Abnormal number of fetal ribs on 3-dimensional ultrasonography: associated anomalies and outcomes in 75 fetuses

Exploring copy number variants in deceased fetuses and neonates with abnormal vertebral patterns and cervical ribs

Background

Cervical patterning abnormalities are rare in the general population, but one variant, cervical ribs, is particularly common in deceased fetuses and neonates. The discrepancy between the incidence in the general population and early mortality is likely due to indirect selection against cervical ribs. The cause for the co‐occurrence of cervical ribs and adverse outcome remains unidentified. Copy number variations resulting in gain or loss of specific genes involved in development and patterning could play a causative role.

Methods

Radiographs of 374 deceased fetuses and infants, including terminations of pregnancies, stillbirths and neonatal deaths, were assessed. Copy number profiles of 265 patients were determined using single nucleotide polymorphism array.

Results

274/374 patients (73.3%) had an abnormal vertebral pattern, which was associated with congenital abnormalities. Cervical ribs were present in 188/374 (50.3%) and were more common in stillbirths (69/128 [53.9%]) and terminations of pregnancies (101/188 [53.7%]), compared to live births (18/58, 31.0%). Large (likely) deleterious copy number variants and aneuploidies were prevalent in these patients. None of the rare copy number variants were recurrent or overlapped with candidate genes for vertebral patterning.

Conclusions

The large variety of copy number variants in deceased fetuses and neonates with similar abnormalities of the vertebral pattern probably reflects the etiological heterogeneity of vertebral patterning abnormalities. This genetic heterogeneity corresponds with the hypothesis that cervical ribs can be regarded as a sign of disruption of critical, highly interactive stages of embryogenesis. The vertebral pattern can probably provide valuable information regarding fetal and neonatal outcome.

Prenatal Incidence and Clinical Value of the Absence of 12th Ribs in a Population in a Setting of Detailed Second-Trimester Sonography

OBJECTIVES

We aimed to determine the incidence of the absence of the (last) 12th ribs in a population in a setting of detailed 2nd-trimester sonography using three-dimensional (3D) ultrasound and to assess whether or not this may be related to chromosomal aneuploidies.

METHODS

Prospectively, we counted fetal ribs for the absence of the (last) 12th ribs in singleton pregnancies of women who presented to our clinic for detailed 2nd-trimester sonography. The assessment was carried out using 3D ultrasound. Volume data sets were acquired with the 3D skeleton mode using the maximum intensity with X-ray-weighted rendering. If the 3D skeleton mode was not sufficient, volume contrast imaging with the OmniView bone mode was used.

RESULTS

The fetal ribs could be visualized in 97.01% of the 1,943 fetuses examined between 20 and 23 weeks' gestation. Timing the examination at 21, 22, or 23 weeks was found to be more successful than conducting it at 20 weeks. Twelfth ribs were found to be absent in 33 fetuses; 16 fetuses had 11 ribs unilaterally and 17 had so bilaterally. None of them had chromosomal abnormalities. Associated anomalies were present in 6 fetuses (18.2%); 2 of the anomalies were major and 4 minor.

CONCLUSION

The incidence of absent 12th ribs in this mixed population was 1.75%. In the absence of additional anomalies, the prognosis is favorable.

Increased prevalence of abnormal vertebral patterning in fetuses and neonates with trisomy 21

PURPOSE

To assess the prevalence of an abnormal number of ribs in a cohort of fetuses and neonates with trisomy 21 and compare this with a subgroup of fetuses without anomalies.

MATERIALS AND METHODS

Radiographs of 67 deceased fetuses, neonates, and infants that were diagnosed with trisomy 21 were reviewed. Terminations of pregnancy were included. The control group was composed of 107 deceased fetuses, neonates, and infants without known chromosomal abnormalities, structural malformations, infections or placental pathology. Cases in which the number of thoracic ribs or presence of cervical ribs could not be reliably assessed were excluded. The literature concerning vertebral patterning in trisomy 21 cases and healthy subjects was reviewed.

RESULTS

Absent or rudimentary 12th thoracic ribs were found in 26/54 (48.1%) cases with trisomy 21 and cervical ribs were present in 27/47 (57.4%) cases. This prevalence was significantly higher compared to controls (28/100, 28.0%, Χ²(1) = 6.252, p = .012 and 28/97, 28.9%, Χ²(1) = 10.955, p < .001, respectively).

CONCLUSIONS

Rudimentary or absent 12th thoracic ribs and cervical ribs are significantly more prevalent in deceased fetuses and infants with trisomy 21.

13 ribs as a predictor of long gap esophageal atresia: myth or reality? Analysis of associated findings of esophageal atresia and abnormal rib count

BACKGROUND

The presence of 13 pairs of ribs on pre-operative chest x-ray has been postulated to be an indicator for long gap esophageal atresia (EA). This study sought to determine the validity of this theory and identify associated pathological conditions in patients with EA and abnormal rib count.

METHODS

Babies with EA from January 2005 - December 2012 were retrospectively analyzed. Information was gathered from neonatal health records and operation notes. Chest x-rays were reviewed to determine rib count. Long gap EA was defined as failure to achieve primary esophageal anastomosis. Statistical analysis performed with Fisher's exact test.

RESULTS

Seventy-six patients were identified. Eight patients had long gap EA, with none of these patients having 13 pairs of ribs. Paradoxically, 10 patients with esophageal atresia +/- trachea-esophageal atresia (EA +/- TEF) and supernumerary ribs underwent primary repair. Nine patients had 11 pairs of ribs, of which 2 had pure EA and a long gap. Using Fisher's exact test to compare the groups of supernumary ribs and non-supernumary ribs there is a p value of 0.587. VACTERL association was identified in 40% of those with supernumerary ribs. Various associated syndromes and concomitant abnormalities were identified.

CONCLUSION

We found no association between 13 pairs of ribs and long gap in esophageal atresia. Those with 13 pairs of ribs were more likely to have associated anomalies, although this was not statistically significant. Our cohort of patients was found to have a range of pathology related to genetic syndromes, further atresias, and malformations, which is well known to be associated with children born with EA +/- TEF.

LEVEL OF EVIDENCE

Prognosis study - level IV.

Reference ranges for vertebral body areas of the fetal lumbosacral spine on 3-dimensional sonography using volume contrast imaging with OmniView

OBJECTIVES; The purpose of this study was to establish reference ranges for vertebral body areas of the fetal lumbosacral spine in the coronal plane on 3-dimensional sonography using volume contrast imaging with OmniView (GE Healthcare, Zipf, Austria). METHODS; An observational cross-sectional study was conducted on 576 healthy pregnant women at gestational ages of 20 weeks to 34 weeks 6 days. Volume contrast imaging with OmniView was used to measure the vertebral body areas (L1-L5, S1, and S2) by positioning a curved line along the fetal lumbosacral spine. To create reference ranges, first- and second-degree linear regression models adjusted using residual analysis and the coefficient of determination (R(2)) were created. To assess reproducibility, two examiners evaluated 40 random volumes using the intraclass correlation coefficient. RESULTS; The mean areas of the vertebral bodies were 102.72 (range, 25-254), 107.29 (range, 30-245), 105.10 (range, 31-231), 99.09 (range, 31-211), 87.74 (range, 11-178), 65.80 (range, 18-161), and 46.54 (range, 12-129) mm(2) for L1, L2, L3, L4, L5, S1, and S2, respectively. In the intraobserver and interobserver reproducibility assessments, intraclass correlation coefficients of greater than 0.80 were found for all fetal vertebral body areas. CONCLUSIONS; Reference values for fetal lumbosacral spine vertebral body areas were determined by 3-dimensional sonography using volume contrast imaging with OmniView, and they were shown to be reproducible.