Fetal Nuchal Translucency: A Prenatal Screening Tool

During fetal nuchal translucency screening, ultrasonography is used to assess for a fluid collection at the nape of the fetal neck. An abnormal fluid collection may be related to genetic disorders and/or physical anomalies. This screening is most accurate when performed between 10 and 14 weeks gestation. Analyzing maternal serum beta-hCG and pregnancy-associated plasma protein A levels increases the accuracy of 1st trimester screening. Nurse practitioners, midwives, and physicians can be certified in performing fetal nuchal translucency screening.     

Nuchal Translucency in the First Trimester

Summary: All fetuses reported as having nuchal (nape of the neck) thickening or translucency detected by a first trimester ultrasound at 2 centres were reviewed to determine the incidence of aneuploidy. Twenty nine pregnancies were registered, amongst which 12 (41%) had an abnormal karyotype, the most common aneuploidy being trisomy 21 (5 fetuses). The likelihood of aneuploidy increased with increasing thickness of the translucency. Where the karyotype was found to be normal, there was complete resolution of this ultrasound appearance by the second trimester in 15 of the 16 ongoing pregnancies: 9 have delivered normal neonates and 6 pregnancies are continuing. The other fetus developed evidence of a skeletal dysplasia by the second trimester.     

Weekly Nuchal Translucency Measurements in Normal Fetuses

Objective: To examine the longitudinal course of nuchal translucency thickness by weekly measurements between 10 and 15 weeks’ gestation in normal fetuses.Methods: Nuchal translucency was measured weekly from 10 to 15 weeks’ gestation in 64 fetuses with normal pregnancy outcome. The median and the fifth, 25th, 75th, and 95th percentiles were calculated.Results: Nuchal translucency measurements varied considerably with gestational age; this variation followed a fetus-specific pattern. In 94% of cases, we observed an increase followed by a steady decrease in nuchal translucency measurement. A visible nuchal translucency was found after 76 and 86 days’ gestation in 97% (95% confidence interval [CI] 89, 100) and 100% (95% CI 94, 100) of the fetuses, respectively. The median nuchal translucency increased from 0.7 mm at 70 days’ gestation to 1.7 mm at 91 days’ gestation, after which it declined to 1.0 mm at 105 days’ gestation.Conclusion: A progressive increase and subsequent decrease in nuchal translucency thickness occurs with advancing gestation in most fetuses, but the timing of the peak thickening appears to be fetus-specific. In this study, each fetus developed a visible nuchal translucency. If the nuchal translucency measurement is 0 mm before 12 weeks, it may be advisable to repeat the measurement at 12 weeks’ gestation. In contrast, a nuchal translucency that cannot be measured from 12 weeks’ gestation onward suggests that this temporary anatomic entity is already in its waning phase.     

产前行妊娠相关血浆蛋白A筛查联合FISH诊断Down综合征

目的 :应用单项妊娠相关血浆蛋白A(PAPP A)筛查与羊水间期荧光原位杂交 (FISH)产前诊断相结合预防妊娠Down综合征胎儿。方法 :采用酶联免疫方法 (ELISA)对孕周分别为 6～ 2 7周的 1839例孕妇进行母血PAPP A单项筛查 ,以低于同一孕周的中位数时视为可能妊娠Down综合征胎儿的高风险孕妇。取高风险孕妇羊水细胞直接进行间期FISH产前诊断并同时用部分羊水细胞遗传学检查作对照。结果 :检出 1例孕 7周孕妇其PAPP A值为 0 0 5 1U/L ,低于同一孕周中位数 2 0多倍。羊水细胞间期FISH结果显示 ,含 5个杂交信号的核占所有杂交核的 38 5 % ,与细胞遗传学分析的 2 1三体核型完全一致。结论 :单项PAPP A筛查与羊水间期细胞FISH相结合是早期防治妊娠Down综合征有效可行的方法。     

血清学筛查与胎儿超声检查在18、13三体综合征产前诊断中的应用

目的:探讨利用孕妇血清学筛查和胎儿超声检查进行18、13三体综合征胎儿产前诊断的有效性。方法:①对78例(A组)产前血清学筛查18、13三体高风险孕妇,拒绝进行产前诊断的孕妇进行随访观察。②对56例(B组)首诊主诉胎儿超声检查有结构异常的孕妇、134例(C组)首诊主诉为产前血清学筛查胎儿18三体高风险的孕妇,于孕18～32周行羊膜腔穿刺羊水细胞培养,或脐血管穿刺脐血细胞培养染色体分析。结果:A组的18三体筛查高风险孕妇有2例出现B超检查结构异常而放弃妊娠,1例产后检查新生儿先天性心脏病。B组发现18三体3例,13三体3例,其他染色体异常7例,异常发现率23.21%(13/56);其中2例18三体合并有血清学筛查高风险。C组发现胎儿异常4例,其中2例确诊为18三体,异常发现率2.99%(4/134)。结论:孕妇血清生化指标筛查结合胎儿超声检查是产前检出18、13三体综合征胎儿的有效检查方法。     

Economic Evaluation of Prenatal Carrier Screening for Fragile X Syndrome

This study is a reanalysis of the first scientific paper published by one of the authors, originally coauthored with Dr. Roy H. Petrie. In honor of Dr. Petrie, these data have been reanalyzed to re-evaluate the data using more sophisticated techniques and to expand on the original findings. This reanalysis examines the contribution of maternal weight gain to infant birthweight and retained maternal weight in the immediate postpartum period, and the effect of weight gains below, at, and above the Institute of Medicine (IOM) guidelines on both infant birthweight and retained maternal weight in the postpartum period. The study population included 487 term, uncomplicated, singleton pregnancies. Body mass index (BMI) was calculated for each woman, and categorized as underweight, normal weight, or overweight. Maternal retained weight was calculated as postpartum weight 2 days after delivery minus pregravid weight. Every kilogram of gestational weight gain increased birthweight by 44.9 g for underweight women, 22.9 g for normal weight women, and 11.9 g for overweight women. For every kilogram of retained weight, birthweight was increased by 35.6 g for underweight women, 15.9 g for normal-weight women, and 5.1 g for overweight women. Increasing weight gains from below to equal to IOM guidelines increased birthweight and maternal retained weight by 317 g (11%) (P < 0.01) and 5 kg (P < 0.01), respectively, for underweight women; 141 g (4–4%) (P < 0.02) and 6.2 kg (P < 0.01), respectively, for normal-weight women; and 200 g (6.4%) (NS) and 6.4 kg (P < 0.01), respectively, for overweight women. Increasing weight gains from equal to above the IOM guidelines increased birthweight and maternal retained weight by an additional 299 g (9.4%) (P < 0.02) and 7.3 kg (P < 0.01), respectively, for underweight women; an additional 196 g (5.9%) (P < 0.01) and 5.9 kg (P < 0.01), respectively, for normal weight women; and an additional 9 g (0.3%) (NS) and 8.3 kg (P < 0.01), respectively, for overweight women. These findings suggest that, beyond a certain level of weight gain, there is a point of diminishing returns (increase in birthweight) at the expense of increasing maternal postpartum obesity for the woman who has gained excessively.     

Prenatal Diagnosis and Genetic Counseling for Mosaic Trisomy 13

Counseling parents of a fetus with trisomy 13 mosaicism remains difficult because of the phenotypic variability associated with the condition; some patients exhibit the typical phenotype of complete trisomy 13 with neonatal death, while others have few dysmorphic features and prolonged survival. This article provides a comprehensive review of the prenatal diagnosis and genetic counseling for mosaic trisomy 13, including confined placental mosaicism 13, mosaic trisomy 13 diagnosed at amniocentesis, and phylloid hypomelanosis in association with mosaic trisomy 13.