2·69 mm (3·2) for head circumference; 0·83 mm (0·9), -0·05 mm (0·8), and -0·84 mm (1·0) for biparietal diameter; 0·63 mm (1·2), 0·04 mm (1·1), and -1·05 mm (1·3) for occipitofrontal diameter; 2·99 mm (3·1), 0·25 mm (3·2), and -4·22 mm (3·7) for abdominal circumference; and 0·62 mm (0·8), 0·03 mm (0·8), and -0·65 mm (0·8) for femur length. We calculated the 3rd, 5th 10th, 50th, 90th, 95th and 97th centile curves according to gestational age for these ultrasound measures, representing the international standards for fetal growth. We recommend these international fetal growth standards for the clinical interpretation of routinely taken ultrasound measurements and for comparisons across populations. Bill & Melinda Gates Foundation.

Sonopelvimetry: An Innovative Method for Early Prediction of Obstructed Labour

Aim: To evaluate an innovative sonopelvimetry method for early prediction of obstructed labour. Methods: A prospective study was conducted in two centers.GPS-based sonopelvimetry, laborProTM (Trig Medical Inc., Yoqneam Ilit, Israel) devise, was used prior to labour in nulliparous women at 39 - 42 weeks gestation remote from labor. Maternal pelvic parameters, including inter-iliac transverse diameter, obstetric conjugate and interspinous diameter were evaluated. Fetal parameters included head station, biparietal diameter and occipitofrontal diameter. Data on delivery and outcome were collected from the electronic files. Results: The innovative use of sonopelvimetry was applied to 154 consecutive women, none of the participants complained of discomfort or complications observed. The mean time of examination was 15 + 2 minutes. Mean time of examination to delivery interval was 4.8 days (range 0 - 16 days). Small interspinous diameter and high head station were the best predictors for obstructed labour. Analysis indicated 87% sensitivity and 61% specificity for birth weight fetal head station and ISD combined in predicting obstructed labour with an area under the curve of 0.77. Conclusions: Our results indicate that GPS-based sonopelvimetry combined with fetal estimated weight is a valuable tool in the risk assessment of obstructed labour. Parameters obtained by sonopelvimetry combined with birth weight may be useful.

Immediate effectiveness of balloon dilatation therapy for patients with dysphagia due to cricopharyngeal dysfunction

Onogi K, Saitoh E, Kondo I, Ozeki M, Kagaya H. Immediate effectiveness of balloon dilatation therapy for patients with dysphagia due to cricopharyngeal dysfunction. Jpn J Compr Rehabil Sci 2014; 5: 87-92. Purpose: To determine the immediate effectiveness of balloon dilatation therapy for patients with dysphagia due to cricopharyngeal dysfunction on videofluoroscopy (VFSS). Methods: The subjects were 11 consecutively recruited patients with central nervous system disease who were suspected of having upper esophageal sphincter (UES) insufficiency based on the presence of a large amount of residue in the pharynx on VFSS. The amount of residue and the occipitofrontal diameter of the UES were measured before and after dilatation. Results: The mean amount of pharyngeal residue was significantly smaller after than before dilatation. However, no significant difference was seen in the occipitofrontal diameter of the upper esophagus after dilatation. When the subjects’ brain lesions were divided into brainstem and supratentorial lesions, the pharyngeal residue was significantly lower in patients with supratentorial lesions than in those with brainstem lesions.

Evaluation of fetal anthropometric measures to predict the risk for shoulder dystocia

To evaluate the quality of anthropometric measures to improve the prediction of shoulder dystocia by combining different sonographic biometric parameters. This was a retrospective cohort study of 12,794 vaginal deliveries with complete sonographic biometry data obtained within 7 days before delivery. Receiver-operating characteristics (ROC) curves of various combinations of the biometric parameters, namely, biparietal diameter (BPD), occipitofrontal diameter (OFD), head circumference, abdominal diameter (AD), abdominal circumference (AC) and femur length were analyzed. The influences of independent risk factors were calculated and their combination used in a predictive model. The incidence of shoulder dystocia was 1.14%. Different combinations of sonographic parameters showed comparable ROC curves without advantage for a particular combination. The difference between AD and BPD (AD - BPD) (area under the curve (AUC) = 0.704) revealed a significant increase in risk (odds ratio (OR) 7.6 (95% CI 4.2-13.9), sensitivity 8.2%, specificity 98.8%) at a suggested cut-off ≥ 2.6 cm. However, the positive predictive value (PPV) was low (7.5%). The AC as a single parameter (AUC = 0.732) with a cut-off ≥ 35 cm performed worse (OR 4.6 (95% CI 3.3-6.5), PPV 2.6%). BPD/OFD (a surrogate for fetal cranial shape) was not significantly different between those with and those without shoulder dystocia. The combination of estimated fetal weight, maternal diabetes, gender and AD - BPD provided a reasonable estimate of the individual risk. Sonographic fetal anthropometric measures appear not to be a useful tool to screen for the risk of shoulder dystocia due to a low PPV. However, AD - BPD appears to be a relevant risk factor. While risk stratification including different known risk factors may aid in counseling, shoulder dystocia cannot effectively be predicted.

Usability of virtual‐reality simulation training in obstetric ultrasonography: a prospective cohort study

To assess the usability of virtual-reality (VR) simulation for obstetric ultrasound trainees. Twenty-six participants were recruited: 18 obstetric ultrasound trainees (with little formal ultrasonography training) and eight certified experts. All performed five sequential VR-simulated crown-rump length (CRL) scans in a single session and three repetitions of biparietal diameter (BPD), occipitofrontal diameter (OFD) and femur length (FL) measurements. Outcome measures included mean percentage deviation from target for all measurements. Time taken to perform each type of scan was recorded. The mean percentage difference for the first scan was significantly greater for the trainee group than for the expert group for BPD (P = 0.035), OFD (P = 0.010) and FL (P = 0.008) and for time taken for the first CRL (P < 0.001) and fetal biometry (including BPD, OFD and FL measurements) scan (P < 0.001), demonstrating that trainees were initially significantly less accurate and less efficient. Over subsequent scans, the trainees became more accurate for all measurements with a significant improvement shown for OFD and FL (P < 0.05). The time taken for trainees to complete CRL and fetal biometry scans decreased significantly (all P < 0.05) with repetition, to near-expert efficiency. All participants were able to use the simulator and produce clinically meaningful biometry results. With repetition, beginners quickly approached near-expert levels of accuracy and speed. These data demonstrate that obstetricians with minimal experience can improve their ultrasonographic skills with short-phase VR-simulation training. The speed of improvement suggests that VR simulation might be useful as a warm-up exercise before clinical training sessions in order to reduce their impact on clinical service.

Assessment of fetal tridimensional cerebellar volumes between genders

ABSTRACT Introduction: The object of this study was to assess the tridimensional cerebellar volume between genders and its correlation to other fetal growth parameters indices. Methods: The author carried out a cross-sectional and prospective study involving 125 normal pregnant women from 22 to 36 weeks of gestation. The assessment of fetal cerebellar volume was performed through Virtual Organ Computer-aided Analysis. The author also assessed other biometric fetal growth indices: biparietal diameter, occipitofrontal diameter, abdominal circumference, head circumference, femur length, anteroposterior cisterna magna diameter, lateral ventricle atria width and estimated fetal weight and its correla -tion to cerebellar volume. The Mancova analysis and Pearson’s correlation coefficient were used with gestational age as independent variable and cerebellar volume as dependent variable. Results: The results showed highly correlating to gestational age, biparietal diameter, occipito-frontal diameter, head circumference, femur length and estimated fetal weight (r-value above 0.90 and p<0.0001). Comparison between gen-ders did not show any significant difference in fetal cerebellar volume throughout pregnancy. Conclusions: The assessment of tridimensional cerebellar volume showed no difference between genders, but there was increasing throughout the pregnancy (p<0.0001). Key words: cerebellar volume, tridimensional ultrasound, fetal gender.

Fetal Sex and Intrauterine Growth Patterns

To analyze the effect of fetal sex on intrauterine growth patterns during the second and third trimesters. We conducted a cross-sectional study of women with uncomplicated singleton pregnancies who underwent sonographic fetal weight estimation during the second and third trimesters in a single tertiary center. The effect of fetal sex on intrauterine growth patterns was analyzed for each of the routine fetal biometric indices (biparietal diameter, head circumference, occipitofrontal diameter, abdominal circumference, and femur length) and their ratios. Sex-specific regression models were generated for these indices and their ratios as a function of gestational age. Sex-specific growth curves were generated from these models for each of the biometric indices and their ratios for gestational weeks 15 to 42. Overall, 12,132 sonographic fetal weight estimations were included in the study. Fetal sex had an independent effect on the relationship between each of the biometric indices and their ratios and gestational age. These effects were most pronounced for biparietal diameter (male/female ratio, 1.021) and the head circumference/femur length and biparietal diameter/femur length ratios (male/female ratios, 1.014 and 1.016, respectively). For the head measurements, these sex-related differences were observed as soon as the early second trimester, whereas for abdominal circumference, the differences were most notable during the late second and late third trimesters. Female fetuses grow considerably slower than male fetuses, and these differences are observed from early gestation. However, the female fetus is not merely a smaller version of the male fetus, but, rather, there is a sex-specific growth pattern for each of the individual fetal biometric indices. These findings provide support for the use of sex-specific sonographic models for fetal weight estimation as well as the use of sex-specific reference growth charts.

Automated Ultrasonographic Measurement of Basic Fetal Growth Parameters

The goal of our study was to compare the accuracy of automated ultrasonographic measurements of fetal biometric parameters with those achieved manually. Manual and automated fetal biometric measurements were performed in 83 patients between 11 + 0 and 40 + 6 weeks of gestation, regardless of BMI, fetal position, placental location and quantity of amniotic fluid. All patients were examined using Siemens Healthcare Ultrasound equipment, Syngo auto OB measurement, with a 6C2 probe (2.5 - 6 MHz) in a 2 D approach. The biometric measurement evaluation included the following parameters: crown-rump length (CRL), biparietal diameter (BPD), occipitofrontal diameter (OFD), head circumference (HC), abdominal circumference (AC), femur length (FL), and humerus length (HL). All patients were divided into four distinct groups according to the gestational age: Group 1: 11 + 0 to 14 + 6 weeks, Group 2: 15 + 0 to 23 + 6 weeks, Group 3: 24 + 0 to 34 + 6 weeks, and Group 4: 35 + 0 to 40 + 6 weeks. The results of the automated measurements were classified in four different groups: Score 1: the automatic measurements were within a range of ± 5 % of the manual measurements, Score 2: the automatic measurements varied within ± 10 % from those done manually, Score 3: the variability range was more than 10 % but less than 50 %, and Score 4: was related to an incorrect measurement. Comparing the automated with the manual measurements, Score 1 was found for 41.74 % of all biometric parameters. 24.37 % of the automated measurements were within Score 2, 11.65 % of the automated measurements showed Score 3 and 22.24 % had Score 4. Score 1 + 2 results were found in more than 62 % of cases for CRL, BPD, OFD, AC, and FL, followed by 55.91 % for HC measurements. The lowest result of 50.45 % was found for HL. Looking in detail at the four gestational age groups, a high range of variation was identified for the automatic biometric results for the different growth parameters: Group 1 had very good or good automatic results (Score 1 + 2) for CRL (76.93 %) and AC (76.47 %). Unacceptable measurements (= Score 3 + 4) were found for BPD (58.82 %), HC (64.71 %) and HL (82.35 %). Group 2 showed very good or good automatic results (Score 1 + 2) for BPD (90 %), OFD (83.34 %), HC (80.00 %), AC (80.00 %), FL (83.33) and HL (80.00 %). Score 3 + 4 results were found in less than 20 % of the cases in this group. Group 3 showed very good or good automatic results (Score 1 + 2) for BPD (87.50 %), OFD (79.17 %), and FL (87.50 %). Score 3 + 4 results were found high to be high for AC (41.66 %), and HL (37.50 %). Group 4 revealed very good or good automatic results (Score 1 + 2) only for OFD (83.34 %), while Score 3 + 4 were found high for BPD (41.67 %), HC (58.33 %), AC (50 %), FL (58.33 %) and HL (58.33 %). The comparison of all gestational age groups showed the best results for automatic measurements to be in the second group (15 + 0 to 23 + 6 weeks). Humerus length was the parameter with the highest unacceptable automated measurements in all 4 groups. Syngo auto OB measurement enables rapid automated measurement of fetal biometric parameters. Despite the fact that a number of problems remain to be solved, the described method may have a significant impact on daily workflow efficiency in fetal biometry.

Validation of Virtual Reality Simulation for Obstetric Ultrasonography

Ultrasonography is an important skill for obstetricians and gynecologists; however, trainees have highlighted ultrasonography as an area of deficiency in their training. We undertook a prospective cross-sectional comparative study to assess content and construct validity of an ultrasound virtual reality (VR) simulator (UltraSim). Twenty-six physicians and sonographers of varied ultrasonography experience were recruited and divided into trainees (no formal ultrasonography training) and expert (certified) categories. They performed a VR simulation crown-rump length (CRL) ultrasound scan and growth ultrasound scan measuring biparietal diameter, occipitofrontal diameter, abdominal anteroposterior and transverse diameters, and femur length. Maximum pool depth (MPD), placental site, and fetal presentation were also assessed. Outcome measures included the mean absolute deviation and the variance of the absolute deviation from true measurements. Accuracy of determining placental site, fetal presentation, and MPD was assessed. The time taken to perform each type of scan was recorded. Trainees had significantly greater variation of measurement of CRL (P = 0.025) than the expert group. For late-pregnancy fetal biometry, the absolute deviation and the degree of variability for all measurements differed. These differences were statistically significant (P < 0.05) for all measurements except abdominal diameters and MPD. Trainees took significantly longer time to obtain CRL and fetal biometric scans (P < 0.001). All subjects correctly identified fetal presentation and placental site. Clinicians with differing ultrasonography expertise showed differing skill with the UltraSim VR simulator, demonstrating construct validity for skills needed in simulation. Consideration should be given to investigating whether trainees with minimal scanning experience can improve their clinical skills and efficiency with VR simulation.

A new automatic algorithm to extract craniofacial measurements from fetal three‐dimensional volumes

Three-dimensional (3D) ultrasound is useful in the prenatal evaluation of fetal craniofacial structures, particularly as it provides a multiplanar view. However, an expert must designate the area of interest and the appropriate view, making measurement of fetal structures using 3D ultrasound both time-consuming and subjective. In this study we propose an image analysis system that measures automatically and precisely the fetal craniofacial structures and evaluate its performance in the second trimester of pregnancy using a new 3D volume analysis algorithm. A universal facial surface template model containing the geometric shape information of a fetal craniofacial structure was constructed from a fetal phantom. Using the proposed image analysis system we fitted this stored template model using a model deformation approach to individual fetal 3D facial volumes from 11 mid-trimester fetuses, and extracted automatically the following standard measurements: biparietal diameter (BPD), occipitofrontal diameter (OFD), interorbital diameter (IOD), bilateral orbital diameter (BOD) and distance between vertex and nasion (VN). The same five parameters were measured manually by an expert and the results compared. Comparison of the algorithm-based automatic measurements with manual measurements made by an expert gave correlation coefficients of 0.99 for BPD, 0.98 for OFD, 0.80 for BOD, 0.83 for IOD and 0.99 for VN. There were no significant differences between automatic and manual measurements. Our proposed system measures precisely the fetal craniofacial structures using 3D ultrasound, making it potentially useful for clinical service. This system could also be applied to other clinical fields in future testing.

Longitudinal reference ranges for fetal ultrasound biometry in twin pregnancies

OBJECTIVE:The purpose of this study was to establish longitudinal reference ranges for fetal ultrasound biometry measurements and growth parameters in twin pregnancies.METHOD:A total of 200 uncomplicated twin pregnancies before 21 weeks of gestation were recruited for this prospective, longitudinal study. Women who abandoned follow-up, pregnancies with unknown outcomes or pregnancies with complications were excluded. Ultrasound scans were performed every three weeks, and biparietal and occipitofrontal diameters, head and abdominal circumferences, and femur diaphysis length measurements were obtained for each fetus at each visit. Estimated fetal weight, biparietal/occipitofrontal diameter, head circumference/abdominal circumference, and femur diaphysis length/abdominal circumference ratios were also calculated. Multilevel regression analysis was performed on normalized data.RESULTS:A total of 807 ultrasound examinations were performed in 125 twin pregnancies between 14 and 38 weeks of gestation (6.5±1.4 scans/pregnancy). Regression analysis demonstrated significant correlations for all variables with gestational age, namely log of the biparietal diameter (r = 0.98), log of the occipitofrontal diameter (r = 0.98), log of the head circumference (r = 0.99), log of the abdominal circumference (r = 0.98), square root of the femur length (r = 0.99), log of the estimated fetal weight (r = 0.99), biparietal/occipitofrontal ratio (r = -0.11), head/abdomen circumference ratio (r = -0.56), and log of the femur length/abdominal circumference ratio (r = 0.61). Values corresponding to the 10th, 50th, and 90th percentiles for estimated fetal weight at 28, 32, and 36 weeks, respectively, were as follows: 937, 1,096, 1,284 g; 1,462, 1,720, 2,025 g; and 2,020, 2,399, 2,849 g.CONCLUSION:In twin pregnancies, fetal ultrasound biometry measurements and growth parameters show a significant correlation with gestational age.

Association of fetal cranial shape with shoulder dystocia

To evaluate whether fetal cranial shape is related to shoulder dystocia. We compared shoulder dystocia cases (n = 18) with controls (normal vaginal deliveries, n = 18) in a retrospective matched-pairs observational study. Subjects were matched for known maternal and fetal risk factors and then evaluated for fetal biometric differences, which were measured by ultrasound near delivery. We tested multivariable risk models to predict shoulder dystocia by logistic regression. Cases had a smaller estimated occipitofrontal diameter (OFD) (P = 0.02) and a larger biparietal diameter/estimated OFD ratio (P = 0.003). A multivariable model including estimated fetal weight, estimated OFD, maternal weight and diabetes mellitus had sensitivity and specificity of 86% and 95%, respectively, and positive and negative likelihood ratios of 18.9 and 0.15, respectively. Estimated OFD significantly increased the predictive value of the model. A small estimated OFD is a risk factor for shoulder dystocia in the presence of other significant risk factors. A multivariable model including estimated OFD can predict shoulder dystocia in a clinically useful range.