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

Management and survival of foetuses with trisomy 18 in a French retrospective cohort

OBJECTIVES

The main objective of this study was to evaluate parents' current demands following the announcement of trisomy 18 and maternal risks.

MATERIAL AND METHODS

A single-centre retrospective study was performed in the Paris Saclay Foetal Medicine Department from 2018 to 2021. All patients followed up in the department who had cytogenetic confirmation of trisomy 18 were included.

RESULTS

89 patients were recruited. The most common malformations at ultrasound examination were cardiac or brain abnormalities, distal arthrogryposis as well as severe intrauterine growth retardation. 29% of foetuses with trisomy 18 had more than three malformations. 77.5% of patients requested medical termination of pregnancy. Among the 19 patients who chose to continue their pregnancy, 10 (52.6%) presented with obstetrical complications, of which 7 (41.2%) experienced stillbirth; five babies were born alive with no survival at 6 months.

CONCLUSION

In France, in the case of foetal trisomy 18, most women request termination of pregnancy. In the post-natal period, the management of a newborn with trisomy 18 is oriented towards palliative care. The mother's risk of obstetrical complications should be part of counselling. Follow-up, support and safety should be the goal of management of these patients, regardless of the patient's choice.

Trisomy 18 in a First-Trimester Fetus with Thoraco-Abdominal Ectopia Cordis

Introduction: Fetuses with trisomy 18 will occasionally also have ectopia cordis. Case report: A routine ultrasound scan at 12 weeks' gestation revealed a large fetal anterior thoraco-abdominal wall defect with an extrathoracic heart and a liver-containing omphalocele. Chorionic villus sampling revealed a 47,XY,+18 karyotype. Additional anomalies detected after termination of the pregnancy included a cleft lip and palate and left radial agenesis. Conclusions: The prenatal diagnosis of ectopia cordis associated with aneuploidy can be made in the first trimester of pregnancy. An extrathoracic heart located in a liver-containing omphalocoele should be considered a thoraco-abdominal ectopia cordis rather than pentalogy of Cantrell.

Importance of Follow-Up and Early Detailed Evaluation in Early Onset Growth Restricted Fetuses

Early onset fetal growth restriction (EO-FGR) is associated with significant feto-maternal complications, therefore efforts should be made to identify the causes and the potential outcome of the pregnancy. Some of the pitfalls in first-trimester imaging of the fetal anomalies are related to the inadequacy of the examination, because of the fetal position and limited clarity in relation to the size of the structures being examined. In this paper we present a case where careful ultrasound scan follow-up and the use of both approaches transabdominal and transvaginal were useful to complete a detailed structural evaluation as part of the diagnosis, management and prognosis of a fetuses diagnosed with EO-FGR in the first trimester and a triploidy with atypical ultrasound features.

The ratio of cavum septi pellucidi width to anteroposterior cerebellar diameter: A novel index as a diagnostic adjunct for prenatal diagnosis of trisomy 18

AIM

To explore the effectiveness of cavum septi pellucidi (CSP) width to anteroposterior cerebellar diameter (APCD) ratio as a diagnostic adjunct for prenatal diagnosis of trisomy 18.

METHODS

Images of normal fetal brain within 15 and 35 weeks were stored in our center from 2016 to 2017. Images of aneuploid fetuses were retrospectively collected from 2004 to 2017. The transverse cerebellar diameter, APCD and CSP width were measured. CSP/APCD and APCD/transverse cerebellar diameter ratios were calculated and compared between euploid and aneuploid fetuses.

RESULTS

One thousand and forty one fetuses were analyzed, including 817 euploid fetuses and 224 aneuploid fetuses (trisomy 21 117 cases, trisomy 18 82 cases, trisomy 13 9 cases, sex-linked 16 cases). No correlation had been found between both ratios and gestational weeks (P > 0.05). In aneuploid groups, means of ratios were both significantly different just between trisomy 18 group and euploid group (P < 0.05). The best area under the curve was shown by the CSP/APCD ratio. The cutoff value of CSP/APCD was 0.46 (sensitivity 87.0%, specificity 85.0%).

CONCLUSION

A wide CSP or cerebellar hypoplasia warrants a more detailed ultrasound screening and genetic counseling. A larger CSP/APCD ratio alerts us to trisomy 18 syndrome, especially in cases with subtle anomalies.

The diagnostic value of a detailed first trimester anomaly scan in fetuses with increased nuchal translucency thickness

Objectives To assess the diagnostic value of an early anomaly scan in fetuses with increased nuchal translucency (NT) in the prediction of aneuploidy. Methods In this study we analyzed the data of pregnant women obtained at their first trimester screening in our unit. The detailed examination routinely includes measurement of NT and a scan for anatomical defects. For fetuses with an NT≥3.5 mm, the diagnostic power of early major sonographic findings (MSF) regarding abnormal karyotype was calculated. Results A total of 7352 first trimester examinations were screened. Two hundred and twenty-two fetuses with an NT≥3.5 mm were analyzed. The median gestational age was 12.5 weeks (range 11.0-14.6) and the median NT was 5.1 mm (range 3.5-15.3). MSF were detected in 51.8% of fetuses with increased NT. Among 115 fetuses with MSF, 91 were aneuploid, yielding a positive predictive value for aneuploidy of 79.1%. In the absence of MSF, the negative predictive value was 70.1%. The presence of MSF was significantly predictive for aneuploidy both in bivariate and multivariate regression analysis. Conclusion Our study underlines the importance of a detailed anatomical ultrasound in fetuses with increased NT, as MSF occurred frequently. However, the diagnostic value of MSF regarding aneuploidies appears to be moderate.

The indications for early prenatal diagnosis of trisomy 18: a 7-year experience at mainland China

Objective: To report the experience with first-trimester prenatal detection of pregnancies complicated by trisomy 18.Study design: Proven cases of trisomy 18 identified between 11 and 14 weeks of gestation were retrospectively reviewed. Information on maternal demographics, prenatal sonographic findings, indications for prenatal diagnosis and chromosomal analysis results was obtained by reviewing medical records.Results: During the 7-year period from January 2011 to December 2017, 89 cases of full trisomy 18 had first-trimester indications for prenatal diagnosis at Guangzhou Women and Children's Medical Center. Eighty-five (95.5%) had abnormal sonographic findings in the first trimester. The most common finding was increased nuchal translucency (55.1%), followed by cystic hygroma (18.0%), omphalocele (14.6%), and fetalis hydrops (11.2%). Four cases (4.5%) were not associated with any abnormal first-trimester sonographic finding, and were diagnosed because of routine positive screening results for trisomy 18. A single case was diagnosed because of a positive cell-free DNA (cfDNA) result.Conclusion: These results demonstrate that a large number of fetuses with trisomy 18 have abnormal sonographic findings in the first trimester, and support the continued utility of first-trimester sonographic examination in the diagnosis of this trisomy even with the availability of cfDNA.

Prenatal Diagnosis of Atrioventricular Block and QT Interval Prolongation by Fetal Magnetocardiography in a Fetus with Trisomy 18 and SCN5A R1193Q Variant

We report a case of fetal trisomy 18 with SCN5A R1193Q variant that presented with sinus bradycardia, 2 : 1 atrioventricular block (AVB), and QT interval prolongation. These complex arrhythmias were diagnosed by fetal magnetocardiography combined with ultrasound findings. Advanced AVB and ventricular arrhythmias were confirmed after birth. Genetic testing of the baby revealed a SCN5A R1193Q variant, which we considered could account for the various arrhythmias in this case.

First-trimester screening for trisomies 18 and 13, triploidy and Turner syndrome by detailed early anomaly scan

OBJECTIVE

To examine the performance of first-trimester ultrasound screening for trisomies 18 and 13, triploidy and Turner syndrome based on fetal nuchal translucency thickness (NT), additional fetal ultrasound markers including anatomy of the nasal bone (NB), blood flow across the tricuspid valve (TV) and through the ductus venosus (DV) and a detailed fetal anomaly scan at 11-13 weeks' gestation.

METHODS

This was a retrospective case-matched study involving pregnant women at 11-13 weeks' gestation. The study population consisted of fetuses with trisomy 18, trisomy 13, triploidy or Turner syndrome. For each fetus with an abnormal karyotype, 50 randomly selected euploid fetuses were added to the study population. In all cases, the crown-rump length and NT were measured. In addition NB, TV flow and DV flow were examined. The summed risk for trisomies 21, 18 and 13 was computed based on: first, maternal age (MA); second, MA and fetal NT; third, MA, NT and one of the markers NB, TV flow or DV flow; fourth, MA, NT and all these markers combined; fifth, MA, NT and fetal anomalies; and, finally, MA, NT, all markers and fetal anomalies.

RESULTS

The study population consisted of 4550 euploid and 91 aneuploid fetuses. Median NT was 1.8 mm in euploid fetuses and 4.8, 6.8, 1.8 and 10.0 mm in fetuses with trisomy 18, trisomy 13, triploidy and Turner syndrome, respectively. The NB, TV flow and DV flow were abnormal in 48 (1.1%), 34 (0.7%) and 99 (2.2%) euploid fetuses, respectively, and in 42 (46.2%), 31 (34.1%) and 62 (68.1%) aneuploid fetuses, respectively. At least one defect was found in 60 (1.3%) euploid and in 76 (83.5%) aneuploid fetuses. For a false-positive rate of 3%, the detection rate for screening based on MA and fetal NT was 75.8%. It increased to 84.6-86.8% when including one of the additional ultrasound markers and it was 90.1% when all three markers were included. When screening was based on MA, fetal NT and a detailed anomaly scan, the detection rate was 94.5% and increased to 95.6% with the addition of NB, TV flow and DV flow.

CONCLUSION

A detailed anomaly scan at 11-13 weeks' gestation can identify about 95% of fetuses with trisomy 18, trisomy 13, triploidy and Turner syndrome. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Screening for trisomy 18 using traditional combined screening vs. ultrasound-based protocol in tertiary center environment

OBJECTIVES

To compare the screening performances of combined screening test risk algorithm for trisomy 18 (T18) using various cutoffs with a multiparameter ultrasound-based method. To compare the general and maternal age (MA)-based screening performances for T18 by means of combined screening and an ultrasound-based method.

METHODS

This was a prospective, multicenter study based on a mixed-risk non-selected population of women referred to referral centers for a first-trimester screening. Each subject was offered a choice between either a traditional combined screening (CSG arm) or an ultrasound-based screening (USG arm). General and MA-based screening performances were measured.

RESULTS

The study population comprised 10 820 pregnancies as follows: 5132 in the CSG arm, including 28 cases of T18, and 5688 in the USG arm, including 29 cases of T18. In the CSG arm, the detection rate (DR) for T18 at a false-positive rate (FPR) of 3% was 86%, whereas the DR was 100% for the USG arm. MA influenced the T18 screening performance in the CSG arm and reduced the DR in MA ranges  <26 years and 31-35 years. This influence was not observed in the USG arm.

CONCLUSIONS

Only, a multiparameter ultrasound-based screening method may be considered an effective alternative to combined screening for T18 screening. The technique exhibits high and stable DRs irrespective of MA.

Parental counseling in trisomy 18: Novel insights in prenatal features and postnatal survival

Data on the outcome of trisomy T18 (T18) when diagnosed during pregnancy are lacking. We performed a retrospective study of pregnancies complicated by T18 diagnosed at our center and a literature search for publications on the topic, with pooled estimates of survival rates at different gestational and post-natal ages. In our series, all the 60 patients included in the analysis had prenatally detected ultrasound anomalies, which were evidenced in the first trimester or at the second trimester scan in 73% of cases. In the continued pregnancies, ultrasound findings did not correlate with prenatal or post-natal outcome. A meta-analysis of available literature and our data showed that 48% [37-60%] of fetuses were live born, and among these 39% [11-72%] survived beyond 48 hr and 11% [3-21%] beyond 1 month. Our results confirm that prenatal ultrasound has high sensitivity in detection of T18 but is not predictive of the outcome of the continued pregnancies. The data on survival support that T18, even when antenatally diagnosed, cannot be considered as a uniformly lethal syndrome.

[Trisomy 18 syndrome: A case report]

INTRODUCTION

The trisomy 18 syndrome occurs due to the presence of an extra chromosome 18 in most cases. The prevalence in infants is estimated at 1:6000 to 1:8000. Those affected have a high mortality rate, only 4% may survive their first year of life. There are few reported cases exceeding five years of age.

OBJECTIVE

The aim of this paper is to report a case of trisomy 18 of long survival with oral cavity features not described in the literature, and to provide information to physicians and paediatricians about aetiology, phenotype, survival and genetic counselling.

CASE REPORT

A 7 year-old female patient with 2 karyotypes performed by lymphocyte culture showing 47XX+18 in all metaphases. She presented with growth deficiency, dysmorphic facies, severe psychomotor retardation and cognitive disability, inability to feed, lack of verbal language, sensorineural hearing loss, ataxia, cerebellar hypoplasia, and genitals with hypoplastic labia majora and minora. In the oral cavity: dome shaped palate, macroglossia, absence of upper central incisors and first upper and lower molars in mouth. X-ray findings showed formation of missing teeth, with late eruption being concluded.

CONCLUSIONS

In cases of trisomy 18 syndrome there is an increased risk of neonatal and infant mortality. The clinical characteristics in utero and in neonates have been well described. Since few cases exceeding five years of age have been reported, the phenotype is yet to be established. In the case being reported we describe oral cavity findings not documented in the literature.

Facial profile markers in second- and third-trimester fetuses with trisomy 18

OBJECTIVES

To evaluate nasal bone length (NBL), maxilla-nasion-mandible (MNM) angle, fetal profile (FP) line, prenasal thickness (PT), prenasal thickness to nasal bone length (PT:NBL) ratio and prefrontal space ratio (PFSR) as markers of trisomy 18 in the second and third trimesters of pregnancy.

METHODS

The NBL, MNM angle, FP line, PT, PT:NBL ratio and PFSR were measured retrospectively from stored two-dimensional images or three-dimensional volumes of trisomy-18 fetuses, and were compared with our previously reported normal ranges for euploid fetuses. Additional ultrasound findings were noted at initial routine second-trimester scan and at subsequent advanced ultrasound examination performed after referral for karyotyping.

RESULTS

A total of 43 trisomy-18 fetuses were included in the analysis. At initial examination, median gestational age was 21 + 2 weeks. NBL and PT were correlated with gestational age (P < 0.001), but the other markers were not. Mean NBL, MNM angle, PT, PT:NBL ratio and PFSR were 3.76 mm, 16.67°, 4.25 mm, 1.39 and 0.87, respectively. The FP line was zero (normal) in 53.7% of cases and negative (abnormal) in 46.3%. All markers were significantly associated with trisomy 18, with the PT:NBL ratio yielding the highest detection rate (88.4%) followed by NBL (83.7%), MNM angle (56.4%), FP line (46.3%), PT (27.9%) and the PFSR (20.5%) (for a 5% false-positive rate for the continuous variables). Various combinations of the four best markers (NBL, FP line, MNM angle and PT:NBL ratio) yielded detection rates of between 72% and 95%. Structural anomalies were not detected in 22% of fetuses at the initial scan and in 2% at the advanced scan.

CONCLUSIONS

The PT:NBL ratio and NBL are robust second- and third-trimester markers for trisomy 18. A negative FP line has a 0% false-positive rate and the potential to differentiate between trisomy 18 and Down syndrome, as in the latter the FP line is often positive. No major anomaly was observed at the initial scan in about a quarter of trisomy-18 fetuses, underlining the role of second-trimester facial marker evaluation.

Absent fetal nasal bone: what does it mean for the euploid fetus?

OBJECTIVES

Our purpose was to review the outcomes of singleton pregnancies in which an absent nasal bone was noted on first- or second-trimester sonography and aneuploidy was not present.

METHODS

We identified singleton pregnancies from 2005 to 2011 in which an absent nasal bone was noted on sonography, aneuploidy was excluded, and newborn examinations were available for review. Sonographic reports were reviewed for anomalies, growth, and amniotic fluid volume. Newborn records were reviewed for physical examinations, complications, and radiologic or genetic tests.

RESULTS

We identified 142 fetuses with a sonographic appearance of an absent nasal bone. We excluded 52 cases with aneuploidy and 33 in which newborn examination information was unavailable. Fifty-seven cases met inclusion criteria. For 3 euploid fetuses with an absent nasal bone on sonography, the presence of additional anomalies on second-trimester sonography ultimately signaled an adverse outcome: the presence of multiple congenital anomalies, a microdeletion syndrome, and a specific genetic diagnosis.

CONCLUSIONS

All cases with adverse outcomes had additional prenatal sonographic findings. For the remainder, normal newborn examination findings provide some reassurance, especially in the setting of otherwise normal second-trimester sonographic findings. A microarray as a test for microdeletion and duplication syndromes in this situation could be considered.

Sonographic markers for early diagnosis of fetal malformations

Fetal malformations are very frequent in industrialized countries. Although advanced maternal age may affect pregnancy outcome adversely, 80%-90% of fetal malformations occur in the absence of a specific risk factor for parents. The only effective approach for prenatal screening is currently represented by an ultrasound scan. However, ultrasound methods present two important limitations: the substantial absence of quantitative parameters and the dependence on the sonographer experience. In recent years, together with the improvement in transducer technology, quantitative and objective sonographic markers highly predictive of fetal malformations have been developed. These markers can be detected at early gestation (11-14 wk) and generally are not pathological in themselves but have an increased incidence in abnormal fetuses. Thus, prenatal ultrasonography during the second trimester of gestation provides a “genetic sonogram”, including, for instance, nuchal translucency, short humeral length, echogenic bowel, echogenic intracardiac focus and choroid plexus cyst, that is used to identify morphological features of fetal Down’s syndrome with a potential sensitivity of more than 90%. Other specific and sensitive markers can be seen in the case of cardiac defects and skeletal anomalies. In the future, sonographic markers could limit even more the use of invasive and dangerous techniques of prenatal diagnosis (amniocentesis, etc.).

Prenatal diagnosis of i(18q) and dup(18q) cases by quantitative fluorescent PCR

Particular sonographic fetal malformations are common in chromosome 18 aberrations, requiring invasive prenatal tests to confirm the diagnosis. Karyotyping is the gold standard assay in these cases, although it is a high complexity, expensive and approximately 2 weeks turnaround time test. On the contrary, quantitative fluorescent PCR is considered an accurate, simple, low cost and rapid assay, particularly useful for the diagnosis of aneuploidies of chromosomes 13, 18 and 21 and for the detection of maternal cell contamination of the sample. Clinical presentation of two cases of rare chromosome 18 defects, diagnosed using both techniques. One case was an isochromosome and the other was a partial duplication. Quantitative fluorescent PCR was an invaluable tool for the cytogenetics laboratory.

The trisomy 18 syndrome

The trisomy 18 syndrome, also known as Edwards syndrome, is a common chromosomal disorder due to the presence of an extra chromosome 18, either full, mosaic trisomy, or partial trisomy 18q. The condition is the second most common autosomal trisomy syndrome after trisomy 21. The live born prevalence is estimated as 1/6,000-1/8,000, but the overall prevalence is higher (1/2500-1/2600) due to the high frequency of fetal loss and pregnancy termination after prenatal diagnosis. The prevalence of trisomy 18 rises with the increasing maternal age. The recurrence risk for a family with a child with full trisomy 18 is about 1%. Currently most cases of trisomy 18 are prenatally diagnosed, based on screening by maternal age, maternal serum marker screening, or detection of sonographic abnormalities (e.g., increased nuchal translucency thickness, growth retardation, choroid plexus cyst, overlapping of fingers, and congenital heart defects ). The recognizable syndrome pattern consists of major and minor anomalies, prenatal and postnatal growth deficiency, an increased risk of neonatal and infant mortality, and marked psychomotor and cognitive disability. Typical minor anomalies include characteristic craniofacial features, clenched fist with overriding fingers, small fingernails, underdeveloped thumbs, and short sternum. The presence of major malformations is common, and the most frequent are heart and kidney anomalies. Feeding problems occur consistently and may require enteral nutrition. Despite the well known infant mortality, approximately 50% of babies with trisomy 18 live longer than 1 week and about 5-10% of children beyond the first year. The major causes of death include central apnea, cardiac failure due to cardiac malformations, respiratory insufficiency due to hypoventilation, aspiration, or upper airway obstruction and, likely, the combination of these and other factors (including decisions regarding aggressive care). Upper airway obstruction is likely more common than previously realized and should be investigated when full care is opted by the family and medical team. The complexity and the severity of the clinical presentation at birth and the high neonatal and infant mortality make the perinatal and neonatal management of babies with trisomy 18 particularly challenging, controversial, and unique among multiple congenital anomaly syndromes. Health supervision should be diligent, especially in the first 12 months of life, and can require multiple pediatric and specialist evaluations.

Absent mandibular gap in the retronasal triangle view: a clue to the diagnosis of micrognathia in the first trimester

OBJECTIVE

To describe a new ultrasound technique that may be useful for the diagnosis of micrognathia in the first trimester of pregnancy.

METHODS

The retronasal triangle (RNT) view is a technique that captures the coronal plane of the face in which the primary palate and the frontal processes of the maxilla are visualized simultaneously. Normal first-trimester fetuses display a characteristic gap between the right and left body of the mandible in this view (the 'mandibular gap'). The presence or absence of this gap was evaluated and measured prospectively during real-time scanning (n = 154) and retrospectively by analyzing three-dimensional (3D) datasets (n = 50) in normal first-trimester fetuses undergoing screening for aneuploidy at 11-13 weeks' gestation. 3D datasets from 12 fetuses with suspected micrognathia were also collected and examined retrospectively for the same features.

RESULTS

The mandibular gap was identified in all 204 normal fetuses and increased linearly with increasing crown-rump length (y = 0.033x + 0.435; R(2) = 0.316), with no statistically significant differences between measurements obtained by two-dimensional ultrasound and 3D offline analysis. Among fetuses with suspected micrognathia, three 3D datasets were excluded from analysis because of poor image quality in one and the diagnosis of a normal chin in two. In the remaining nine fetuses, the mandibular gap was absent and was replaced by a bony structure representing the receding chin in seven (77.8%) cases and was not visualized due to severe retrognathia in the remaining two (22.2%) cases. All fetuses with micrognathia had associated anomalies, including seven with aneuploidy and two with skeletal dysplasia.

CONCLUSIONS

The RNT view may be a helpful technique for detecting micrognathia in the first trimester. The absence of the mandibular gap or failure to identify the mandible in this view is highly suggestive of micrognathia and should prompt a targeted ultrasound scan to assess for other anomalies. Further research is needed to determine the false-positive and false-negative rates of this technique.

Diagnosis of fetal limb abnormalities before 15 weeks: cause for concern

OBJECTIVES

The purposes of this study were (1) to identify cases of limb abnormalities identified before 15 weeks and correlate with outcomes and (2) to assess first-trimester nuchal translucency examinations to determine how frequently the upper and lower limbs were identified.

METHODS

A retrospective review was conducted of sonographic studies up to 15 weeks' gestational age from 2003 to 2010 at our high-risk fetal center. Data were collected regarding fetal gestational age, limb abnormalities, associated anatomic abnormalities, pregnancy outcomes, karyotypes, autopsy results, and the utility of transabdominal sonography, transvaginal sonography, and 3-dimensional sonography. A retrospective analysis of 100 consecutive first-trimester examinations was also conducted to assess the sensitivity of transabdominal sonography in visualization of limb buds.

RESULTS

A total of 15 cases were identified with a mean gestational age of 12 weeks 6 days. Club hand was the most common abnormality seen (8 cases), followed by absence of long bones (5 cases), a missing limb (5 cases), club foot (5 cases), shortening of long bones (2 cases), abnormal hands (2 cases), clenched hands (2 cases), and overlapping digits (1 case). Trisomy 18 was present in 9 cases. Transabdominal sonography allowed for detection of all limb buds in 100 consecutive nuchal translucency examinations and 9 of 15 cases of limb abnormalities. Four of the cases resulted in fetal death, and the remaining 11 cases were terminated.

CONCLUSIONS

Fetal limb abnormalities can be detected on sonography before 15 weeks' gestational age and are often associated with serious congenital conditions, especially trisomy 18. Transabdominal sonography alone can show most of these abnormalities, although transvaginal and 3-dimensional sonography can provide additional information. Targeted evaluation of fetal limbs during sonography before 15 weeks should be considered in high-risk populations.