Diagnostic accuracy and limitations of post-mortem MRI for neurological abnormalities in fetuses and children

AIM

To compare the diagnostic accuracy of non-invasive cerebral post-mortem magnetic resonance imaging (PMMRI) specifically for cerebral and neurological abnormalities in a series of fetuses and children, compared to conventional autopsy.

MATERIALS AND METHODS

Institutional ethics approval and parental consent was obtained. Pre-autopsy cerebral PMMRI was performed in a sequential prospective cohort (n = 400) of fetuses (n = 277; 185 ≤ 24 weeks and 92 > 24 weeks gestation) and children <16 years (n = 123) of age. PMMRI and conventional autopsy findings were reported blinded and independently of each other.

RESULTS

Cerebral PMMRI had sensitivities and specificities (95% confidence interval) of 88.4% (75.5 to 94.9), and 95.2% (92.1 to 97.1), respectively, for cerebral malformations; 100% (83.9 to 100), and 99.1% (97.2 to 99.7) for major intracranial bleeds; and 87.5% (80.1 to 92.4) and 74.1% (68 to 79.4) for overall brain pathology. Formal neuropathological examination was non-diagnostic due to maceration/autolysis in 43/277 (16%) fetuses; of these, cerebral PMMRI imaging provided clinically important information in 23 (53%). The sensitivity of PMMRI for detecting significant ante-mortem ischaemic injury was only 68% (48.4 to 82.8) overall.

CONCLUSIONS

PMMRI is an accurate investigational technique for identifying significant neuropathology in fetuses and children, and may provide important information even in cases where autolysis prevents formal neuropathological examination; however, PMMRI is less sensitive at detecting hypoxic-ischaemic brain injury, and may not detect rarer disorders not encountered in this study.

Association of isolated short femur in the mid-trimester fetus with perinatal outcome

OBJECTIVES

To evaluate the prevalence of fetal isolated short femur in a cohort of women screened for Down syndrome by the integrated test, and to compare the outcome of fetuses with isolated short femur in the mid-trimester with that of fetuses with normal femur length (controls).

METHODS

This was a retrospective cohort study of 1262 women booked for antenatal care and delivery at University College London Hospital. All women had integrated testing in the late first and early second trimesters and a detailed anomaly scan in the mid-trimester. All scan reports, screening results and neonatal data were analyzed statistically.

RESULTS

The fetal femur was short (< 5(th) percentile) in 5.1% of patients and 4.7% had isolated short femur. In pregnancies with isolated short femur, the birth weight was significantly lower and there were higher rates of small-for-gestational age (SGA) and low birth weight (LBW) infants, compared with controls (P < 0.01). The odds ratios for SGA and LBW in pregnancies with isolated short femur were 3.0 (95% CI, 1.5-5.9) and 2.60 (95% CI, 1.1-6.2), respectively. Isolated short femur was associated significantly with low levels of pregnancy-associated plasma protein-A (P = 0.001).

CONCLUSIONS

Isolated short femur in the mid-trimester fetus is associated with fetal growth restriction and SGA. In the context of normal Down syndrome screening and a normal anomaly scan, this marker should be regarded as a predictor for SGA, and fetal growth should be monitored during these pregnancies.

Practical issues drawn from the implementation of the integrated test for Down syndrome screening into routine clinical practice

We have evaluated a cohort of women booked for antenatal care at University College London Hospitals. The uptake of screening was 64.4% and was significantly higher (73 versus 46%) in women who booked before 14 weeks. Of the women who booked before 14 weeks, 96.8% opted for the integrated test (IT). Overall, 5.3% failed to attend for the second blood test. The false-positive rate in the women who had the IT was 2.9%. All 11 cases of Down syndrome were detected prenatally. Our study is the first to evaluate implementation of the IT into routine clinical practice.

Dysplastic and polycystic kidneys: diagnosis, associations and management

Cystic and bright kidneys can pose a significant diagnostic dilemma when discovered as an incidental finding at the time of a routine fetal ultrasound scan. There are diverse aetiologies with equally variable implications for the prognosis in the affected fetus, and for future pregnancies. Accurate antenatal diagnosis in the absence of any positive family history is often not possible and a team approach to management (to include the fetal medicine specialist, paediatric nephrologist or urologist, geneticists and in some cases, pathologist) is essential. In this review we will attempt to describe the embryology and aetiology of these conditions and suggest an approach to management.

Prenatal diagnosis of fetal abnormality: psychological effects on women in low-risk pregnancies

When given an adverse prenatal diagnosis, parents are deeply shocked and experience acute grief. This review considers the psychological outcomes for parents whether they opt to terminate the pregnancy or continue, either through choice or because termination is not an option. It covers the full spectrum of malformation from treatable, through those carrying a risk of significant handicap, to lethal. It draws on two types of studies: those that are retrospective and qualitative, describing feelings and aspects of care, and those that are prospective and assess psychological state with standardized measures of grief, anxiety and depression. The relationship between psychological outcome and possible associated variables, such as individual characteristics, nature of the abnormality and obstetric factors is described and evaluated. In addition, the authors draw on both scientific and support group literature to summarize good practice for the care of parents receiving an unexpected diagnosis of fetal abnormality.

Ultrasound markers of fetal chromosomal abnormality: a survey of policies and practices in UK maternity ultrasound departments

OBJECTIVE

To evaluate the management of pregnancies where the fetus was found to have one or more sonographic markers of possible fetal chromosomal abnormality.

DESIGN

Prospective anonymous postal survey of UK obstetric ultrasound units.

MAIN OUTCOME MEASURES

The management of pregnancies where the fetus is found to have a sonographic marker of aneuploidy.

POPULATION

All 252 maternity ultrasound units in the United Kingdom.

METHODS

Postal questionnaire to the superintendent sonographer in routine maternal ultrasound departments.

RESULTS

Questionnaires were returned from 179 maternity units (71%). Of the respondents 94% offered a fetal anomaly scan at 16-20 weeks' gestation and 59% performed a dating scan at 10-14 weeks. Screening for Down syndrome was available in 99% of all maternity units. The recognition of sonographic 'soft signs' for possible fetal chromosomal abnormality varied considerably between the units. When sonographers were asked about their unit's policy regarding offering amniocentesis to women with sonographic markers, 8-78% discussed amniocentesis when the marker was isolated and 53-88% when another abnormality was found. Eighty nine percent of units documented the abnormal ultrasound findings in the hospital notes and 88% of the women were informed of the findings regardless of the intention to offer amniocentesis.

CONCLUSION

The practice of routine ultrasound examination is well established in UK, though precise policies vary. The existing wide variations in management policies possibly reflect a lack of data derived from low risk populations. There is a need to collect such data from low risk populations with known screening practices so that national guidelines to standardize practice can be formulated.

Popliteal pterygium syndrome: a clinical study of three families and report of linkage to the Van der Woude syndrome locus on 1q32

Popliteal pterygium syndrome (PPS) is a rare autosomal dominant disorder, thought to occur with an incidence of approximately 1 in 300 000 live births. The main clinical manifestations are popliteal webbing, cleft lip, cleft palate, lower lip pits, syndactyly, and genital and nail anomalies. This report describes the clinical features in two families with PPS and one isolated case, showing the range of anomalies found both within and between the families. PPS has some features in common with Van der Woude syndrome (VWS), also inherited as an autosomal dominant condition, with cleft lip/palate and, more distinctively, lower lip pits. Although the gene for VWS has not yet been identified, it has been localised to within 1.6 cM in the region 1q32-41. To determine whether PPS and VWS represent allelic forms of the same gene, three families were genotyped for markers flanking and within the critical region. A multipoint lod score of 2.7 was obtained, with no evidence of recombination, supporting the hypothesis that these two disorders are allelic.

Prenatal screening for chromosome abnormalities

An abnormal chromosome complement (aneuploidy) contributes significantly to fetal loss during pregnancy, as well as to perinatal morbidity and mortality. The contribution of chromosomal abnormalities to fetal loss decreases as pregnancy continues with an estimated 50% of first trimester spontaneous abortions due to chromosomal abnormalities, but only 5% of stillbirths (after 28 weeks). Prenatal screening for aneuploidy (in particular Down syndrome) can be undertaken using maternal serum biochemistry, fetal ultrasound or a combination of both. In this chapter the advantages and disadvantages of screening programmes currently in use, or undergoing evaluation, will be reviewed.

A distinctive overgrowth syndrome with polysyndactyly

We report a female infant with 3-4 syndactyly of the fingers and postaxial polydactyly of all four limbs. She was large at birth and died at the age of 6 months.

Prenatal ultrasound findings in a fetus with otopalatodigital syndrome type II

We describe the prenatal diagnosis and post mortem findings, including fetal radiographs and bone histology, in a fetus with oto-palato-digital syndrome type II. The differential diagnosis and recurrence risks are discussed.

Pitfalls in counselling: the craniosynostoses

We describe three families to highlight the variability of expression and penetrance that can occur in the craniosynostoses. In two of the families, gene carriers were only identified in retrospect by looking at photographs of other family members. In the third family, identical twins were initially thought to be discordant for sagittal craniosynostosis until early skull x rays were examined and both were found to be affected. The dilemmas faced when counselling these families are discussed.

A case of atelosteogenesis

Atelosteogenesis is a rare chondrodysplasia characterised by rhizomelic short limbed dwarfism, thoracic hypoplasia, multiple joint dislocations, talipes equinovarus, and early death. The diagnosis is confirmed radiologically: short, distally tapering humeri, absent or hypoplastic fibulae, deficient vertebral ossification with coronal clefting, and anarchic ossification of phalanges are characteristic findings. We report a male child with this condition born to first cousin Bengali parents.