Fetal birth weight prediction by 2D and 3D in Chinese population
Our centre has demonstrated that birth weight prediction model based on fractional thigh volume, biparietal diameter, abdominal circumference and femur length is reliable for late third trimester in Chinese population, and allows a better prediction over the Hadlock model. 315 healthy late third trimester fetuses within 5 days of delivery were prospectively examined by 2D and 3D ultrasonography (US). After volume acquisition, fractional thigh volume which includes only the middle 50% of the whole thigh was calculated automatically after manually tracing soft tissue borders of 5 slices from a transverse view of the femur. The interobserver and intraobserver reliability of the 3DUS measurement were small (all intraclass correlation coefficients>=0.95). The prediction model using TVol, femur length (FL), abdominal circumference (AC) and biparietal diameter (BPD) provided the most precise weight estimation with random error of 4.75% and R2 of 0.825. It correctly predicted 69.5% and 95.3% birth weights to within 5% and 10% of actual weight. By comparison, the Hadlock model with standard fetal biometry (BPD, HC, AC and FL) gave a random error of 7.69%. The percentage of birth weight prediction within 5% and 10% of actual birth weight was 46.3% and 82.6%, respectively. Our results indicated that the precision of birth weight prediction to within 5% and 10% of actual birth weight in Chinese population at term gestation can be improved by adding 3D thigh volume to conventional 2D fetal biometric measurements.
Microarray CGH in prenatal diagnosis
Microarray CGH (aCGH) is a new technology which is used in diagnosis of babies and children presenting with congenital abnormalities. Its use in prenatal diagnosis is less well established but potentially it can replace conventional cytogenetics as the most common prenatal diagnostic test and can also complement conventional cytogenetics. We plan to compare aCGH and conventional cytogenetics in prenatal diagnosis regarding chromosomal imbalance detection, concordance rate, reporting time, and cost. We would also like to study cases with phenotypic abnormalities but apparently normal chromosome constitutions (from conventional cytogenetics) with aCGH using high density probes, along with parental samples to look for unbalanced chromosomal rearrangements not detectable by conventional cytogenetics. Array CGH will also be used to investigate abnormal karyotypes such as duplications, microdeletions, marker chromosomes and apparently balanced translocations to refine the cytogenetic diagnosis.
Are herbal medicinal products more teratogenic than Western pharmaceutical products?
More than 10% of pregnant women in various countries reported the use of herbal medicinal products for various reasons. Although consumers often think that herbal medicinal products are risk free, the evidence available today suggests that some herbal medicinal products are associated with risks. Our centre has performed a retrospective small study to compare the differences in fetal outcomes between women who took herbal medicinal products and women who took Western pharmaceutical products in pregnancy. There was no significant difference in the prevalence of fetal abnormalities between them. We have conducted a prospective study on the effect of herbal medicinal products in pregnancy and confirmed that there was no significant difference.
Hematopoietic stem cell culture and microRNA expression / DNA repair for point mutation
Hematopoietic stem cells (HSC) are capable of self-renewal and differentiating into cells of all blood lineages. We investigated the enrichment of HSC and its ex vivo expansion in serum free medium. Down regulation of a miRNA was found to significantly increase the expression of transcription factors, HoxB3 and HoxB6; and inhibition of the miRNA up-regulated proliferation of CD34+CD38- hematopoietic stem/progenitor cells. This information will be used to further investigate stem cell ex-vivo expansion. A human b-thalassemia major hematopoietic progenitor cell line and a human b-thalassemia minor hematopoietic progenitor cell line are established for investigation on site-directed DNA repair of 654 mutation.
A combination of biochemical and sonographic markers from the first to the third trimesters is a novel approach that could address the pathophysiological aspects of complicated pregnancies. Expressions of IGFs and IGFBPs would be examined in the placentae of all cases and controls to correlate with evidence of clinical placental hypertrophy. Analysis will be performed in relation to the actual infant outcome in terms of birthweight percentile ranking and perinatal complications. The results could provide the basis for the construction of a clinical scoring system utilizing biochemical and sonographic markers to identify pregnancies at risk of different complications in a manner similar to the use of biochemical and sonographic markers in the screening for chromosomal defects.
Use of three-dimensional ultrasound in prenatal diagnosis
We have performed a study on the use of Three-dimensional Extended Imaging TM (3DXI), a new post processing program, in examination of normal and abnormal structures, and found that 3DXI can provide additional information over 2D ultrasound examination (2DUS). More recently, we have showed that the combined approach of 2DUS and 3DUS with both orthogonal planar and multi-slice view modes significantly improved the prenatal detection rate for a cleft palate compared with 2D ultrasound alone (88.9% vs 22.2%) without decreasing the specificity.
The 3D rendered images of fetal face are fascinating to the mothers. However, a randomized controlled study by us indicated that the addition of 3D/4DUS did not cause a significant reduction in maternal anxiety in pregnancies at risk of fetal abnormalities compared with conventional 2DUS alone.
We have performed a study on the use of XI VOCALTM, a new modality to measure 3D volumetry. XI VOCALTM (with 10, 15, 20 slices) can be used interchangeably with multiplanar technique (1 mm interval) for the measurement of fetal volume at 11 to 14 weeks’ gestation. We further investigated the use of XI VOCALTM in the measurement of placental volumetry.
We also studied 3D in ultrasound training. Our results showed that fetal biometric measurements obtained by an inexperienced operator using both 2D and 3D ultrasound were reproducible and showed good agreement with those obtained by an experienced operator. The use of 3D ultrasound by an inexperienced operator allows faster measurement of fetal biometric parameters than does the use of 2D ultrasound, and also seems to facilitate the acquisition of higher-quality images for the measurement of AC.
Non-invasive prenatal diagnosis of β-thalassemia
In collaboration with the Department of Medicine and Genomic Centre, we searched for new informative SNP markers surrounding the HBB and studied the feasibility of using SNP markers to exclude pregnancies affected by β-thalassemia major.
Discourse analysis of prenatal genetic counselling (in collaboration with the Department of Linguistics, School of Humanities)
It is increasingly recognized that medicine cannot be isolated from the humanities. Over 100 consultations with pregnant women receiving advice on prenatal screening of fetal Down syndrome have been videotaped and transcribed to study the strategies used by healthcare professionals in helping women to make an informed choice and the relative roles of the healthcare professional and the woman during the consultation. Factors such ethnicity, culture, language proficiency and how they may influence the consultation are also be studied. Results from this series of studies may help healthcare professional to improve communication with patients.