对比不同超声估重公式预测巨大胎儿体质量

目的 观察不同超声估重（SFEW）公式预测巨大胎儿的准确率，分析其影响因素。方法 回顾629例巨大儿，根据体质量分为A组和B组；将产前超声所测双顶径（BPD）、头围（HC）、腹围（AC）及股骨长（FL）代入不同公式，比较SFEW预测值与出生后实测值的差异。结果 不同估算公式SFEW测值均明显低于实测值（P均<0.001），其中Hadlock公式预测值与实测值的差异最小；产前超声生物学测值与出生后实测体质量及身长低度相关（r_s<0.50）。B组身长、体质量指数（BMI）及各超声生物学测值均明显大于A组（P均<0.05）；不同公式计算B组误差均明显大于A组（P均<0.05）。结论 SFEW有效可行，但易低估胎儿体质量，各公式参数不能充分体现巨大胎儿躯干外脂肪分布差异对体质量的影响可能是原因之一。     

Nomograms of the axial fetal cerebellar hemisphere circumference and area throughout gestation.

OBJECTIVE: The widely applied transcerebellar diameter (TCD) obtained at axial cranial imaging, measures the distance between the lateral aspects of the cerebellum and incorporates the width of the cerebellar vermis. Our objective was to create reference ranges of axial fetal cerebellar hemisphere circumference (CHC) and area (CHA), independent of the cerebellar vermis, throughout gestation. METHODS: This cross-sectional study involved pregnant patients between 14 and 41 weeks of gestation. Inclusion criteria consisted of well-established dates (confirmed by early ultrasound), non-anomalous singleton fetuses and intact amniotic membranes. Sonographic measurements included biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), humerus length (HL), TCD, and estimated fetal weight (EFW). Values of axial fetal CHC and CHA were each calculated as the mean of three separate measurements. The 5th, 50th and 95th centiles were estimated at each week of gestational age (GA) by least-squares regression for the mean and standard deviation (SD) of the CHC and CHA as functions of GA. r2 and associated P-values for the relationships of CHC and CHA with other sonographic biometric measurements were calculated. RESULTS: The study included 651 consecutive patients. All attempts at obtaining axial fetal CHC and CHA were successful. Mean maternal age was 27.3+/-6.7 years, median gravidity was 1 (range 1-16), and median parity was 1 (range 0-6). Mean CHC (cm) throughout gestation was modeled as -2.091+0.2563xGA (weeks) (SD=-0.075+0.0164xGA), and mean CHA (cm2) was modeled as 0.245-0.0765xGA+0.00506xGA2 (SD=1.167-0.1565xGA+0.006785xGA(2)-0.00008028xGA3). Fetal axial CHC and CHA correlated significantly and strongly with BPD, HC, AC, HL, FL, TCD and EFW (all R2 values were >or=0.95, and all P-values were <0.001). CONCLUSION: Nomograms of axial fetal cerebellar hemisphere circumference and area throughout gestation, independent of the cerebellar vermis, have been provided.     

Fetal transabdominal biometry at 11-14 weeks of gestation.

OBJECTIVE: To establish comprehensive transabdominal ultrasonographic reference ranges for viable normal singleton human fetuses at 11-14 weeks' gestation. METHODS: Single transabdominal ultrasound measurements were taken once per pregnancy at a gestational age of between 11+0 and 14+0 weeks (crown-rump length, 45-84 mm), in viable singleton fetuses with nuchal translucency < or = 3 mm and without detectable structural anomalies, using four standard planes: (i) biparietal diameter (BPD) and fronto-occipital diameter (FOD) resulting in head circumference (HC), anterior horn (Va), posterior horn (Vp), and hemisphere (HEM); (ii) transcerebellar diameter (TCD) and cisterna magna (CM); (iii) abdominal anteroposterior (AAP) and abdominal transverse diameter (ATD) resulting in abdominal circumference (AC); and (iv) femur length (FL). The respective ratios Va/HEM, Vp/HEM, HC/AC, BPD/FL, BPD/FOD, FL/CRL, FL/BPD and FL/AC and the estimated weight were derived. Reference ranges were constructed and the mean and 5th and 95th centiles were plotted against gestation. RESULTS: There was a general increase in biometric parameters with gestation. The ratios for the ventricles vs. hemisphere and BPD/FL ratio decreased while the BPD/FOD and HC/AC ratios remained constant. Analysis of the reference range for BPD/FL was performed in both 167 and 664 fetuses and the results showed almost the identical type of equation, indicating a high degree of accuracy for the growth charts. CONCLUSIONS: We have established comprehensive reference ranges for first-trimester fetal biometry by transabdominal sonography. These charts may have a role in the diagnosis of early onset symmetrical or asymmetrical growth restriction and in the interpretation of measurements in chromosomally abnormal fetuses, and they may help in the detection of skeletal dysplasias or acrania/anencephaly.     

Ultrasonic assessment of fetal growth in the nonhuman primate (Macaca mulatta)

Serial ultrasound measurements of fetal growth were made during uncomplicated pregnancy in 28 time-mated rhesus monkeys. Gestational sac (GS) size, crown-rump length (CRL), biparietal diameter (BPD), head circumference (HC), head area (HA), abdominal circumference (AC), abdominal area (AA), and femur length (FL) were measured. Average longitudinal growth curves for each parameter were obtained from individual fetal growth curves. Data analysis indicated that the linear model was optimal for GS, CRL, HA, AA, and FL. The linear-quadratic model was optimal for AC, and the linear-cubic model was optimal for BPD and HC.     

Morphological and functional evaluation of normal and abnormal fetal growth by ultrasonography

Correction or estimation of gestational age is essential for the evaluation of fetal growth. When necessary, an appropriate fetal biometric parameter should be selected depending on fetal size. In the first trimester, crown–rump length (CRL) is appropriate, especially when the CRL is 20–40 mm. In the second trimester, biparietal diameter (BPD), head circumference (HC), and femur length (FL) are of equal predictability. Fetal weight estimation is still the basis of evaluation of fetal growth. The most predictable formula currently available includes the parameters BPD (or HC), abdominal circumference (AC), and FL. Serial measurements of AC are useful for diagnosis of intrauterine growth restriction (IUGR) and macrosomia. Quantitative evaluation of soft tissue deposition may be informative for macrosomia. Functional evaluation using Doppler velocimetry is essential in IUGR cases associated with uteroplacental insufficiency. Analysis of blood velocity waveforms of the umbilical and intracranial arteries, predominantly the middle cerebral artery, is widely performed. An increase in the pulsatility index (PI) or resistance index (RI) of the umbilical artery and/or a decrease in the PI or RI of the middle cerebral artery are highly predictable for fetal hypoxia and/or acidosis.     

Fetal clavicle length throughout gestation: a nomogram.

OBJECTIVE: To create a nomogram of fetal clavicle length (CL) throughout gestation. METHODS: Cross-sectional study of patients between 14 and 42 weeks' gestation. Inclusion criteria consisted of well-established dates (consistent with early ultrasound), singleton, non-anomalous fetuses, and intact amniotic membranes. Sonographic measurements included biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), humerus length (HL) and sonographically estimated fetal weight (SEFW). For every case, the average of three separate measurements of the CL was used. The 5th, 50th and 95th centiles were obtained by least squares regression. Pearson's correlation coefficient and associated P-values for the relationships between CL and other biometric measurements were calculated. The data were compared to a nomogram of the CL generated in 1985 from the measurement of 85 fetuses. RESULTS: A total of 623 consecutive patients were studied. In all but three cases, CL was successfully measured. Mean maternal age was 27.7 +/- 6.2 years, median gravidity 3 (range, 1-14) and median parity 1 (range, 0-9). Mean CL (mm) = -75.30 + 32.70*ln(GA) and SD = -0.41 + 0.08328*GA, where ln represents the natural logarithm and GA the gestational age in weeks. Fetal CL correlated significantly and strongly with BPD, HC, AC, HL, FL and the logarithm of SEFW, with Pearson correlation values of 0.973, 0.977, 0.976, 0.979, 0.977 and 0.979, respectively (all P < 0.001). Measurements according to comparable 1985 data were consistently substantially below the present data (smaller CL for any given GA except below 17 weeks' gestation). CONCLUSIONS: We propose a new nomogram of CL, which differs significantly from the previously published nomogram. We suggest that the present data reflect the use of high-resolution ultrasound technology and propose that these data, based on a large number of fetuses, replace the previous nomogram. We also suggest that the '1 mm = 1 week' rule of thumb should no longer be used, since it can be erroneous by as much as 6 weeks.     

Sex-specific fetal weight prediction by ultrasound.

OBJECTIVE: To improve sonographic birth-weight prediction by developing fetal gender-specific formulae. METHODS: This was a retrospective cross-sectional study. Two gender-specific formulae were produced from the data of 527 patients and the data of a further 349 patients were used to evaluate the formulae. Inclusion criteria were a singleton live fetus, gestational age above 25 weeks, birth weight between 1000 g and 4500 g and fetal biometry within 8 days of delivery. Data retrieval was specifically for the purpose of this study. RESULTS: To yield the best-fit weight formula for each fetal gender we employed step-wise regression analysis based on fractional polynomials with the biometric parameters biparietal diameter (BPD), head circumference (HC), transverse abdominal diameter (TAD), abdominal circumference (AC) and femur length (FL): estimated fetal weight for girls (g) = - 4035.275 + 1.143 x BPD3 + 1159.878 x AC1/2 + 10.079 x FL3 - 81.277 x FL2 [in cm]; estimated fetal weight for boys (g) = 43576.579 + 1913.853 x log10BPD + 0.01323 x HC3 + 55.532 x AC2 - 13602.664 x AC1/2 - 0.721 x AC3 + 2.31 x FL3 [in cm]. These formulae showed superior results compared with those of conventional weight formulae. CONCLUSION: Gender-related fetal weight calculation allows optimized prediction of fetal weight at birth.     

Intrapartum fetal weight estimation: a comparison of three formulae

To determine the relative accuracy of fetal weight estimation using the biparietal diameter (BPD), the abdominal circumference (AC), and the femur length (FL) in three formulae (BPD/AC, FL/AC, and BPD/AC/FL), 63 patients in labor were examined. All patients delivered within 24 hours of ultrasound examination. A good correlation was found between the estimated fetal weight and the actual birth weight, using the three formulae: BPD/AC (r = 0.96); FL/AC (r = 0.95); and BPD/AC/FL (r = 0.96). The FL/AC formula overestimated fetal weight (P less than 0.01), however, particularly in fetuses weighing more than 2000 g. The mean percentage error with the BPD/AC formula was 0.99 per cent, 3.82 per cent with the FL/AC, and 2.43 per cent with the BPD/AC/FL formula. This study showed that although all three formulae were comparable, the best estimation of the birth weight was obtained when either the BPD/AC or the BPD/AC/FL formulae were used. Additionally, the results demonstrate that reliable estimates of fetal weight can be made even at term or in laboring patients.     

Are the international ultrasound reference standards appropriate for Iranian fetuses

SUMMARY: The article describes the development of ultrasound tables for biparietal diameter (BPD), femur length (FL), abdominal circumference (AC), and head circumference (HC) for fetuses in Iran. It was attempted to determine if racial differences exist between Iranian and Australian fetuses in ultrasound measurements of BPD, HC, AC, and FL. The sample for this study consisted of 70 Iranian and 93 Australian pregnant women. The Iranian women received prenatal care and delivered at Fatemieh Hospital in Shahrood, Iran during October 1998 through February 1999. All these women had an ultrasound scan for anomalies in the second trimester. We selected only those pregnancies in which the estimated date of delivery by last menstrual period was within +/-14 days of the estimated date of delivery determined by the initial ultrasound examination. The data from Australian fetuses were obtained from the ultrasound section at the Wollongong Hospital in Australia. Birth weight differences were observed, with Australian infants being heavier than Iranian infants. The results also showed Australian fetuses have longer FL and larger HC, AC, and BPD than Iranian fetuses in the third trimester. Overall, this study shows that race-specific standards for estimating gestation age (GA) may be an important consideration in improving the accuracy of ultrasound estimation of GA. Because the evaluation of retardation growth retardation is so dependent on GA, assessment using standards specific to the Iranian race may more accurately classify infants and improve the prenatal diagnosis of fetal growth disturbances. Using European or Australian standards may cause overestimation of the rate of growth-retarded fetuses in Iranian pregnancies.     

胎儿超声生物学指标的Z-评分值在评估胎儿生长发育中的应用研究

摘 要 目的 探讨孕中、晚期超声生物学指标的Z-评分对评估胎儿生长发育的应用价值。方法 选取我院单胎孕妇中,筛查出巨大儿（A组）103例,胎儿生长受限（B组）48例,合并妊娠期糖尿病而血糖控制满意、出生体质量正常儿（C组）169例分别作为观察组,正常妊娠、胎儿体质量正常的196例为正常对照组。回顾分析中孕期（20+1～24周）、晚孕早期（28+1～33周）、晚孕晚期（34+1周～分娩）三个阶段的生长参数,包括胎儿双顶径（BPD）及头围（HC）、腹围（AC）、股骨长（FL）、头腹围比值（HC/AC）、腹围的Z-评分（AC的Z-评分）、头腹围比值的Z-评分（HC/AC的Z-评分）,比较不同阶段两组间各生长参数的差异、GDM的巨大儿与非GDM的巨大儿间的差异。结果 在中孕期、晚孕早期、晚孕晚期三个阶段,A组腹围的Z-评分值明显大于正常对照组、B组腹围的Z-评分明显小于正常对照组（P＜0.05）,且随孕龄的增加, A组、B组腹围的Z-评分值与正常对照组的偏离度进行性加大。C组在中孕期、晚孕早期腹围的Z-评分值与正常对照组无明显差别,仅在晚孕晚期其腹围的Z-评分值略高于正常对照组（P=0.045）。GDM的巨大儿组与非GDM的巨大儿组在体型上存在差异,表现为晚孕后期,GDM的巨大胎儿组头腹围比的Z-评分值小于非GDM的巨大儿组（P＜0.05）。传统超声生物学指标中,在中孕期（20+1～24周）只有A组的AC与正常对照组有差异、B组与正常组无明显差异。晚孕早期、晚孕晚期两阶段A组、B组BPD、HC、AC、FL、HC/AC均与正常对照组有差异（P＜0.05）,但无法直观判断各指标与正常对照组的偏离程度。结论：超声生物学指标的Z-评分有助于更准确定量评估胎儿宫内生长发育状况,在诊断胎儿宫内生长发育异常以及动态观察随访中有一定临床应用价值,值得推广。     

Estimation of Fetal Weight in Fetuses With Abdominal Wall Defects

Objective. Estimation of fetal weight is particularly challenging in fetuses with abdominal wall defects (AWDs). We sought to compare the accuracy and screening efficiency for intrauterine growth restriction (IUGR) of 2 recent sonographic formulas to those of the Hadlock formula (Am J Obstet Gynecol 1985; 151:333–337) in fetuses with AWDs. Methods. This was a retrospective cohort study of fetuses with AWDs. Fetuses with sonographically estimated fetal weights (EFWs) within 14 days before delivery were included. Using the individual biometric measurements, EFWs were calculated using the Honarvar (Int J Gynaecol Obstet 2001; 73:15–20; femur length [FL]), Siemer (Ultrasound Obstet Gynecol 2008; 31:397–400; FL, biparietal diameter [BPD], and occipitofrontal diameter), and Hadlock (BPD, head circumference, abdominal circumference, and FL) formulas. The calculated EFWs were adjusted for interval growth between the dates of sonography and delivery using published sonographic fetal growth velocity standards. Accuracy and screening efficiency for IUGR were compared. Results. Seventy‐six fetuses were included: 53 with gastroschisis and 23 with omphalocele. The median gestational age at delivery was 36.6 weeks (range, 25.0 to 39.0 weeks). The Siemer formula had the lowest mean percentage error (?2.5% [95% confidence interval (CI), ?6.2% to +1.2%]) without systematic bias (P = .182). The Hadlock formula had the highest precision (random error, 11.4%), sensitivity (91%), and accuracy for predicting IUGR (85% [95% CI, 77% to 94%]). Conclusions. None of the 3 sonographic formulas is ideal for estimating fetal weight in fetuses with AWDs. The Siemer formula should be used when accuracy in the absolute EFW is the goal. For the purpose of making the more clinically relevant diagnosis of IUGR, use of the Hadlock formula is justified.     

Sex-specific antenatal reference growth charts for uncomplicated singleton pregnancies at 15-40 weeks of gestation.

OBJECTIVE: Female fetuses, on average, weigh less than male fetuses at all gestational ages. The purpose of this study was to compare female and male fetuses in terms of intrauterine ultrasound growth measurements and to develop gestational-age-related charts based on a computerized perinatal database. METHODS: This was a retrospective study of unselected women in the second and third trimesters of pregnancy, who had a normal scan at 10-14 weeks. Data analysis was performed using measurements obtained from a mixed-race population of 4234 women, who underwent 5198 ultrasound examinations. The scans were performed by four trained sonographers, according to a standardized protocol. Routine measurements included biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL). The main end-points were sex- and race-specific differences in fetal biometry, which were also used to estimate fetal weight. RESULTS: The base-line demographic characteristics and risk factors were comparable in female and male fetuses. Significant differences in fetal BPD, HC, AC and estimated fetal weight, but not FL, were seen between male and female fetuses. Centile charts for each of these variables were constructed for both male and female fetuses. CONCLUSIONS: This study suggests that small but consistent sex-related differences in prenatal BPD, HC and AC measurements are established by as early as 15 weeks of gestation. The use of sex-specific nomograms may improve the prenatal assessment of fetal growth as well as the diagnosis of structural abnormalities.     

巨大胎儿体质量估测新公式的建立和验证

目的 创建用于巨大胎儿体质量估测新公式,并将新公式和现有的25个公式进行比较.方法 对1153例胎儿(其中239例巨大胎儿)在出生前1周以内行产科超声检查,测量胎儿双顶径(BPD)、头围(HC)、腹围(HC)、和股骨长(FL),出生后记录胎儿体质量.采用逐步回归法设计新公式,1034例(914例非巨大胎儿+120例巨大胎儿)数据用于建立新的全范围体质量预测公式,239例巨大胎儿中120例数据为训练集,被用于建立疑似巨大胎儿胎重估测公式,其余119例巨大胎儿(测试集)用于公式验证,并与国内外常用25个公式相比较.结果 全范围体质量估测公式为:lgBW=0.180(HC)+0.00628 (AC)-0.00318(HC)2+0.00173 (AC) (FL)+0.0000430 (BPD) (HC)2.疑似巨大胎儿胎重估测公式为:lgBW=0.730(BPD) -0.0375 (BPD)2+0.000264 (AC) (FL).新估测公式对119例测试集的平均误差为(- 87.89±230.95)g,平均绝对百分误差为(4.4±3.9)％,25个公式中误差最小公式的平均估测误差为(115.61±345.09)g,平均绝对百分误差为(6.8±5.4)％,新公式与公认的其他常用公式相比,平均绝对误差、平均绝对百分误差均为最低.结论 新公式评估胎儿体质量的准确性较高.新公式适宜于评估中国胎儿体质量,尤其适合评估巨大胎儿体质量.     

Intraobserver and interobserver reproducibility of fetal biometry.

OBJECTIVE: To assess the intra- and interobserver reproducibility of ultrasound measurements of fetal biometric parameters. METHODS: We assessed the intraobserver and the interobserver agreement in measurements of fetal biparietal diameter (BPD), abdominal circumference (AC), head circumference (HC) and femur length (FL) on 122 singleton pregnancies. Patients were each examined twice by the first sonographer to determine the intraobserver reliability of measurements of fetal biometry. Subsequently, during the same ultrasound examination, a second blinded sonographer measured fetal biometric parameters to assess interobserver reliability. The consensus between and among observers was analyzed using the intraclass correlation coefficient (intra-CC) and interclass correlation coefficient (inter-CC) and the reliability coefficients (RC, alpha) for the four biometric measurements. A value > 0.75 was considered a reliable consensus for the intra-CC and inter-CC. A Bland and Altman plot was also created for the fetal biometric parameters to assess the repeatability of the measurements. RESULTS: Reliable consensus was observed for both the intra-CC and inter-CC and RC for all four biometric parameters. The intra-CC with the 95% CI and RC for the BPD, AC, HC and FL were as follows: 0.996 (0.995, 0.997), alpha 0.998; 0.994 (0.992, 0.996), alpha 0.997; 0.996 (0.994, 0.997), alpha 0.998; and 0.994 (0.992, 0.996), alpha 0.997, respectively. Similarly, the inter-CC with the 95% CI and RC for the same parameters were as follows: 0.995 (0.993, 0.997), alpha 0.998; 0.980 (0.971, 0.990), alpha 0.990; 0.994 (0.992, 0.996), alpha 0.997; and 0.990 (0.985,0.993), alpha 0.995, respectively. The Bland and Altman plots demonstrated a high degree of repeatability of BPD, AC, HC, and FL measurements. CONCLUSION: Our results demonstrate that the intra- and interobserver reproducibility of ultrasound measurements of fetal biometry are highly reliable.     

The fetal transverse cerebellar diameter/abdominal circumference ratio: a gestational age-independent method of assessing fetal size

The relationship between the fetal TCD and the AC throughout pregnancy was investigated in a prospective, cross-sectional study of 700 well dated, normal pregnancies between 14 and 42 weeks of gestation and tested in 30 known SGA infants. Fetal measurements included the TCD, AC, BPD, HC, and FL. The TCD/AC ratio was calculated for each patient. Statistical analysis using linear regression and Student's t-test was performed. Strong correlation existed between gestational age and transcerebellar diameter (R2 = 0.9464), between gestational age and AC (R2 = 0.9685), and between TCD and AC (R2 = 0.9561). The TCD/AC ratio was normally distributed with a mean +/- SD of 13.69 +/- 0.94% (median, 13.71%). The 10th and 90th percentiles were 12.50% and 14.86%, respectively. The ratio remained constant throughout pregnancy with respect to gestational age (R2 = 0.0084). A TCD/AC ratio greater than the 90th percentile was present in 87% (26/30) known SGA infants. The TCD/AC ratio is a stable, gestational age-independent parameter that may be useful in the early detection of fetal growth abnormalities.     

超声监测胎儿血流动力学变化预测胎儿生长发育的价值

【目的]探讨超声检测胎儿动静脉的血流动力学参数和径线对预测胎儿生长发育的价值。【方法】回顾性分析产前二维超声及彩色多普勒血流显像对170例胎儿进行各项参数测定,根据测定结果,将其分为正常对照组和宫内生长迟缓（IUGR）组,测量脐动脉、大脑中动脉、颈内动脉和腹主动脉的搏动指数（PI）、阻力指数（RI）及脐动脉收缩期最大流速与舒张末期流速的比值（S／D）,测量胎儿静脉导管血流量（QDV）和脐静脉的血流量（QuV）,计算静脉导管（DV）分流率,测定胎儿升主动脉和肺动脉收缩期峰值速度（PFV）,测量一般径线包括胎儿的双顶径、头围、腹围、股骨长度,测量产后胎儿体重并进行Apgar评分。【结果]IUGR组脐动脉和腹主动脉的PI、RI及S／D测值明显比对照组增高,IUGR组大脑中动脉和颈内动脉的PI、RI及S／D测值比对照组低,IUGR组升主动脉和肺动脉的PFV明显低于对照组胎儿,差异具有统计学意义（P〈0．05）。两组胎儿的QDV无明显差异,但IUGR组的QuV显著下降且DV分流率显著升高,差异均有统计学意义（P〈0．05）。36周IUGR组的胎头双顶径（BPD）、胎儿头围（HC）、胎儿腹围（AC）和胎儿股骨长（FL）明显比对照组低,差异有统计学意义（P〈0．05）。【结论】超声通过综合监测胎儿血流动力学和一般径线的变化,可以全面、客观地评价胎儿生长发育情况。     

Growth standards for anatomic measurements and growth rates derived from longitudinal studies of normal fetal growth.

A statistical procedure for deriving growth standards for anatomic measurements and their growth rates from longitudinal studies of fetal growth was evaluated using Rossavik growth models for the biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur diaphysis length (FDL) determined in a previous study of normal fetal growth. For each anatomic parameter, the coefficients c and s of the model was used to define a set of growth curves that constituted the boundary growth curves of a region containing 95% of the growth curves of this data set. The set of boundary growth curves was used to specify the mean, lower limit, and upper limit values for the anatomic parameter and its growth rate at weekly intervals between 14 and 38 weeks, menstrual age. Comparison of these values to those determined from cross-sectional studies of fetal growth gave differences of -1.9% to 4.8% (SD: +/- 0.9 to +/- 2.6) for mean vs. predicted value of the anatomic measurements. For the lower limit, similar values were 0.4% to 13.8% (SD: +/- 1.7 to +/- 8.8); for the upper limit the values were 8.3% to 18.0% (SD: +/- 1.5 to +/- 7.0). Comparisons of HC growth rates determined using polynomial and Rossavik growth models gave values of -3.4% (SD: +/- 4.4) for mean vs. predicted value, -12.6% (SD: +/- 10.6) for the lower limit and 5.2% (SD: +/- 9.3) for the upper limit. The degree of agreement was similar for AC growth rates.(ABSTRACT TRUNCATED AT 250 WORDS)     

产前部分上臂容积测量与新生儿出生体质量的相关性

目的探讨三维超声5D Limb技术测量正常孕晚期临产前7 d内胎儿部分上臂容积（AVol）在新生儿估算出生体质量（EFW）中的应用价值。 方法选取2018年7月至2019年6月期间在苏州市吴中人民医院超声科进行产检的临产前7 d内的115例胎儿作为研究对象,运用二维、三维超声技术为孕妇产检,并记录相关测量值,主要包括双顶径、股骨长度、头围、腹围、AVol。采用单因素和多因素线性回归分析各参数与新生儿BW之间的相关性,并建立回归方程产生新的BW估算公式。以新生儿BW为金标准,Hadlock经典公式为对照,运用χ²检验比较Hadlock经典公式与新公式的估算符合率（绝对误差和相对误差）的差异。再将胎儿按照BW分为低BW组、正常BW组和巨大儿组,运用配对t检验比较2种公式估算3组胎儿BW的相对误差（系统误差±随机误差）的差异。 结果单因素相关分析显示,BW与双顶径、头围、腹围、股骨长度、AVol均具有相关性（r=0.477、0.515、0.506、0.404、0.827,P均＜0.001）;多因素回归分析显示,腹围、AVol为新生儿BW估算的独立影响因素（P=0.007、＜0.001）;基于双顶径、头围、腹围、股骨长度、AVol构建回归方程EFW（AVol）=-2470.985+56.547×双顶径+33.225×头围+50.142×腹围+169.806×股骨+47.203×AVol。EFW（AVol）公式估算BW的绝对误差符合率和相对误差符合率均高于Hadlock经典公式（65.2% vs 48.7%;84.3% vs 64.3%）,差异具有统计学意义（P=0.011、＜0.001）。EFW（AVol）公式和Hadlock经典公式估算低BW组、正常BW组和巨大儿组胎儿BW的相对误差分别为（19.5%±7.2% vs 44.8%±29.6%）、（5.5%±4.3% vs 7.8%±5.5%）、（5.3%±3.4% vs 8.5%±4.5%）,2种公式对正常BW组胎儿BW估算的相对误差比较,差异具有统计学意义（P＜0.001）。 结论AVol与BW相关性显著,可作为新参数应用于估算新生儿BW的临床实践中。     

Cumulative sum (CUSUM) analysis in the assessment of trainee competence in fetal biometry measurement.

OBJECTIVE: To determine the value of cumulative sum (CUSUM) analysis in assessing trainee proficiency in fetal biometry measurement. METHODS: Three primary healthcare doctors with no prior ultrasound training were recruited. Each trainee measured the fetal biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL) on 100 consecutive pregnant women. The supervisor repeated the measurements. The CUSUM for each set of trainee measurements was calculated at a set failure rate of 10%. The point at which the graph fell below two consecutive boundary lines indicated the number of examinations required to achieve competence. RESULTS: The CUSUM graphs showed that the rate of learning measurement skills varied among the three trainees. The graph for the CUSUM series for BPD and HC measurement for all trainees fell below two consecutive boundary lines and remained there, indicating competence. The CUSUM series for AC measurement for two of the trainees indicated that competence was achieved; however, for the third trainee, while the graph fell below two consecutive boundary lines, indicating competence, it rose again, crossing two consecutive boundary lines. This indicated a loss of competence and the need for further training. FL measurements for the same trainee never fell below two consecutive boundary lines, indicating failure to achieve competence; the other two achieved competence, but failed to maintain it. CONCLUSIONS: CUSUM is a useful tool for identifying points of competence and for quantifying the duration of ultrasound training required for each trainee. It provides an early indication of performance, and highlights difficulties in individual performance.     

The importance of quality management in fetal measurement.

OBJECTIVES: The aims of this study were to evaluate factors contributing to inaccuracy in fetal measurements and to assess the clinical importance of measurement quality. METHODS: One hundred images of biparietal diameter (BPD), head circumference (HC) and abdominal circumference (AC) measurements were collected from six centers (1800 measurements); the proportion meeting quality criteria was assessed. Four hundred images of AC were collected from one center, each image measured by ellipse fitting and tracing methods; clinical agreement between the methods was assessed. Fetal weight estimation (EFW) errors were compared between quality controlled and non-quality controlled studies. Images of three ACs on each of 400 fetuses were collected; where one measurement failed to meet quality criteria, it was compared with an optimal measurement on the same fetus. RESULTS: Eighty-nine percent, 87% and 60% of BPD, HC and AC, respectively, met all quality criteria. Limits of agreement between ellipse and traced AC were -4.7 mm to 12.5 mm; 22% of sections were non-elliptical. EFW errors were significantly different but were confounded by differences in time to delivery. Limits of agreement between optimal and suboptimal AC measurements were -15.1 mm to 7.7 mm. CONCLUSIONS: AC quality criteria are less easily recognized and obtained than those for head measurements; training, adherence to protocols and audit are important. Differences between ellipse and traced AC may not justify the use of separate charts; the number of non-elliptical sections suggests that ellipse fitting is not appropriate. Comparison between EFW errors is not a suitable tool for audit. Failure to meet quality criteria results in clinically significant errors.