Triploidy: antenatal sonographic features with post-mortem correlation

Are non-invasive or minimally invasive autopsy techniques for detecting cause of death in prenates, neonates and infants accurate? A systematic review of diagnostic test accuracy

OBJECTIVES

To assess the diagnostic accuracy of non-invasive or minimally invasive autopsy techniques in deaths under 1 year of age.

DESIGN

This is a systematic review of diagnostic test accuracy. The protocol is registered on PROSPERO.

PARTICIPANTS

Deaths from conception to one adjusted year of age.

SEARCH METHODS

MEDLINE (Ovid), EMBASE (Ovid), CINAHL (EBSCO), the Cochrane Library, Scopus and grey literature sources were searched from inception to November 2021.

DIAGNOSTIC TESTS

Non-invasive or minimally invasive diagnostic tests as an alternative to traditional autopsy.

DATA COLLECTION AND ANALYSIS

Studies were included if participants were under one adjusted year of age, with index tests conducted prior to the reference standard.Data were extracted from eligible studies using piloted forms. Risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies-2. A narrative synthesis was conducted following the Synthesis without Meta-Analysis guidelines. Vote counting was used to assess the direction of effect.

MAIN OUTCOME MEASURES

Direction of effect was expressed as percentage of patients per study.

FINDINGS

We included 54 direct evidence studies (68 articles/trials), encompassing 3268 cases and eight index tests. The direction of effect was positive for postmortem ultrasound and antenatal echography, although with varying levels of success. Conversely, the direction of effect was against virtual autopsy. For the remaining tests, the direction of effect was inconclusive.A further 134 indirect evidence studies (135 articles/trials) were included, encompassing 6242 perinatal cases. The addition of these results had minimal impact on the direct findings yet did reveal other techniques, which may be favourable alternatives to autopsy.Seven trial registrations were included but yielded no results.

CONCLUSIONS

Current evidence is insufficient to make firm conclusions about the generalised use of non-invasive or minimally invasive autopsy techniques in relation to all perinatal population groups.PROSPERO registration numberCRD42021223254.

Fetal Hand Abnormalities in the First-Trimester Scan: A Report of Two Cases

Two cases of fetal hand abnormalities are presented in this report. The first one is a case of unilateral fetal syndactyly detected in the first trimester routine scan, resulting in the early diagnosis of a severe genetic condition by invasive testing and early termination of pregnancy. By doing so, we ensured that the woman was managed in the most appropriate way. In the second case, we describe a fetus with bilateral hand polydactyly, which was combined with a cardiac defect - incompatible with extrauterine life. This was once again diagnosed during the first trimester scan. An uncomplicated termination of pregnancy was achieved in the first trimester of pregnancy.

Prenatal diagnosis of genetic aberrations in fetuses with short femur detected by ultrasound: A prospective cohort study

OBJECTIVES

To investigate the genetic aberrations in fetuses with short femur and explore the relationships with respect to degree of femoral shortening and the initial diagnostic gestational age GA.

METHODS

Singleton pregnancies with fetal short femur who consented to amniocentesis and to single nucleotide polymorphism (SNP) array and Sanger sequencing for G380R mutations in FGFR3 gene were enrolled in this 5-year period prospective study. Clinical follow-up assessments were performed after birth.

RESULTS

Of a total of 161 fetuses, the prevalence of genetic aberrations was 16.2% (26/161), comprised of 65.4% (17/26) with chromosomal abnormalities and 34.6% (9/26) with G380R mutations. All fetuses with chromosomal abnormalities had FL 2-4SDs below GA. Fewer chromosomal abnormalities were detected in fetuses with short femurs presenting in the third trimester. Significantly more FGFR3 mutations were detected in fetuses with FL below -4SDs. All fetuses with FL 2-4SDs below GA diagnosed as achondroplasia were between 22 and 24 gestational weeks, and all of those diagnosed in third trimester had FL below -4SDs.

CONCLUSION

In this small cohort study, we demonstrated that different degrees of femur shortness may be attributed to different genetic aberrations. SNP array should be regarded as the first-tier test for fetuses with FL 2-4SDs below GA. The prognoses for fetuses with FL 2-4SDs below GA was significantly better than those with FL below 4SDs.

Triploid pregnancy-Clinical implications

Triploidy is a life-limiting genetic aberration resulting from an extra haploid set of chromosomes of paternal (diandric triploidy) or maternal origin (digynic triploidy). Triploidy affects around 1%-2% of all conceptions. The majority of cases is miscarried at early developmental stages. In consequence of genomic imprinting, parental origin affects the phenotype of triploid pregnancies as well as the prevalence and spectrum of related maternal complications. Distinctive ultrasound features of both triploid phenotypes as well as characteristic patterns of biochemical markers may be useful in diagnosis. Molecular confirmation of the parental origin allows to predict the risk of complications, such as gestational trophoblastic neoplasia, hyperthyroidism, hypertension, or preeclampsia associated with the paternal origin of triploidy. Diagnosis of partial hydatidiform mole associated with diandric triploidy is challenging especially in the first trimester pregnancy loss due to the limitations of both histopathology and ultrasound. We present important clinical aspects of triploid pregnancies and indicate unresolved issues demanding further studies.

Recurrent fetal triploidy: is there a genetic cause?

Triploidy is currently understood as a sporadic genetic disorder, with no recognisable risk of recurrence nor identifiable risk factors. In cases of triploidy, chances of thriving through the second trimester of fetal development are very slim, with most of these pregnancies ending as early miscarriage. We report a case of repeated triploid pregnancies in the same woman, from different fathers, achieving the second trimester of pregnancy; elective termination was decided in both cases, after an amniocentesis revealing a triploid karyotype. Both triploid pregnancies are described and compared; prenatal laboratorial markers, sonographic features, clinical course and pathological findings are analysed and matched with fetal autopsy and placental pathological study. Reported findings strongly point to recurrent triploidy of maternal origin, and so the possibility of a genetic predisposition should be considered. Investigation is required to assess the presence of an underlying genetic mechanism in this setting, thus enabling a better genetic/obstetric counselling.

Triploidy in a Live-Born Extremely Low Birth Weight Twin: Clinical Aspects

Triploidy is a rare chromosomal aberration characterized by a karyotype with 69 chromosomes. Triploid fetuses usually are miscarried in early pregnancy. We present a case of a triploid twin and a genetically unaffected co-twin, conceived through in vitro fertilization. A discordant growth was registered at 20 weeks of gestation. Cesarean section was performed at 355/7 gestational week. The second twin was extremely growth restricted female (780 g) with oligohydramnios and severe respiratory distress, and died at 20 hours of age. The autopsy revealed unilobar left lung, bilobar right lung, and cysts of the terminal bronchioles. Quantitative fluorescent polymerase chain reaction detected triploidy compatible pattern. So, early intrauterine growth restriction may be a sign of triploidy, which must be proven by pre or postnatal genetic testing.

Prenatal sonographic features can accurately determine parental origin in triploid pregnancies

Objective

To describe the prenatal sonographic features and maternal biochemical markers in triploid pregnancies and to assess whether prenatal phenotype can determine genetic origin.

Methods

We performed a retrospective multicenter cohort study that included all triploid pregnancies diagnosed between 2000 and 2018 in two Fetal Medicine Units in Amsterdam. Fetal growth, presence of structural anomalies, extra‐fetal anomalies, and maternal biochemical markers were retrieved. Asymmetrical intrauterine growth restriction was diagnosed when the head‐to‐abdominal circumference (HC/AC) ratio was >95th centile. Parental origin was analyzed via molecular genotyping in 46 cases (38.3%).

Results

One hundred and twenty triploid pregnancies were identified, of which 86 cases (71.6%) were detected before 18 weeks of gestation. Triploidy of maternal origin was found in 32 cases (69.6%) and was associated with asymmetrical growth restriction, a thin placenta, and low pregnancy‐associated plasma protein A and free beta‐human chorionic gonadotrophin (β‐hCG) levels. Triploidy of paternal origin was found in 14 cases (30.4%) and was associated with an increased nuchal translucency, placental molar changes, and a high free β‐hCG. Prospective prediction of the parental origin of the triploidy was made in 30 of the 46 cases based on phenotypical ultrasound presentation, and it was correct in all cases.

Conclusion

Asymmetrical growth restriction with severe HC/AC discrepancy is pathognomonic of maternal triploidy. Placental molar changes indicate a paternal triploidy. Moreover, triploidy can present with an abnormal first trimester combined test, with serum levels on the extreme end. When available results of maternal serum markers can support the diagnosis of parental origin of the triploidy, an accurate assessment of the parental origin based on prenatal sonographic features is possible, making DNA analysis redundant.

Digynic triploidy in a fetus presenting with semilobar holoprosencephaly

OBJECTIVE

We present digynic triploidy in a fetus with semilobar holoprosencephaly (HPE).

CASE REPORT

A 32-year-old, gravid 1, para 0, woman underwent prenatal ultrasound examination at 12 weeks of gestation, and the ultrasound showed relative macrocephaly, a small non-cystic placenta, and a fetus with absent nasal bone and semilobar HPE. The pregnancy was terminated subsequently, and a 50-g fetus was delivered with a relatively enlarged head and premaxillary agenesis. The placenta was small and non-cystic. Postnatal cytogenetic analysis of the umbilical cord revealed a karyotype of 69, XXX. Postnatal DNA marker analysis using quantitative fluorescent polymerase chain reaction assays and the polymorphic short tandem repeat markers for chromosome 18 and 20 on the placental tissues showed a diallelic pattern with a dosage of 1:2 (paternal allele to maternal allele ratio), indicating a maternal origin of the triploidy.

CONCLUSION

Fetuses with digynic triploidy may present relative macrocephaly, semilobar HPE and a small placenta on prenatal ultrasound.

Triploid twin gestation with single fetal demise associated with partial mole and pre-eclampsia

Both partial mole and twin gestation are conditions associated with the risk of the early onset of pre-eclampsia. In cases of twin gestation, the death or selective termination of a severely growth-restricted fetus may lead to the reversal of maternal pre-eclampsia because of the involution or death of the pathological placenta, as has been reported by some authors. This case demonstrates that in a twin triploid gestation, in spite of the demise of one of the fetuses, the respective partial molar placenta can continue to grow and may contribute to the development or to the worsening of the pre-eclampsia.

Triploidy: Variation of Phenotype

OBJECTIVES

Triploidy (69, XXX; 69, XXY; 69, XYY) accounts for 1% of conceptions, but the affected fetus often does not survive past the first trimester. Fetal development in triploidy is rare. A consecutive series was used to describe the fetal and placental phenotypes and compare them with previous publications.

METHODS

Fifty-four triploid fetuses were identified in the Active Malformations Surveillance Program between 1972 and 2012 at Brigham and Women's Hospital in Boston. The phenotype was described from prenatal imaging and autopsy findings.

RESULTS

The diagnosis was confirmed by chromosome analysis in 53 of the 54 fetuses. Twenty-seven (50%) of the affected fetuses were identified during pregnancy. The abnormalities identified by prenatal ultrasound included renal malformations, heart defects, hydrocephalus, holoprosencephaly, and myelomeningocele. At autopsy, syndactyly, usually between fingers 3 and 4, was identified in 37 (69%) of the fetuses. Thirteen (24%) of the infants had the histologic features of a partial hydatidiform mole in the placenta.

CONCLUSIONS

The presence of major malformations and growth restriction during pregnancy makes triploidy a potential diagnosis. There are no obligate clinical features in triploidy. Syndactyly, especially 3-4 syndactyly of the hands, is a distinctive feature. Cystic changes in the placenta can be seen by ultrasound during pregnancy. There was no difference in the phenotype between triploid infants associated with partial moles and those with nonmolar placentas.

Prenatal diagnosis of amniotic band syndrome - risk factors and ultrasonic signs

OBJECTIVE

The aim of this study was to describe our experience with amniotic band syndrome (ABS), define specific sonographic characteristics and common features.

METHODS

Patients diagnosed with ABS underwent detailed ultrasound evaluation at the time of diagnosis and during follow-up. Their ultrasound examinations and medical records concerning the current pregnancy and past medical records were analyzed.

RESULTS

Ten pregnancies were diagnosed with ABS. Most pregnancies were diagnosed at the beginning of the second trimester. Two cases were bichorionic twin pregnancies involving one of the fetuses and these were the only women who continued their pregnancies to term. The other eight cases with ABS chose to terminate their pregnancies. One pregnancy was conceived following trachelectomy. We found a significantly higher rate of prior uterine surgeries (p = 0.008) in patient with ABS compared to control. In three cases, all above 15 weeks of gestation, a small vestige at the distal part of the amputated limb was observed.

CONCLUSIONS

ABS diagnosed in early pregnancy can be a sporadic event. However, there is a higher risk of ABS in pregnancies preceded by uterine procedures. The ultrasonic vestige sign at the amputated limb may contribute to the diagnosis of ABS.

Chromosomal abnormalities associated with neural tube defects (I): full aneuploidy

Fetuses with neural tube defects (NTDs) carry a risk of chromosomal abnormalities. The risk varies with maternal age, gestational age at diagnosis, association with other structural abnormalities, and family history of chromosome aberrations. This article provides an overview of chromosomal abnormalities associated with NTDs in embryos, fetuses, and newborn patients, and a comprehensive review of numerical chromosomal abnormalities associated with NTDs, such as trisomy 18, trisomy 13, triploidy, trisomy 9, trisomy 2, trisomy 21, trisomy 7, trisomy 8, trisomy 14, trisomy 15, trisomy 16, trisomy 5 mosaicism, trisomy 11 mosaicism, trisomy 20 mosaicism, monosomy X, and tetraploidy. NTDs may be associated with aneuploidy. Perinatal identification of NTDs should alert one to the possibility of chromosomal abnormalities and prompt a thorough cytogenetic investigation and genetic counseling.

The second trimester genetic sonogram

The genetic sonogram, a fetal anatomic survey targeted at identifying features associated with aneuploidy, is carried out between 15 and 20 weeks' gestation. It has evolved as an adjunctive screening tool capable of further refining the individualized risk-calculation for trisomy that is based on maternal age or serum screening markers. The significance of a range of major structural anomalies and so-called "soft-markers" for trisomy, detected both in isolation and in combination, has been widely investigated. This review serves to describe the key components of the second trimester genetic sonogram and to illustrate how these markers are integrated into risk assessment for aneuploidy.

First-trimester screening for fetal triploidy at 11 to 14 weeks: a role for fetal biometry

OBJECTIVE

Intrauterine growth restriction in triploidy has been reported as early as in the first trimester. This study was undertaken to evaluate the ability of first-trimester crown rump length (CRL)-based charts to detect triploid fetuses.

MATERIAL AND METHODS

Analysis of fetal biometry in cases of triploidy diagnosed in the first trimester over the last three years. Biometry for abdominal circumference (AC), head circumference (HC) and biparietal diameter (BPD) was analyzed in relation to both gestational age (GA)-based charts and to CRL-based charts.

RESULTS

Five cases of fetal triploidy were diagnosed at 11 to 14 weeks. Screening based on nuchal translucency (NT) and maternal age showed a risk > 1/300 in only one of the 5 cases of triploid fetus. In all of these five cases, CRL-based biometry was grossly abnormal, although it was abnormal in only two of these five cases in relation to GA-based charts.

CONCLUSION

First-trimester CRL-based biometry charts seem to reflect early asymmetrical growth delay in triploidy more accurately than GA-based charts. CRL-based biometry is likely to improve the early detection of triploid pregnancies without leading to dating error.

Pre- and postnatal diagnosis of limb anomalies: A series of 107 cases

This is a 3-year retrospective study of 107 cases presenting with limb anomalies detected either on prenatal ultrasound scan, or after birth. These limb malformations are developmental anomalies, and can be isolated, syndromic, or associated with multiple malformations. Cases were ascertained through the prenatal diagnosis center, the pediatrics department, and the feto-pathology department. Several criteria were analyzed including sex ratio, prenatal diagnosis, karyotype, termination of pregnancies, clinical or pathological examination, pediatric or surgical and/or genetic assessment, and whether or not a diagnosis was made. Positional deformities and syndactyly were excluded. Limb anomalies were detected prenatally in 45% of the cases, and a diagnosis was made in 78%, including isolated, syndromic, or chromosomal anomalies. Sixty-one per cent of the infants had follow-up, either pediatric, surgical, or genetic. Prenatal multidisciplinary assessment is fundamental to assist with counseling, as is the post-natal follow-up of the infant. The diagnosis, if made, will obviously influence the information that will be given to the parents and the management of the malformation. If the pregnancy is terminated, feto-pathological examination is essential to help make a diagnosis, and guide recurrence risks. We are currently undertaking a prospective study, and we will develop a protocol of investigations in the future, depending on the type of the malformation identified.

Second trimester ultrasound screening for chromosomal abnormalities

The use of prenatal ultrasound has proven efficacious for the prenatal diagnosis of chromosomal abnormalities. The first sonographic sign of Down syndrome, the thickened nuchal fold, was first described in 1985. Since that time, multiple sonographically-identified markers have been described as associated with Down syndrome. The genetic sonogram, involving a detailed search for sonographic signs of aneuploidy, can be used to both identify fetuses at high risk for aneuploidy and, when normal, can be used to decrease the risk for aneuploidy for a pregnancy when no sonographic markers are identified. Combining the genetic sonogram with maternal serum screening may be the best method of assessing aneuploidy risk for women who desire such an assessment in the second trimester. Trisomy 18, Trisomy 13, and triploidy are typically associated with sonographically identified abnormalities and have a high prenatal detection rate. The use of the described sonographic signs in low-risk women requires further investigation, however, patients at increased risk for aneuploidy due to advanced maternal age or abnormal serum screening can benefit from a genetic sonogram screening for sonographic signs of aneuploidy to adjust their baseline risk of an affected fetus.

Partial hydatidiform mole: clinicopathological features, differential diagnosis, ploidy and molecular studies, and gold standards for diagnosis

Partial hydatidiform mole is optimally diagnosed histopathologically when four microscopic features coexist: 1) two populations of villi, 2) enlarged villi (> or = 3-4 mm) with central captivation, 3) irregular villi with geographic, scalloped borders with trophoblast inclusions, and 4) trophoblast hyperplasia (usually focal and involving syncytiotrophoblast). Pathologic mimics of partial mole include Beckwith-Wiedemann syndrome, placental angiomatous malformation, twin gestation with complete mole and existing fetus, early complete hydatidiform mole, and hydropic spontaneous abortion. Because partial hydatidiform mole results from diandric triploidy, flow cytometry (or another method to assess ploidy) can be utilized by pathologists for supporting diagnostic classification of problematic specimens, or for educational or quality assurance purposes. Confirmation of the histopathologic diagnosis by ploidy or molecular studies is important for scientific reports of partial hydatidiform mole, especially when unusual or aggressive outcomes (such as choriocarcinoma) are reported.

Sonographic markers of fetal aneuploidy

A variety of ultrasound findings can be identified in fetuses with fetal aneuploidy. Typical findings vary with both the chromosome abnormality and gestational age at time of the ultrasound examination. Increased NT is the primary marker during the first trimester, whereas a variety of markers may be seen during the second trimester. The presence of ultrasound markers increases the risk for fetal aneuploidy, whereas a normal ultrasound reduces the risk. Optimal risk assessment includes consideration of other risk factors including maternal age, family history, and biochemical markers. It is expected that combined risks, incorporating ultrasound findings and biochemistry, will be available in the near future. How first-trimester screening is integrated with second-trimester screening remains to be determined.