The development of the fetal thymus: an in utero sonographic evaluation

OBJECTIVES: To establish a nomogram for fetal thymus size during gestation. METHODS: The study is a prospective, cross sectional evaluation of 403 male and female fetuses between 14 and 38 weeks of normal singleton pregnancies. Measurements of fetal thymus size were performed by high resolution transvaginal ultrasonography between 14 and 17 weeks' gestation, and by transabdominal ultrasonography after 18 weeks' gestation. RESULTS: Adequate thymus size measurements were obtained in all 403 fetuses. Thymus size as a function of gestational age was expressed by the regression equation: (square root) thymus size (mm)= -39.39+4.41 x gestational age (weeks). The correlation coefficient, r=0.965, was found to be highly statistically significant (p<0.0001). The normal mean and the 90% prediction limits were defined. CONCLUSION: The present data offer the normal range of fetal thymus size from early stages of gestation that may allow intrauterine assessment of its development. It may be helpful in the prenatal diagnosis of thymic pathologies.     

The fetal mandible: an in utero sonographic evaluation between 11 and 31 weeks' gestation

OBJECTIVE: To construct a growth chart of the mandible throughout gestation. METHODS: A prospective cross-sectional study of normal singleton pregnancies was conducted. Measurements of the fetal mandibular transverse and antero-posterior diameters were performed with high-resolution transvaginal and transabdominal ultrasonography in 490 pregnant women with singleton low-risk pregnancies between 11 and 31 weeks' gestation. RESULTS: The mandibular transverse and antero-posterior diameters were recorded by week of gestation and the ratio was calculated: mandibular ratio (MR) = 1.7759 - 0.01047 x gestational week. There was a negative linear correlation (-1.047%) for each incoming week of gestation. Normal values (+/-1SD and 2SD) were established. CONCLUSION: The present data provides a normal range of fetal mandibular diameters during normal pregnancies and introduces a new parameter, the mandibular ratio, for the intrauterine assessment of the fetal mandibular development.     

Four chamber view plus three-vessel and trachea view for a complete evaluation of the fetal heart during the second trimester

OBJECTIVE: To test the efficacy of a recently introduced ultrasonic scanning plane (three vessel and trachea view -3VTV- plus color flow mapping -3VTVC) on a low-risk population for detection of congenital heart disease (CHD). PATIENTS AND SETTING: Antenatal clinic dealing with local low-risk population. All antenatal patients having a second trimester scan in a 1 year period. All patients had a 3VT plus 3VTC views added to routine four chamber view. Postnatal examinations were performed according to standard hospital protocol. RESULTS: 2847 patients were examined. The plane was achievable in all 23 fetuses with CHD detected, three false negative (aortic coarctation) and two false positive. Sensitivity of the examination was 88.5%, as high as more sophisticated and difficult targeted cardiac scanning. The extra time necessary to perform the test was minimal. CONCLUSION: 3VTV and 3VTCV were satisfactory used as imaging planes in a busy antenatal clinic in a low-risk population. They could be easily added to the four chamber view as routine screening for CHD and increase the detection rate to 90%.     

Three-vessel view of the fetal heart: in utero development of the great vessels

OBJECTIVES: The purpose of our study is to provide reference values for the great vessels obtained from images of the three-vessel view of the fetal heart, with an emphasis on the size discrepancy of the great vessels. METHODS: From February 2003 to May 2003, the main pulmonary artery (MPA), ascending aorta (AA), and SVC were measured in well-dated, nonanomalous fetuses scanned at 14-38 weeks of gestation. RESULTS: The size of each great vessel had a significant positive relationship with advance in gestation (P < 0.001); MPA (mm) = -2.76 + 0.34 x GA, ascending aorta (AA) (mm) = -1.73 + 0.26 x GA - 1.18E - 05 x GA(3), and SVC (mm) = 0.33 + 0.01 x GA(2) - 4.12E - 05 x GA(3). The AA/MPA ratio was significantly decreased with advance in gestation, while the SVC/AA ratio was significantly increased; AA/MPA ratio = -1.24 - 0.03 x GA + 3.88E - 04 x GA(2); P < 0.001, SVC/AA ratio = 0.63 - 5.43E - 03 x GA + 1.96E - 04 x GA(2); P < 0.001. CONCLUSION: On the three-vessel view of the fetal heart, the interpretation of the size discrepancy of the great vessels needs to be adjusted according to fetal growth.     

The early development of the fetal kidney-an in utero sonographic evaluation between 13 and 22 weeks' gestation

OBJECTIVES: To establish a nomogram for early fetal kidney development during early gestation. METHODS: The study is a prospective, cross-sectional evaluation of 275 male and female fetuses between 13 and 22 weeks in normal singleton pregnancies. Measurements of fetal kidney length were performed by high resolution transvaginal ultrasonography between 14 and 17 weeks' gestation, and by transabdominal ultrasonography beyond 18 weeks' gestation. RESULTS: Adequate kidney length measurements were obtained in all 275 normal fetuses as well as in six fetuses with urinary tract anomalies. Kidney length as a function of gestational age was expressed by the regression equation: (square root) kidney length (mm) = -11.66 + 1.52 x gestational age (weeks). The correlation coefficient, r = 0.983 was found to be highly statistically significant (p < 0.0001). The normal mean and the 90% prediction limits were defined. Four cases with single kidney and two cases with posterior urethral valve had kidney length above the 95% upper limit. CONCLUSION: The present data offer a normal range of fetal kidney length from early stages of gestation that may allow intrauterine assessment of its development. It may also be helpful in the early prenatal diagnosis of renal abnormalities.     

Pathologic correlation of sonographic echogenic foci in the fetal heart

The goal of the current paper is to present, on the basis of six investigated fetal hearts, the pathological substrate of prenatally, sonographically diagnosed echogenic intramyocardial foci. The right ventricle, left ventricle, interventricular septum and papillary muscles of both ventricles of six hearts of the fetuses of high-risk pregnant women showing sonographically diagnosed intramyocardial echogenic foci were investigated. At termination of pregnancy all the women were between the 20th and the 24th week of gestation. Of the six cases, four were induced abortions and two were spontaneous abortions. For the control group we investigated the hearts of two fetuses without heart defects at the 22nd and 23rd week of gestation which had proven extracardial anomalies and a normal karyotype. Both cases were induced abortions which prenatally showed no echogenic cardiac foci. In all eight cases a prenatal karyotyping was performed. In the six cases with echogenic foci the location and number of the foci were determined both prenatally and by means of histologic sections; the size of the foci was measured as well. Histological staining was with routine haematoxylin-eosin; Masson-Goldner was used for connective tissue; Kossa for calcification; and Berlin blue for haemosiderin. Histologically, in all six cases, intramyocardial calcifications surrounded by fibrotic tissue were in: papillary muscle of the left ventricle in six cases; papillary muscle of the right ventricle in one case; and the subendocardial myocardium of the right ventricle in one case. Four cases had one, one case had two and one case had three calcified foci. Three cases had cardiac and two cases had extracardiac anomalies. Four cases had chromosome anomalies: two were trisomy 21, one trisomy 13 and one triploidy. The remaining two cases had a normal karyotype. No case showed pathological changes of the chordae tendinae, myocardial cell necrosis or inflammation. There were no patho-morphological differences between the intramyocardial calcifications of the papillary muscles in cases with chromosome anomalies and with normal karyotype. As the patho-morphological correlate of the sonographically diagnosed echogenic foci, histological investigation on all six fetal hearts showed coarse intramyocardial calcifications surrounded by myocardial fibrosis. Conventional histological methods gave no indication of the cause of the intramyocardial calcifications.     

In utero evaluation of fetal cardiac structure: a preliminary report

Fetal echocardiography as a tool for the prenatal diagnosis of cardiac structural abnormalities was utilized in 27 consecutive patients who were referred for evaluation. Four abnormalities were recognized prenatally and confirmed postnatally. A fifth was identified postnatally. The sensitivity and specificity of this diagnostic test were 80% and 100%, respectively. The utilization of this tool in a tertiary care setting by an adequately trained team has proved to be helpful and is recommended.     

Detailed sonographic mappings of normal fetal brain anatomy in utero at six levels in the axial plain

An investigation of real time sonographic features of the normal fetal brain at six levels in the axial plain was undertaken between the 26th and 40th week of gestation. Structures such as cerebrum, midbrain, basal ganglia, ventricular system, vascular system, and cerebellum can be routinely identified if ultrasound is performed systematically. The sonographic appearance of detailed brain anatomy at each level is presented with the hope that it may provide a systematic form of scanning the fetal brain. With such standardization of technique many erroneous interpretations may possibly be avoided.     

Transvaginal sonographic evaluation of the fetal central nervous system.

This article describes the sonographic appearance of the central nervous system (CNS) from about 6 weeks to term. Highlights of CNS development and the chronologic appearance of sonographically detected new structures throughout gestation are presented.     

Axial growth of the fetal eye and evaluation of the hyaloid artery: in utero ultrasonographic study

The aims of this prospective, cross-sectional study were to report axial ocular growth during human gestation, to determine the presence of the hyaloid artery (HA) and its blood flow, and to provide a timetable for HA regression. The study group comprised 231 low-risk singleton pregnancies between 14 and 38 weeks' gestation. Ocular axial length (OAL), anterior chamber depth (ACD) and posterior chamber depth (PCD) were measured using high-resolution ultrasound. The growth of these eye segments in correlation with gestational age (GA) was established. The presence of the HA and its regression were determined. By using power Doppler, ultrasound blood flow within the HA was estimated. HA regression is a gradual process that is not evident before 18 weeks' gestation. In all fetuses beyond 29 weeks' gestation, no HA could be detected (P<0.001). Blood flow within the HA was documented only until the 16th week of gestation. The correlation coefficients, r=0.924, 0.784 and 0.929, for OAL, ACD and PCD, respectively, were found to be highly statistically significant (P<0.0001). The present data offer normative measurements of the fetal axial eye lengths, timetable for HA regression and flow cessation.     

客观评价胎心监护应用的局限性

胎心监护是目前产程中监护胎儿的主要手段，但其广泛应用并未降低脑瘫发生率及新生儿死亡率，反而增加了剖宫产及阴道手术产率。近年来提出的胎心监护三级评价系统对客观评价胎心监护也存在一定的局限性。     

Congenital heart disease and fetal thoracoabdominal anomalies: associations in utero and the importance of cytogenetic analysis.

We examined the frequency with which congenital heart disease (CHD) and cytogenetic abnormalities were found associated with omphalocele, gastroschisis, duodenal atresia and posterior diaphragmatic hernias. We performed fetal echocardiograms on 80 patients with these diagnoses and found congenital heart disease in 13 of 37 with omphalocele (35%), 2 of 17 with gastroschisis (12%), 4 of 15 with duodenal atresia (27%), and 2 of 11 with posterior diaphragmatic hernia (18%). Karyotypes were obtained in 74 and were abnormal in 24 (32%). Although most fetuses with these extracardiac malformations and abnormal karyotypes had associated CHD, many did not. Normal karyotypes were found in 69% of fetuses with CHD and omphalocele, and 50% of fetuses with CHD and duodenal atresia. We conclude that CHD may be present in fetuses with extracardiac malformations whether or not the karyotype is normal and that the prenatal evaluation of fetuses with these lesions should include both karyotype and fetal echocardiography. Although karyotypes play an important role in prenatal diagnosis, they are not predictive of normal cardiac structure when normal in the abnormalities studied. Even when the karyotype is normal in the presence of these abnormalities, fetal echocardiography is indicated.     

In utero ischemic injury: sonographic diagnosis and medicolegal implications

The antenatal diagnosis of fetal neurologic injury has profound medical and legal implications. We report a case of antenatally diagnosed intracranial lesions including parenchymal hemorrhage in an otherwise physically normal infant. Computerized tomography in the newborn period demonstrated diffused ischemic damage with secondary cystic changes in addition to intracranial hemorrhage.     

Ultrasonic evaluation of the fetal human heart

The fetal echocardiogram has demonstrated its utility for visualizing the fetal human heart during the second and third trimesters of pregnancy. The potential utility of the technique for establishing accurate anatomic diagnoses of major congenital cardiac malformations has been established. These data have been utilized to counsel prospective parents and formulate management plans for the remainder of pregnancy and the intrapartum and immediate postpartum periods. Diagnoses have been established as early as the 16th to 18th week of gestation, raising in some cases the moral and ethical question of termination of pregnancy.