Fetal ear assessment and prenatal detection of aneuploidy by the quantitative three-dimensional ultrasonography.

The purposes of this study were to use quantitative three-dimensional (3-D) ultrasonography to establish the normal charts of three fetal ear-growth indexes, (ear length, ear width and ear area), and to validate their efficacy in the prenatal diagnosis of fetal trisomies, either separately or as a combination. Using quantitative 3-D ultrasonography, we performed a prospective study to measure the three fetal ear growth indexes (i.e., ear length, ear width and ear area) in 129 singleton pregnancies, including 122 normal fetuses and 7 trisomies. The ear shape was also evaluated in these fetuses using both 2-D and 3-D ultrasonography. Our results showed that: First, 3-D ultrasonography offers better visualization and easier evaluation of fetal ears than 2-D ultrasonography. Second, when using the quantitative assessment of 3-D ultrasonography, the measurements of ear length, ear width and ear area were all correlated significantly with gestational age in normal pregnancies (r = 0.881, 0.848, and 0.890, respectively). In addition, 3 of 7 fetal trisomies had ear length below the tenth percentile, 1 had ear width below the tenth percentile, and 2 had ear area below the tenth percentile. Furthermore, with the combination of these three measurements, (including ear length, ear width and ear area), the sensitivity in detecting fetal trisomies was elevated to 57.1% and the specificity was 83.2%. In conclusion, 3-D ultrasonography reduces the limitations of 2-D ultrasonography in the evaluation of fetal ears. However, fetal ear measurement may not be used as a single ultrasonographic parameter in identifying aneuploid fetuses. We recommend using the combination of these three ear growth indexes to enhance the detection rate of aneuploidy.

Systemic assessment of fetal hemodynamics by Doppler ultrasound.

The aim of our study was to investigate the parameters of fetal circulation of normal pregnancies and their relationship to fetal cardiac output. We performed a cross-sectional study of 315 normal singleton pregnancies between 20 and 40 weeks' gestation without fetal chromosomal or structural malformations. After follow-up to delivery, 212 patients who fit all the criteria were enrolled for final analysis. Blood flow velocity waveforms were obtained from the tricuspid and mitral ventricular inflow, ascending aorta (AAO), pulmonary artery (PA), middle cerebral artery (MCA), renal artery (RA), umbilical artery (UA), descending aorta (DAO), inferior vena cava (IVC) and ductus venosus (DV) using duplex (real-time Doppler) ultrasound (US) scanner. The peak velocity of DV, AAO, PA and MCA were also obtained. At the intracardiac level, the ratio of peak flow velocity of E wave to peak flow velocity of A wave (E:A ratio) of mitral valve (MV) increased more rapidly than tricuspid valve (TV) E:A ratio. For the great vessels, aortic peak velocity remained higher than the pulmonary peak velocity with advancing gestation. The cardiac output closely correlated to the cardiac compliance and flow resistance indices at arterial and venous level. The acceleration time in the fetal arteries increased with advancing gestation in AAO, PA, MCA and DAO, but it decreased in RA and kept constant in UA. In addition, the acceleration time of UA was unrelated to cardiac output. The changes of the fetal intracardiac, arterial and venous impedances were remarkable through the gestation and related to cardiac output. Fetal cardiac output correlated well with the changes of arterial resistance, except with the DAO. The ventricular compliance increased with advancing gestation, especially in the left side, and was highly related to the change of cardiac output. The acceleration time in major arteries positively correlated with the gestational age and cardiac output, except in UA and RA; this indicates the difference of the changes of mean arterial pressure in uteroplacental circulation, fetal organs and great vessels. In conclusion, the fetal cardiac output correlated well with the ventricular compliance and was influenced by both hemodynamic changes in peripheral resistance and mean arterial pressure.

The clinical significance of the irregular fetal heart rhythm.

OBJECTIVE: Irregular fetal heart rhythms are common in clinical practice, but there is little information available on their significance or appropriate management. STUDY DESIGN: This was a retrospective review of fetuses seen during 10 years that either were referred for fetal echocardiography because of a fetal arrhythmia or were found incidentally to have an arrhythmia during fetal echocardiography for other indications. RESULTS: From 1988 through 1997 we performed 5566 fetal echocardiograms on 4838 different fetuses. There were 614 fetuses with irregular fetal heart rhythms. Among 595 referred for arrhythmias, extrasystoles were found in 255 (42.9%), normal rhythms were seen in 330 (55.4%), and hemodynamically significant arrhythmias were seen in 10. There were 2 fetuses with arrhythmias and structural heart disease. Nine of 10 fetuses with hemodynamically significant arrhythmias survived. An additional five neonates were found to have hemodynamically significant arrhythmias only postnatally. A total of 15 fetuses (2. 4%) among those referred for irregular rhythms had significant arrhythmias. CONCLUSIONS: Irregular fetal heart rhythms signify hemodynamically significant arrhythmias in a small but important proportion of fetuses. Those without persistent irregularities on evaluation can be followed up with routine prenatal care.

Color Doppler imaging of placental masses: differential diagnosis and fetal outcome.

OBJECTIVES: To evaluate the application of Doppler imaging in the differential diagnosis of placental masses and perinatal outcome. METHODS: A retrospective study of all cases referred for suspicion of placental chorioangioma over a nine and a half year period. Only cases in which color flow mapping and pulsed Doppler examination were performed were considered. RESULTS: Fourteen cases fulfilled the criteria and included seven cases of chorioangioma, two cases of placental hemorrhage and five cases of a placental mass which resolved during pregnancy. All cases of chorioangioma could be distinguished by increased blood flow within the mass. Polyhydramnios was associated with six cases of chorioangioma. Rapid tumor growth, premature labor and neonatal death occurred in one case. Premature labor occurred in six cases of chorioangioma and both cases of placental hemorrhage. IUGR was associated with two cases of chorioangioma and both cases of placental hemorrhage. All cases of resolving placental mass delivered uneventfully at term. CONCLUSIONS: Color Doppler is a useful tool in the differentiation of placental masses. Such masses should be followed up regularly because their growth rate is variable and unpredictable.

Assessment of Doppler velocimetry of the fetal umbilical artery by multigate spectral Doppler scanning and traditional pulsed Doppler ultrasonography plus color flow mapping.

The Doppler signal of blood flow originates from the sonographic scattering from the circulating red blood cells. However, the physics of blood flow is complex as expressed by the Bernoulli equation, and the flow velocity at different positions in the laminar flow of the same vessel is variable. Using multigate spectral Doppler scanning, we recorded multiple Doppler flow signals over a segment of the umbilical artery and compared the results with traditional pulsed Doppler ultrasonography. The intraobserver variations of the pulsatility index, the resistive index, and the systolic-to-diastolic ratio were evaluated in 30 human fetuses between 29 and 42 weeks of gestation. The correlation coefficient was calculated to establish the relationship between the results of multigate spectral Doppler scanning and the traditional pulsed Doppler ultrasonographic method. The Doppler indices of these two measurements are all significantly correlated. However, since a significant difference exists between the Doppler flow measurements of multigate spectral Doppler scanning and the traditional pulsed Doppler ultrasonographic method, the range of measurement agreement for these two methods suggests that this difference should be taken into account in the interpretation of Doppler flow velocity measurements.

Immunohistochemical localization of inducible nitric oxide synthase on human fetal amnion in intra-amniotic infection.

OBJECTIVES: Amniotic fluid levels of nitric oxide metabolites are significantly elevated in intra-amniotic infection. We hypothesized that fetal amnion is a possible site for the production of nitric oxide. Because inducible nitric oxide synthase is the key enzyme responsible for the generation of nitric oxide in patients with intra-amniotic infection, we used immunohistochemistry to localize it on human fetal amnion. STUDY DESIGN: Human fetal amnions were obtained from patients with and without intra-amniotic infection (n = 5, respectively). Intra-amniotic infection was diagnosed by positive amniotic fluid cultures and placental pathologic features. Human fetal amniotic membranes were processed into tissue blocks and embedded in paraffin. A rabbit polyclonal antibody against human inducible nitric oxide synthase was used as the primary antibody, followed by avidin-biotin immunoperoxidase localization. Normal rabbit serum was used as a negative control and ovarian carcinoma cells were used as the positive control. RESULTS: Anti-inducible nitric oxide synthase labeling of human fetal amniotic membranes in patients with intra-amniotic infection showed positive immunostaining of epithelial cells, specifically in the cytoplasm of the perinuclear area. In contrast, no anti-inducible nitric oxide synthase immunostaining on human fetal amniotic membranes could be identified in patients without intra-amniotic infection. CONCLUSIONS: Our data provide important evidence that inducible nitric oxide synthase can be induced on human fetal amnion in intra-amniotic infection. These findings strongly support our hypothesis that human fetal amnion may be a possible site for the synthesis of nitric oxide after inducible nitric oxide synthase is induced in response to infectious products in intra-amniotic infection.

Prenatal diagnosis of otocephaly using two-dimensional and three-dimensional ultrasonography.

We report a case of the prenatal diagnosis of a very rare anomaly, namely isolated otocephaly, using two-dimensional and three-dimensional ultrasound at 24 weeks of gestation. Two-dimensional ultrasound revealed polyhydramnios, absence of a stomach shadow, hypotelorism and a proboscis-like mass. Three-dimensional ultrasound gave a precise demonstration of the striking craniofacial features of otocephaly including agnathia, synotia, microstomia and protuberance of the nose-mouth fusion. The use of three-dimensional ultrasound provided a whole view of the very rare lethal malformation in utero and contributed significantly to prenatal diagnosis.

Prenatal sonographic characteristics and Doppler blood flow study in a case of a large fetal mediastinal teratoma.

Although fetal mediastinal teratomas may result in respiratory distress in the neonatal period and lead to perinatal mortality, they are rarely diagnosed prenatally. Furthermore, their impact on fetal hemodynamics has never been described. We report a case of a large fetal mediastinal teratoma prenatally visualized at 38 weeks' gestation by both two- and three- dimensional ultrasound. We also describe the associated changes in the Doppler flow velocimetry, namely, a decrease in cardiac output, prolonged acceleration time in the pulmonary artery and an increase in the umbilical artery S/D ratio. The baby was well at the 5-month follow-up after an operation in the neonatal period. From our case, we believe that accurate prenatal diagnosis and assessment by two- and three-dimensional ultrasound as well as Doppler flow velocimetry may contribute to a better perinatal outcome.

Predicting birth weight by fetal upper-arm volume with use of three-dimensional ultrasonography.

OBJECTIVE: Our purpose was to determine the usefulness and accuracy of the three-dimensional ultrasonography assessed fetal upper-arm volume in predicting birth weight. STUDY DESIGN: From June 1996 to October 1996, we performed a prospective study of ultrasonography on 105 pregnant women without fetal structural anomaly or aneuploidy. Both the traditional two-dimensional ultrasonographic parameters and three-dimensional ultrasonography for fetal upper arm volume were measured within 48 hours of delivery. RESULTS: The upper arm volume correlated well with birth weight (r = 0.92, n = 105, p < 0.0001). With use of linear and polynomial regression, we obtained a best-fit new formula, Birth weight = 1088.60 + 36.024 x Upper-arm volume. The accuracy of this new formula is compared with that of two Chinese equations predicting fetal weight reported before and other formulas commonly used in the world as well. Our formula is more accurate in predicting birth weight than all the other formulas by traditional two-dimensional ultrasonography, either in error, percentage error, or absolute error. Another group by prospective validation further proved this finding. CONCLUSION: The upper-arm volume assessed by three-dimensional ultrasonography can accurately predict birth weight, and its accuracy is superior to the previous, formulas. Our study has at least validated the application of upper-arm volume by three-dimensional ultrasonography in estimating fetal weight. Further larger series are needed to confirm our findings.

PIP: The capability of fetal upper-arm volume assessed by 3-dimensional ultrasonography to predict birth weight was investigated in a prospective study involving 105 women who delivered live infants at National Cheng Kung University Hospital (Tainan, Taiwan) in 1996. Mean birth weight was 3312 grams (range, 1194-4425 g). Upper-arm volume was measured within 48 hours of delivery by both traditional 2-dimensional ultrasonography and the 3-dimensional technique. 3-dimensional ultrasonography has the advantage of being independent of fetal position and is not influenced by arm shape. Upper-arm volume was highly correlated with birth weight (p 0.0001). Through use of linear and polynomial regression, a best-fit new formula for predicting birth weight was derived: 1088.60 + 36.024 x upper-arm volume. Compared with 4 pre-existing formulas, the new formula (with upper-arm volume measured by 3-dimensional ultrasonography) had the lowest values in terms of error (0.0 g), absolute error (153.7 g), and percentage error (0.53%) in predicting birth weight. A large-scale prospective study is underway at this hospital to further validate the new formula.

Three-dimensional ultrasound-assessed fetal thigh volumetry in predicting birth weight.

OBJECTIVE: To compare the accuracy of three-dimensional ultrasound-assessed fetal thigh volumetry in predicting birth weight with that of other commonly used formulas composed of biparietal diameter (BPD), abdominal circumference (AC), and femur length (FL) by two-dimensional ultrasound. METHODS: We assessed the thigh volume of 100 fetuses using three-dimensional ultrasound. Meanwhile, their BPD, AC, and FL were measured by two-dimensional ultrasound. All infants were delivered within 48 hours after the ultrasound examinations. From polynomial regression analysis, we generated a best-fit formula for the thigh volume to predict birth weight. The accuracy of this thigh-volume formula was compared with those of three formulas commonly used in the United States. In addition, another group of 50 fetuses was measured for prospective validation. RESULTS: The high volume assessed by three-dimensional ultrasound was highly correlated with birth weight (r = 0.89, n = 100, P < .0001). The best-fit formula for thigh volume to predict birth weight was linear, and it was superior to the other commonly used two-dimensional formulas in predicting birth weight. The predicting error (0 g), percent error (0.7%), absolute error (176.1 g), and absolute percent error (5.8%) of the thigh-volume formula were all smaller than those of the other formulas (n = 100, all P < .05). In addition, the thigh-volume formula predicted birth weight more accurately than the other two-dimensional formulas in the prospective-validation group. The three-dimensional formula had smaller mean values of predicting error (38.6 g), percent error (1.5%), absolute error (160.0 g), and absolute percent error (5.1%) than the two-dimensional formulas (n = 50, all P < or = .001), as well as the smallest variances of the above errors (178.1 g, 5.6%, 84.3 g, and 2.9%, respectively). CONCLUSION: The three-dimensional ultrasound-assessed thigh volume has better accuracy in predicting birth weight than the commonly used formulas by two-dimensional ultrasound, and it may improve fetal weight prediction in clinical practice. However, a large-scale prospective validation study may be needed to confirm our conclusions.

Prenatal diagnosis of ectopia cordis at 10 weeks of gestation using two-dimensional and three-dimensional ultrasonography.

We report here the earliest prenatal diagnosis to date of a case of ectopia cordis using both two-dimensional and three-dimensional ultrasound at 10 weeks of gestation. Both two-dimensional and three-dimensional ultrasound clearly revealed a thoracoabdominal ectopia cordis and an omphalocele. Histopathological examination confirmed the prenatal ultrasonic findings. In addition to an ectopia cordis, a supraumbilical hepato-omphalocele, absence of a pericardium and an anterior diaphragmatic defect were seen, although there was a normal sternum. These pathological findings, suggested that our case was a variant of pentalogy of Cantrell.

Fetal heart volume assessment by three-dimensional ultrasound.

Heart volume may provide important information on the status of fetal hemodynamics. However, traditionally fetal heart volume has been assessed with the erroneous assumption that the fetal heart is spherical or elliptical. With the advent of three-dimensional ultrasound, accurate assessment of organ volume has become feasible. The objectives of this study were to compare the reproducibility of two-dimensional ultrasound and three-dimensional ultrasound in the assessment of heart volume, and to test whether heart volume assessed by the traditional method of two-dimensional ultrasound equates to that assessed by three-dimensional ultrasound. If it proved to be significantly different, we aimed to find a new constant which, if incorporated into the traditional formula used to determine heart volume, would enable us to achieve more accurate volumes with two-dimensional ultrasound. In total, 50 normal singleton fetuses ranging from 20 to 30 weeks' gestation were included in the study. Both the traditional two-dimensional and the new three-dimensional volume measurements were compared. The results showed that three-dimensional ultrasound has a better reproducibility than two-dimensional ultrasound in heart volume assessment and that heart volume assessed by the traditional formula of two-dimensional ultrasound is significantly larger than that measured by three-dimensional ultrasound (p < 0.001). We therefore propose that, if the traditional two-dimensional equation is to be used, the constant for heart volume could be modified to 0.4563 (SE = 0.0153, n = 50) to achieve more accurate results. With this new constant, the heart volume derived by two-dimensional ultrasound was not found to differ from that measured by three-dimensional ultrasound. From our series, we conclude that three-dimensional ultrasound is theoretically the best method for the assessment of heart volume. However, because of the limitations of three-dimensional ultrasound (i.e. it is not routinely available, it is more expensive and more time-consuming) two-dimensional ultrasound in practical terms should be the method of choice. Although we were able to improve the accuracy of the heart volume measurements using a new constant in the traditional two-dimensional formula, the new constant will not improve variability, which can only be reduced by three-dimensional ultrasound.