Frontonasal fold thickness-to-nasal bone length ratio as a prenatal sonographic marker for trisomy 21 in a low-risk population.

OBJECTIVES: To report normative data for the fetal nasal bone length (NBL), frontonasal fold (FNF) thickness, and the FNF/NBL ratio and to study their performance in the sonographic screening of trisomy 21 in a normal, unselected Latin American population. METHODS: Women undergoing a routine sonographic examination between 16 and 32 weeks' gestation at a primary health care center in Santiago, Chile, were prospectively recruited for NBL and FNF thickness measurements. Pregnancies with maternal/fetal complications were subsequently excluded from analysis. Correlations between NBL, FNF thickness, and FNF/NBL ratio and gestational age were assessed with the Spearman correlation coefficient (ρ). To generate reference percentiles for NBL and FNF thickness, adjusted regression models were derived using a statistical method for calculating reference percentiles of fetal biometric parameters. RESULTS: A total of 1922 cases complied with entry criteria. Both the NBL and the FNF thickness increased with gestational age. However, the FNF/NBL ratio remained constant (ρ= 0.016; P = .95), with a mean value of 0.68 and 95th and 99th percentile values of 0.84 and 0.90, respectively. During the study period, all 4 fetuses with trisomy 21 diagnosed in this low-risk population had an FNF/NBL ratio above the 99th percentile, whereas only 3 had NBL below the fifth percentile, and 3 had FNF thickness above the 95th percentile. CONCLUSIONS: The FNF/NBL ratio is a promising marker for the sonographic screening of trisomy 21 in the low-risk population; however, further prospective studies including larger numbers of fetuses with trisomy 21 are warranted to determine the clinical value of this marker. As the NBL is dependent on the ethnicity of the population screened, determination of normative data for NBL and the FNF/NBL ratio in different ethnic populations is also recommended before including this method in the routine screening for aneuploidy.

Ectopia cordis in a first-trimester sonographic screening program for aneuploidy.

We review the sonographic features, antenatal course, and perinatal outcomes in 7 cases of ectopia cordis diagnosed in the first trimester. Four cases were associated with a large omphalocele (pentalogy of Cantrell) and 2 with a body stalk anomaly. The remaining fetus had isolated thoracic ectopia cordis. Two pregnancies were terminated; 2 fetuses died in utero; 2 infants died after delivery; and 1 died at 3 months of age. We conclude that the diagnosis of ectopia cordis can easily be established during the first trimester. In agreement with the currently available literature, the prognosis of ectopia cordis in our series was uniformly poor.

Prenatal sonography in hydranencephaly: findings during the early stages of disease.

The purpose of this report is to describe the prenatal sonographic findings in fetuses with hydranencephaly diagnosed during the early stages of disease. Four cases with characteristics of hydranencephaly were retrospectively identified from 2 Latin American fetal medicine referral centers. Information on maternal demographics, sonographic findings, antenatal courses, and pregnancy outcomes was retrieved from the ultrasound reports and medical records. Cases were diagnosed between 21 and 23 weeks' gestation. The sonographic findings were similar in all cases and included absent cerebral hemispheres, which were replaced by homogeneous echogenic material filling the supratentorial space, and preservation of the thalami, brain stem, and cerebellum. The head circumference measurement was within the normal range, but the transverse cerebellar diameter was below the fifth percentile in 3 of the 4 cases. A follow-up scan in 1 of these cases demonstrated the classic anechoic fluid-filled appearance of hydranencephaly 2 weeks after diagnosis. Confirmation of the diagnosis was available in 2 cases, by postmortem examination in 1 and by fetal magnetic resonance imaging in the other. No further investigations were performed in the 2 women who opted for termination of pregnancy. In conclusion, during the early stages of disease, hydranencephaly is characterized by the presence of a large intracranial saclike structure containing homogeneous echogenic material, representing blood and necrotic debris secondary to massive liquefaction of the developing cerebral hemispheres.

First-trimester sonographic findings in trisomy 18: a review of 53 cases.

OBJECTIVE: To report our experience with first-trimester sonographic findings in pregnancies complicated by trisomy 18. METHODS: Proven cases of trisomy 18 undergoing sonographic examination between 11 + 0 and 13 + 6 weeks of gestation were retrospectively identified. Information on maternal demographics, prenatal sonographic findings, and chromosomal analysis results was obtained by reviewing the ultrasound reports and medical records. RESULTS: During the 12-year period from July 1997 to June 2009, 53 cases of full trisomy 18 had first-trimester sonographic examination performed at our institution. All but one fetus displayed one or more abnormal sonographic finding, most commonly increased nuchal translucency thickness (n = 48, 91%). Absent or hypoplastic nasal bone was documented in 53% of the fetuses in which this marker was specifically looked for. Structural anomalies included omphalocele in 11 (21%), abnormal posturing of the hands in three (6%), megacystis in two (4%), and abnormal four-chamber view of the heart in two (4%). Early-onset fetal growth restriction and bradycardia were documented in 14 (26%) and 4 (8%) of the cases, respectively. CONCLUSIONS: Our study demonstrates that a large number of fetuses with trisomy 18 have abnormal sonographic findings in the first trimester. However, the sonographic features usually found in the second-trimester are difficult to detect at an early gestational age. The recognition of the specific first-trimester sonographic pattern of trisomy 18 may allow improved detection of this serious condition in early pregnancy.

Megacystis associated with an umbilical cord cyst: a sonographic feature of a patent urachus in the first trimester.

OBJECTIVE: The purpose of this series was to report the first-trimester sonographic findings, antenatal course, and outcome in fetuses with a patent urachus. METHODS: We conducted a review of ultrasound reports and medical charts from 3 pregnancies complicated by a congenital patent urachus detected in the first trimester. RESULTS: All 3 fetuses had megacystis and an umbilical cord cyst close to the fetal abdominal insertion that was detected in the first trimester. In 2 cases, the megacystis resolved spontaneously while the umbilical cord cyst worsened in appearance; among them, massive edema of the umbilical cord was documented in 1, and evidence of partial bladder exstrophy was detected in the third trimester in the other. Both cases required neonatal surgery with no complications. In the remaining case, the fetus died in the early second trimester. Postmortem examination confirmed the diagnosis of a patent urachus, an allantoic cyst, and thrombosis of the umbilical vessels. CONCLUSIONS: Megacystis is a warning sign of a patent urachus in the first trimester. The prognosis of this condition is generally good; however, fetal death can occur secondary to compression of umbilical vessels due to the expanding allantoic cyst.

Endoscopic laser coagulation of feeding vessels in large placental chorioangiomas: report of three cases and review of invasive treatment options.

OBJECTIVE: To report three cases of large placental chorioangiomas managed with endoscopic laser coagulation of the feeding vessels, and review the literature regarding cases of chorioangioma treated with invasive techniques. METHODS: Intrauterine endoscopic surgery was performed using a 2.5-mm fetoscope under epidural anesthesia. Coagulation of the feeding vessels was attempted with laser energy, and the operation was completed with amniodrainage. RESULTS: The feeding vessels were successfully coagulated in one case, resulting in a term delivery. Histopathologic examination of the placenta confirmed a capillary chorioangioma with extensive necrosis. There were intraoperative complications in the other two cases, including bleeding at the site of coagulation requiring intrauterine transfusion in one, and incomplete vascular ablation in the other. In the former case the infant was born prematurely and developed chronic renal insufficiency. In the latter, the fetus died within the first week of the surgery. CONCLUSIONS: There are limited interventions available for the management of large, symptomatic placental chorioangiomas. Although they can be treated with endoscopic laser coagulation of the feeding vessels, fetal bleeding, exsanguination, and death are potential complications of the procedure; therefore, this technique should be used with caution. The role of this treatment modality in the early devascularization of placental chorioangiomas prior to the development of significant complications warrants consideration.

Endoscopic laser surgery in severe second-trimester twin-twin transfusion syndrome: a three-year experience from a Latin American center.

OBJECTIVE: In order to assess the outcome of pregnancies complicated by severe second trimester twin-twin transfusion syndrome (TTTS) undergoing treatment with endoscopic laser surgery, we reviewed our experience following the implementation of an institutional fetal surgery program. METHODS: Patients presenting with monochorionic-diamniotic twin pregnancies complicated by severe TTTS before 26 weeks of gestation were offered endoscopic laser surgery to coagulate placental vascular anastomoses. Using regional anesthesia and guided by real-time sonography, anastomoses were identified and selectively coagulated. At the end of the procedure, amniodrainage was performed to restore normal amniotic fluid volume. Follow-up and delivery were carried out at the referring institutions. Six-month follow-up was performed in all cases. RESULTS: During a 3-year period from September 2003 to December 2006, 33 consecutive cases of severe TTTS were operated on at a median gestational age of 21 weeks (range 17-25). Nine (27.3%) cases were classified as stage II, 21 (63.6%) as stage III, and three (9.1%) as stage IV. The placenta was anterior or predominantly anterior in 15 (45.5%) of the cases. Overall, both twins were born alive in 16 (48.5%) cases, only one twin was born alive in 11 (33.3%), and neither was born alive in the remaining six (18.2%). Therefore, 81.8% (27 of 33) of the pregnancies resulted in at least one liveborn infant. Among them, the mean gestational age at delivery was 32 weeks (range 23-38) and the mean birthweight of the liveborn infants was 1591 g (range 350-3800). Thirty-four infants survived the perinatal period, yielding an overall perinatal survival rate of 51.5%, with 75.8% (25 of 33) of the pregnancies resulting in at least one perinatal survivor. All neonatal deaths were associated with extreme prematurity. CONCLUSIONS: This preliminary experience suggests that selective laser coagulation appears to be a good treatment option in cases of monochorionic twin pregnancies complicated by severe TTTS. However, technical skills and adequate equipment are required for implementing a fetal surgery program. Auditing outcomes during the learning curve would help in identifying potential problems.

First-trimester ultrasonographic screening for trisomy 21 using fetal nuchal translucency and nasal bone.

OBJECTIVE: To report our experience with first-trimester screening for trisomy 21 by using the combination of nuchal translucency thickness and nasal bone assessment. METHODS: Pregnant women from a predominantly Latin American population consisting of patients at both low risk and high risk for chromosomal defects underwent first-trimester ultrasonographic screening. Nuchal translucency thickness and nasal bone were assessed by two accredited fetal medicine specialists. Cases of trisomy 21 were identified from the cytogenetics laboratory logbook. RESULTS: Over a 3-year period, 1,287 consecutive singleton pregnancies were screened. The median maternal age was 33 years (range 14-47 years), with 456 (35.4%) women aged 35 years or older at the time of the scan. Overall, 110 fetuses (8.5%) had nuchal translucency thickness greater than the 95th percentile for gestational age and 25 (1.9%) had absent nasal bone. Trisomy 21 was diagnosed in 31 cases. Among them, the nuchal translucency thickness was increased in 28 and the nasal bone was absent in 13 (detection rates of 90.3% and 41.9%, respectively; P<.01). All but one (92.3%) of the trisomy 21 fetuses with absent nasal bone had increased nuchal translucency. Only two of the normal fetuses had an absent nasal bone in the first trimester. CONCLUSION: In our population, increased nuchal translucency thickness is the most important ultrasonographic marker of trisomy 21. In contrast, the nasal bone seems to have a less prominent role in identifying the fetus at risk for trisomy 21 due to its lower detection rate. However, an absent nasal bone should be considered as a highly predictive marker of trisomy 21.

Discordant lower urinary tract obstruction in early twin gestations: management and outcome.

OBJECTIVE: To report our experience with the management of twin pregnancies discordant for lower urinary tract obstruction. METHODS: Cases of twin pregnancies discordant for lower urinary tract obstruction were identified from our fetal medicine database. Information on ultrasonographic findings, antenatal course, pregnancy complications, and perinatal outcome was obtained by reviewing medical records or contacting the referring obstetricians. RESULTS: Five twin pregnancies discordant for lower urinary tract obstruction were diagnosed between 11 and 15 weeks of gestation. There were 3 dichorionic and 2 monochorionic pregnancies (1 diamniotic and 1 monoamniotic). The dichorionic pregnancies were managed conservatively, resulting in a pregnancy loss of both twins in 1 case, a single fetal death at 29 weeks in 1 case, and an early neonatal death due to lung hypoplasia of the affected twin in 1 case. On the other hand, both monochorionic twin pregnancies were managed with serial vesicocenteses. In both cases, the prenatal course was complicated, 1 by premature rupture of the membranes and the other by cord entanglement, requiring delivery at 29 and 31 weeks, respectively. Among the 4 continuing pregnancies with complete perinatal outcome, none of the affected twins survived, and the structurally normal twins were delivered between 29 and 36 weeks and discharged from the hospital in good condition. CONCLUSION: Twin pregnancies discordant for lower urinary tract obstruction are at high risk of perinatal death and premature delivery. Prenatal intervention seems not to be associated with an improved perinatal outcome of the affected twin, but it may be beneficial in selected cases to attain viability of the unaffected twin.

First-trimester sonographic diagnosis of holoprosencephaly: value of the "butterfly" sign.

OBJECTIVE: To study the value of choroid plexus dysmorphology as a screening tool for the first-trimester sonographic diagnosis of holoprosencephaly in a high-risk population. METHODS: A total of 378 consecutive pregnancies undergoing chorionic villus sampling between 11 and 14 weeks' gestation were scanned before the procedure, following the recommendations of the Fetal Medicine Foundation (London, England). A cross-sectional view of the fetal brain, including the visualization of both choroid plexuses (the "butterfly" sign), was obtained in all cases. RESULTS: There were 3 cases in which the butterfly sign was not identified. In these cases, the first-trimester diagnosis of holoprosencephaly was confirmed by the presence of a single monoventricular cavity and fused thalami. Two of these fetuses had features of facial dysmorphism at the time of presentation and 2 had extracranial anomalies, including a cystic hygroma in 1 and a small omphalocele and polydactyly in another. Chromosomal analysis showed trisomy 13 in 2 cases and a ring chromosome 13 in the other. CONCLUSIONS: This series suggests that failure to identify the butterfly sign is a warning sign of holoprosencephaly in the first trimester. Systematic identification of the butterfly sign at the time of sonographic assessment of nuchal translucency provides a valuable tool for the early screening of holoprosencephaly.