Performance of a targeted cell-free DNA prenatal test for 22q11.2 deletion in a large clinical cohort.

OBJECTIVE: 22q11.2 deletion is more common than trisomies 18 and 13 combined, yet no routine approach to prenatal screening for this microdeletion has been established. This study evaluated the clinical sensitivity and specificity of a targeted cell-free DNA (cfDNA) test to screen for fetal 22q11.2 deletion in a large cohort, using blinded analysis of prospectively enrolled pregnancies and stored clinical samples. METHODS: In order to ensure that the analysis included a meaningful number of cases with fetal 22q11.2 deletion, maternal plasma samples were obtained by prospective, multicenter enrolment of pregnancies with a fetal cardiac abnormality and from stored clinical samples from a research sample bank. Fetal genetic status, as evaluated by microarray analysis, karyotyping with fluorescence in-situ hybridization or a comparable test, was available for all cases. Samples were processed as described previously for the Harmony prenatal test, with the addition of DANSR (Digital Analysis of Selected Regions) assays targeting the 3.0-Mb region of 22q11.2 associated with 22q11.2 deletion syndrome. Operators were blinded to fetal genetic status. Sensitivity and specificity of the cfDNA test for 22q11.2 deletion were calculated based on concordance between the cfDNA result and fetal genotype. RESULTS: The final study group consisted of 735 clinical samples, including 358 from prospectively enrolled pregnancies and 377 stored clinical samples. Of 46 maternal plasma samples from pregnancies with a 22q11.2 deletion, ranging in size from 1.25 to 3.25 Mb, 32 had a cfDNA result indicating a high probability of 22q11.2 deletion (sensitivity, 69.6% (95% CI, 55.2-80.9%)). All 689 maternal plasma samples without a 22q11.2 deletion were classified correctly by the cfDNA test as having no evidence of a 22q11.2 deletion (specificity, 100% (95% CI, 99.5-100%)). CONCLUSIONS: The results of this large-scale prospective clinical evaluation of the sensitivity and specificity of a targeted cfDNA test for fetal 22q11.2 deletion demonstrate that this test can detect the common and smaller, nested 22q11.2 deletions with a low (0-0.5%) false-positive rate. Although the positive predictive value (PPV) observed in this study population was 100%, the expected PPV in the general pregnant population is estimated to be 12.2% at 99.5% specificity and 41.1% at 99.9% specificity. The use of this cfDNA test to screen for 22q11.2 deletion could enhance identification of pregnancies at risk for 22q11.2 deletion syndrome without significantly increasing the likelihood of maternal anxiety and unnecessary invasive procedures related to a false-positive result. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal ultrasonographic fetal rib length measurement: correlation with gestational age.

The availability of normal data on fetal rib bone length would be of value in a variety of circumstances under which ultrasound examinations are performed. Fetal rib length measurements were obtained in 257 singleton fetuses in a prospective cross-sectional study. The study population consisted of pregnancies between 14 and 40 weeks with no evidence of growth disturbances, or structural or karyotypic abnormalities. Fetal rib length, as a function of gestational age, was expressed by the regression equation: RL = -0.5834 + 0.2030 (GA), where RL is the rib length in centimeters and GA the gestational age in weeks. The correlation was R = 0.94 (p < 0.0001). The normal limits of fetal rib length are defined, and a high correlation between fetal rib length, gestational age, and other standard determinants of fetal growth is demonstrated. Our results indicate that fetal rib length can be a useful adjunct in determining normal fetal growth and in the management of the pregnancy with fetal skeletal dysplasia.

Antenatal diagnosis and treatment of fetal goitrous hypothyroidism: case report and review of the literature.

The recognition and treatment of fetal hypothyroidism are believed to be important to optimize growth and intellectual development in affected fetuses. We present a case of fetal goiter diagnosed by ultrasonography in the second trimester of pregnancy. Cordocentesis performed at 28 weeks confirmed the presence of fetal hypothyroidism. Fetal therapy was performed with weekly intra-amniotic injections of thyroxine from 29 to 36 weeks. A repeat cordocentesis at 35 weeks showed normalization of fetal thyroid function. The fetal goiter decreased rapidly in size following fetal treatment. Amniotic fluid levels of thyroid stimulating hormone (TSH) and free thyroxine were obtained with each amniocentesis. Sulfated iodothyronine concentrations in maternal blood were obtained before and after fetal thyroxine treatment. This report discusses the role of amniotic fluid levels of TSH and free thyroxine and maternal levels of sulfated iodothyronine in the diagnosis and management of fetal hypothyroidism. A review of the English literature is presented.

A non-human primate model for the in utero chronic catheterization of the umbilical vein. A preliminary report.

Short-term ultrasound-guided fetal umbilical cord catheterization in humans has been reported. However, before chronic umbilical vein catheterization is attempted in humans the technique must be tested in the non-human primate model. If the fetus was to tolerate this procedure, chronic fetal umbilical vein catheterization could be used for drug administration, parenteral fetal nutrition or to monitor the changes of hematologic parameters during and after open or endoscopic fetal surgery. In this study, 4 pregnant baboons were used to test the feasibility of ultrasound-guided umbilical vein catheterization. Although the umbilical vein was successfully catheterized in all the animals, only 1 fetus survived the postoperative period. The 3 immediate fetal deaths were due to a fetal intra-amniotic hemorrhage, while the most likely cause of death of the 4th animal was infection. In the surviving fetus and mother, blood was sampled once a day. Neither fetomaternal hemorrhage nor thrombosis could be documented. We conclude that ultrasound-guided transplacental umbilical vein chronic catheterization is technically difficult but feasible in the baboon model. Further studies in this model are needed to improve the catheterization technique and to monitor the extent of time that the catheter may be tolerated within the umbilical vein.

Ultrasonographic growth and Doppler hemodynamic evaluation of fetuses of obese women.

All fetuses benefit from ultrasonographic estimation of gestational age and evaluation of growth patterns. Monitoring the pregnancies of obese women is perceived as more difficult than monitoring those of nonobese women. The aim of this study was to determine if maternal obesity affects the growth and Doppler resistance indices (RI) of the fetus. Twenty-eight women with a preconception weight > 90.7 kg underwent obstetric ultrasonographic evaluations from the 20th week of gestation. Their ultrasonographic data were compared with those of controls. Ten of the obese women developed gestational diabetes and had lower umbilical artery RIs for a given gestational age (P < .0001) than did those obese women without other medical complications, those with medically controlled pregnancy-induced hypertension or those from the control population. The relation between fetal unit weight and umbilical artery RIs was established. The pattern of RI changes was similar in all groups when estimated fetal weight instead of gestational age was used as the covariant. Fetal growth and Doppler velocimetry can be monitored adequately in obese women. Gestational diabetes significantly influences the pattern of fetal growth and the impedance to flow in the umbilical artery.

Ultrasonic prediction of discordant growth in twin pregnancies.

In this prospective study conducted from 1984 through 1987, the ability to correctly predict growth discordancy in twin gestations by ultrasonic estimated fetal weights is examined. Discordancy was defined as an intertwin birth weight difference of 25% or greater. This method resulted in a sensitivity rate of 77% and a specificity rate of 92%. The positive predictive value of an abnormal test (i.e. discordant growth) was 67% and the negative predictive value of a normal test (i.e. concordant growth) was 95%. The perinatal mortality rate of 217/1,000 in discordant twin fetuses was significantly higher than 29/1,000 in the concordant twins in this study population (p < 0.01) and even more of a contrast to the rate of 10/1,000 in our singleton population. Accurate prediction of discordant twin pregnancies which are at high risk for poor outcome opens the opportunity for potential in utero treatment modalities.

Sonographic measurement of the fetal iliac bone: growth and relation to femur length in assessment of gestational age.

Diagnostic ultrasonography has given us the opportunity to diagnose several congenital malformations in utero. Skeletal dysplasias is a heterogeneous group of disorders of the skeleton. Although disorders of bone growth are often diagnosed in utero, it is usually a general diagnosis because the exact syndrome cannot be specified. This is due to the fact that many anomalies of the skeleton have similar features. The wing of the iliac bone can be either affected or normal in skeletal dysplasias and its appearance may help in the differential diagnosis. This study was undertaken to establish values for the width of the iliac bone wing during normal gestations and thus enable us to use it in the evaluation of fetal growth and the recognition of specific congenital anomalies.

Extraovular and intraovular uterine contraction monitoring. A comparison.

We tested a new method of monitoring intrauterine contraction pressure. The pressure transducer is simply inserted between the fetal membranes and uterus after checking placental placement with ultrasonography. To evaluate this method, a prospective, randomized study was done to compare intraovular versus extraovular intrauterine contraction monitoring in patients undergoing serial labor induction with oxytocin. Study parameters were length of labor, cesarean section rate, Apgar scores and febrile morbidity rate. Two groups of 32 patients each underwent oxytocin induction for postdatism, diabetes or hypertensive disorders of pregnancy. Our results show that extraovular intrauterine contraction monitoring resulted in a better outcome with respect to all the parameters evaluated. Specifically, it had a shorter induction interval, lower cesarean section rate, lower rate of maternal febrile morbidity and comparable neonatal complications. The technique was safe and easy to learn and apply.

Fetoplacental and uteroplacental Doppler blood flow velocity analysis in premature rupture of membranes.

The value of Doppler velocimetry in predicting fetal distress or perinatal infection was investigated in 60 patients with premature rupture of the membranes (PROM) between 25 and 38 weeks of gestation. Studies were performed in the umbilical and uterine arteries after admission to the hospital and repeated every 24 to 76 hours until delivery. Results of the last study, performed less than 24 hours before delivery and comparison between longitudinal studies in the same patient, failed to disclose statistical differences between patients who did or did not develop the perinatal complications under study. We conclude that Doppler velocimetry is not a sensitive enough means of predicting fetal distress or infection in PROM.

Twin pregnancy. Ultrasonographically observed changes in fetal presentation.

The changes in fetal presentation throughout pregnancy were observed ultrasonographically in 332 sets of twins. Seventy-eight percent of the leading twins were vertex at 26-30 weeks' gestational age, 75% at 31-34 weeks and 81% at 35-38 weeks. The incidence of nonvertex presentation for either twin was 73.0%, 64.5% and 59.5% at the same gestational ages. The results are not significantly different from those on concordant twins delivered at the same gestations. Thus, one can counsel parents of twins at all gestational ages in regard to the potential for malpresentation.

Antenatal classification of hydrops fetalis.

Among 12,572 pregnant women referred for ultrasound examination from 1985-1990, 76 fetuses had ultrasonographic findings of hydrops fetalis, ten immune and 66 nonimmune. Fetuses with cystic hygroma (20), heart defects or arrhythmias (13), or other congenital anomalies (15) accounted for the majority of the nonimmune cases. Antenatal chromosomal studies were available in 42 fetuses with nonimmune hydrops, of which 14 (34%) were abnormal with seven monosomes and six trisomies. Seventeen cases of hydrops (22%) were classified as idiopathic because they had no recognizable etiology. It is concluded that: 1) The ultrasonographic incidence of fetal hydrops in referral centers can be as high as one in 165 pregnancies; 2) most cases of fetal hydrops are of the nonimmune type, which can occur in a low-risk population and can be detected with early second-trimester ultrasound screening; and 3) the complexity of this condition and the high rate of chromosomal abnormalities require referral to a high-risk center for evaluation and pregnancy management.

Color Doppler imaging in the assessment of uteroplacental blood flow in abnormal first trimester intrauterine pregnancies. An attempt to define etiologic mechanisms.

The addition of color Doppler imaging (CDI) to the vaginal probe now enables sonographers to study more accurately the maternal-fetal circulation at the early stages of the gestation. Doppler studies of normal intrauterine first trimester gestations have been published, and our investigation was an attempt to study uteroplacental blood flow in abnormal intrauterine first trimester gestations. Although the calculated indices did not differ significantly from those found in normal gestations, we did find a higher rate of color detection in gestations defined as anembryonic as compared to those defined as missed abortions. Circulation abnormalities probably play a significant role in early pregnancy failures, and we believe CDI will help define the different etiologic mechanisms causing these early complications.

Doppler evaluation of the fetoplacental circulation in the latent phase of preterm premature rupture of membranes.

Blood velocity waveform analysis by pulsed Doppler ultrasonography in preterm premature rupture of membranes is described. Reduced amounts of amniotic fluid did not impair determination of the resistance indices from the umbilical artery. Good results were obtained from the internal carotid artery in 82% of cases. Failure in measurements at the internal carotid artery occurred when fetal head engagement prevented good study planes. Ninety-three percent of umbilical artery determinations fell within the normal limits for our control population as did 89.2% of those at the internal carotid artery. No differences in the resistance indices could be attributed to the length of the latent period in prematurely ruptured membranes or subclinical chorioamnionitis. Therefore, if a mother or fetus has an underlying condition that affects fetoplacental circulation, the resulting abnormal blood velocity waveform should reflect this condition rather than the effect of ruptured membranes.

Value of a random single Doppler study of the umbilical artery for predicting perinatal outcome.

A prospective blinded study was performed on 191 high-risk patients with pregnancies ranging from 25 to 42 weeks gestation to investigate the value of a single Doppler analysis of the umbilical artery blood flow waveform (systolic-to-diastolic ratio, S/D) for predicting poor perinatal outcome. This was defined as the presence of heavy meconium, delivery of a growth-retarded infant, an umbilical cord arterial pH less than 7.2, or a 5-minute Apgar score less than 7. The interval between Doppler examination and delivery ranged from 12 hours to 15 weeks. No clinical data were available to the examiner performing the Doppler study. Moreover, the Doppler measurements were unknown to the attending physicians. The sensitivity, specificity, and positive and negative predictive values of the Doppler study in predicting outcome were 30.4%, 92.9%, 36.8%, and 92.6%, respectively, with an adverse outcome prevalence of 12%. These results indicate that a single random S/D ratio from the umbilical artery is not an adequate screening test for the risk of perinatal complications.

Transvaginal color Doppler imaging in the assessment of uteroplacental blood flow in the normal first-trimester pregnancy.

Characteristic changes of low resistance and high diastolic blood flow velocity were identified by Doppler studies starting in the early phase of the second trimester. These changes were attributed by some authors to trophoblastic invasion of the uterine vasculature converting the uterus into a low-resistance organ. Because of technical limitations previous studies were confined to the uterine artery and its main branches. With the development of color Doppler and transvaginal ultrasonography we can now identify blood flow in various small vessels in the placental bed. This study was performed to assess the ability of color Doppler ultrasonography to evaluate subtrophoblastic blood flow by color identification in the early phase of normal pregnancy from 5 to 9 weeks' gestation. Results show that the characteristic increase in diastolic blood flow is evident as early as 5 weeks' gestation.

Death due to high-output cardiac failure in fetal sacrococcygeal teratoma.

Fetal sacrococcygeal teratoma (SCT) is being recognized with increasing frequency. Placentomegaly and hydrops fetalis are preterminal events, and it has been suggested that fetal death may be due to high-output cardiac failure from arteriovenous shunting through the tumor. We had a chance to examine this hypothesis when a 21-week fetus presented with a huge sacrococcygeal teratoma. There were marked placentomegaly, cardiomegaly, hyperdynamic ventricles, and a pericardial effusion. Doppler studies showed tremendous flow through the SCT with extreme enlargement of the inferior vena cava, consistent with congestive heart failure from increased flow through the tumor. Hydrops developed, and the fetus was delivered because of placental abruption. This case provides supportive evidence that the teratoma acts as a large arteriovenous shunt, causing high-output cardiac failure. We have now collected 18 more cases of sacrococcygeal teratoma diagnosed in utero. Of the total 45 cases of fetal SCT, 9 had placentomegaly and/or fetal hydrops and all 9 fetuses died in utero or shortly after birth. We conclude that the only hope for survival in these severely affected fetuses is to reduce blood flow to the tumor before birth.

Placental histology in fetuses between 18 and 23 weeks' gestation with abnormal karyotype.

Placentas from karyotypically abnormal fetuses (18 to 23 weeks' gestation) were analyzed prospectively at the light microscopic level. Group I consisted of 14 control placentas. Group II consisted of 14 placentas from fetuses with an abnormal karyotype. Secondary and tertiary stem villi counts, small muscular artery counts, and total vessel counts were determined per 100 x field. There were no differences in secondary and tertiary stem villi counts between groups. A significant decrease in small muscular artery counts (p less than 0.01) and total vessel counts (p less than 0.01) was noted in group II. Placental and fetal weights were comparable between groups. This undervascularization may represent placental immaturity as a result of arrested or delayed angiopoiesis. It appears that this abnormality is established before the third trimester and may be enhanced by late vascular obliteration as reported by others. These data substantiate the concept that the structure and function of the placenta is determined to a great degree by fetal karyotype and may help explain the morbidity and mortality seen in these fetuses.

Combined intravascular-intraperitoneal transfusions in hydropic twins due to Rh (D) alloimmunization.

Fetal hydrops due to Rh (D) alloimmunization can be reversed by ultrasound-guided intravascular transfusions with improvement in perinatal morbidity and mortality. We report a case of in utero intravascular transfusion in hydropic twins which reversed all the hydropic findings within 3 days. A simple intraperitoneal transfusion was performed in each twin 2 weeks later, and only one neonatal exchange transfusion was required for the ultimate survival of both twins.

Ultrasonographic measurement of fetal femur length in growth disturbances.

Ultrasonographic measurement of fetal femur length is a recognized technique for determination of gestational age and fetal growth. A total of 280 pregnant women were studied, each of whom had pathologies with the potential to either accelerate or delay fetal growth. There were 1000 measurements of the fetal femur length performed on these 280 fetuses. A total of 125 fetuses were found to have a growth disturbance-91 with asymmetrical intrauterine growth retardation and 34 with macrosomia. Comparison of fetuses with either intrauterine growth retardation or macrosomia with appropriate-for-gestational-age fetuses showed that the femur length is not statistically affected by intrauterine growth abnormalities.