The frontal space measurement in euploid and aneuploid pregnancies at 11-13 weeks' gestation.

OBJECTIVE: The aim of this study is to evaluate whether the measurement of the frontal space (FS) improves first trimester combined aneuploidy screening. METHODS: We have presented a retrospective study including 2D images of the nuchal translucency measurement of 300 euploid and 133 trisomic fetuses that were seen at the prenatal department at the University of Tuebingen, Germany. For the FS measurement, a mandibulo-maxillary line (MML) was created by connecting the anterior edge of the mental protuberance and anterior edge of the maxilla. The MML was then extended upwards. A measurement was taken perpendicular from the MML to the skin line over the point of largest excursion of the fetal forehead. After transformation into z-scores based on the crown rump length, the FS distribution in fetuses with trisomy 21, 18, and 13 was compared with the euploid group by using a student's t-test. RESULTS: The mean FS in euploid fetuses was 1.25 mm. In fetuses with trisomy 21, 18, and 13, the mean FS measurements were 2.96, 3.22, and 2.03 mm. In euploid and trisomy 21, 18, and 13 pregnancies, FS measurements were above the 95th centile in 5.3%, 41.1%, 34.3%, and 12.5% of the cases. The mean z-scores were significantly higher in trisomy 21 and 18. CONCLUSION: First trimester FS measurement may improve first trimester combined screening.

Idiopathic polyhydramnios and postnatal abnormalities.

OBJECTIVE: To investigate the proportion and type of fetal anomalies that are associated with polyhydramnios and to examine whether in cases with idiopathic polyhydramnios during the course of pregnancy and fetal anomalies only diagnosed after birth, antenatal characteristics differ. METHODS: This was a retrospective study involving all pregnancies with polyhydramnios defined by a deepest pool of amniotic fluid ≥8 cm and a detailed ultrasound examination, a 75 g glucose tolerance test and a TORCH serology. RESULTS: Between 2004 and 2010, 272 pregnancies fulfilled the inclusion criteria. In 89 (32.7%) and 65 (23.9%) cases, there was a fetal anomaly or diabetes. In 118 (43.4%) pregnancies, polyhydramnios was classified as idiopathic. In 11 (9.3%) of the 118 fetuses, an anomaly was found after birth, mainly gastrointestinal atresia. In these cases, median deepest pool of amniotic fluid was 9.6 cm, and median estimated fetal weight was at the 69th centile, whereas in cases without anomalies diagnosed after birth, median deepest pool was 9.0 cm and median estimated fetal weight at the 90th centile (Mann-Whitney U test: deepest pool p = 0.116, and estimated fetal weight centile p = 0.377). There was also no difference in the maternal and gestational age distribution of these cases (Mann-Whitney U test: maternal age p = 0.293, and gestational age p = 0.499). CONCLUSION: In about 40% of pregnancies, polyhydramnios remains unexplained during the course of pregnancy. In 10% of these cases, an anomaly will only be found after birth. In this group, antenatal characteristics such as amniotic fluid volume, estimated fetal weight or gestational and maternal age at the time of diagnosis do not help to detect these anomalies before birth.

Sex-specific differences in the concentration of tubular parameters in the amniotic fluid of second trimester fetuses.

OBJECTIVE: Renal dysplasia and obstructive uropathy are more common in males and are associated with an increased tubular loss of electrolytes. We aimed to compare the midtrimester concentration of tubular parameters in the prenatal period between healthy male and female fetuses. METHODS: Amniotic fluid was collected at 16 weeks of gestation at the time of genetic amniocentesis. The concentration of sodium, chloride, potassium, calcium, phosphate, magnesium, α1-microglobulin, creatinine and urea was determined in the amniotic fluid of 92 male and 108 female fetuses. RESULTS: The concentration of sodium, chloride and calcium was not significantly higher in male than in female fetuses. In contrast, the concentration of potassium (p=0.01), phosphate (p=0.04), magnesium (p=0.04) and α1-microglobulin (p=0.04) was significantly increased in the amniotic fluid of male fetuses. The concentration of electrolytes correlated to the concentration of creatinine, urea and α1-microglobulin. CONCLUSION: The concentration of specific tubular parameters in the amniotic fluid was higher in male compared with female fetuses. Whether this might point to sex-specific differences in tubular function in second trimester fetuses or reflect glomerular filtration or other interfering factors remains speculative.

Intraoperator and interoperator repeatability of manual and semi-automated measurement of increased fetal nuchal translucency according to the operator's experience.

OBJECTIVE: To compare the intraoperator and interoperator repeatability of manual and semi-automated measurement of increased nuchal translucency (NT) in sonographers with different levels of experience. METHODS: One hundred NT images without measurements were selected from the digital database. Half had NT measurements between 2.5 and 3.5 mm, and half had NT measurements above 3.5 mm. Five operators (two experts, three general gynaecologist) measured fetal NT manually and automatically. Each operator was blinded to any pre-existing measurements. Each image was measured twice by each operator. Intraoperator repeatability was assessed by standard deviation of within sonographer repeated measurement. Interoperator repeatability was assessed as difference towards the gold standard, which was defined as the mean measurement of experts. RESULTS: The overall standard deviation of the difference between the first and the second manual measurements was 0.14 and 0.10 mm for moderate and severely increased NT. It was 0.10 and 0.08 mm with the semi-automated system. Mean difference between the manual measurement of nonexpert operators and the gold standard was -0.01 mm for moderately increased NT and 0.02 mm for severely increased NT. With the semi-automated measurement, mean bias was similar. CONCLUSION: The automated NT measurement leads to a further standardization of the NT assessment process. Especially inexperienced operators may benefit from this tool.

Prediction of birth weight discordance in twin pregnancies by second- and third- trimester ultrasound.

INTRODUCTION: Our purpose was to examine whether the prenatal prediction of a critical birth weight discordance (BWD) in twin pregnancies can be improved by using either different formulae for prenatal fetal weight estimation or single biometric measurements or by assessing the intertwin discordance in the second trimester rather than shortly before birth. MATERIAL AND METHODS: We conducted a retrospective study involving 196 twin pregnancies with an ultrasound examination between 18 and 25 weeks of gestation and one within 14 days prior to delivery. The accuracy was assessed by comparing the prenatal intertwin discordance (PID) with the BWD. PID was estimated by 5 common fetal weight estimation formulae and by single biometric measurements prior to delivery and in the second trimester. RESULTS: The fetal weight estimation accuracy was similar in mono- and dichorionic pregnancies and the smaller and the larger twin. PID was most accurate with the fetal weight estimation formulae prior to delivery. The second-trimester measurements resulted in an underestimation of the BWD. Detection and false-positive rates for a BWD ≥20% were about 65 and 15%. DISCUSSION: About two thirds of the twin pregnancies with a relevant BWD can be detected prior to delivery. An optimal detection rate requires fetal weight estimation close to delivery.