Prenatal vs postnatal diagnosis of 22q11.2 deletion syndrome: cardiac and noncardiac outcomes through 1 year of age.

BACKGROUND: The 22q11.2 deletion syndrome is the most common microdeletion syndrome and is frequently associated with congenital heart disease. Prenatal diagnosis of 22q11.2 deletion syndrome is increasingly offered. It is unknown whether there is a clinical benefit to prenatal detection as compared with postnatal diagnosis. OBJECTIVE: This study aimed to determine differences in perinatal and infant outcomes between patients with prenatal and postnatal diagnosis of 22q11.2 deletion syndrome. STUDY DESIGN: This was a retrospective cohort study across multiple international centers (30 sites, 4 continents) from 2006 to 2019. Participants were fetuses, neonates, or infants with a genetic diagnosis of 22q11.2 deletion syndrome by 1 year of age with or without congenital heart disease; those with prenatal diagnosis or suspicion (suggestive ultrasound findings and/or high-risk cell-free fetal DNA screen for 22q11.2 deletion syndrome with postnatal confirmation) were compared with those with postnatal diagnosis. Perinatal management, cardiac and noncardiac morbidity, and mortality by 1 year were assessed. Outcomes were adjusted for presence of critical congenital heart disease, gestational age at birth, and site. RESULTS: A total of 625 fetuses, neonates, or infants with 22q11.2 deletion syndrome (53.4% male) were included: 259 fetuses were prenatally diagnosed (156 [60.2%] were live-born) and 122 neonates were prenatally suspected with postnatal confirmation, whereas 244 infants were postnatally diagnosed. In the live-born cohort (n=522), 1-year mortality was 5.9%, which did not differ between groups but differed by the presence of critical congenital heart disease (hazard ratio, 4.18; 95% confidence interval, 1.56-11.18; P<.001) and gestational age at birth (hazard ratio, 0.78 per week; 95% confidence interval, 0.69-0.89; P<.001). Adjusting for critical congenital heart disease and gestational age at birth, the prenatal cohort was less likely to deliver at a local community hospital (5.1% vs 38.2%; odds ratio, 0.11; 95% confidence interval, 0.06-0.23; P<.001), experience neonatal cardiac decompensation (1.3% vs 5.0%; odds ratio, 0.11; 95% confidence interval, 0.03-0.49; P=.004), or have failure to thrive by 1 year (43.4% vs 50.3%; odds ratio, 0.58; 95% confidence interval, 0.36-0.91; P=.019). CONCLUSION: Prenatal detection of 22q11.2 deletion syndrome was associated with improved delivery management and less cardiac and noncardiac morbidity, but not mortality, compared with postnatal detection.

Prenatal diagnosis of Myhre syndrome with a heterozygous pathogenic variant in SMAD4 gene presented with thick nuchal translucency and cardiac abnormalities.

Prenatal testing was performed in a 39-year-old Chinese pregnant woman referred for increased nuchal translucency measuring 5.7 mm. Non-invasive prenatal testing and SNP array study on amniotic fluid samples were normal. Whole exome sequencing (WES) was initiated further as the fetus had pericardial effusion of 1.2 mm, thickened myocardium over the right ventricular lateral wall and aberrant right subclavian artery. A detailed fetal echocardiogram also revealed persistent left superior vena cava and dilated coronary sinus at 20 weeks. From whole exome sequencing of the trio, a de novo heterozygous variant NM_005359.5(SMAD4): c.1499T>C (p.Ile500Thr) was detected. This pathogenic variant has been reported in the postnatal case cohort of Myhre syndrome. This condition is characterized by facial dysmorphism, intellectual disability, hearing loss, skeletal abnormalities and potential life threatening respiratory or cardiovascular manifestations. Termination of pregnancy was performed at 23 weeks. Small chins, pre-axial polydactyly, brachydactyly and clinodactyly were noted in the abortus. Ultrasound findings of increased nuchal translucency, thickened myocardium and pericardial effusion prompted further genetic evaluation for the prenatal diagnosis of Myhre syndrome by whole exome sequencing.

Impact of COVID-19 pandemic on preterm delivery.

OBJECTIVE: Controversies exist on whether the pandemic lockdown has resulted in a lower rate of preterm deliveries. A higher stillbirth rate was also reported. This retrospective observational study aimed to examine the rate of preterm delivery and stillbirth in a tertiary hospital in Hong Kong during COVID-19 pandemic. METHODS: Data from 8787 singleton pregnancies at Queen Mary Hospital between April 2018 to September 2021 were retrieved from the clinical management system and obstetric database. Rates of preterm delivery (<37 weeks), low birth weight infants (<2500 g), and stillbirth in the pre-pandemic (April 2018 to September 2019) and pandemic (April 2020 to September 2021) periods were compared. RESULTS: Total numbers of singleton deliveries during the pre-pandemic and pandemic periods were 5064 and 3723, respectively. Background demographics were comparable, except 3 were higher rates of cesarean sections (30.7% vs. 25.8%; p < 0.05) and hypertensive disorders (1.4% vs. 0.7%; p < 0.05) in the pandemic cohort. Moreover, more women with a spontaneous onset of labor had a history of preterm delivery (3.5% vs. 2.4%; p < 0.05) during the pandemic. Rates of low birth weight infants (8.7% vs. 7.4%; p = 0.03) and spontaneous preterm deliveries (2.6% vs. 1.7%; p = 0.01), particularly spontaneous moderate-to-late preterm delivery (32-36 weeks) (1.9% vs. 1.2%; p = 0.01) were significantly higher during COVID-19. However, no statistical difference was found in stillbirth rates (0.2% vs. 0.4%; p = 0.17). CONCLUSIONS: Rates of spontaneous preterm delivery and low birth weight babies increased significantly during the COVID-19 pandemic. This could be related to an increase in maternal stress, or a change in behavioral patterns for pregnant women.

Prenatal presentation in two fetuses with features of Beckwith Wiedemann syndrome-An unexpected diagnosis of androgenetic chimera and its clinical implications.

Beckwith Wiedemann Syndrome (BWS, OMIM 130650) is an imprinting disorder that may present antenatally with a constellation of sonographic features namely polyhydramnios, macrosomia, macroglossia, omphalocele, placental mesenchymal dysplasia, cardiomegaly, nephromegaly, fetal hydrops, and other rare anomalies. Paternal uniparental disomy in chromosome 11p15 imprinting region accounts for 20% of all BWS, and 8% among those were due to genome-wide paternal uniparental disomy (GWpUPD). GWpUPD is a rare condition and usually results in prenatal lethality. The 31 liveborns reported in the literature demonstrate female predominance in surviving GWpUPD. Here, we reported two prenatal cases which initially presented with features suggestive of BWS, which subsequently were confirmed to have GWpUPD. Further trio SNP genotyping analysis using SNP-based chromosomal microarray revealed androgenetic biparental chimera as the underlying cause. Finally, we highlighted the importance of recognizing GWpUPD as a possible cause in a fetus presenting with BWS phenotype, as it carried a different disease prognosis, tumor predisposition, manifestations of other imprinting disorders, and possibility in unmasking autosomal recessive disorders from the paternal alleles.

20 years review of antenatal diagnosis of haemoglobin Bart's disease and treatment with intrauterine transfusion.

OBJECTIVE: To review prenatal diagnosis and outcome of alpha thalassaemia major through universal antenatal screening. METHOD: This was a retrospective study on ultrasound features, antenatal diagnosis, in-utero intervention and long term outcome of pregnancies at risk of Haemoglobin Bart's hydrops foetalis syndrome attending prenatal diagnosis from 2000 to 2019 at Tsan Yuk Hospital in Hong Kong. RESULTS: Among 390 foetuses from 373 at-risk pregnancies, 122 (31%) prenatal invasive procedures were performed and 65 affected foetuses were diagnosed antenatally. For foetuses with ultrasound features of anaemia, the diagnostic yield of BHFS was 73%. Cardiomegaly carried a positive predictive value of 65.2% while its absence had the highest negative predictive value (96.0%). Three women having affected foetuses continued pregnancy and received intrauterine transfusion beginning 20 weeks of gestation. All babies were born alive and non-hydropic. They were managed with regular transfusion and cured by haematopoietic stem cell transplantation. CONCLUSIONS: Absence of ultrasound features of anaemia had high negative predictive value for alpha thalassaemia major. Couple at risk of having affected foetus could be offered serial ultrasound surveillance. Invasive testing for pregnancies with features of foetal anaemia provided high diagnostic yield. Intrauterine transfusion corrected foetal anaemia and allowed long term transfusion free survival without significant neurological sequelae following postnatal transplant therapy.

Cost-effectiveness analysis of chromosomal microarray as a primary test for prenatal diagnosis in Hong Kong.

BACKGROUND: Chromosomal microarray (CMA) has been shown to be cost-effective over karyotyping in invasive prenatal diagnosis for pregnancies with fetal ultrasound anomalies. Yet, information regarding preceding and subsequent tests must be considered as a whole before the true cost-effectiveness can emerge. Currently in Hong Kong, karyotyping is offered free as the standard prenatal test while genome-wide array comparative genome hybridization (aCGH), a form of CMA, is self-financed. A new algorithm was proposed to use aCGH following quantitative fluorescent polymerase chain reaction (QF-PCR) as primary test instead of karyotyping. This study aims to evaluate the cost-effectiveness of the proposed algorithm versus the current algorithm for prenatal diagnosis in Hong Kong. METHODS: Between November 2014 and February 2016, 129 pregnant women who required invasive prenatal diagnosis at two public hospitals in Hong Kong were prospectively recruited. The proposed algorithm was performed for all participants in this demonstration study. For the cost-effectiveness analysis, cost and outcome (diagnostic rate) data were compared with that of a hypothetical scenario representing the current algorithm. Further analysis was performed to incorporate women's willingness-to-pay for the aCGH test. Impact of government subsidies on the aCGH test was explored as a sensitivity analysis. RESULTS: The proposed algorithm dominated the current algorithm for prenatal diagnosis. Both algorithms were equally effective but the proposed algorithm was significantly cheaper (p ≤ 0.05). Taking into account women's willingness-to-pay for an aCGH test, the proposed algorithm was more effective and less costly than the current algorithm. When the government subsidy reaches 100%, the maximum number of diagnoses could be made. CONCLUSION: By switching to the proposed algorithm, cost saving can be achieved whilst maximizing the diagnostic rate for invasive prenatal diagnosis. It is recommended to implement aCGH as a primary test following QF-PCR to replace the majority of karyotyping for prenatal diagnosis in Hong Kong.

The Accuracy of Self-Screening of Group B Streptococcus in Pregnant Women-A Randomized Crossover Study.

OBJECTIVE: Universal screening of vaginal and rectal group B streptococcus (GBS) carriage in pregnant women is now recommended in many countries to identify at-risk pregnancies and reduce the risk of early-onset GBS disease in newborn infants. This study compared self-screening by pregnant women with screening by health care workers in a largely Chinese population. METHODS: A randomized crossover study was conducted in Hong Kong. All women attending the GBS screening visit at 35-37 weeks gestation between May and October 2015 were approached for recruitment. Consenting participants underwent both self-screening and screening by health care workers. Group 1 had health care worker screening swabs first, and group 2 had self-screening first. A positive GBS diagnosis was made if either swab was positive. The sensitivity of each approach was calculated by comparison with this gold standard. Acceptance of GBS self-screening and neonatal outcomes was analyzed (Canadian Task Force Classification I). RESULTS: Of the 672 women approached, 428 (63.7%) consented to the study. The prevalence of GBS was 19.7% (83 of 422). Sensitivities of self-screening and screening by health care workers were 61.4% (51 of 83) and 97.6% (81 of 83), respectively (P < 0.05). Women who used vaginal pessaries and non-Chinese women had a higher positive concordance rate with health care workers (P < 0.05). Neonatal outcomes of GBS-positive mothers were similar in the concordant and discordant groups. CONCLUSION: The sensitivity of self-screening of GBS in Hong Kong was lower than the sensitivity of screening by health care workers. Cultural difference needs to be considered when implementing self-screening in different populations.

Bridging the gap from prenatal karyotyping to whole-genome array comparative genomic hybridization in Hong Kong: survey on knowledge and acceptance of health-care providers and pregnant women.

PURPOSE: The use of array comparative genomic hybridization (aCGH) has been increasingly widespread. The challenge of integration of this technology into prenatal diagnosis was the interpretation of results and communicating findings of unclear clinical significance. This study assesses the knowledge and acceptance of prenatal aCGH in Hong Kong obstetricians and pregnant women. The aim is to identify the needs and gaps before implementing the replacement of karyotyping with aCGH. Questionnaires with aCGH information in the form of pamphlets were sent by post to obstetrics and gynecology doctors. METHOD: For the pregnant women group, a video presentation, pamphlets on aCGH and a self-administered questionnaire were provided at the antenatal clinic. RESULT: The perception of aCGH between doctors and pregnant women was similar. Doctors not choosing aCGH were more concerned about the difficulty in counseling of variants of unknown significance and adult-onset disease in pregnant women, whereas pregnant women not choosing aCGH were more concerned about the increased waiting time leading to increased anxiety. Prenatal aCGH is perceived as a better test by both doctors and patients. CONCLUSION: Counseling support, training, and better understanding and communication of findings of unclear clinical significance are necessary to improve doctor-patient experience.

Hemoglobin A1c in early pregnancy to identify preexisting diabetes mellitus and women at risk of hyperglycemic pregnancy complications.

BACKGROUND: Unrecognized diabetes mellitus during pregnancy could pose serious maternal and neonatal complications. A hemoglobin A1c level of ≥6.5% was used to diagnose both diabetes mellitus in nonpregnant individuals and diabetes in pregnancy. As the hemoglobin A1c level could be influenced by maternal physiological changes, the optimal cutoff in early pregnancy to detect women with diabetes in pregnancy and associated complications remains unclear. OBJECTIVE: This study aimed to evaluate the diagnostic performance of various hemoglobin A1c levels and the optimal hemoglobin A1c cutoff to identify mothers with diabetes in pregnancy diagnosed by the gold standard 75 g oral glucose tolerance test before 24 weeks of gestation. In addition, the pregnancy and neonatal outcomes were compared using the optimal hemoglobin A1c cutoff. STUDY DESIGN: A retrospective cohort study was conducted between 2004 and 2019. Women with at least 1 risk factor of gestational diabetes mellitus received an oral glucose tolerance test before 24 weeks of gestation. Terminology of hyperglycemia first detected during pregnancy by oral glucose tolerance test was classified as either diabetes in pregnancy or gestational diabetes mellitus following the World Health Organization's recommendation. Women who met the diagnostic criteria of diabetes in pregnancy and early-onset gestational diabetes mellitus (ie, before 24 weeks of gestation) and had a paired hemoglobin A1c measurement within 4 weeks of their early oral glucose tolerance test were studied. Sensitivity, specificity, and positive and negative predictive values at various hemoglobin A1c cutoffs were calculated for the detection of diabetes in pregnancy. The optimal hemoglobin A1c level was identified from the constructed receiver operating characteristic curves. Multivariate binary logistic regression analyses were performed to calculate the unadjusted and adjusted odds ratios for pregnancy complications. RESULTS: There were 63,111 deliveries, and 22,949 women underwent an oral glucose tolerance test before 24 weeks of gestation. A total of 157 and 3210 women met the diagnostic criteria of diabetes in pregnancy and early-onset gestational diabetes mellitus using an oral glucose tolerance test, respectively. Only 346 participants had a paired hemoglobin A1c and oral glucose tolerance test measurement (82 cases with diabetes in pregnancy and 264 cases with early-onset gestational diabetes mellitus). The receiver operating characteristic curve identified an optimal hemoglobin A1c cutoff of 5.7% to diagnose diabetes in pregnancy, with a sensitivity of 64.6%, specificity of 81.1%, positive predictive value of 51.5%, and negative predictive value of 88.1%. A hemoglobin A1c cutoff of either 5.9% or 6.5% could miss 47.6% or 73.2% of women with diabetes in pregnancy. In multivariate logistic regression analysis, a hemoglobin A1c level of ≥5.7% increased the risk of maternal insulin use (adjusted odds ratio, 6.69; 95% confidence interval, 3.44-12.99), macrosomia (adjusted odds ratio, 7.43; 95% confidence interval, 1.90-29.00), and shoulder dystocia (adjusted odds ratio, 6.56; 95% confidence interval, 1.161-37.03). CONCLUSION: The optimal hemoglobin A1c cutoff to detect diabetes in pregnancy diagnosed using an oral glucose tolerance test before 24 weeks of gestation was 5.7%, but this cutoff could not reliably identify diabetes in pregnancy owing to the low sensitivity. However, an early hemoglobin A1c level of ≥5.7% indicated increased risks of pregnancy and neonatal complications.

Maternal serum anti-Mullerian hormone level is not superior to chronological age in predicting Down syndrome pregnancies.

OBJECTIVE: To compare the difference in maternal serum anti-Mullerian hormone (AMH) level between Down syndrome pregnancies and unaffected pregnancies, and to evaluate its performance as a screening marker for Down syndrome pregnancy. METHOD: A total of 145 pregnancies affected by foetal Down syndrome and 290 unaffected controls matched with maternal age and gestational age were selected, and their archived first or second trimester serum retrieved for AMH assay. RESULTS: There was no significant difference in maternal serum AMH level between pregnancies affected and unaffected by foetal Down syndrome. Our first trimester serum samples had higher AMH concentration compared to second trimester samples. CONCLUSIONS: Maternal serum AMH level, as a marker of ovarian age, is not superior to chronological age in predicting Down syndrome pregnancies. Despite the cross-sectional nature of our study, the variation of maternal serum AMH concentration with gestational age warrants further investigation.

Obstetric outcomes in women with polycystic ovary syndrome and isolated polycystic ovaries undergoing in vitro fertilization: a retrospective cohort analysis.

OBJECTIVE: This retrospective cohort study evaluated the obstetric outcomes in women with polycystic ovary syndrome (PCOS) and isolated polycystic ovaries (PCO) undergoing in vitro fertilization (IVF) treatment. METHODS: We studied 104 women with PCOS, 184 with PCO and 576 age-matched controls undergoing the first IVF treatment cycle between 2002 and 2009. Obstetric outcomes and complications including gestational diabetes (GDM), gestational hypertension (GHT), gestational proteinuric hypertension (PET), intrauterine growth restriction (IUGR), gestation at delivery, baby's Apgar scores and admission to the neonatal intensive care unit (NICU) were reviewed. RESULTS: Among the 864 patients undergoing IVF treatment, there were 253 live births in total (25 live births in the PCOS group, 54 in the PCO group and 174 in the control group). The prevalence of obstetric complications (GDM, GHT, PET and IUGR) and the obstetric outcomes (gestation at delivery, birth weight, Apgar scores and NICU admissions) were comparable among the three groups. Adjustments for age and multiple pregnancies were made using multiple logistic regression and we found no statistically significant difference among the three groups. CONCLUSION: Patients with PCO ± PCOS do not have more adverse obstetric outcomes when compared with non-PCO patients undergoing IVF treatment.

Whole-genome array CGH evaluation for replacing prenatal karyotyping in Hong Kong.

OBJECTIVE: To evaluate the effectiveness of whole-genome array comparative genomic hybridization (aCGH) in prenatal diagnosis in Hong Kong. METHODS: Array CGH was performed on 220 samples recruited prospectively as the first-tier test study. In addition 150 prenatal samples with abnormal fetal ultrasound findings found to have normal karyotypes were analyzed as a 'further-test' study using NimbleGen CGX-135K oligonucleotide arrays. RESULTS: Array CGH findings were concordant with conventional cytogenetic results with the exception of one case of triploidy. It was found in the first-tier test study that aCGH detected 20% (44/220) clinically significant copy number variants (CNV), of which 21 were common aneuploidies and 23 had other chromosomal imbalances. There were 3.2% (7/220) samples with CNVs detected by aCGH but not by conventional cytogenetics. In the 'further-test' study, the additional diagnostic yield of detecting chromosome imbalance was 6% (9/150). The overall detection for CNVs of unclear clinical significance was 2.7% (10/370) with 0.9% found to be de novo. Eleven loci of common CNVs were found in the local population. CONCLUSION: Whole-genome aCGH offered a higher resolution diagnostic capacity than conventional karyotyping for prenatal diagnosis either as a first-tier test or as a 'further-test' for pregnancies with fetal ultrasound anomalies. We propose replacing conventional cytogenetics with aCGH for all pregnancies undergoing invasive diagnostic procedures after excluding common aneuploidies and triploidies by quantitative fluorescent PCR. Conventional cytogenetics can be reserved for visualization of clinically significant CNVs.

Fetus in fetu--from prenatal ultrasound and MRI diagnosis to postnatal confirmation.

We report a case of fetus in fetu presented as a complex intra-abdominal heterogeneous cystic lesion during ultrasound examination of the fetus at 25 weeks of gestation. Progressive growth of this mass was noted in the prenatal period. Fetal magnetic resonance imaging provided additional information to aid in the prenatal diagnosis. This allows proper counselling for the parents and helps to plan the postnatal management. Surgical excision was carried out in the early neonatal period and the diagnosis of fetus in fetu was confirmed.

Nuchal translucency in pregnancies conceived after assisted reproduction technology.

PURPOSE OF REVIEW: Nuchal translucency is one of the important markers in the first trimester during antenatal screening for fetal Down's syndrome. With the observation of alterations in biochemical markers in pregnancies conceived after assisted reproduction, this review presents current information related to the thickness of nuchal translucency in these pregnancies. RECENT FINDINGS: Early small studies did not demonstrate any discrepancy in the thickness of nuchal translucency in fetuses from assisted reproduction and from spontaneous pregnancies, but there has been recent evidence to suggest an increased level of nuchal translucency in singletons from various modes of assisted-reproduction technology. Nuchal translucency in twins following assisted reproduction did not, however, show a similar increase. Although the effect of chorionicity was not specifically addressed, nuchal translucency thickness in twins born after assisted reproduction was reported to be comparable to that in spontaneous singletons. It is possible that singletons and twins after assisted reproduction exhibit different antenatal behavior and pregnancy courses. SUMMARY: Similar to other biochemical markers of fetal Down's syndrome, nuchal translucency is increased in singletons after assisted-reproduction technology. Further studies on twin pregnancies, in particular dichorionic twins, are necessary before conclusive evidence can be drawn for multiple pregnancies.

Maternal serum pregnancy-associated plasma protein-A and free beta-human chorionic gonadotrophin in pregnancies conceived with fresh and frozen-thawed embryos from in vitro fertilization and intracytoplasmic sperm injection.

OBJECTIVE: Maternal serum pregnancy-associated plasma protein-A (PAPP-A) and free beta-human chorionic gonadotrophin (beta-hCG) are useful markers in the screening of Down syndrome in the first trimester. We investigated the effect of intracytoplasmic sperm injection (ICSI), freezing and thawing of embryos on the levels of these two analytes in assisted reproduction pregnancies. METHODS: We recruited 149 women who conceived after assisted reproduction with fresh embryos (92 from conventional IVF and 57 from ICSI), 85 women who conceived with frozen-thawed embryos (54 from conventional IVF and 31 from ICSI) and 401 women with spontaneous conceptions as controls. The concentrations of PAPP-A and free beta-hCG were measured between 10 and 14 weeks and were converted to multiples of medians (MoM) for comparisons. RESULTS: Median PAPP-A MoMs were significantly reduced in ICSI pregnancies in the fresh and frozen-thawed embryo subgroups (0.70 and 0.66 MoM respectively) and in the IVF fresh embryo subgroups (0.83 MoM), as compared to controls (1.00 MoM). Free beta-hCG MoM was significantly reduced in the IVF fresh embryos subgroup (0.87 MoM), but not in the other three subgroups. CONCLUSION: Further studies for exploring the underlying pathophysiology and adjustment in the marker levels for screening of Down syndrome are warranted in pregnancies conceived after assisted reproduction.

Pilot study on the midsecond trimester examination of fetal nasal bone in the Chinese population.

OBJECTIVES: Hypoplasia of the nasal bone of fetuses affected by trisomy 21 and other aneuploidies could be detected by prenatal ultrasound examination and was an important new marker in the detection of Down syndrome in the second trimester. Racial differences in fetal nasal bone length have been reported. However, there was no reference range for the fetal nasal bone length (NBL) in the Chinese population. We conducted a pilot study to investigate the reproducibility of the measurement of fetal NBL in the mid second trimester and to determine whether there is any difference in NBL between the Chinese and the Caucasian population. METHODS: From June 2002 to February 2003, 198 Chinese women were examined. Ultrasound measurements of NBL were performed on a strictly midsagittal plane in normal singleton fetuses at 15 to 23 weeks' gestation. RESULTS: The mean difference in the NBL between the two investigators was small (mean = 0.043 mm; 95% CI, -0.033 to 0.12), and there was substantial agreement between the measurements for each observer. Limits of agreement were -0.48 to 0.35 and -0.29 to 0.22 mm in the two investigators respectively. It was found that the median length of the nasal bones increased from 3.5 mm at 15 weeks to 6.7 mm at 23 weeks' gestation. There was a linear relationship between the length of the nasal bone and the gestational age. CONCLUSION: It was demonstrated that the measurement of nasal bone length was feasible and reproducible in the second trimester. The fetal nasal bone length in Chinese population appeared shorter than that of Caucasian and African-Americans. There is a need to establish a reference range of fetal NBL for the Chinese population.

Attitude of at-risk subjects towards preimplantation genetic diagnosis of alpha- and beta-thalassaemias in Hong Kong.

OBJECTIVES: The aim of the study was to assess whether preimplantation genetic diagnosis (PGD) was an acceptable alternative to prenatal diagnosis in couples at risk of giving birth to a child with alpha- or beta-thalassaemia in an Asian population. METHODS: An information leaflet was distributed to the women at risk. They were asked to complete a questionnaire after having an interview with a designated investigator. RESULTS: A total of 141 valid questionnaires were analysed; 82.3% of the women considered PGD either the same or better than conventional prenatal diagnosis. Women with an affected child or a subfertility problem were more willing to accept PGD and to undergo this procedure in their future pregnancies. Their main concern about PGD was damage to the embryo during the PGD procedure. The most important perceived advantage of PGD was avoidance of termination of an affected pregnancy. CONCLUSIONS: PGD is an acceptable alternative to conventional prenatal diagnosis in women at risk of giving birth to a child with alpha- or beta-thalassaemia in an Asian population. This is particularly true in women with a subfertility problem and in women who already have an affected child.

Sonographic features of ileal duplication cyst at 12 weeks.

Enteric duplication cyst is a congenital abnormality that is believed to arise from abnormal recanalization of the bowel during embryogenesis. Previous reports suggest that the condition may be suspected prenatally by sonographic demonstration of an intra-abdominal cystic mass in the second and third trimesters. We present the sonographic features of a fetus with ileal duplication cyst at 12 weeks of gestation, which show that the condition may present in the first trimester of pregnancy.