Prenatal Diagnosis Of Congenital Anomalies

1. 妊娠期经腹宫颈长度评估无法识别大量宫颈短的妇女：妊娠期经腹宫颈长度评估不足以识别宫颈短因而有早产风险的妇女。虽然经阴道超声（US）被认为是诊断妊娠期宫颈短的金标准，但一些研究人员继续提出，经腹宫颈长度评估可用于识别宫颈短的患者。为了检验经腹超声在鉴别超声短宫颈中的价值，我们比较了220名孕妇两种方法获得的宫颈内长度的再现性和一致性。220名参与者中约有10% （n=21）经阴道超声检查宫颈长度<25 mm。其中，只有43% （n=9）被经腹超声正确识别为宫颈短。相对于经腹超声，经阴道超声在2D图像和立即获得的3D体积数据集之间的比较具有更高的可重复性。因此，我们得出的结论是，使用经腹超声检查不适合用于识别应该随后进行经阴道超声检查以诊断宫颈短的患者。经阴道超声应作为测量宫颈内管的主要方法。

1. Transabdominal evaluation of uterine cervical length during pregnancy fails to identify a substantial number of women with a short cervix: Transabdominal evaluation of uterine cervical length during pregnancy is not adequate to identify women with a short cervix and therefore at risk for preterm delivery. While transvaginal ultrasound (US) is considered the gold standard for the diagnosis of a short cervix during pregnancy, several investigators continue to propose that transabdominal cervical length assessment can be used to identify patients with a short cervix. To examine the value of transabdominal sonography in the identification of a sonographic short cervix, we compared reproducibility and agreement of endocervical length obtained by both methods in 220 pregnant women. Approximately 10% (n=21) of the 220 participants had a cervical length <25 mm by transvaginal US. Among them, only 43% (n=9) were correctly identified as having a short cervix by transabdominal US. Transvaginal US was more reproducible based on comparisons between 2D images and immediately acquired 3D volume datasets relative to transabdominal US. Therefore, we conclude that the use of transabdominal US is not appropriate to identify patients who should have a subsequent transvaginal US to diagnose a short cervix. Transvaginal US should be used as the primary method for measuring the endocervical canal. 2. Magnetic resonance diffusion weighted imaging - reproducibility of regional apparent diffusion coefficients for the normal fetal brain: The purpose of this study was to examine the reproducibility of regional apparent diffusion coefficient (ADC) measurements of the normal brain in 50 second and third trimester (19-37 wks) fetuses from healthy women. The secondary objective was to characterize the age-related changes in water diffusivity from various white and gray matter regions in nonsedated fetuses. Single-shot diffusion-weighted imaging (DWI) of the fetal brain was obtained using a 1.5-Tesla MR scanner and a 6-channel body array coil. ADC maps were created using 0 and 1000 b-values along 3 orthogonal directions. Two examiners independently measured ADC values in the cerebellar hemispheres (CH), pons, thalamus, basal ganglia (BG), centrum semiovale (CSO), frontal (FWM), parietal (PWM), temporal (TWM), and occipital white matter (OWM). Correlation between ADC values and menstrual age was assessed by linear regression. ADC values either remained constant (BG, FWM, PWM, TWM, CSO) or decreased (CH, pons, thalamus) with advancing menstrual age. Mean intra-observer bias for ADC measurements was not significantly different from zero. Small differences in inter-observer bias were detected for CH (1.260.20 vs. 1.200.18, p=0.006), PWM (1.370.29 vs. 1.330.26, p=0.02), and CSO (1.360.29 vs. 1.330.28, p<0.0001). We conclude that manually traced ADC measurements from fetal DWI are reproducible with an acceptable degree of inter-examiner variability. 3. The relationship of newborn adiposity to fetal growth based on birth weight or the modified neonatal growth assessment score: The primary objective of this study was to develop reference ranges of neonatal adiposity using air displacement plethysmography (ADP). These reference ranges were subsequently used to compare 2 different methods for evaluating neonatal nutritional status. Percentage body fat (%BF) and % fat mass (%FM) were derived from 324 normal newborns delivered between 35-41 wks, post-menstrual age. Results were stratified for 92 of these newborns with corresponding fetal biometry using 2 methods for classifying nutritional status: 1) population-based weight percentiles; and 2) a modified neonatal growth assessment score (m3NGAS51). The m3NGAS51 is used to evaluate neonatal growth outcome on the basis of weighted growth potential realization index (GPRI) profile for weight, head circumference, mid-thigh circumference, abdominal circumference, and crown heel length. GPRI values compare the actual neonatal size measurement to predicted values using an appropriate 2nd trimester Rossavik fetal growth model obtained from prenatal scans. At the 50th percentile, %BF varied from 7.7% (35 wks) to 11.8% (41 wks), while the corresponding 50th percentiles or total FM range was 186436 g. Among a subset of 92 neonates, no significant differences in adiposity were found between small for gestational age, appropriate for gestational age, and large for gestational age groups using population-based weight standards. Classification of the same neonates using m3NGAS51 showed significant differences in mean %BF between corresponding groups. We concluded that conventional population-based weight criteria for neonatal nutritional status can lead to misclassifications on the basis of adiposity. A neonatal growth assessment score which considers the growth potential of several anatomic parameters from 2nd trimester fetal biometry appears to more effectively classify malnourished newborns. 4. Prospective validation of fetal weight estimation using fractional limb volume: Our group developed a novel fetal soft tissue parameter, fractional limb volume, for the prenatal assessment of nutritional status and for improving the precision of fetal weight estimation. This investigation prospectively evaluated these new weight prediction models over a broader range of birth weights than previously reported. Pregnant women underwent 3D ultrasonography (n = 164) within 4 days of delivery. Birth weights ranged from 235 5,790 grams. Fetal measurements were extracted using volume data sets for biparietal diameter, abdominal circumference, femur diaphysis length, fractional arm volume, and fractional thigh volume. Fractional limb volumes were manually traced from a central portion of the humerus or femur diaphysis. Mean % difference (systematic error) and standard deviation of the % differences (random error) were calculated for estimated fetal weight (EFW). The proportion of newborns with EFW within 5% or 10% of birth weights were compared to a modified formula using model coefficients from the same local population sample. Deliveries occurred between 21.7 to 42 weeks, menstrual age. Optimal model performance (1.9 6.6%) resulted from using a combination of biparietal diameter, abdominal circumference, and fractional thigh volume. The precision of this model was superior to results from using a modified model (1.1 8.4%) although accuracy of these predictions was slightly decreased for females. For all fetuses, the prediction model that incorporated fractional thigh volume correctly classified a greater proportion of EFW within 5% (55.1% versus 43.7%, p = 0.03) or 10% (86.5% versus 75.9%, p < 0.05) of birth weight when compared to a modified model for our local population sample. We concluded that fractional thigh volume can be added to 2D sonographic measurements of the head and trunk to improve precision of EFW. This approach supports the inclusion of soft tissue development as part of a weight estimation procedure for the assessment of generalized fetal nutritional status.