Early prenatal diagnosis of skeletal anomalies

A Sporadic Case of COL1A1 Osteogenesis Imperfecta: From Prenatal Diagnosis to Outcomes in Infancy-Case Report and Literature Review

Osteogenesis imperfecta (OI), also known as brittle bone disease, belongs to a rare heterogeneous group of inherited connective tissue disorders. In experienced prenatal centers, severe cases of OI can be suspected before birth from the first trimester prenatal ultrasound screening. In this article, we describe a case report of OI suspected at the 26th week of gestation and the patient's outcomes in infancy one year after birth, as well as compare our case to other prenatally or soon-after-birth suspected and/or diagnosed OI clinical case reports in the literature. This case was managed by a multidisciplinary team. In this clinical case, OI was first suspected when prenatal ultrasound revealed asymmetric intrauterine growth restriction and skeletal dysplasia features. The diagnosis was confirmed after birth using COL1A1 gene variant detection via exome sequencing; the COL1A1 gene variant causes OI types I-IV. The familial history was negative for both pregnancy-related risk factors and genetic diseases. At one year old, the patient's condition remains severe with bisphosphonate therapy.

Congenital Limb Defects: A Retrospective Cohort Study and Overview of the Literature

PURPOSE

Congenital limb defects are common malformations that are often associated with other organ defects and genetic disorders. Since prenatal detection is challenging and classification is often complex, the aim of this study was to describe a large cohort of fetuses with congenital limb defects and to identify characteristics that are essential for prenatal evaluation, counselling, and management.

MATERIALS AND METHODS

In this retrospective cohort study, all cases of confirmed fetal limb defects from two centers for prenatal ultrasound between 2001 and 2021 were evaluated. Cases with skeletal dysplasia were excluded from this study. Demographic data, association with genetic disorders, and correlation with maternal parameters were analyzed statistically.

RESULTS

170 fetuses were included in this study. 60% were diagnosed with a reduction anomaly and 40% with a duplication anomaly. The majority of fetuses were male, and in 73.5% of all cases, additional malformations were present. Among the genetic causes, trisomy 13 and 18 were the most common in this cohort.

CONCLUSION

Congenital limb malformations are important markers for complex fetal disorders that warrant referral to specialists in prenatal ultrasound. To improve prenatal detection, care should be taken to visualize all fetal extremities already in early pregnancy.

Does isolated nuchal translucency from 2.5 to 2.9 mm increase the risk of fetal chromosome disease?

Increased fetal nuchal translucency (NT) is a common ultrasonic manifestation during pregnancy. Many studies have confirmed that NT ≥ 3 mm is a high risk factor for adverse pregnancy outcome. However, when NT is between 2.5 and 2.9 mm, will it increase the risk of fetal chromosome abnormalities and other diseases? What is the most appropriate method for prenatal chromosome evaluation? At present, it has not been widely reported in the literature, and the conclusion is also controversial. This prospective cohort study included fetal samples from women who underwent amniocentesis from 2017 to 2020. The samples of the experimental group were fetuses with NT ≥ 2.5 mm at 11 to 13 + 6 weeks of gestation, with or without ultrasonographic anomaly. The control group contained fetal NT < 2.5 mm without ultrasonographic anomalies. All amniotic fluid samples were tested by copy number variants sequencing. In 262 fetal samples with isolated NT from 2.5 to 2.9 mm, the detection rate of aneuploidy was 3.4% (9/262), and the risk of aneuploidy was significantly higher than that of the control group (1.4%, 32/2331) (relative risk 2.5, 95% CI 1.2-5.2). The detection rates of other pathogenic/likely pathogenic copy number variants in the two groups were 0.8% (2/262) and 1.3% (31/2331), respectively, which was not statistically significant (relative risk 0.6, 95% CI 0.1-2.4). Our results showed that isolated NT from 2.5 to 2.9 mm increased the risk of fetal chromosome aneuploidy. Therefore, noninvasive prenatal screening is recommended as the first choice for prenatal chromosome evaluation in this population.

Increased nuchal translucency after low-risk noninvasive prenatal testing: What should we tell prospective parents?

Three decades ago, the observation that first trimester fetuses with excess fluid accumulation at the back of the neck were more likely to be aneuploid, gave rise to a new era of prenatal screening. The nuchal translucency (NT) measurement in combination with serum biomarkers and maternal age, resulted in the first trimester combined screening (FTCS) program. The introduction of noninvasive prenatal testing (NIPT) over the past decade has introduced the option for parents to receive highly sensitive and specific screening information for common trisomy from as early as 10 weeks gestation, altering the traditional pathway FTCS pathway. The retention of the 11-13-week NT ultrasound remains important in the detection of structural anomalies; however, the optimal management of pregnancies with a low-risk NIPT result and an isolated increased NT measurement in an era of advanced genomic testing options is a new dilemma for clinicians. For parents, the prolonged period between the initial diagnosis in first trimester, and prognostic information at each successive stage of investigations up to 22-24 weeks, can be emotionally challenging. This article addresses the common questions from parents and clinicians as they navigate the uncertainty of having a fetus diagnosed with an increased NT after a low-risk NIPT result and presents suggested approaches to management.

Prenatal genetic diagnosis of cranioectodermal dysplasia in a Polish family with compound heterozygous variants in WDR35

The ciliary chondrodysplasias represent a group of clinically and genetically heterogeneous disorders that affect skeleton development. Cilia are organelles that project from the surface of many cell types and play an important role during prenatal and postnatal human development. Cranioectodermal dysplasia (Sensenbrenner syndrome, CED) is a ciliopathy primarily characterized by craniofacial, skeletal, and ectodermal abnormalities. To date six genes have been associated with CED: IFT122, WDR35, WDR19, IFT140, IFT43, and IFT52. Prenatal diagnosis of CED is challenging, and genetic testing can facilitate making a correct diagnosis. Here, we report on a family with two male siblings affected by CED: a 3.5 year-old patient and his 2 year-old brother. Molecular analysis of the proband at 1 year of age revealed compound heterozygous variants in WDR35: c.3G>A [p.(Met1-Ala30delinsMetfsTer4)] and c.2522A>T [p.(Asp841Val)]. Ultrasound examination during the second pregnancy revealed an increased nuchal translucency of 4.5 mm and a hypoplastic nasal bone at 12 weeks of gestation. Prenatal diagnostic testing was offered because of an increased risk for chromosomal abnormalities and recurrence risk for CED. Prenatal genetic analysis of a chorionic villus sample detected the WDR35 variants previously identified in the elder brother. This is the first report of a prenatal genetic diagnosis in CED.

Noninvasive prenatal sequencing for multiple Mendelian monogenic disorders among fetuses with skeletal dysplasia or increased nuchal translucency

OBJECTIVES

To evaluate the performance of noninvasive prenatal sequencing for multiple Mendelian monogenic disorders (NIPS-M) among fetuses with skeletal abnormalities or increased nuchal translucency (NT).

METHODS

Pregnancies with fetal skeletal abnormalities or increased NT (≥3.0 mm) observed by ultrasonography were recruited between October 2017 and March 2019. Parental blood from 13 couples were collected for NIPS-M testing reported. All the NIPS-M results were followed up by invasive diagnostic testing or neonatal examination.

RESULTS

Among the 13 cases, 8 (61.5%) yielded positive results for pathogenic variants in the FGFR3, COL1A1, RAF1, PTPN11 and SOS1 genes by NIPS-M. One case was excluded for further analysis due to insufficient fetal DNA (<4.5%). De novo mutations were reported in six of the eight positive cases (75%). The other two were inconclusive as the pathogenic variants were detected in both plasma and genomic DNA of the mothers. The sensitivity of NIPS-M was 100%.

CONCLUSIONS

Our pilot study demonstrates that NIPS-M is an accurate approach for detection of multiple monogenic disorders among fetuses with skeletal abnormalities or increased NT. It serves as an alternative and highly sensitive method to provide valuable molecular information for these groups of women who are reluctant to undergo invasive procedure.

5-year experience of a tertiary center in major congenital abnormalities in singleton pregnancies

OBJECTIVE

To demonstrate major congenital abnormalities delivered or terminated at our institution between 2014 and 2018.

MATERIALS AND METHODS

Necessary information was retrieved from the registries of the delivery room and electronic database of Hacettepe University Hospital, Ankara.

RESULTS

This study was consisted of 307 major congenital anomalies. The incidence of major congenital anomalies was 2.9 per 1,000 live births, while the majority of the cases were related to cardiovascular, central nervous system, and diaphragmatic hernia with 97, 87, and 25 cases at each group, respectively. Rate of termination of pregnancy (TOP) and live birth were 35.1 and 59.2%, respectively. The overall infant mortality rate was 28.9% in cases with live birth, while this rate was highest in cardiovascular system abnormalities and diaphragmatic hernia. Out of 182 newborns, 92.8% admitted to the neonatal intensive care unit after the delivery. Median gestational week at TOP was 21(20).

CONCLUSION

We have shown that TOP and infant mortality rates were 35.1 and 28.9%, respectively in pregnancies with fetal malformations. Detailed multidisciplinary counseling must be provided for parents in pregnancies with major congenital abnormalities.

Prenatal diagnosis of Desbuquois dysplasia type 1 by whole exome sequencing before the occurrence of specific ultrasound signs

Desbuquois dysplasia is a very severe and sometimes lethal form of osteochondrodysplasia characterized by prenatal onset of severe micromelic short stature, joint laxity with multiple joint dislocations, specific radiographic features, and facial dysmorphism. Here, we report a case for which whole exome sequencing allowed early prenatal diagnosis of Desbuquois dysplasia before the detection of characteristic ultrasound signs of the disease.

Thanatophoric dysplasia type 1 with tectal plate dysplasia and aqueductal stenosis

INTRODUCTION

Skeletal dysplasias are a heterogeneous group of disorders comprising of more than 300 entities, many of which manifest in the prenatal period, emphasizing the importance of accurate prenatal diagnosis. Detection of a lethal skeletal dysplasia via prenatal ultrasound is often straightforward. However, establishing the specific diagnosis and detailed evaluation of intracranial anomalies are often challenging. Fetal magnetic resonance imaging (MRI) is superior to ultrasound in the detection of abnormal sulcation pattern, corpus callosal agenesis, and posterior fossa anomalies. Hence, it has the potential of delineating neuroimaging features that may not be fully elucidated by ultrasound. The objective of this article is to describe an unusual case of thanatophoric dysplasia (TD) with dysplastic tectal plate and resultant aqueductal stenosis diagnosed on fetal MRI. To the best of our knowledge, this has never been reported before in the literature. A comprehensive review of literature pertaining to TD-associated CNS abnormalities will also be included.

CONCLUSIONS

Our reported case adds to the current limited knowledge of this rare entity and emphasizes the crucial role of fetal MRI in expanding the neuroimaging phenotypes of TD.

A full-term infant with type II thanatophoric dysplasia

Objectives

To report a neonate with clinical findings consistent with thanatophoric dysplasia (TD). Only a few cases of this rare and lethal skeletal disorder have been reported in South-East Asia.

Case presentation

A 37-year-old Asian female, fourth gravida at 39 weeks, presented to our hospital for an elective cesarean section due to polyhydramnios, frank breech and gestational hypertension. The father was a 42-year-old Asian male. There was no history of rashes, fever, alcohol intake, substance drug abuse, smoking habit or radiation exposure. Ultrasound (US) of 34-weeks’ gestation found a baby with frontal bossing, prominent temporal lobe, clover-skull and low nasal bridge. The thoracic diameter was smaller than the abdominal diameter. Short limbs without bowing were noted in femur and humeral bones. The patient delivered a baby boy, 4115 g, APGAR scores were 5 and 7 at 1 and 5 min. The baby had a dysmorphic face, frontal bossing, low nasal bridge, low-set ears and short neck. The thorax was narrow and abdomen was protuberant. The upper and lower proximal limbs appeared short. A chest X-ray revealed short, curved ribs and opacification of both lungs. He had respiratory distress shortly after birth and had persistent severe respiratory distress despite adequate mechanical ventilation. On the third day, he had cardiac arrest; resuscitation was not done due to family request. The baby was declared deceased due to cardiopulmonary failure related to his congenital anomaly.

Conclusions

Ultrasonography could readily indicate TD prenatally. The pregnancy can continue up to late third trimester without miscarriage. Most of the neonates die in utero; those who survive are dependent on ventilator.

Noninvasive prenatal test for FGFR3-related skeletal dysplasia based on next-generation sequencing and plasma cell-free DNA: Test performance analysis and feasibility exploration

OBJECTIVE

To explore the feasibility and accuracy of a noninvasive prenatal test for fibroblast growth factor receptor 3 (FGFR3)-related skeletal dysplasia based on next-generation sequencing (NGS) of plasma cell-free DNA.

METHOD

Fragmented genome DNA (gDNA) of fetuses with achondroplasia (ACH) and thanatophoric dysplasia type I (TD I) was mixed with postdelivery maternal plasma cell-free DNA to generate spiked samples of different modeled fetal fractions. Multiplex polymerase chain reaction was used to amplify the 19 FGFR3 loci, and the amplification products were then sequenced by NGS to detect the fetal mutant alleles. Then, maternal plasma samples of pregnant women carrying ACH (n = 4) and TD I fetuses (n = 2), as well as healthy controls (n = 15), were tested by NGS, and the test performance was evaluated.

RESULTS

Fetal FGFR3 mutations were detected in all artificial mixtures with fetal gDNA concentrations above 3%. In clinical validation, our method identified all fetal FGFR3 mutant alleles from maternal plasma, with no false positive results. The sensitivity and specificity of our method were 100% (95% CI, 54.1%-100%) and 100% (78.2%-100%), respectively.

CONCLUSION

Our method had a favorable performance for noninvasively detecting fetal FGFR3 mutations in maternal plasma, highlighting its promising value in developing a noninvasive prenatal test for de novo and paternally inherited disorders.

Prenatal diagnosis of skeletal dysplasias using a targeted skeletal gene panel

OBJECTIVE

This study aimed to perform an accurate and precise diagnosis for fetuses with suspected skeletal anomalies based on an incomplete and limited ultrasound phenotype.

METHODS

Proband-only targeted skeletal gene panel sequencing was performed on 12 families who had fetuses with suspected skeletal anomalies based on ultrasound evaluations at a mean gestational age of 24 weeks and 3 days. The fetuses all had normal standard genetic testing yield (karyotyping and microarray).

RESULTS

In 10 of 12 fetuses, panel sequencing provided a diagnosis or possible diagnosis with identification of variants in the following genes: FGFR3, COL1A2, IHH, COL2A1, and DYNC2H1. Two cases revealed novel variants in COL2A1 and DYNC2H1.

CONCLUSIONS

Our study suggests that targeted skeletal gene panel sequencing is highly sensitive for prenatal diagnosis of fetuses presenting with unexpected ultrasound findings suggestive of a skeletal dysplasia.

The impact of third-trimester genetic counseling

OBJECTIVE

To evaluate the impact of genetic counseling (GC) during the third trimester by analyzing changes in pregnancy management and the correlation with postnatal findings.

METHODS

This was a retrospective study. Pregnancy course and neonatal follow-up were analyzed according to the reason for referral and implementation of recommendations.

RESULTS

The records of neonates born to 181 women were retrieved. Fifty-two women (group 1-29%) qualified for pregnancy termination under Israeli guidelines and laws, and 129 (group 2-71%) were not at the time they were referred. By another division: 104 women (group 3-57%) followed the physician's diagnostic recommendations completely after counseling including amniocentesis, fetal MRI, targeted ultrasound scans, fetal echocardiography. Seventy-seven declined amniocentesis (group 4-43%). Additional abnormalities were detected postpartum in all groups without statistically difference: 3/52 (10%) in group 1, 9/129 (7%) in group 2, 6/104 (6%) in group 3, and 6/77 (8%) in group 4).

CONCLUSION

GC in the third trimester of pregnancy provided the couple with a sharper more focused picture and assisted them to perceive the significance of new, significant fetal findings which attest to the value of the GC.

Comparative X-ray morphometry of prenatal osteogenesis imperfecta type 2 and thanatophoric dysplasia: a contribution to prenatal differential diagnosis

OBJECTIVE

The purpose of the paper was to assess the morphometric parameters to improve the specificity of the ultrasound (US) signs for the early differential diagnosis between two lethal dysplasias, as thanatophoric dysplasia (TD) and osteogenesis imperfecta type 2 (OI-2).

METHOD

The diaphyseal length and the bowed shape of long bones associated with vertebral body dimension assessment were investigated in a group of 14 pregnancy terminations carried out in the time period 2007-2013. The definitive diagnosis was established after pregnancy termination by means of skeletal standardized X-rays, histopathology and gene analysis.

RESULTS

TD and OI-2 long bones were significantly shorter than controls. No significant differences were observed between the two dysplasias. The bowing angle was higher in OI-2; a true angulation or eventually axial displacement was present only in the latter. Furthermore, they did not show any evidence of vertebral collapse. The thanatophoric dysplasia presented less bowed long bones, and never true angulation. The spine was steadily characterized by flattened anterior vertebral bodies.

CONCLUSION

Long bone shortening is not a sufficient and accurate sign for early sonographic differential diagnosis between TD and OI-2. Angled diaphysis, axial diaphyseal displacement and a conserved vertebral body height in the prenatal period support the diagnosis of osteogenesis imperfecta type 2, while moderately regular bowed diaphysis associated with platyspondyly that of thanatophoric dysplasia.

A revisit of the fetal foot length and fetal measurements in early pregnancy sonography

Objectives

To present the fetal measurements in relation to the foot length at 10–16 weeks gestation on antenatal ultrasound.

Materials and methods

We reviewed the fetal measurements in 47 scans performed at 10–16 weeks gestation in women attending routine antenatal care. The fetal measurements and measurement ratios were examined in relation to the foot length.

Results

The fetal biparietal diameter, head circumference, abdominal circumference, femur length and foot length increase linearly with the gestational age at 10–16 weeks gestation. The correlation between fetal foot length and fetal biparietal diameter, head circumference, abdominal circumference and femur length are better than with the crown rump length. The femur length to foot length ratio and the femur length to abdominal circumference ratios increase with the gestational age in an inverse relationship throughout the same period.

Conclusion

Fetal foot length is an accurate estimate of the gestational age in early pregnancy. Compared with crown rump length, the correlation between foot length and other fetal measurements is better. The fetal measurements ratios are gestational age dependent between 10–16 weeks. Gestational age specific ratio should be used in this period.

A Case of Thanatophoric Dysplasia Type I with Fetal Hydrops in the First Trimester

During a routine prenatal exam, a 36-year-old female in her third pregnancy was diagnosed with fetal hydrops at 11 weeks of gestation. The pregnancy was monitored with periodic ultrasounds; however, spontaneous resolution was not observed. Amniotic fluid examination at 16 weeks of gestation showed a normal karyotype; however, macrocephaly, a narrow thorax, and shortening of the long bones were observed on ultrasonography. With the strong suspicion of a fetal skeletal disease, specifically thanatophoric dysplasia (TD), and after extensive genetic counseling, termination of the pregnancy was performed per the parents' wishes with mechanical cervical dilation and gemeprost (PGE1) administration. Following delivery, the fetus was found to have macrocephaly, a narrow bell-shaped thorax, and a protuberant abdomen, as well as curved long bones, H-shaped platyspondyly, and curved clavicles on skeletal radiography. As a result, the fetus was diagnosed with TD type I. This case illustrates that although TD is a rare disease, an accurate prenatal diagnosis can be made with the use of ultrasonography.

Stem cell transplantation before birth - a realistic option for treatment of osteogenesis imperfecta?

Osteogenesis imperfecta (OI) is characterized by severe bone deformities, growth retardation and bones that break easily, often from little or no apparent cause. OI is a genetic disorder primarily with defective type I collagen with a wide spectrum of clinical expression. In the more severe cases, it can be diagnosed before birth. Transplantation of mesenchymal stem cells (MSC) has the potential to improve the bone structure and stability, growth and fracture healing. Prenatal and postnatal cell transplantation has been investigated in preclinical and clinical studies of OI and suggests that this procedure is safe and has positive effects. Cell transplantation resulted in improved linear growth, mobility and reduced fracture incidence. However, the effect is transient and for this reason re-transplantation may be needed. So far there is limited experience in this area, and proper studies are required to accurately determine if MSC transplantation is of clinical benefit in the treatment of OI. In this review, we summarize what is currently known in this field.

Prenatal diagnosis of musculoskeletal conditions

Ultrasonography is a safe, cost-effective tool used to prenatally detect common musculoskeletal conditions, including clubfoot, skeletal dysplasias, limb-length discrepancies, spinal abnormalities, and hand and other upper extremity deformities. With increased detection of such abnormalities, prenatal parental counseling by orthopaedic surgeons is being requested more frequently. Counseling is important for family education on prognosis and treatment options. A thorough understanding of the common musculoskeletal conditions diagnosed on prenatal ultrasonography, classification of these conditions, and the correlations of these classifications to postnatal severity allows the orthopaedic surgeon to conduct well-informed counseling sessions with families. Accurate information and counseling aids parents in understanding their child's diagnosis, assists clinicians in planning treatment algorithms, and optimizes family preparedness.

Increased first-trimester nuchal translucency associated with thanatophoric dysplasia type 1

Thanatophoric dysplasia (TD) is the most frequent form of lethal skeletal dysplasia. Prenatal diagnosis is commonly accomplished in the second-trimester scan, but occasionally TD is found to be associated with increased nuchal translucency (NT) at first-trimester screening for aneuploidies. TD may not be clearly distinguished from the other skeletal dysplasias. A definite diagnosis can be established by molecular genetic analysis to find out the abnormal mutations in the fibroblast growth factor receptor 3 (FGFR3) gene. We reported a case of TD type 1 detected by first-trimester NT measurement, and confirmed by molecular analysis of FGFR3 gene using high-resolution melting analysis.

Prenatal Sonographic Detection of Skeletal Dysplasias

Skeletal dysplasias are a genetically heterogeneous group of disorders that can be diagnosed prenatally by sonography. Differentiating these disorders in the prenatal period can be difficult. However, differentiating known lethal disorders from nonlethal disorders can improve patient care and plan of action. This case study presents multiple pterygia, flexion contractures, and skeletal abnormalities, which are consistent with multiple pterygium syndrome, or Escobar syndrome.

Advances in evaluating the fetal skeleton

In this review, we discuss aspects of the prenatal diagnosis of fetal skeletal malformations, concentrating on the advantages offered by different imaging techniques and the approaches that are of value in evaluating a suspected skeletal dysplasia. We also briefly address the findings in some of the commoner malformations of the fetal skeleton that may be encountered.

Skeletal development on fetal magnetic resonance imaging

Prenatal magnetic resonance imaging (MRI) is being increasingly used, in addition to standard ultrasound, for the diagnosis of congenital diseases beyond the central nervous system. Previous studies have demonstrated that MRI may be useful for the in utero visualization of spinal dysraphism and for differentiating between isolated and complex skeletal disorders with associated abnormalities. More recently, attention has focused on the visualization of the human fetal skeleton for the delineation of normal and pathological development of skeletal structures. On 1.5 T, in particular, echoplanar imaging enables the delineation of various epimetaphyseal structures and morphometric measurements of the fetal long bones from 18 gestational weeks until term. This information gathered from prenatal MRI might be helpful in the diagnosis of focal bone abnormalities and generalized skeletal disorders, such as bone dysplasias. Further clinical research, along with the refinement of the newest techniques, will enable expansion of the preliminary findings and help in determining the impact of fetal magnetic resonance bone imaging in the routine clinical setting. This review summarizes the current data in the literature and the authors' clinical experience with the magnetic resonance visualization of the developing fetal skeleton and also comments on the potential future applications of this technique.

Improved detection rate of structural abnormalities in the first trimester using an extended examination protocol

OBJECTIVE

To assess the potential of first-trimester sonography in the detection of fetal abnormalities using an extended protocol that is achievable with reasonable resources of time, personnel and ultrasound equipment.

METHODS

This was a prospective two-center 2-year study of 5472 consecutive unselected pregnant women examined at 12 to 13 + 6 gestational weeks. Women were examined using an extended morphogenetic ultrasound protocol that, in addition to the basic evaluation, involved a color Doppler cardiac sweep and identification of early contingent markers for major abnormalities.

RESULTS

The prevalence of lethal and severe malformations was 1.39%. The first-trimester scan identified 40.6% of the cases detected overall and 76.3% of major structural defects. The first-trimester detection rate (DR) for major congenital heart disease (either isolated or associated with extracardiac abnormalities) was 90% and that for major central nervous system anomalies was 69.5%. In fetuses with increased nuchal translucency (NT), the first-trimester DR for major anomalies was 96%, and in fetuses with normal NT it was 66.7%. Most (67.1%) cases with major abnormalities presented with normal NT.

CONCLUSIONS

A detailed first-trimester anomaly scan using an extended protocol is an efficient screening method to detect major fetal structural abnormalities in low-risk pregnancies. It is feasible at 12 to 13 + 6 weeks with ultrasound equipment and personnel already used for routine first-trimester screening. Rate of detection of severe malformations is greater in early- than in mid-pregnancy and on postnatal evaluation. Early heart investigation could be improved by an extended protocol involving use of color Doppler.

Antenatal diagnosis and management of life-limiting conditions

Whereas structural fetal abnormalities are relatively frequent occurrences, many of these do not impact measurably on future life and/or are amenable to postnatal therapy. A small minority are considered to be potentially lethal or life-limiting. Examples include specific skeletal dysplasias, urinary tract abnormalities - typically those which lead to anhydramnios and pulmonary hypoplasia, some disorders of the central nervous system and trisomies 13 and 18. Without seeking to compile an exhaustive list of such conditions, we discuss the principles and new considerations in relation to antenatal diagnosis and perinatal management of such disorders.

Safe, accurate, prenatal diagnosis of thanatophoric dysplasia using ultrasound and free fetal DNA

Objective

To improve the prenatal diagnosis of thanatophoric dysplasia by defining the change in fetal size across gestation and the frequency of sonographic features, and developing non-invasive molecular genetic diagnosis based on cell-free fetal DNA (cffDNA) in maternal plasma.

Methods

Fetuses with a confirmed diagnosis of thanatophoric dysplasia were ascertained, records reviewed, sonographic features and measurements determined. Charts of fetal size were then constructed using the LMS (lambda-mu-sigma) method and compared with charts used in normal pregnancies and those complicated by achondroplasia. Cases in this cohort referred to our Regional Genetics Laboratory for molecular diagnosis using cffDNA were identified and results reviewed.

Results

Forty-two cases were scanned in our units. Commonly reported sonographic features were very short and sometimes bowed femora, frontal bossing, cloverleaf skull, short fingers, a small chest and polyhydramnios. Limb shortening was obvious from as early as 13 weeks' gestation, with minimal growth after 20 weeks. Analysis of cffDNA in three of these pregnancies confirmed the presence of the c.742C>CT (p.Arg248Cys) or the c.1948A>AG (p.Lys650Glu) mutation in the fibroblast growth factor receptor 3 gene.

Conclusion

These data should improve the accuracy of the sonographic diagnosis of thanatophoric dysplasia and have implications for reliable and safe targeted molecular confirmation using cffDNA. © 2013 The Authors. Prenatal Diagnosis published by John Wiley & Sons Ltd.

Early fetal anatomical sonography

Over the past decade, prenatal screening and diagnosis has moved from the second into the first trimester, with aneuploidy screening becoming both feasible and effective. With vast improvements in ultrasound technology, sonologists can now image the fetus in greater detail at all gestational ages. In the hands of experienced sonographers, anatomic surveys between 11 and 14 weeks can be carried out with good visualisation rates of many structures. It is important to be familiar with the normal development of the embryo and fetus, and to be aware of the major anatomical landmarks whose absence or presence may be deemed normal or abnormal depending on the gestational age. Some structural abnormalities will nearly always be detected, some will never be and some are potentially detectable depending on a number of factors.

Clubfeet and associated abnormalities on fetal magnetic resonance imaging

OBJECTIVE

Clubfoot, or talipes equinovarus (TEV), is commonly diagnosed on prenatal ultrasound. This study sought to visualize TEV and associated abnormalities on fetal magnetic resonance imaging (MRI) compared with ultrasound.

METHODS

This retrospective study included the MRI scans of 44 fetuses with TEV using postnatal assessment and autopsy as standard of reference. Isolated TEV was differentiated from complex TEV with associated abnormalities. MRI findings and previous ultrasound diagnoses were compared.

RESULTS

Isolated TEV was found in 19/44 (43.2%) fetuses and complex TEV in 25/44 (56.8%). Associated abnormalities consisted of the following: central nervous system/spinal abnormalities in 13/25 (52.0%) fetuses; musculoskeletal abnormalities in 7/25 (28.0%); thoracic abnormalities in 3/25 (12.0%); a tumor in one case; and hydrops fetalis in one. Of the 44 cases, 35 (79.5%) pregnancies were delivered, and nine (20.5%) pregnancies, which were terminated, all had complex TEV. Of the 42 available ultrasound reports, additional MRI findings were made in 8/42 (19.0%) cases. MRI did not add findings in isolated TEV on ultrasound. In 4/44 (9.1%) cases, autopsy revealed additional findings compared with prenatal imaging.

CONCLUSION

Fetal MRI enables differentiation between isolated and complex TEV. Isolated TEV on ultrasound may not be an MRI indication, whereas MRI may be useful in cases of complex TEV.