The effect of associated structural malformations in the prediction of chromosomal abnormality risk of fetuses with echogenic bowel

Objective: Our aim is to determine the frequency of chromosomal abnormalities and also to identify the role of structural malformations on the chromosomal abnormality risk among fetuses with echogenic bowel.

Methods: Over a 6-year period fetuses with echogenic bowel (FEB) were retrospectively evaluated. The pregnancies with intra-amniotic bleeding history, congenital infection, cystic fibrosis and intrauterine growth retardation were excluded from the study. Types and frequency of sonographically detected fetal malformations were identified. Chromosomal abnormality incidences according to association with soft markers and major fetal abnormalities were compared.

Results: Of the 281 fetuses with echogenic bowel, 105 (37.37%) were isolated, 78 (27.76%) were associated with soft markers and 98 (34.87%) were associated with major abnormalities. There were 30 (10.7%) fetuses with abnormal karyotypes. The chromosomal abnormality rate of the groups of isolated FEB, FEB?+?soft markers and FEB?+?major abnormalities were 6.7%, 7.7% and 17.4%, respectively.

Conclusions: Chromosomal abnormality risk in fetuses with echogenic bowel should be evaluated according to additional sonographic findings. Association of structural malformations increases the chromosomal abnormality risk, although this risk is not significant with the presence of soft markers alone.     

The association of echogenic fetal lungs with trisomy 21

OBJECTIVE: To evaluate the association between echogenic appearing lungs on ultrasonographic examination of the fetus and aneuploidy. METHODS: Cases in which echogenic lungs were prospectively identified on ultrasonographic examination were collected. Other abnormal ultrasonographic findings were documented, as were patient data pertinent to the risk of aneuploidy, such as maternal age and results of serum screening. The chromosomal complement of each identified case is reported. RESULTS: Five fetuses were identified with diffusely echogenic lungs on ultrasound examination over a two-year period. In three of the five cases, there were other ultrasound abnormalities, although in only one of these was a major congenital abnormality detected. In all three of these cases, the fetal chromosomal complement showed trisomy 21. In 1 of the 2 cases in which the echogenic lungs were an isolated finding, the fetus also was found to have trisomy 21. CONCLUSIONS: Bilateral and diffusely echogenic lungs appear to have an association with fetal trisomy 21.     

Obstetric ultrasonographic findings and fetal chromosomal abnormalities: Refining the association

OBJECTIVE: In an attempt to refine the role of ultrasonography in screening and identifying fetuses at risk for chromosomal abnormalities, a retrospective review of patients undergoing genetic amniocentesis was undertaken. STUDY DESIGN: Computer databases from the perinatal biology laboratory and cytogenetics laboratory of our institution were correlated to compare the results of the fetus' ultrasonographic examination with the cytogenetic results from amniocentesis. Univariate and multivariate analysis were used to determine the best correlations between ultrasonographic findings and chromosomal abnormalities (study 1). The results were used to construct regression analysis formulas and a Neural Network program to predict the presence or absence of chromosomal abnormalities in a second set of patients (study 2) undergoing genetic amniocentesis. RESULTS: One hundred twenty-five chromosomal abnormalities were found in 3775 fetuses in study 1 (3.3%). Multivariate analysis showed significant correlations between anomalies of the central nervous system, heart, face and neck, and extremities and increased nuchal fold, increased bowel echogenicity, abnormal biparietal diameter-to-femur ratio, and the presence of chromosomal abnormalities. Regression equations and a Neural Network program successfully predicted the presence or absence of fetal chromosomal abnormalities in a second set of 901 at-risk fetuses. CONCLUSION: A normal ultrasonographic examination result in patients who are at increased risk for fetal chromosomal abnormalities reduces the risk 2- to 3-fold, whereas the presence of any major ultrasonographic abnormality or certain minor abnormalities significantly increases the risk. The application of these results to low-risk patients is still premature.     

Mild fetal lateral cerebral ventriculomegaly: clinical course and outcome

The neonatal, pathologic outcome and karyotypic abnormalities are reported for 44 fetuses with mild ventriculomegaly diagnosed antenatally. Seventeen of these 44 fetuses (39%) had other ultrasonographic defects, and five (12%) had abnormal karyotypes. Five pregnancies were electively aborted and three other fetuses died in the neonatal period. Twenty-six (72%) of the remaining 36 live-born neonates are developmentally and clinically normal at 3 to 18 months of age. Twenty-one of these 26 had isolated mild ventriculomegaly as the only ultrasonographic finding. The other 10 live-born infants are developmentally impaired, and five of these 10 had mild ventriculomegaly as the only prenatal ultrasonographic abnormality. In conclusion, these data show that fetuses with mild ventriculomegaly have a lower incidence of associated anomalies and a better outcome than fetuses with more severe ventricular dilatation, as reported in the literature. The majority of fetuses with mild ventriculomegaly as an isolated finding and a normal karyotype are developing normally.     

The role of the second trimester genetic sonogram in screening for fetal Down syndrome

The Genetic Sonogram is an ultrasound examination done on second trimester fetuses that not only evaluates the fetus for structural malformations, but also searches for the sonographic markers of fetal Down syndrome. The main markers that comprise the genetic sonogram include the nuchal fold, short femur and humerus, pyelectasis, hyperechoic bowel, echogenic intracardiac focus, and any major abnormality. The absence of any marker on a second trimester scan conveys a 60-80% reduction in prior risk of Down syndrome based on advanced maternal age or serum screen risk. The presence of sonographic markers, either singly or in combination, will raise the baseline risk of Down syndrome using likelihood ratios calculated for each individual marker. Using this approach, approximately 75% of fetuses with Down syndrome can be identified by modifying the patient's baseline risk according to the results of the ultrasound. The second trimester scan will likely continue to play an important role in the future in the detection of aneuploidy.     

Ultrasound markers for Down syndrome

Trisomy 21 (Down syndrome) is the most common chromosomal abnormality. Sonographic findings in fetuses with Down syndrome include both structural abnormalities and nonstructural abnormalities or "markers." These markers are known as "soft markers" of aneuploidy. These markers are nonspecific, often transient. The most commonly studied soft markers of aneuploidy include a thickened nuchal fold, long bones shortening, mild fetal pyelectasis, echogenic bowel, echogenic intracardiac focus, FMF angle > 90 degrees, pathologic velocity of Ductus venosus and choroid plexus cyst.     

Significance of echogenic foci in the left ventricle of the fetal heart in a low-risk population

OBJECTIVE: To determine if there exists a significant association between prenatally detected left ventricular echogenic foci and chromosomal abnormalities. METHODS: Over a 10-month period the presence of intracardiac echogenic foci was recorded on all low-risk patients referred for anatomical assessment. The study group consisted of 113 singleton fetuses and was compared to a control group with no foci. RESULTS: Among the study group with echogenic foci, 5 chromosomal abnormalities (three trisomies) were detected. In the control group only one chromosomal abnormality was diagnosed. CONCLUSION: An association exists between the finding of intracardiac echogenic foci in the fetus and the presence of chromosomal abnormalities.     

The impact of the use of the isolated echogenic intracardiac focus as a screen for Down syndrome in women under the age of 35 years.

OBJECTIVE: The purpose of this study was to determine the public health impact of the routine offering of amniocentesis to women under the age of 35 years who have an isolated fetal echogenic intracardiac focus on second trimester ultrasound scan. STUDY DESIGN: A decision analytic model was designed that compared the accepted standard of second trimester triple marker screen for Down syndrome to a policy in which amniocentesis with an isolated echogenic intracardiac focus on ultrasound in addition to the triple marker screen is offered to all women in the United States who are <35 years of age. A sensitivity of 20%, an echogenic intracardiac focus screen positive rate of 5%, and a risk of Down syndrome of 1:1000 were assumed. A sensitivity analysis was performed that varied the screen positive rate, the sensitivity of echogenic intracardiac focus for Down syndrome, and the prescreen risk for Down syndrome in the population. RESULTS: With the baseline sensitivities, rates, and risks, the use of isolated echogenic intracardiac focus as a screen would result in an additional 118,146 amniocenteses performed annually to diagnose 244 fetuses with Down syndrome. These amniocenteses would result in 582 additional miscarriages. It would be necessary to perform 485 amniocenteses that would result in 2.4 procedure-related losses for each additional Down syndrome fetus that was identified. CONCLUSION: Although the echogenic intracardiac focus appears to be associated with a small increased risk of Down syndrome, its use as a screening tool in low-risk populations would lead to a large number of amniocenteses and miscarriages to identify a small number of Down syndrome fetuses.     

常见产前超声软指标和微小异常的超声诊断及进一步处理建议

产前超声软指标和微小异常有时可为一过性,但有时则与胎儿遗传学异常风险升高有一定的相关性。本文对胎儿颈项透明层增厚、颈后皱褶厚度增厚、轻度侧脑室增宽、脉络丛囊肿、小脑延髓池增宽、鼻骨缺失或短小、轻度肾盂扩张、肠管回声增强、心室内强回声灶、轻度长骨短小、单脐动脉这几个较为常见且具有临床意义的超声软指标和微小异常的定义及超声特征、临床咨询要点和进一步处理建议进行归纳、阐述,以期对临床医生的产前咨询工作有一定启发和帮助。     

Fetal echocardiography: accuracy and limitations in a population at high and low risk for heart defects.

OBJECTIVE: Our objective was to assess the accuracy of prenatal echocardiography in detecting congenital heart defects in patients at high and low risk for structural cardiac anomalies. STUDY DESIGN: Sixty-nine consecutive fetuses with congenital heart defects who had had prenatal ultrasonography at greater than or equal to 18 weeks' gestation were evaluated to determine the accuracy of prenatal ultrasonography in identifying structural cardiac defects. Thirty-nine patients were at high risk and 30 patients were at low risk for cardiac anomalies. All fetuses were scanned with standard four-chamber and outflow tract views. Data concerning extracardiac anomalies and karyotypic abnormalities were tabulated. The accuracy of the four-chamber view alone in identifying congenital heart defects was evaluated. RESULTS: Fifty-seven of 69 fetuses (83%) were prenatally identified ultrasonographically as having a heart defect. There was no difference in the sensitivity of detecting cardiac anomalies between high-risk and low-risk groups. When the four-chamber view was used, only 63% of fetuses were recognized as having an abnormal heart. Extracardiac anomalies were noted in 36% and karyotypic abnormalities in 17% of patients. CONCLUSION: The four-chamber and outflow tract views done routinely in an ultrasonography laboratory seeing a mixed population of patients was successful in detecting 83% of fetuses with structural cardiac malformations. Because 43% of the fetuses with heart defects were referred for low-risk indications, systematic ultrasonographic examination of the fetal heart should not be reserved only for those at high risk.     

Aberrant right subclavian artery as a new cardiac sign in second- and third-trimester fetuses with Down syndrome

OBJECTIVE: The right subclavian artery arises normally as the first vessel from the brachiocephalic artery of the aortic arch. An aberrant right subclavian artery arises as a separate vessel from the aortic isthmus and crosses to the right, behind the trachea. This variant is present in <1% of the normal population; however, in subjects with Down syndrome, an incidence between 19% and 36% was reported. The purpose of this study was to assess the possibility of the detection of an aberrant right subclavian artery in fetuses with Down syndrome. STUDY DESIGN: Fourteen consecutive fetuses with prenatally detected Down syndrome were examined between 18 and 33 weeks of gestation. The presence of an aberrant right subclavian artery was determined by visualization of the transverse 3-vessel trachea view of the upper thorax with color Doppler ultrasonography. RESULTS: The right subclavian artery was visualized in 100% of fetuses (14/14) with Down syndrome. An aberrant right subclavian artery was identified in 35.7% of trisomy 21 fetuses (5/14). In 1 fetus, the aberrant right subclavian artery was the only abnormal ultrasound finding. In 3 fetuses, an aberrant right subclavian artery was associated with an intracardiac echogenic focus plus additional extracardiac markers. In the fourth fetus, an aberrant right subclavian artery was associated with an atrioventricular septal defect. All 9 fetuses with Down syndrome with a normal origin of the right subclavian artery had additional cardiac and/or extracardiac abnormalities. In 12 cases, pregnancy was terminated; 2 fetuses were live born. CONCLUSION: This preliminary study suggests that the in utero identification of an aberrant right subclavian artery may be a new ultrasound marker to be found in fetuses with Down syndrome. Further studies are required to assess the incidence of aberrant right subclavian artery in normal fetuses.     

Trisomy 21. Second-trimester ultrasound

Not every aspect of sonographic examination reveals karyotypic abnormalities. Ultrasound examination of a fetus with trisomy 21 generally reveals normal amniotic fluid, normal placentation, and normal fetal growth. In addition, other chromosomal abnormalities have many of the same sonographic findings as Down syndrome, and many findings have a large overlap with phenotypically normal fetuses. The importance of second-trimester ultrasound screening for Down syndrome has remained great because of its ease of use and relative effectiveness. Trained sonographers can adjust the relative risk for trisomy 21 and alter the need for genetic amniocentesis. It is important that parents understand the limitations of a screening test and the risks and benefits of possible subsequent confirmatory testing. If a major structural abnormality is identified on ultrasound, karyotype determination should be considered. Nuchal thickness in the first or second trimester remains the most clinically useful marker for trisomy 21. The predictive value of all the markers depends on the population studied and can be modified by a host of biochemical markers and historical factors. If fetal karyotype analysis could be performed without sampling through the uterus, prenatal diagnosis could be offered to all pregnant women, and screening would be unnecessary. Despite its limitations, ultrasound will have an important role in prenatal diagnosis at least until isolating and testing fetal cells from maternal blood or other sources becomes practical and widely available. Whether used alone or in conjunction with additional biochemical or molecular serum markers, ultrasound is an important and powerful tool in prenatal genetic evaluation.     

An isolated intracardiac echogenic focus as a marker for aneuploidy

OBJECTIVE: This study was undertaken to evaluate the relationship of an isolated fetal intracardiac echogenic focus in a population of patients with a mixed risk for aneuploidy when presenting for prenatal diagnosis. STUDY DESIGN: All women referred to our institution for screening ultrasound were prospectively evaluated for the presence of an intracardiac echogenic focus in the fetal heart. Each patient was evaluated for the presence of clinical risk factors including ultrasound findings, biochemical screening, and maternal age. The population of patients was then described and neonatal outcomes were obtained. RESULTS: A total of 10,875 patients were referred and 176 cases of fetal intracardiac echogenic foci were evaluated. There was an overall prevalence of 1.6% in our population. The patients with other ultrasound findings and/or maternal age older than 35 years who underwent amniocentesis had 3 abnormal karyotypes identified and had identifiable risk factors. In the group less than 35 years, the relative risk was 2.55 of having an amniocentesis for an isolated echogenic focus (with no cases of fetal aneuploidy found) in comparison with our referred group of nonadvanced maternal age patients without any ultrasound markers or findings. CONCLUSION: This isolated echogenic finding appears to be a benign variant and not an increased risk for fetal aneuploidy. The chromosomal abnormalities were seen in the group with risk factors including maternal age and/or other ultrasound findings. Evaluation of maternal age, biochemical markers, and ultrasound markers should be used together to help determine the risk of patients with an isolated echogenic focus.     

Prenatal diagnosis of aneuploidy and deletion 22q11.2 in fetuses with ultrasound detection of cardiac defects

OBJECTIVE: We report a prospective database evaluation of the occurrence of aneuploidy and deletion 22q11.2 after prenatal detection of cardiac abnormalities. To ensure the maximum inclusion, all cardiac defects were considered, with the exception of echogenic intracardiac foci. STUDY DESIGN: Prenatal specimens with ultrasound findings of cardiac defects were identified. Physicians were provided supplementary information that described the risk of deletion 22q11.2 syndrome if the karyotype was normal. On approval, fluorescence in situ hybridization was performed to identify the 22q11.2 microdeletion. RESULTS: Prenatal detection of cardiac abnormalities identified aneuploidy or unbalanced chromosome rearrangements in 41% of the cases that were studied. In those fetuses with normal karyotypes, 3% had the deletion 22q11.2. CONCLUSION: These results indicate that prenatal ultrasound findings of congenital heart defects identify fetuses who are at increased risk for chromosome abnormalities. Fetuses with normal karyotypes should consider having fluorescence in situ hybridization studies for the microdeletion 22q11.2 syndrome. Chromosome and fluorescence in situ hybridization studies of family members should be recommended when a fetus is identified as having the deletion 22q11.2.     

Trisomies and other chromosome abnormalities detected after positive sonographic findings

OBJECTIVE: To evaluate the rate of trisomies and other chromosome abnormalities after positive ultrasound findings in thefirst and second trimester of pregnancy. STUDY DESIGN: The study investigated chromosome abnormalities detected in cases with prior abnormal ultrasoundfindings. During a 10-year period there were 1907 invasive interventions carried out with the purpose of chromosome analysis. The intervention was genetic amniocentesis in 1619 cases and chorionic villus sampling in 288. RESULTS: Karyotyping revealed 103 cases (5.4%) of chromosome abnormalities. Abnormalities with subcutaneous edema were examined: abnormal karyotype was found in 20% of cases with nonimmune hydrops, 48.1% of cases with cystic hygroma and 53.8% of cases with nonimmune hydrops and cystic hygroma together, 8.3% of cases with nuchal edema in the first trimester and 5.5% in the second trimester. The incidence of chromosome abnormalities in cases of cerebral anomalies was 6.3% of cases with ventricular dilatation, 3.6% of cases with choroid plexus cysts and 15.9% of cases with other cranial anomalies. Regarding abnormalities of the heart, isolated echogenic intracardiac focus and ventricular septal defects were not associated with chromosome abnormality, but, in conjunction with other positive ultrasound findings, the incidence of chromosome abnormalities was 7.9% and 26.7%, respectively. Other anomalies of the heart and large blood vessels showed an abnormal karyotype incidence of 18.2%. In cases of unilateral pyelectasis unassociated with other anomalies, the incidence of chromosome abnormalities was 1%. In cases of bilateral pyelectasis or pyelectasis associated with other anomalies, the incidence was 3%. In terms of anomalies of the abdominal wall and abdomen, the incidence of association with chromosome abnormalities was 9.5% in cases of omphalocele, 11.8% in cases of duodenal atresia and 5.7% in cases of echogenic bowel. In cases of short femur and humerus the rate of abnormal karyotypes was 16%. CONCLUSION: Ultrasound plays an important role in prenatal diagnosis. In cases of positive ultrasound findings, karyotyping is reasonable.     

孕中期羊水细胞染色体核型分析及其异常核型发生率的比较

目的：分析孕中期羊水细胞染色体核型及比较不同异常核型的发生率,并对各种异常核型的临床意义进行探讨。方法1998年9月至2010年11月在复旦大学附属妇产科医院集爱遗传与不育诊疗中心行羊水细胞染色体检查的孕妇共13 648例,抽取并培养成功的羊水标本共计13 795份,即13 795个胎儿获得核型诊断,对上述胎儿根据其母亲（孕妇）不同检查指征进行分组：当孕妇年龄≥35岁时为高龄孕妇组（4065个）;血清学筛查提示高危时为血清筛查高危组（6462个）;超声筛查出现异常征象时为超声异常征象组（1539个）;已知夫妇中有一方为染色体异常时为夫妇染色体异常组（108个）;除此之外,其他胎儿列为其他因素组（1621个）。采用羊水细胞培养法对各组胎儿进行染色体核型分析,并用荧光原位杂交技术对78个≥26孕周的胎儿行常见非整倍体快速诊断,对153个核型异常胎儿的父母进行淋巴细胞核型分析。结果 (1)各组异常核型分类及其构成：13 795个胎儿中共发现异常核型388个,异常核型发生率为2.813％(388/13 795)。388个异常胎儿中,非整倍体最多,为59.8％ (232/388);常染色体结构异常为24.7％( 96/388);嵌合体为12.4％( 48/388);其他较少见的异常核型包括标记染色体为1.3％ (5/388),性染色体结构异常为1.0％(4/388),三倍体为0.8％(3/388)。除了夫妇染色体异常组,其他各组均以非整倍体占绝大多数,有4例罕见的非整倍体,分别出现在高龄孕妇组、超声异常征象组及血清筛查高危组。超声异常征象组异常核型种类最多,而夫妇染色体异常组其胎儿染色体异常种类最集中（常染色体结构异常）。嵌合体主要分布在血清筛查高危组,占该组异常核型的20.0％ (29/145)。(2)异常核型种类及发生率：异常核型种类中以21三体最为常见,占全部异常核型的35.6％( 138/388),其次为常染色体平衡性结构重排为20.6％ (80/388)、嵌合体为12.4％ (48/388)、18三体为11.3％ (44/388),其他较常见的异常核型包括常染色体非平衡性结构重排和45,X0,各为4.1％(16/388),47,XXY为3.9％(15/388)。(3)父母淋巴细胞核型分析：153个胎儿进行了其父母淋巴细胞的核型分析,并最终确定了胎儿异常核型来源：家族性异常58个,新发生的异常95个。78个胎儿的荧光原位杂交技术诊断结果与G显带核型全部一致,其中2个为21三体。结论不同检查指征孕妇的胎儿异常核型的构成不同;孕中期胎儿异常核型种类繁多,致畸风险与异常核型种类有关。     

Chromosomal abnormalities in fetuses with ultrasonographically detected neural tube defects

We analyzed the karyotype of fetuses with ultrasonographically detected neural tube defects (NTDs). In our study, we included a total of 194 fetuses with NTDs. We analyzed the type of NTD, the karyotype, maternal age, fetal gestational age at diagnosis, and fetal sex. Of the 194 fetuses with NTDs, 87 were anencephalic and 107 had other, nonanencephalic, NTDs. A total of 12 fetuses were shown to have chromosomal abnormalities. Three of 87 anencephalic fetuses (3.45%) had chromosomal abnormalities. The sex ratio for anencephalic fetuses was 65.5% : 34.5% for female and male fetuses. Nine of 107 fetuses with other NTDs (8.41%) had chromosomal abnormalities. Seven fetuses had isolated NTDs and a further seven fetuses had additional ultrasonographic anomalies. Two of the latter had abnormal karyotypes. The sex ratio of all other NTD cases was 67.3% : 32.7% for female and male fetuses. The high number of chromosomal abnormalities justifies prenatal karyotyping in all fetuses with ultrasonographically diagnosed NTDs.     

Abnormal pregnancy sonogram: selective indication for fetal karyotype

The inability to make a definitive diagnosis in the fetus with a sonographically identified abnormality often results in parental and physician uncertainty. An antenatal chromosome evaluation could resolve this uncertainty. Forty-one fetuses with an abnormal ultrasound examination were tested for karyotypic abnormality using a variety of specimens. Nearly one-third (13 of 41) of these fetuses had various chromosome abnormalities. There were only seven survivors in this series, underscoring the often poor prognosis when a significant ultrasound defect is detected antenatally. Knowledge of the fetal chromosome constitution in the setting of an abnormal ultrasound has important epidemiologic, cost-benefit, counseling, and pregnancy management implications.     

Should determination of the karyotype be systematic for all malformations detected by obstetrical ultrasound?

OBJECTIVE: The aim of this study was to determine whether karyotyping should be performed for every fetal malformation detected in low risk populations. METHODS: A karyotype was obtained from 428 fetuses examined over a 10-year period after fetal malformation was diagnosed using obstetrical ultrasound. These fetuses were separated into two groups, one with isolated malformations and the other with multiple malformations. The association between each type of malformation and the result of karyotype was evaluated. RESULTS: Forty-eight chromosomal abnormalities were encountered in 428 fetuses (11.2%). The karyotype was abnormal in 32/343 (9.3%) fetuses with isolated malformations and 16/85 (18.8%) fetuses with multiple malformations (p=0.022). The probability of an abnormal karyotype among the group of isolated malformation depended on the anatomical system involved (p<0.001). Our study demonstrated several isolated malformations without chromosomal abnormality (hydronephrosis with high obstruction, unilateral multicystic dysplastic kidney, gastroschisis, intestinal dilatation, meconium peritonitis, cystic adenomatoid malformation, pulmonary sequestration, tumor, vertebral anomaly). CONCLUSION: Each fetus with multiple malformations needs a chromosomal analysis. Within the group of isolated malformations, our study emphasizes that medical maternal history and the type of malformation need to be taken into account before performing a fetal karyotype.     

Cystic fibrosis and chromosome abnormalities associated with echogenic fetal bowel.

OBJECTIVE: To determine the prevalence of cystic fibrosis mutations and chromosome abnormalities in the fetuses of a heterogeneous population of pregnant women referred for prenatal testing for echogenic fetal bowel. METHODS: Fetal or parental samples obtained after a second-trimester sonographic finding of echogenic fetal bowel were submitted to a referral diagnostic laboratory during a 2-year period. Results of DNA testing and karyotyping on these samples were analyzed to determine the prevalence of cystic fibrosis transmembrane reductase gene mutations and chromosome abnormalities. RESULTS: Of 244 cases tested, two fetuses were positive for two cystic fibrosis mutations. This rate (0.8% or two of 244) is 20 times higher than the general white population rate of one per 2500. In a third case, both parents were carriers but the fetus was not tested. Nine (8%) of 113 fetuses tested had one cystic fibrosis mutation. Of 106 fetuses for whom chromosome results were available, three (2.8%) fetuses had a chromosomal abnormality: two had trisomy 21 and one had Klinefelter syndrome. A fourth fetus carried a de novo, apparently balanced, 5;12 translocation. CONCLUSION: These laboratory results are representative of a broad spectrum of clinical settings and indicate a generalized increased risk associated with this sonographic finding. Therefore, when a second-trimester sonographic diagnosis of fetal echogenic bowel is made, fetal testing for both cystic fibrosis and chromosome abnormalities is warranted.