Osteogenesis imperfecta and other skeletal dysplasias presenting with increased nuchal translucency in the first trimester

Prenatal diagnosis of diaphanospondylodysostosis (DSD): a case report

We present a case of diaphanospondylodysostosis (DSD) which showed increased nuchal translucency at 1st trimester and missing ossification of the lower spine, short ribs with posterior gaps, and absent nasal bone in midtrimester. Autopsy revealed additionally bilateral nephroblastomatosis. Molecular genetic analysis showed a new mutation in the BMPER gene.

A case of fetal osteogenesis imperfecta type 2A: longitudinal observation of natural course in utero and pitfalls for prenatal ultrasound diagnosis

We present a case of osteogenesis imperfecta (OI) type 2A in which a natural course in utero was observed from 23 weeks' gestation to term. At 23 weeks' gestation, a sonographic examination showed a cloverleaf skull-like head, a narrow thorax, and marked shortening of the long bones with bowing of the femurs and humeri. Follow-up examinations showed that the cloverleaf skull-like head was not evident at 28 weeks' gestation. Discontinuity of the ribs and femurs was observed at 26 and 30 weeks' gestation, respectively. This finding suggested bone fractures, which were confirmed by three-dimensional computed tomography at 32 weeks' gestation. Ultrasonographic findings of bones, including the long bones and calvarium, changed with advancing gestation during the second trimester. Characteristic features of OI type 2A were evident during the late second to early third trimesters. Repeated ultrasonographic examinations together with three-dimensional computed tomography are necessary for the definitive diagnosis of OI type 2A in the second trimester.

Skeletal dysplasias

The skeletal dysplasias are a group of more than 450 heritable disorders of bone. They frequently present in the newborn period with disproportion, radiographic abnormalities, and occasionally other organ system abnormalities. For improved clinical care, it is important to determine a precise diagnosis to aid in management, familial recurrence, and identify those disorders highly associated with mortality. Long-term management of these disorders is predicated on an understanding of the associated skeletal system abnormalities, and these children are best served by a team approach to health care surveillance.

Use of fetal nuchal translucency in the first trimester to predict single-gene disorders

OBJECTIVE

To assess the predictive value of fetal nuchal translucency (NT) measurement in the prenatal diagnosis of single-gene disorders.

METHODS

From January 1996 to December 2006, fetal NT was prospectively measured before chorionic villi sampling in 169 pregnancies at high risk for a single-gene disorder at 11 to 13 weeks of pregnancy.

RESULTS

No differences were found between the 63 affected and 116 nonaffected fetuses in pregnancy demographic characteristics, in mean NT measurements, expressed either in millimetres [1.8 (95% CI:1.6-1.9) vs 1.7 (95% CI:1.6-1.8)] or in multiples of the median [1.19 (95%CI: 1.04-1.35) vs 1.14 (95%CI: 1.05-1.23)], or in median NT. The percentage of increased NT above the 95(th) percentile was similar for affected (9.5%) and nonaffected (11.2%) fetuses.

CONCLUSION

Not all single-gene disorders are associated with enlarged NT, therefore NT cannot be regarded as a generic marker for single-gene disorder but only for a limited number of these conditions.

Additional first-trimester ultrasound markers

The first trimester (11-13 +6 weeks) ultrasound examination is useful for several reasons: determination of an accurate date of confinement, diagnostic purposes, and screening for fetal defects. Nuchal translucency measurement combined with maternal serum markers (free b-human chorionic gonadotropin and pregnancy-associated plasma protein A) is the mainstay of first-trimester screening for chromosomal defects. However, over the past decade additional ultrasound markers have been developed that improve the performance of this type of screening. The novel markers include evaluation of the nasal bone, fronto-maxillary angle measurement, and Doppler evaluations of the blood flow across the tricuspid valve and in the ductus venosus.

Pattern and prenatal diagnosis of skeletal dysplasias in Qatar population

OBJECTIVE

To determine the pattern of skeletal dysplasias in Qatar population and to assess the accuracy of prenatal diagnosis and prognosis.

METHODS

This was a retrospective descriptive study of 30 women with high risk for skeletal dysplasias. The recruited women were submitted to clinical assessment, ultrasound scanning using 2-dimensional, 3-dimensional/4-dimensional and colour Doppler technique with possible molecular diagnosis. The findings were compared with the postnatal or postmortem assessments. Final diagnosis was based on clinical examination, skeletal survey, autopsy and molecular testing as deemed necessary.

RESULTS

Thirty cases of skeletal dysplasia were antenatally diagnosed over 4-year period with family history in few cases. Among many entities thanatophoric dysplasia showed largest prevalence [7(23%)]. Prenatal diagnosis was accurate in 76% of foetuses while the first indicator of abnormality was a suspected anomaly found during routine ultrasound assessment in most cases [17(56%)]. Prediction of lethality based on ultrasound findings was 100% accurate.

CONCLUSIONS

This study confirmed the possibility of good prenatal diagnosis of skeletal dysplasias present among Qatar population. Diagnosis based on ultrasound assessment will improve by adding molecular techniques with positive impact on prenatal care.

First Trimester Ultrasound Screening: An Update

For many years, the main use of ultrasound in the first trimester of pregnancy was to confirm viability and to establish gestational age. Indeed, the crown-rump length measurement in the first trimester remains the most accurate method to estimate the gestational age even today. However, improvements in ultrasound equipment and improvement in our understanding of normal and abnormal fetal development allows us now to perform a much more complete first trimester fetal evaluation. This pertains not only to the diagnosis of fetal anomalies but also to screening for fetal defects. The combination of the nuchal translucency measurement and maternal serum biochemistries (free β-hCG and PAPP-A) has been shown to be an extremely efficient way to screen for fetal aneuploidy. The addition of other first trimester markers such as the nasal bone evaluation, frontomaxillary facial angle measurement, and Doppler evaluation of blood flow across the tricuspid valve and through the ductus venosus improves the screening performance even further by increasing the detection rates and decreasing the false positive rates. Several of the first trimester markers also are useful in screening for cardiac defects. Furthermore, significant nuchal translucency thickening has been associated with a variety of genetic and nongenetic syndromes. A recently described first trimester marker called the intracerebral translucency appears to hold great promise in screening for open spine defects. Finally, it appears that a first trimester evaluation (uterine artery Doppler and the measurement of certain biochemical markers in the maternal serum) significantly improves the assessment of the risk of preeclampsia.

PRENATAL DIAGNOSIS OF SKELETAL DYSPLASIAS

Skeletal anomalies occur with a frequency of around 1:500 and can present a diagnostic challenge when detected prenatally. Increasingly more sophisticated imaging such as MRI or CT may elucidate features more easily interpreted by postnatal radiologists. The aetiology of these anomalies is varied and includes aneuploidy, genetic syndromes, skeletal dysplasias, teratogens, disruption and maternal disease, making a multidisciplinary approach to the diagnosis essential. The estimated prevalence of skeletal dysplasias varies from 2–3/10,000 to 4–7/10,000 and diagnosis may require biochemical, cytogenetic, molecular genetic or haematological investigation. Clinical genetic input is often required as the family history or parental examination may yield valuable clues to the diagnosis. This review will briefly describe the normal embryology and sonographic appearances of fetal limb development and go on to suggest a systematic approach to the diagnosis of fetal skeletal dysplasias.

Fetus with osteogenesis imperfecta presenting as increased nuchal translucency thickness in the first trimester

Type II osteogenesis imperfecta (OI) is a perinatally lethal disorder due to type I collagen abnormalities that has been diagnosed successfully in the second trimester. We report a case of type II OI that was confirmed on postmortem histology and radiography presenting as increased nuchal translucency in the first trimester.

First-trimester ultrasound diagnosis of skeletal dysplasia associated with increased nuchal translucency thickness

A series of five cases of skeletal dysplasia is reported in which the diagnosis was reached at the 11-14-week routine ultrasound examination in our referral center. All five cases had increased nuchal translucency thickness (NT) associated with bone abnormalities. We review the current literature on skeletal dysplasia in the first trimester of pregnancy associated with increased NT.

First trimester ultrasonography in screening and detection of fetal anomalies

An obstetrical ultrasound examination provides invaluable information regarding the fetus. Until the mid-1980s, ultrasound in the first trimester was limited to localization of the pregnancy, establishing viability, and accurate dating. With the advent of high-resolution ultrasound and transvaginal scanning, a significant amount of information about the fetus can be gained and provided to the patient at a very early stage in gestation. This article provides an overview of the role of first trimester (11-13 + 6 weeks' gestation) ultrasound in screening and diagnosis of fetal anomalies. The first trimester is an ideal time for screening for aneuploidy, primarily due to the advantages that nuchal translucency (NT) measurement provides. NT measurement is also useful in establishing the risk of congenital cardiac disorders and a number of genetic and non-genetic syndromes. Significant NT thickening is associated with an increase in perinatal morbidity and mortality. Potential mechanisms resulting in increased NT are discussed. A number of new ultrasound markers for fetal aneuploidy have been investigated over the past several years, some of which appear to improve the screening efficacy of early ultrasonography. The role of these is reviewed. A number of fetal anomalies can now be consistently diagnosed in the first trimester. Their appearance at this early gestational age is discussed as well. It is clear that, data obtained by first trimester ultrasound are useful in counseling expectant parents and in planning the appropriate follow-up.

Advanced first trimester screening (AFS): an improved test strategy for the individual risk assessment of fetal aneuploidies and malformations

OBJECTIVE

First trimester risk assessment for fetal aneuploidies is computed on the base of a general background risk, which is depending on the maternal age. Thereby, the adjusted risk tends to rise with increasing age. Obversely, more unsuspicious fetal parameters [measurement of the nuchal translucency (NT) and biochemical parameters, free beta human chorionic gonadotropine (fbetaB-Hcg) and pregnancy associated plasma protein A (Papp-A)] have to be observed to result in an unsuspicious test at higher age. It was the aim of this study to investigate the potential value of a novel risk assessment algorithm explicitly disregarding the maternal age.

METHODS

This was an ultrasound cohort study of 1,463 singleton pregnancies at 11-14 weeks of gestation undergoing a first trimester screening for fetal aneuploidies by measuring the (NT), Papp-A and fbeta-hCG. In each case, the pregnancy outcome was obtained. Regarding either the detection of genetic affections or the combined detection of genetic or somatic anomalies, the test performance parameters (sensitivity, specificity, positive and negative predictive values) were calculated and compared with each other. For risk calculation the standard Fetal Medicine Foundation (FMF)-Software and an alternative software with a similar algorithm (JOY-Software) were utilized. Compared to this, the risk assessment had been modified by implementing a novel calculation algorithm (advanced first trimester screening algorithm, AFS) purposely disregarding the maternal age and again, the test performance parameters had been computed and were compared with the first ones.

RESULTS

At the mere genetic analysis, all four test-strategies revealed to have identical sensitivity and negative predictive values. Compared to the standard FMF-Software, the JOY-Software showed a reduced false positive rate. In addition, in both softwares, the false positive rate is highly significant-reduced by implementing the AFS-algorithm. At combined genetic and somatic analysis, analogous results on different counts could be found.

CONCLUSION

In the effort to create an algorithm characterising somatic and fetal conditions of the fetus most properly, the inclusion of maternal age is not a helpful value and excluding the age from risk calculation leads to a high significant reduction of the false positive rate. Further, a comparable marked increase of both, specificity and positive predictive values, can be achieved for the FMF- and JOY-Software on the background of the generally more favourable JOY test performance.

Specific osseous spurs in a lethal form of hypophosphatasia correlated with 3D prenatal ultrasonographic images

BACKGROUND

Hypophosphatasia is an osseous dysplasia with highly variable clinical expression, ranging from a recessive lethal prenatal type to late onset dominant short stature with premature shedding of teeth. Lethal forms of hypophosphatasia include short limb dwarfism with lack of ossification, especially on the vertebral bodies, very slender ribs and clavicles, and bowed, short lower extremities, with a bifid aspect of the diaphyses. Alkaline phosphatase is abnormally low in liver, bone, kidney and plasma.

METHODS

We present here the prenatal images of a lethal form of hypophosphatasia, diagnosed precociously because of specific osseous spurs in a context of recurrent short limb dwarfism.

RESULTS

Prenatal 3D ultrasonography has shown these spurs as early as 18 weeks. Molecular biology found compound heterozygous mutations in the gene TNSALP.

CONCLUSION

In a context of short limb dwarfism, the search for these specific osseous spurs orient strongly toward the diagnosis of lethal hypophosphatasia.

Increased first-trimester fetal nuchal translucency thickness in association with chondroectodermal dysplasia (Ellis-Van Creveld syndrome)

Increased nuchal translucency thickness (NT) is an established sonographic marker of fetal chromosomal abnormality. Several structural fetal defects and genetic syndromes including a range of skeletal dysplasias have been reported in association with increased NT. We report the first case of fetal Ellis-Van Creveld syndrome presenting as raised fetal NT at 13 weeks' gestation. Ultrasonography at 18 weeks' gestation demonstrated a narrow thorax, marked shortening of the long bones with bowed femora and hexadactyly of hands and feet. Pregnancy was terminated at 23 weeks' gestation. The postmortem radiological examination revealed short and bowed long bones with rounded metaphyses, postaxial polydactyly of hands and feet, short ribs and narrow thorax. The acetabular roofs were horizontal with medial and lateral spurs. This case adds a further type of severe skeletal dysplasia to the list of genetic syndromes which may present as increased fetal NT in the late first trimester.

Increased nuchal translucency with normal karyotype

Increased fetal nuchal translucency (NT) thickness between 11 and 14 weeks' gestation is a common phenotypic expression of chromosomal abnormalities, including trisomy 21. However, even in the absence of aneuploidy, nuchal thickening is clinically relevant because it is associated with an increase in adverse perinatal outcome caused by a variety of fetal malformations, dysplasias, deformations, dysruptions, and genetic syndromes. Once the presence of aneuploidy is ruled out, the risk of perinatal outcome dose not statistically increase until the nuchal translucency measurement reaches 3.5 mm or more (>99th percentile). This increase in risk occurs in an exponential fashion as the NT measurement increases. However, if the fetus survives until midgestation, and if a targeted ultrasound at 20 to 22 weeks fails to reveal any abnormalities, the risk of an adverse perinatal outcome and postnatal developmental delay is not statistically increased.

Prenatal diagnosis of fetal skeletal dysplasias by combining two-dimensional and three-dimensional ultrasound and intrauterine three-dimensional helical computer tomography

OBJECTIVE

To evaluate the contribution of new imaging techniques in the prenatal diagnosis of skeletal dysplasia.

METHODS

Between May and October 2003, a prospective study was conducted in a single referral center. Three-dimensional ultrasound (3D-US) and three-dimensional helical computer tomography (3D-HCT) were performed after two-dimensional ultrasound (2D-US) in six cases of skeletal dysplasia. Diagnostic accuracy and detailed findings with each of the three techniques were compared with postnatal radiological findings.

RESULTS

There were three cases of achondroplasia, two cases of osteogenesis imperfecta type II and one case of chondrodysplasia punctata. Termination of pregnancy was performed in five cases and one fetus with osteogenesis imperfecta type II was delivered at term by Cesarean section. 2D-US made the correct diagnosis in four cases. 3D-US and 3D-HCT achieved an accurate diagnosis in all six cases. 3D-HCT and 3D-US identified significantly more abnormalities than did 2D-US (3D-HCT: 94.3% (33/35); 3D-US: 77.1% (27/35); 2D-US: 51.4% (18/35); P < 0.01). The diagnosis was made between 27 and 36 weeks' gestation in all cases. The advantage of 3D-HCT over 3D-US was the possibility of imaging the entire fetus.

CONCLUSION

3D-US and 3D-HCT seem to be useful complementary methods to 2D-US, and may improve accuracy of the prenatal diagnosis of skeletal disorders. These new imaging technologies may have a role in the prenatal multidisciplinary approach to the diagnosis of skeletal dysplasias.

A newly recognized autosomal recessive syndrome with abnormal vertebral ossification, rib abnormalities, and nephrogenic rests

We describe three cases of a severe malformation syndrome in siblings of both sexes. The characteristic features observed were absent intrauterine ossification of an apparently normal cartilaginous spinal column; rib abnormalities, with unossified segments and posterior gaps; thoracic hypoplasia; and multiple intralobar nephrogenic rests in the kidneys. This syndrome can be identified in early pregnancy by ultrasound scans due to the lack of ossification of the thoraco-lumbar spine and its association with increased nuchal translucency thickness. We suggest that this is a newly recognized autosomal recessive syndrome.

First-trimester diagnosis of osteogenesis imperfecta associated with encephalocele by conventional and three-dimensional ultrasound

To illustrate the three-dimensional sonographic features of a rare genetic disorder, we report on prenatal diagnosis of osteogenesis imperfecta congenita associated with encephalocele at 13 weeks of gestation, using conventional and three-dimensional ultrasound. Because the parents were first-degree cousins and on the basis of the family history, a recessive autosomal inheritance was suspected. Of seven previous pregnancies, five were unaffected and two had been terminated in the second trimester owing to a similar abnormality (one affected boy and one affected girl). In the case we present, the diagnosis was made on the basis of two-dimensional ultrasound performed by physicians aware of the history; the quality of three-dimensional ultrasound imaging suggests that this technique might have contributed toward establishing a precise diagnosis in the absence of a positive family history. Besides, the global view provided by three-dimensional surface-rendering images made the parents more confident of the accuracy of the diagnosis. Although osteogenesis imperfecta congenita is generally considered as autosomal dominant, the case we report suggests that it may be inherited in a recessive autosomal fashion at least when associated with encephalocele. Three-dimensional ultrasound confirmed the conventional two-dimensional examination and was helpful in convincing the parents of the accuracy of the diagnosis.

The role of fetal nuchal translucency in prenatal screening

PURPOSE OF REVIEW

An update of findings from studies on first trimester nuchal translucency screening.

RECENT FINDINGS

New first trimester markers can substantially improve efficacy of screening. When fully informed, preliminary data indicate that women prefer first trimester above second trimester testing.

SUMMARY

Recent reports on nuchal translucency screening reiterate the importance of standardization of technique and quality control as proposed by the Fetal Medicine Foundation in London. Effective quality control can be achieved through quantitative analysis of operator specific data. Three-dimensional ultrasound does not provide substantially higher success rates in obtaining reliable nuchal translucency measurements than two-dimensional ultrasound. New data confirm the previously reported association between increased nuchal translucency and increased rate of spontaneous fetal loss, genetic syndromes and a high prevalence (15%) of anomalies, among which cardiac defects are the commonest. Researchers agree that increased nuchal translucency ought to be an indication for specialized echocardiography. Promising data have become available on new markers that can enhance first trimester screening. It is estimated that when assessment of nasal bone and maternal serum analytes are taken into account, first trimester screening can identify 97.5% of trisomy 21 pregnancies for a 5% false-positive rate. It is stressed that parents need to be informed about the possible implications of screening before testing. Preliminary data indicate that when appropriately informed, women prefer first trimester above second trimester testing. Furthermore, the uptake of screening is likely to be relatively low among younger women.

Hypophosphatasia associated with increased nuchal translucency: a report of two affected pregnancies

Perinatal hypophosphatasia is a lethal autosomal recessive skeletal abnormality with a birth prevalence of about 1 per 100 000. It is characterized by deficiency of the tissue-nonspecific isoenzyme of alkaline phosphatase causing abnormal bone mineralization. In the two affected fetuses from the same family ultrasound examination at 14 and 12 weeks, respectively, demonstrated increased nuchal translucency thickness, hypomineralization of the skull and spine, narrowing of the chest and shortening of the limbs.

The skeletal dysplasias

The skeletal dysplasias are a large, heterogeneous group of genetic conditions characterized by abnormal development, growth and maintenance of the elements (bones) that comprise the human skeleton. Many result in disproportionate short stature. The classification of these disorders has evolved over the past 30 years from purely clinical-pathological descriptions to a nosology that now also reflects their underlying molecular aetiology. Accurate diagnosis of these disorders requires comprehensive documentation of the history, analysis of longitudinal growth patterns, rigorous clinical evaluation of the individual and family, complete radiographic survey and, when available, examination of chondro-osseous specimens. The specific genetic defects underlying many of these conditions have now been elucidated, allowing links to be established between phenotype and genotype. Management revolves around treatment to prevent or minimize medical complications, psychosocial support of patients and their families, education of the medical profession and wider community and modification of the environment where appropriate.

Reference values for fetal limb biometry at 10-14 weeks of gestation

OBJECTIVES

To calculate reference ranges for fetal limb measurements obtained by transabdominal ultrasound at 10-14 weeks of gestation.

METHODS

Six hundred and six normal fetuses were examined transabdominally in a cross-sectional study by a single observer. The crown-rump length of the fetuses ranged from 31 to 78 mm. Measurement of the length of the humerus, ulna, femur, tibia and foot was attempted from the longest section of each structure. To assess intraobserver repeatability, three sets of repeated measurements were obtained in 26 fetuses.

RESULTS

An appropriate ultrasound measurement was obtained in a percentage of cases ranging from 93.2% to 97.9%. A significant correlation was found between crown-rump length measurements and humerus length (r = 0.74, P < 0.001), ulna length (r = 0.70, P < 0.001), femur length (r = 0.77, P < 0.001), tibia length (r = 0.69, P < 0.001) and foot length (r = 0.58, P < 0.001). Crown-rump length-specific reference ranges for each measurement were calculated with the method of scaled absolute residuals. The study of intraobserver variability showed coefficients of variation ranging from 7.9 to 10.0% and intraclass correlation coefficients ranging from 0.89 to 0.94.

CONCLUSIONS

Fetal limb size is strongly correlated with crown-rump length. Despite a significant biological variability of the measurements, the availability of reference ranges could be of help in the early diagnosis of fetal skeletal dysplasias.

Osteogenesis imperfecta in pregnancy: two case reports and review of literature

Osteogenesis imperfecta (OI) is an inherited disease where basic pathology is of defective maturation of collagen. It is more common in women, and the incidence in pregnancy is 1 in 25,000 to 30,000. A multidisciplinary approach is necessary. Ideally, genetic counseling is sought before conception. Once pregnant, prenatal diagnosis can be established by chorion villous sampling. Serial scans would identify the affected fetus with fractures. A cesarean delivery is advocated if the fetus is affected or if the mother has pelvic fractures. An experienced anesthetist should be involved. Because these women are more likely to have a postpartum hemorrhage due to uterine atony, Syntocinon infusion and close observation in the third stage is indicated.

Outcome of pregnancy in chromosomally normal fetuses with increased nuchal translucency in the first trimester

OBJECTIVES

To study the outcome of chromosomally normal pregnancies with increased nuchal translucency at the 10-14-week scan.

DESIGN

Retrospective study of 1320 chromosomally normal singleton pregnancies with nuchal translucency of > or = 3.5 mm. In addition to fetal karyotyping these patients were managed with follow-up scans at 14-16 and 20-22 weeks, specialist fetal echocardiography and in selected cases by infection screening and further genetic testing.

RESULTS

In the 1320 pregnancies there were 68 (5.15%) spontaneous abortions or intrauterine deaths, 18 (1.36%) neonatal and infant deaths and 154 (11.67%) terminations of pregnancy. In the 1080 (81.82%) survivors, 60 (5.56%) had abnormalities requiring medical or surgical treatment or leading to mental handicap. The chance of a livebirth with no defects in the group with nuchal translucency of 3.5-4.4 mm was 86%, for those with translucency of 4.5-5.4 mm it was 77%, for those with translucency of 5.5-6.4 mm it was 67%, and for those with translucency of > or = 6.5 mm it was 31%.

CONCLUSIONS

Increased fetal nuchal translucency is associated with chromosomal abnormalities, many fetal defects and genetic syndromes. In the majority of cases a series of antenatal investigations, including fetal karyotyping, detailed scans, fetal echocardiography, as well as genetic testing and infection screening, that can be completed by 20 weeks of gestation would distinguish between the pregnancies destined to result in adverse outcome and those leading to the delivery of infants without major defects.