Increased latency of absent end-diastolic flow in the umbilical artery of monochorionic twin fetuses.

OBJECTIVE: To determine if absent end-diastolic flow (AEDF) in the umbilical artery (UA) has a longer latency in monochorionic (MC) twin fetuses compared to singleton or dichorionic twin (DC) fetuses. METHODS: One hundred and eight pregnancies with a fetus with AEDF were reviewed: 47 MC and 17 DC twin pregnancies and 44 singletons. Because twin-twin transfusion syndrome (TTTS) is a potential confounder when determining latency, subgroup analysis was also performed on the 21 MC affected pregnancies without TTTS. Latency of AEDF (in days) was defined as the difference between the gestational age at diagnosis of AEDF and gestational age at delivery or intrauterine death. RESULTS: Latency was similar in MC twins (median, 39 days) and DC twins (30 days) but longer compared to singletons (11 days; P = 0.0001). After excluding pregnancies with TTTS, latency in non-TTTS MC twins (54 days) was longer than in both singletons and DC twins. This was due to an earlier gestational age at AEDF in non-TTTS MC twins of 20 weeks compared to 27 weeks in both singleton and DC twins because median gestational age at delivery was similar in MC twins, DC twins and singletons. CONCLUSIONS: The latency period of UA AEDF is longer in MC twins than in singletons. Our data suggest that in MC twin fetuses without TTTS, AEDF begins earlier and lasts about twice as long as in DC twin fetuses, which is consistent with placental insufficiency not being the sole factor mediating abnormal UA waveforms in MC placentation. This observation is important in counseling and managing twin pregnancies discordant for AEDF.     

Reference values for ductus venosus Doppler flow measurements at 10-14 weeks of gestation.

OBJECTIVES: To calculate reference ranges for ductus venosus Doppler measurements obtained transabdominally at 10-14 weeks of gestation. DESIGN: Two hundred and one normal fetuses with a crown-rump length (CRL) ranging from 38 to 88 mm were examined in a cross-sectional study. The pulsatility index for veins (PIV), peak velocity during ventricular systole (S-wave), lowest forward velocity during atrial contraction (A-wave) and time-averaged maximum velocity (TAMXV) were recorded from the ductus venosus. Flow velocity waveforms were also classified as normal or abnormal according to the presence (normal) or absence or reversal (abnormal) of frequencies during atrial contraction. RESULTS: Three of 201 fetuses showed an abnormal flow pattern (1.5%; 95% exact confidence interval, 0.3-4.3%). In the 198 fetuses with a normal flow pattern, the mean PIV ranged from 1.07 at a CRL of 38 mm to 1.00 at a CRL of 88 mm (r = -0.093; P = 0.19). A significant increase in mean blood flow velocity with increasing CRL was noted for the S-wave (27.0 cm/s to 33.6 cm/s; r = 0.17; P = 0.02), the A-wave (5.9 cm/s to 7.8 cm/s; r = 0.14; P = 0.04) and the TAMXV (19.4 cm/s to 25.3 cm/s; r = 0.19; P < 0.01). Crown-rump length-specific reference ranges for each parameter were calculated using the method of scaled absolute residuals. CONCLUSIONS: Abnormal ductus venosus flow patterns could be observed in normal fetuses, even if they ocurred with a low prevalence. Reference values for Doppler measurements were established in fetuses with normal patterns of flow.     

The clinical significance of absent or reverse end-diastolic flow in the fetal aorta and umbilical artery.

The clinical utility of Doppler blood flow investigations of the fetal and fetoplacental vessels is still under debate as far as timing of the delivery is concerned. However, in cases of absent or reverse end-diastolic flow, fetal compromise is usually very severe. As a consequence, we have investigated the possibility of using this information as a guide to obstetrical management. Altogether, 32 fetuses with absent or reverse end-diastolic flow in the fetal descending aorta and/or umbilical artery were studied.Reverse flow was observed in 11 cases and absence of end-diastolic flow in 21 cases. The two groups are considered separately. No significant difference was found in the mean gestational age at delivery. However, a highly significant difference was found in the mean birth weight and perinatal mortality rate.All the cases of perinatal mortality were encountered in the group presenting with reverse flow (mortality rate, 63.6%). All the live fetuses were delivered by Cesarean section and no neonatal mortality was observed in this group. Two cases of handicap were observed, one in each group. In our experience, reverse flow indicates the necessity for immediate delivery if no other clinical contraindications are present. Absence of end-diastolic flow can be observed for longer periods without adverse outcome. Absence of end-diastolic flow always precedes the appearance of fetal distress. Therefore, we believe that, after exclusion of conditions such as fetal abnormalities or extreme prematurity, a planned delivery should be considered.     

Vesicocentesis at 10-14 weeks of gestation for treatment of fetal megacystis.

This report of four cases shows that fetal vesicocentesis at 10-14 weeks of gestation is a useful treatment option in some cases with megacystis. Although megacystis at this gestation has been reported, there are few studies examining the role of early vesicocentesis. The natural history of the condition and outcome following treatment is reviewed with reference to the literature.     

Reference values for fetal limb biometry at 10-14 weeks of gestation.

OBJECTIVES: To calculate reference ranges for fetal limb measurements obtained by transabdominal ultrasound at 10-14 weeks of gestation. METHODS: Six hundred and six normal fetuses were examined transabdominally in a cross-sectional study by a single observer. The crown-rump length of the fetuses ranged from 31 to 78 mm. Measurement of the length of the humerus, ulna, femur, tibia and foot was attempted from the longest section of each structure. To assess intraobserver repeatability, three sets of repeated measurements were obtained in 26 fetuses. RESULTS: An appropriate ultrasound measurement was obtained in a percentage of cases ranging from 93.2% to 97.9%. A significant correlation was found between crown-rump length measurements and humerus length (r = 0.74, P < 0.001), ulna length (r = 0.70, P < 0.001), femur length (r = 0.77, P < 0.001), tibia length (r = 0.69, P < 0.001) and foot length (r = 0.58, P < 0.001). Crown-rump length-specific reference ranges for each measurement were calculated with the method of scaled absolute residuals. The study of intraobserver variability showed coefficients of variation ranging from 7.9 to 10.0% and intraclass correlation coefficients ranging from 0.89 to 0.94. CONCLUSIONS: Fetal limb size is strongly correlated with crown-rump length. Despite a significant biological variability of the measurements, the availability of reference ranges could be of help in the early diagnosis of fetal skeletal dysplasias.     

Uterine artery Doppler at 11-14 weeks of gestation in chromosomally abnormal fetuses.

OBJECTIVE: To determine whether the major chromosomal abnormalities are associated with impaired placentation in the first trimester of pregnancy. METHODS: This was a prospective study of 692 singleton pregnancies undergoing fetal karyotyping at 11-14 weeks of gestation. Uterine artery Doppler was carried out and the mean pulsatility index was calculated just before chorionic villus sampling. RESULTS: The fetal karyotype was normal in 613 pregnancies and abnormal in 79, including 39 cases of trisomy 21, 11 of trisomy 18, 11 of trisomy 13, eight of Turner syndrome and 10 with other defects. There were no significant differences in the median value of uterine artery mean PI between any of the individual groups. Although in the combined group of trisomy 18, trisomy 13 and Turner syndrome fetuses, the median pulsatility index (1.60) was significantly higher than in the chromosomally normal group (median pulsatility index, 1.51; P = 0.021), in the majority of abnormal fetuses (24 of 30) mean pulsatility index was below the 95th centile of the normal group (mean pulsatility index, 2.34). There was no significant association between uterine artery mean pulsatility index and fetal nuchal translucency thickness or fetal growth deficit. CONCLUSIONS: The high intrauterine lethality and fetal growth restriction associated with the major chromosomal abnormalities are unlikely to be the consequence of impaired placentation in the first trimester of pregnancy.     

Reproducibility of ductus venosus Doppler flow measurements at 11-14 weeks of gestation.

OBJECTIVES: To assess the intra- and interobserver repeatabilities of fetal ductus venosus Doppler measurements at 11-14 weeks of gestation. DESIGN: Flow velocity waveforms were recorded transabdominally. Intraobserver repeatability was studied in 22 fetuses in whom four repeated measurements were performed by the same observer. Interobserver repeatability was assessed in 54 fetuses in each of whom two observers performed two repeated measurements. The pulsatility index for veins (PIV), peak velocity during ventricular systole (S wave), peak velocity during atrial contraction (A wave) and time-averaged maximum velocity (TAMV) were recorded. Reproducibility of the Doppler measurements was analyzed by calculating repeatability coefficient, coefficient of variation (CV), intraclass correlation coefficient (ICC), mean differences and their limits of agreement. Cohen's k-coefficient was used for categorical data. RESULTS: Intraobserver repeatability was good with a CV of 10%, 13%, 22% and 13% and an ICC of 0.85, 0.94, 0.94 and 0.95, respectively, for PIV, S wave, A wave and TAMV. Interobserver repeatability was also good, and no bias between the observers was detected. A CV of 8.8%, 14%, 27% and 15% and an ICC of 0.86, 0.84, 0.87 and 0.84, respectively, for PIV, S wave, A wave and TAMV were obtained. There was 100% agreement for the detection of normal/abnormal blood flow. CONCLUSIONS: Intra- and interobserver repeatability of all parameters was acceptable, allowing for the detection of moderate to large changes in Doppler measurements.     

Fetal transabdominal biometry at 11-14 weeks of gestation.

OBJECTIVE: To establish comprehensive transabdominal ultrasonographic reference ranges for viable normal singleton human fetuses at 11-14 weeks' gestation. METHODS: Single transabdominal ultrasound measurements were taken once per pregnancy at a gestational age of between 11+0 and 14+0 weeks (crown-rump length, 45-84 mm), in viable singleton fetuses with nuchal translucency < or = 3 mm and without detectable structural anomalies, using four standard planes: (i) biparietal diameter (BPD) and fronto-occipital diameter (FOD) resulting in head circumference (HC), anterior horn (Va), posterior horn (Vp), and hemisphere (HEM); (ii) transcerebellar diameter (TCD) and cisterna magna (CM); (iii) abdominal anteroposterior (AAP) and abdominal transverse diameter (ATD) resulting in abdominal circumference (AC); and (iv) femur length (FL). The respective ratios Va/HEM, Vp/HEM, HC/AC, BPD/FL, BPD/FOD, FL/CRL, FL/BPD and FL/AC and the estimated weight were derived. Reference ranges were constructed and the mean and 5th and 95th centiles were plotted against gestation. RESULTS: There was a general increase in biometric parameters with gestation. The ratios for the ventricles vs. hemisphere and BPD/FL ratio decreased while the BPD/FOD and HC/AC ratios remained constant. Analysis of the reference range for BPD/FL was performed in both 167 and 664 fetuses and the results showed almost the identical type of equation, indicating a high degree of accuracy for the growth charts. CONCLUSIONS: We have established comprehensive reference ranges for first-trimester fetal biometry by transabdominal sonography. These charts may have a role in the diagnosis of early onset symmetrical or asymmetrical growth restriction and in the interpretation of measurements in chromosomally abnormal fetuses, and they may help in the detection of skeletal dysplasias or acrania/anencephaly.     

Jugular vein and carotid artery blood flow in fetuses with increased nuchal translucency at 10-14 weeks' gestation.

OBJECTIVE: The aim of our study was to obtain measurements of the jugular vein and carotid artery pulsatility index (PI) at 10-14 weeks' gestation in chromosomally normal and abnormal fetuses with or without increased nuchal translucency (NT), in order to explore whether a relationship exists between increased NT and overperfusion of the head. METHODS: This was a prospective study involving 179 pregnant women at high risk for chromosomal anomalies or structural malformations who were referred for chorionic villus sampling or first-trimester ultrasound examination at 10-14 weeks' gestation, respectively. Color and pulsed Doppler ultrasound were used to obtain jugular vein and carotid artery blood flow velocity waveforms at the level of the mid-neck. All Doppler measurements were obtained by a single investigator. The PIs of the jugular vein and carotid artery were correlated with NT measurement and fetal karyotype. RESULTS: Doppler measurements of the jugular vein and carotid artery were successfully obtained in 90.5% of the fetuses. The fetal karyotype was abnormal in 13 cases, including three trisomies 21 and two trisomies 18, and normal in 149 cases. In the group with normal karyotype the NT was above the 95th percentile in 22 cases (15%). No correlation between the jugular vein or the carotid artery PI and the thickness of the NT was found. There were no significant differences when comparing the values of the jugular vein and carotid artery PI between the group with normal NT and the group with increased NT, or between the group with a normal karyotype and an abnormal karyotype. CONCLUSION: Our results suggest that NT is not related to blood flow impedance in either the carotid artery or the jugular vein. Overperfusion and venous congestion of the head do not appear to be a causative pathophysiological mechanism involved in increased NT.     

First-trimester reversed end-diastolic flow in the umbilical artery is not always an ominous sign.

We report five cases of first-trimester reversed end-diastolic flow in the umbilical artery. Diagnoses were performed between 8 and 12 gestational weeks. All but one case appeared as a transient early finding. Second-trimester fetal demise occurred in two cases. One case delivered at 32 weeks with severe growth restriction but recovered well. The other two cases had a good pregnancy outcome. Our experience suggests that this early Doppler finding is not always an ominous sign.     

Single umbilical artery at 11-14 weeks' gestation: relation to chromosomal defects.

OBJECTIVE: To determine the possible association between single umbilical artery (SUA) at 11-14 weeks of gestation and the incidence of chromosomal abnormalities. METHODS: Color flow imaging of the fetal pelvis was used to determine the number of umbilical arteries in 717 fetuses immediately before chorionic villus sampling for karyotyping at 11-14 weeks' gestation. RESULTS: Single umbilical artery (SUA) was diagnosed in 21/634 (3.3%) chromosomally normal fetuses, in 5/44 (11.4%) with trisomy 21, 14/18 (77.8%) with trisomy 18 and 2/21 (9.5%) with other chromosomal defects. In the chromosomally normal group there was no significant difference in median fetal crown-rump length or nuchal translucency (NT) between those with a single and those with two umbilical arteries. In the 42 fetuses with SUA the expected number of cases of trisomy 21, estimated on the basis of maternal age, gestational age and fetal NT, was 4.7, which was not significantly different from the observed 5. The corresponding numbers for trisomy 18 were 2.0 for expected and 14 for observed (Fisher's exact test P = 0.0016). CONCLUSION: A SUA at 11-14 weeks' gestation has a high association with trisomy 18 and other chromosomal defects.     

Normal cardiac flow velocities at 14-16 weeks of gestation measured by transvaginal ultrasound.

OBJECTIVE: Doppler ultrasound has been used to study the flow velocities through the valves and arteries of the fetal heart. Using transvaginal sonography, we sought to determine normal values for flow velocities through the fetal heart valves at 14-16 weeks of gestation. METHODS: Eighty-seven normal fetuses were examined. The flow velocity waveforms were visualized using Doppler ultrasound with the sample volume calipers placed just distally to the four fetal valves. Peak E- and A-wave velocities were recorded for the tricuspid and mitral valves and peak systolic flow velocities were recorded for the ascending aorta and pulmonary arteries. Linear regression for comparison of flow velocities with gestational age was performed. RESULTS: There was no significant correlation between any of the velocities and gestational age. CONCLUSIONS: Flow velocities through the fetal cardiac valves remain unchanged at 14-16 weeks of gestation as measured by transvaginal Doppler sonography.     

正常孕10～19周胎儿静脉导管彩色血流频谱的初步探讨

目的探讨经腹彩色多普勒超声获取10～19周胎儿静脉导管血流频谱的正确采样及检测方法并建立其阻力指数（RI）、搏动指数（PI）、心室收缩期峰值流速与心房收缩期最低流速比值（S／A）的正常参考值范围；探讨生理性零或反向房收缩（RA）波在正常10～14周胎儿静脉导管中的发生率。方法随机选取111例孕10～19周的正常单胎孕妇，在不校正测量角度的情况下进行胎儿静脉导管血流频谱检测，对血流参数RI、PI和S／A值与孕周进行相关和回归分析。结果静脉导管的血流参数值随着胎龄的增加而减低，其95％的参考值范围分别为R10．34～0．90、P10．21～1．32和S／A1．23～6．65；10～14周胎龄段的50例胎儿静脉导管血流频谱中未见零或RA波。结论应用经腹彩色多普勒超声对10～19周胎儿静脉导管进行血流动力学评价方法简单，结果准确，容易掌握；静脉导管血流参数RI、PI和S／A值随着胎龄的增加而减低，其参考值范围可进一步应用于对胎儿染色体畸形和严重心脏畸形的研究；10～14周正常胎儿静脉导管内是否存在生理性零或RA波有待于进一步研究。     

Prevalence of neurological damage in monochorionic twins with selective intrauterine growth restriction and intermittent absent or reversed end-diastolic umbilical artery flow.

OBJECTIVE: To assess the incidence of parenchymal lesions on early and late neonatal brain scans and its association with the presence or absence of intermittent absent or reversed end-diastolic umbilical artery flow velocity (A/REDV) in monochorionic twins complicated by selective intrauterine growth restriction (IUGR), as compared to dichorionic twins and monochorionic twins without selective IUGR. METHODS: This was a prospective cohort study involving 42 monochorionic twins diagnosed with selective IUGR and managed expectantly. The presence or absence of intermittent A/REDV was recorded in all cases. This study group was compared to dichorionic twins (n = 29) and monochorionic twins without selective IUGR (n = 32) delivered at 26-34 weeks during the study period. All infants underwent an early neonatal brain scan (at or before the fourth day of postnatal life) and at least one follow-up scan during the first 28 days of postnatal life. Perinatal outcome and the incidence of neurological damage were compared between the study groups. RESULTS: The incidence of intrauterine fetal death (IUD) and periventricular leukomalacia was significantly increased in monochorionic twins complicated with selective IUGR, as compared with the other study groups. Intermittent A/REDV was observed in 22/42 (52.4%) twin pairs, and was always present in the growth-restricted twin. The incidence of IUD (overall 9/44 (20.5%) vs. 0/40, P < 0.001; smaller twin 6/22 (27.3%) vs. 0/20, P < 0.05) and parenchymal brain damage (overall 7/35 (20.0%) vs. 2/40 (5.0%), P = 0.07; larger twin 7/19 (36.8%) vs. 1/20 (5.0%), P < 0.05) was significantly higher in pregnancies with intermittent A/REDV than in those without intermittent A/REDV. Brain damage usually occurred in the larger twin, irrespective of whether the smaller twin was liveborn or not. CONCLUSIONS: The presence of intermittent A/REDV in monochorionic twins with selective IUGR identifies a subgroup with an elevated risk of intrauterine demise of the smaller twin and neurological damage in the larger twin; this latter finding is not restricted to cases with IUD of the cotwin.     

Uterine artery Doppler at 11-14 weeks of gestation to screen for hypertensive disorders and associated complications in an unselected population.

OBJECTIVES: To establish reference values for the first-trimester uterine artery (UtA) pulsatility index (PI) and to investigate the role of UtA Doppler in the early prediction of hypertensive disorders and their associated complications in an unselected Mediterranean population. METHODS: A prospective study including 1091 consecutive singleton pregnancies undergoing routine early ultrasound screening at 11-14 weeks of gestation was performed. The left and right UtA were examined by color and pulsed Doppler transvaginally. The mean PI and the presence of bilateral protodiastolic notching were cross-sectionally recorded. Reference ranges were calculated and the pregnancies were followed for occurrence of pre-eclampsia, gestational hypertension, intrauterine growth restriction, placental abruption and stillbirth. The sensitivity and predictive values of a mean UtA-PI>95th percentile and the presence of bilateral notching in the prediction of these pregnancy complications were calculated. RESULTS: A total of 999 women were finally included. Both the mean UtA-PI and the prevalence of bilateral notches showed a significant linear decrease between 11 and 14 weeks' gestation. Sixty-seven (6.7%) pregnancies developed at least one of the formerly described complications, including 22 (2.2%) cases of pre-eclampsia and 37 (3.7%) cases with intrauterine growth restriction. Compared with women with a normal outcome, complicated pregnancies showed a significantly higher mean PI (2.04 vs. 1.75; P<0.05, t-test) and a higher prevalence of bilateral notching (58% vs. 41%; P<0.05, Chi-square test). Using the 95th percentile in mean UtA-PI as a cut-off, 23.9% (95% CI, 13.7-34.1) of complicated pregnancies and 30.8% (95% CI, 5.68-55.85) of severe cases were identified. CONCLUSIONS: Our results suggest that pregnancies with an increased risk of developing hypertensive disorders and related complications already have an abnormally increased UtA-PI in early pregnancy. However, the use of a single uterine Doppler measurement for screening purposes in unselected early pregnancy populations has limited clinical value. The use of UtA-PI combined with other screening tests needs to be determined by further investigation.     

Relationship between nuchal translucency at 11-14 weeks and nuchal fold at 20-24 weeks of gestation.

OBJECTIVES: To examine the relationship between the measurement of nuchal translucency in the first trimester and nuchal fold in the second trimester in normal pregnancy. METHODS: This was a prospective study of 592 singleton pregnancies. Fetal nuchal translucency was measured at 11-14 weeks of gestation and nuchal fold at 20-24 weeks of gestation. Linear regression models were used to assess the relationship between nuchal translucency and nuchal fold after adjustment for gestational age. RESULTS: There was no significant association between nuchal translucency and nuchal fold thickness. CONCLUSION: It is possible that measurement of nuchal translucency and nuchal fold may provide an independent contribution in screening for trisomy 21.     

Hypertrophic cardiomyopathy-like changes in monochorionic twin pregnancies with selective intrauterine growth restriction and intermittent absent/reversed end-diastolic flow in the umbilical artery.

OBJECTIVE: To evaluate the prevalence of hypertrophic cardiomyopathy-like (HCL) changes in monochorionic twins with selective intrauterine growth restriction (sIUGR) and intermittent absent/reversed end-diastolic flow (iAREDF), also defined as Type III sIUGR, and the clinical relevance of this condition. METHODS: A total of 80 pregnancies with sIUGR were studied, 40 with, and 40 without iAREDF. HCL changes were defined as an increased thickness of either left or right ventricular wall (mean > 2 SD) estimated with M-mode ultrasonography. Data were plotted on normal reference values constructed from 75 uncomplicated monochorionic twin pregnancies (150 fetuses) at 22-34 weeks' gestation. Perinatal outcomes in pregnancies with and without HCL changes were compared. RESULTS: In the group with iAREDF, 8/40 of the larger twins (20%) had HCL changes (five bilaterally, two in the right, and one in the left ventricle) as compared with 1/40 (2.5%) in fetuses without iAREDF (P = 0.03). No differences were observed in the smaller twin (1/40 in both groups). HCL changes were not associated with a significant increment in perinatal mortality as only one large fetus from the group with iAREDF died in utero. In the remaining 10 cases, no differences in the intertwin weight discordance, placental surface discordance, or rate of neonatal neurological damage were observed. However, all 10 presented mildly abnormal neonatal cardiac findings that resolved over time with no apparent short-term impact on cardiac function. CONCLUSIONS: HCL changes in the larger twin should be regarded as part of the spectrum of findings in Type III monochorionic-sIUGR (presenting iAREDF). This finding does not seem to be associated with an increased rate of short-term neurological or cardiac complications.     

Megacystis at 10-14 weeks of gestation: chromosomal defects and outcome according to bladder length.

AIMS: To examine the prevalence of chromosomal defects and outcome of fetuses with megacystis at 10-14 weeks of gestation. METHODS: At the 10-14-week scan fetal megacystis was defined by a longitudinal bladder diameter of 7 mm or more. In 145 such fetuses the fetal karyotype and pregnancy outcome were examined in relation to the longitudinal diameter of the fetal bladder. RESULTS: Chromosomal defects, mainly trisomies 13 and 18, were present in 30 cases. In the group with longitudinal bladder diameter of 7-15 mm the incidence of chromosomal defects was 23.6% (26/110), whereas in those with bladder diameter > 15 mm the incidence was 11.4% (4/35). The fetal nuchal translucency (NT) was above the 95th centile of the normal range for crown-rump length in a higher proportion of cases with abnormal rather than normal karyotype (76.7% compared to 31.3%; Chi-square P < 0.0001). The expected number of cases of trisomy 21, estimated on the basis of maternal age, gestational age and fetal NT, was 6.2 rather than the observed 2 and the corresponding numbers for trisomies 13 or 18 were 4.2 for expected and 24 for observed. In the chromosomally normal group with longitudinal bladder diameter of 7-15 mm follow-up scans demonstrated spontaneous resolution of the megacystis in 90% of the cases and enlargement of the megacystis and/or the development of echogenic kidneys in 10%. In contrast, none of the cases with bladder diameter > 15 mm demonstrated spontaneous resolution of the megacystis. CONCLUSIONS: In fetal megacystis with longitudinal bladder diameter of 7-15 mm there is a risk of about 25% that the fetus will have a chromosomal defect but in the chromosomally normal group there is spontaneous resolution of the megacystis in about 90% of cases. If the bladder diameter is > 15 mm the risk of chromosomal defects is about 10% and in the chromosomally normal group the condition is invariably associated with progressive obstructive uropathy.     

Ear length in trisomy 21 fetuses at 11-14 weeks of gestation.

OBJECTIVE: To determine the value of measuring fetal ear length at 11-14 weeks of gestation in screening for chromosomal defects. METHODS: The fetal ear length was measured in 450 fetuses immediately before chorionic villus sampling for karyotyping at 11-14 weeks of gestation. RESULTS: The median gestational age was 12 (range, 11-14) weeks. The fetal ear was successfully examined in all cases. The fetal karyotype was normal in 409 cases and abnormal in 41, including 32 cases of trisomy 21. In the chromosomally normal group the fetal ear length increased significantly with crown-rump length from a mean of 3.7 mm at 45 mm to 6.9 mm at 84 mm. In the trisomy 21 fetuses the median ear length was significantly below the normal mean for crown-rump length by 0.45 mm (P = 0.013) but it was below the 5(th) centile of the normal range in only two (6.3%) of the cases. There was no significant association between the delta score of ear length and delta nuchal translucency in either the chromosomally normal (r = - 0.015, P = 0.753) or the trisomy 21 fetuses (r = - 0.014, P = 0.94). CONCLUSIONS: At 11-14 weeks of gestation the ear length in trisomy 21 fetuses is significantly reduced but the degree of deviation from normal is too small for this measurement to be useful in screening for trisomy 21.