Detection of fetal structural abnormalities at the 11-14 week ultrasound scan.

The aim of this study was to evaluate the detection of fetal structural abnormalities by the 11-14 week scan. 2853 pregnant women were submitted to a routine ultrasound scan between the 11th and 14th week and the fetal skull, brain, spine, abdominal wall, limbs, stomach and bladder were examined. Following the scans the patients were examined in the second or third trimester of pregnancy. An isolated increased nuchal translucency was not considered an abnormality. However, these patients had an early echocardiography assessment. Fetal structural abnormalities were classified as major or minor and of early or late onset. A total of 130 (4.6%) defects were identified and 29 (22.3%) of these were diagnosed at the 11-14 week scan, including nine cardiac defects associated with increased nuchal translucency. The antenatal ultrasound detection rate was 71.5%, and 31.2% were detected in the first-trimester assessment. 78.8% of the major defects were diagnosed by the prenatal scan and 37.8% by the 11-14 week scan. Fetal structural abnormalities at the 11-14 week scan were detected in approximately 22.3% of the cases, therefore, a second-trimester anomaly scan is important in routine antenatal care to increase the prenatal detection of fetal defects.     

Screening for fetal aneuploidies and fetal cardiac abnormalities by nuchal translucency thickness measurement at 10-14 weeks of gestation as part of routine antenatal care in an unselected population.

OBJECTIVES: To evaluate first trimester pregnancy screening for fetal aneuploidy and congenital heart defects by maternal age and nuchal translucency measurement and screening for fetal aneuploidies and congenital heart defects by ultrasound in an unselected population. DESIGN: A prospective study. SETTING: Fetal medicine unit, St George's Hospital, London. SAMPLE: 4523 consecutive viable fetuses at 10-14 weeks with a crown-rump length between 38 and 80 mm were scanned transabdominally (93%) or transvaginally (7%). METHODS: Screening was performed by calculating the background risk from maternal age, gestational age and obstetric history, which was then adjusted with the nuchal translucency measurement in relation to crown-rump length (adjusted risk). MAIN OUTCOME MEASURES: Measurements of crown-rump length and nuchal translucency thickness. An adjusted risk of > 1:270 was considered as a positive screening test. Pregnancy outcome was obtained through karyotyping, outcome questionnaires and examination of the newborn infants. RESULTS: Mean maternal age was 29-4 years and mean gestational age 12.2 weeks. Screening was positive in 230/4523 fetuses (5.1%), when the adjusted risk (mean 1:2649) was > 1:270. Fetal karyotype was abnormal in 23 (0.51%) cases, including twelve with trisomy 21, five trisomy 18, one trisomy 13, one trisomy 10, one monosomy X and two triploidies. For a false positive rate of 4.7%, the sensitivity of this test was 78% in detecting any fetal aneuploidy. Only one out of nine major congenital heart defects in this population was found within the 110 euploid fetuses with increased nuchal translucency thickness (> 2.5 mm). CONCLUSION: Screening for fetal aneuploidy by maternal age and nuchal translucency measurement can be effective in an unselected population. However, our results do not support its effectiveness in the detection of cardiac abnormalities.     

Ultrasound screening for fetal major abnormalities at 11-14 weeks

BACKGROUND: This study was planned to evaluate the efficiency of the 11-14 week scan in detecting fetuses with major fetal structural abnormalities. METHODS: Some 1,290 pregnant women were submitted to a routine ultrasound scan between the 11th and 14th week after the detection of the fetal viability. The fetal anatomy was examined transabdominally, and in suspected cases transvaginally. Following the scans, the patients were examined in the second or third trimester of pregnancy. Fetal structural abnormalities classified as major and early onset were noted. Isolated choroid plexus cysts, cardiac defects not requiring treatment, mild ventriculomegaly, and mild renal pelviectasis in second trimester were not included. RESULTS: Twenty-four (1.86%) fetuses with various defects were identified, and 17 of these were diagnosed at the 11-14 week scan. The antenatal ultrasound detection rate of the fetuses with major anomalies was 95%, and 70% were detected in the first-trimester assessment. Four cardiac defects associated with genetic syndromes or requiring operation were included (0.31%) in this series. Two of the fetuses with cardiac defects (50%) had an increased nuchal translucency thickness. In this group, none of the fetuses with karyotype anomalies was born alive. CONCLUSIONS: The first-trimester scan is important in routine antenatal care for early detection of fetal defects, and determination of the fetuses at risk of cardiac anomalies and genetic syndromes.     

The value of sonography in early pregnancy for the detection of fetal abnormalities in an unselected population.

OBJECTIVE: To determine the value of early pregnancy sonography in detecting fetal abnormalities in an unselected obstetric population. DESIGN Prospective cross-sectional study. All women initially underwent transabdominal sonography and when the anatomical survey was considered to be incomplete, transvaginal sonography was also performed (20.1%). Nuchal translucency was measured and karyotyping was performed as appropriate. SETTING: University Department of Obstetrics and Gynaecology. PARTICIPANTS: 6634 sequential unselected women (mean maternal age 29.9 years, range 13-50; mean gestational age 12+4 weeks, range 11+0-14+6), carrying 6443 live fetuses participated in this study. MAIN OUTCOME MEASURE: Detection rate of fetal anomalies and the associated cost per case detected in early pregnancy. RESULTS: The incidence of anomalous fetuses was 1.4% (92/6443) including 43 chromosomal abnormalities. The detection rate for structural abnormalities was 59.0% (37/63, 95% CI 46.5-72.4) and the specificity was 99.9% in early pregnancy. When the first and second trimester scans were combined, the detection for structural abnormalities was 81.0% (51/63, 95% CI 67.7-89.2). Seventy-eight percent (31/40) of chromosomal abnormalities (excluding three cases of XXY) were diagnosed at 11-14 weeks, either because of a nuchal translucency greater than or equal to the 99th centile for gestational age (43%; 17/40, 95% CI 27.4-60.4), or due to the presence of structural abnormalities (35%; 14/40, 95% CI 21.2-52.8). Sixty-five percent (15/23) of cases of trisomy 21 were also diagnosed either because of having a nuchal translucency greater than or equal to the 99th centile (57.0%; 13/23) or due to the presence of a structural abnormality (9.0%; 2/23). Overall, the detection rate of structurally abnormal fetuses was 59% (37/63) in early pregnancy and 81% in combination with the second trimester scan. The cost per abnormality diagnosed in early pregnancy is estimated to be pound sterling 6258 per structurally abnormal fetus, pound sterling 7470 per chromosomal abnormality and pound sterling 4453 per anomalous fetus. CONCLUSION: The majority of fetal structural and chromosomal abnormalities can be detected by sonographic screening at 11-14 weeks, but the second trimester scan should not be abandoned.     

First trimester sonographic detection of chromosomal abnormalities in an unselected population

Objective To investigate the role of first trimester sonography in detecting chromosomal abnormalities in an unselected obstetric population.
Methods 2281 women (mean maternal age 30 years [range 16-47]; mean gestational age 12⁺³ weeks [range 11-14]) underwent transabdominal scanning to assess fetal structure and, if anatomical survey was considered to be incomplete (31% of cases), transvaginal sonography was also performed. Measurement of nuchal translucency was included and karyotyping performed as considered appropriate.
Results There were 16 chromosomal abnormalities; 13 (81%) were diagnosed at 11-14 weeks either because of a nuchal translucency greater than or equal to the 99th centile for gestational age (7/16; 44% [95% CI 25-63]) or due to the presence of structural abnormalities (6/16; 38% [95%CI 14.2–61.81). Seventy-five percent of cases of trisomy 21 were also diagnosed either because of having a nuchal translucency greater than or equal to the 99th centile (5/8; 63%) or due to the presence of a structural abnormality (1/8; 13%).
Conclusions A significant proportion of fetal chromosomal abnormalities can be detected by first trimester sonographic screening to assess fetal structural appearance. The sensitivity of detection can be improved by combining measurement of nuchal translucency with detailed examination of fetal anatomy.     

Screening for fetal aneuploidies and fetal cardiac abnormalities by nuchal translucency thickness measurement at 10–14 weeks of gestation as part of routine antenatal care in an unselected population

Objectives To evaluate first trimester pregnancy screening for fetal aneuploidy and congenital heart defects by maternal age and nuchal translucency measurement and screening for fetal aneuploidies and congenital heart defects by ultrasound in an unselected population.
Design A prospective study.
Setting Fetal medicine unit, St George's Hospital, London.
Sample 4523 consecutive viable fetuses at 10–14 weeks with a crown–rump length between 38 and 80 mm were scanned transabdominally (93%) or transvaginally (7%).
Methods Screening was performed by calculating the background risk from maternal age, gestational age and obstetric history, which was then adjusted with the nuchal translucency measurement in relation to crown–rump length (adjusted risk).
Main outcome measures Measurements of crown–rump length and nuchal translucency thickness. An adjusted risk of > 1:270 was considered as a positive screening test. Pregnancy outcome was obtained through karyotyping, outcome questionnaires and examination of the newborn infants.
Results Mean maternal age was 29.4 years and mean gestational age 12.2 weeks. Screening was positive in 230/4523 fetuses (5.1%), when the adjusted risk (mean 1:2649) was > 1:270. Fetal karyotype was abnormal in 23 (0.51%) cases, including twelve with trisomy 21, five trisomy 18, one trisomy 13, one trisomy 10, one monosomy X and two triploidies. For a false positive rate of 4.7%, the sensitivity of this test was 78% in detecting any fetal aneuploidy. Only one out of nine major congenital heart defects in this population was found within the 110 euploid fetuses with increased nuchal translucency thickness (> 2.5 mm).
Conclusion Screening for fetal aneuploidy by maternal age and nuchal translucency measurement can be effective in an unselected population. However, our results do not support its effectiveness in the detection of cardiac abnormalities.     

The value of ultrasound visualization of the ovaries during the routine 11-14 weeks nuchal translucency scan

OBJECTIVE: To investigate the feasibility and possible value of routine screening for ovarian pathology in asymptomatic pregnant women at 11-14 weeks' gestation. STUDY DESIGN: A policy of routine ovarian visualization was implemented in 2925 pregnant women attending for a nuchal translucency scan at 11-14 weeks' gestation. In all cases, an attempt was made to visualize the ovaries on transabdominal ultrasound scan. Simple cysts were defined as unilocular cysts with regular internal walls and no solid components, which contained clear anechoic fluid. All other cysts were classified as complex. Simple cysts<5 cm in diameter were all managed expectantly with no further follow-up. All women with large simple cysts>or=5 cm in diameter or complex cysts had further detailed follow-up scans. Surgical intervention during pregnancy was offered to women with clinical symptoms suggestive of cyst complications or those with ultrasound features suggestive of malignancy. All other women were managed expectantly until after delivery. RESULTS: Adnexal cysts were found in 728/2925 (24.9%) pregnant women. 400/728 (55%) women had simple cysts<5 cm in diameter, whilst 328/728 (45%) women had large simple or complex cysts requiring follow-up. On subsequent scans, cysts resolved spontaneously in 278/328 (84.8%) women. A total of 33/728 (4.5%) women with ultrasound evidence of adnexal cyst underwent surgery. In one woman the intervention was required because of pain, one woman had suspected cancer on ultrasound scan and the remaining 31/33 (94%) of operations were performed at patients' requests. All the cysts were found to be benign on histological examination. The overall intervention rate was 1.1/100 screened pregnant women or 4.5/100 cysts detected on ultrasound scan. CONCLUSION: Asymptomatic adnexal cysts detected in the first trimester of pregnancy are unlikely to be malignant or to cause clinical symptoms antenatally. The policy of routine ultrasound visualization of the ovaries in pregnancy cannot be justified.     

First trimester ultrasonographic diagnosis of fetal structural abnormalities in a low risk population

Objectives Ultrasonographic screening between 12⁺⁰¹ and 13⁺⁶ weeks for fetal structural abnormalities using transab dominal sonography and, where necessary, transvaginal sonography in a low risk population.
Design A prospective observational study
Setting London teaching hospital
Methods Pregnant women with a total of 1632 low risk viable fetuses between 12⁺⁰ and 13⁺⁶ weeks of gestation were scanned using transabdominal and, where necessary, transvaginal sonography (40%). If the anatomical survey was normal, the women underwent routine 18-20 week anomaly scans. Pregnancy outcomes were obtained from radiological and neonatal computerised databases, and postal or telephone patient enquiry.
Results Seventeen (1.0%) major structural abnormalities were diagnosed in the study group. Of these, 11 (64.7%) were diagnosed at the 12-13 week scan, three diagnosed in the mid-trimester and three postnatally. Of the fetal abnormalities diagnosed antenatally, 78.6% were diagnosed in the first trimester. The sensitivity of abnormality detection by the combination of both first and second trimester scans was 82.3%. In addition, a significant number of missed abortions (   n = 36  ) were also diagnosed by the first trimester scan.
Conclusion This study has demonstrated the potential of screening a low risk population for fetal abnormalities at 12-13 weeks of gestation using transabdominal sonography and, where necessary, transvaginal sonography. Larger studies are required to establish the clinical value of the first trimester scan.     

Ultrasound screening of fetal structural abnormalities at 12 to 14 weeks in Hong Kong

OBJECTIVE: Ultrasound screening for fetal abnormalities is conventionally performed at 18 to 20 weeks of gestation. Recent data suggested that many fetal structural abnormalities could be detected by ultrasound examination at 12 to 14 weeks of pregnancy. In this study, we investigated the effectiveness of early ultrasound examination in the detection of fetal abnormalities in women aged 35 years or older. METHODS: From February 1998 to March 2001, pregnant women aged 35 or above were examined by transabdominal and transvaginal sonography between 12 and 14 weeks of gestation. If the anatomical survey was normal, the women underwent routine 16- to 20-week ultrasound examination. Pregnancy outcome was obtained from the hospital records or by contacting the subjects. RESULTS: Twenty-six of the 1609 fetuses had structural abnormalities. Fourteen were detected at the ultrasound examination at 12 to 14 weeks. Detection rate was 53.8% (14/26; 95% CI 44, 64) with a false-positive rate of 0.3% (5/1583; 95% CI 0.16, 0.44). Six additional abnormalities (23.1%, 6/26) were detected at 16- to 20-week ultrasound examination. The overall detection rate of structural abnormalities was 76.9% (20/26; 95% CI 68.6, 85.2). CONCLUSIONS: The effectiveness of ultrasound examination at 12 to 14 weeks to screen for fetal abnormalities approached that achieved at 20 weeks and can be a good adjunct to the conventional examination.     

Specific formulas improve the estimation of fetal weight by ultrasound scan

Abstract

Objective: To develop and evaluate local, sex specific, small for gestational age (SGA) specific, large for gestational age (LGA) specific and combined (biometry, sex and Doppler indices) formulas for ultrasound estimated fetal weight (EFW).

Method: Low-risk singleton pregnancies that delivered within 7 days from ultrasound examination were assessed. A formula-generating group (1407 pregnancies) and a validation group (469 pregnancies) were created. Fractional regression analysis was used to develop the formulas. Systematic error, random error, fraction within the 10% of actual birth weight and Bland–Altman analysis were used.

Results: The local formula and the Hadlock formula with local co-efficients performed better than the Hadlock formula. The SGA-specific formula, the LGA-specific formula and the combined formula had the lower systematic error (MSE: +0.0022291, ?0.4226888, +0.8386222, respectively) and the narrower 95% LOA (?292.8 to +292.23, ?485.6 to +461.5, ?425.7 to +450.46, respectively). The SGA- and the LGA-specific formulas had higher fraction within the 10% of actual birth weight (81.5% and 84%, respectively).

Conclusions: Local formulas improve the EFW calculation. The combined formula can further optimize the accuracy and precision. Application of specific formulas for the small and the large fetus had the most pronounced effect in improving fetal weight estimation.     

Screening for Down syndrome using first-trimester combined screening followed by second trimester ultrasound examination in an unselected population

BACKGROUND: Recent studies have reported the efficacy of first trimester combined screening for Down Syndrome based on maternal age, serum markers (human chorionic gonadotropin, pregnancy-associated plasma protein A), and ultrasound measurement of fetal nuchal translucency. However, those do not incorporate the value of the widely accepted routine 20-22 week anomaly scan. STUDY DESIGN: We carried out a multi-centre, interventional study in the unselected population of a single health authority in order to assess the performance of first trimester combined screening, followed by routine second trimester ultrasound examination and/or screening by maternal serum markers (free beta-hCG and alpha-fetoprotein measurement or total hCG, alpha-fetoprotein and unconjugated estriol measurement) when incidentally performed. Detection and screen positive rates were estimated using a correction method for non verified issues. A cost analysis was also performed. RESULTS: During the study period, 14,934 women were included. Fifty-one cases of Down Syndrome were observed, giving a prevalence of 3.4 per 1000 pregnancies. Of these, 46 were diagnosed through first (N=41) or second (N=5) trimester screening. Among the 5 screen-negative Down syndrome cases, all were diagnosed postnatally after an uneventful pregnancy. Detection and screen positive rates of first trimester combined screening were 79.6% and 2.7%, respectively. These features reached 89.7 and 4.2%, respectively when combined with second trimester ultrasound screening. The average cost of the full screening procedure was 108 euro (120 $) per woman and the cost per diagnosed Down syndrome pregnancy was 7,118 euro (7,909 $). CONCLUSION: Our findings suggest that one pragmatic interventional two-step approach using first-trimester combined screening followed by second trimester detailed ultrasound examination is a suitable and acceptable option for Down syndrome screening in pregnancy.