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Biomedical subjects

S F Wong

Publications and source records attributed to S F Wong.

At least 19 recordsLinked to original sources
PubMed2006

Continuous dynamic spinal motion analysis.

STUDY DESIGN: Continuous dynamic lumbar intervertebral flexion-extension is assessed by a videofluoroscopy with a new auto-tracking system. OBJECTIVES: To develop and validate a new method for the continuous assessment of lumbar kinematics. SUMMARY OF BACKGROUND DATA: Instability of the lumbar spine is thought to be associated with low back pain, but the diagnosis remains difficult. Functional radiographs have been used for diagnosis of spinal instability but error and limitation exist, whereas videofluoroscopy provides a cost-effective way for such analysis. However, common approaches of image analysis of videofluoroscopic video are tedious and time-consuming because of the low quality of the images. Physicians have to extract the vertebrae manually in most cases; thus, continuous motion analysis is hardly achieved. METHODS: A new system that can perform automatic vertebrae segmentation and tracking is developed. In vitro and in vivo validity were evaluated. Intervertebral flexion and extension was assessed in 30 healthy volunteers. RESULTS: In vitro and in vivo validity tests have been conducted with good results. A linear-liked pattern of the intervertebral flexion-extension (IVFE) curves in different levels was found, and the IVFE decreased in descending order from L1-L5 at different points of range of motion in flexion. Conversely, extension is evenly contributed at different levels, and the concavity of lumbar lordosis increases steadily in backward movement. CONCLUSIONS: The newly developed technique in assessing the dynamic lumbar motion is reliable and able to analyze the lumbar intervertebral movement from videofluoroscopic images automatically and accurately. The proposed system requires less human intervention than common approaches. It may have a potential value in the evaluation of spinal "instability" in clinical practice.

Adult↗
PubMed2006

Three-dimensional ultrasound findings of spondylocostal dysostosis in the second trimester of pregnancy.

Spondylocostal dysostosis (SCD) is a rare congenital disorder that is characterized by vertebral segmentation and formation defects, and asymmetrical rib anomalies. We describe a case diagnosed during the second trimester of pregnancy with the sonographic features of abnormal alignment of the spine, hemivertebrae in the thoracic spine and kyphoscoliosis. Three-dimensional ultrasound demonstrated a 'fan-like' rib cage with fusion of the ribs. The postmortem findings confirmed the ultrasound findings and were consistent with SCD.

Abortion, Therapeutic↗
PubMed2006

Fetal growth patterns in fetuses of women with pregestational diabetes mellitus.

OBJECTIVE: To assess the effect of glucose control on the rate of growth of fetuses in women with pregestational diabetes mellitus (Types 1 and 2). METHODS: All pregestational diabetic women booked at Mater Mothers' Hospital, Brisbane, Australia, between 1 January 1994 and 31 December 2002, were included. Pregnancies with congenital fetal anomalies, multiple pregnancies, and pregnancies terminated prior to 20 weeks' gestation were excluded. Dating scans were performed before 14 weeks' gestation and serial scans were performed at 18, 24, 28, 32 and 36 weeks. Fetal parameters, including biparietal diameter, femur length and abdominal circumference, were recorded. The daily growth rates for biparietal diameter, femur length, and fetal abdominal area were calculated and compared with those in a low-risk (non-diabetic) population. The growth rates in fetuses of women with satisfactory diabetic control (HbA1c < 6.5%) and unsatisfactory control (HbA1c > or = 6.5%) in the three trimesters were compared. RESULTS: A total of 174 diabetic pregnancies were included and a total of 997 ultrasound scans were performed. The growth rates for fetuses of mothers with diabetes mellitus were significantly higher than for those in the low-risk population. The z-scores for biparietal diameter, femur length, and fetal abdominal area were 0.18, 0.59 and 1.44, respectively. Fetuses of diabetic mothers with high HbA1c in the first trimester had significantly greater fetal abdominal area growth rate than those with normal HbA1c (fetal abdominal area z-score of 1.7 vs. 0.75, P = 0.009). Although the fetal abdominal area z-scores in fetuses of diabetic mothers with high HbA1c in the second or third trimesters were also higher than those with normal HbA1c levels, the differences did not reach statistical significance. Maternal obesity did not influence the fetal growth rate. CONCLUSION: The rate of growth of fetuses of diabetic mothers differs from that of the normal population. Growth acceleration persists until the late third trimester. Moreover, periconceptional glucose control appears to have a significant effect on accelerated growth of the fetal abdominal area.

Adult↗
PubMed2006

The placentas of patients with severe acute respiratory syndrome: a pathophysiological evaluation.

AIMS: The pathology of the placentas delivered from pregnant women who had severe acute respiratory syndrome (SARS) in Hong Kong was studied. METHODS: The pathology of the placentas was retrospectively studied in detail and compared with control sets. The clinical data of the women and neonates were also reviewed. RESULTS: A total of seven placentas were studied. The placentas from two women convalescent from SARS in the first trimester were normal. In three placentas delivered in the acute stage of SARS, there were increases in intervillous or subchorionic fibrin which might be related to disturbances in maternal placental blood flow due to the hypoxic respiratory disease. Extensive fetal thrombotic vasculopathy (FTV) with sharply demarcated zones of avascular fibrotic villi was noted in the placentas of two patients convalescent from SARS in the third trimester. Both pregnancies had intrauterine growth retardation, oligohydramnios and newborns small for gestation. The aetiology of the FTV might be related to thrombotic tendency due to SARS or placental hypoxia. CONCLUSIONS: This report highlights placental pathology that was probably the result of pathophysiological alteration of the maternal fetal unit during SARS. Further studies are required to delineate the relationship between severe maternal respiratory disease, placental pathology and pregnancy outcome.

Adult↗
PubMed2005

Assessment of the Pediatric Index of Mortality (PIM) and the Pediatric Risk of Mortality (PRISM) III score for prediction of mortality in a paediatric intensive care unit in Hong Kong.

OBJECTIVE: To compare two models (The Pediatric Risk of Mortality III score and Pediatric Index of Mortality) for prediction of mortality in a paediatric intensive care unit in Hong Kong. DESIGN: Prospective case series. SETTING: A five-bed paediatric intensive care unit in a general hospital in Hong Kong. PATIENTS: All patients consecutively admitted to the unit between April 2001 and March 2003. MAIN OUTCOME MEASURES: Scores for both models compared with observed mortality. RESULTS: A total of 303 patients were admitted to the paediatric intensive care unit during the study period. The median age was 2 years, with an interquartile range of 7 months to 7 years. The male to female ratio was 169:134 (55.8%:44.2%). The median length of hospital stay was 3 days. The overall predicted number of deaths using The Pediatric Risk of Mortality III score was 10.2 patients whereas that by Pediatric Index of Mortality was 13.2 patients. The observed mortality was eight patients. The area under the receiver operating characteristics curve for the two models was 0.910 and 0.912, respectively. CONCLUSION: The predicted mortality using both prediction models correlated well with the observed mortality.

Child↗
PubMed2004

Bacteriological screening of expressed breast milk revealed a high rate of bacterial contamination in Chinese women.

A screening programme for expressed breast milk (EBM) revealed the alarming fact that our study group had the highest rate of contamination ever reported. The programme started in July 2002 and involved a group of Chinese women whose premature babies were in the neonatal intensive care unit. EBM was considered to be contaminated if there was any growth of pathogens, including Gram-negative bacteria, enterococci or Staphylococcus aureus, or if the total bacterial count was >10(5) cfu/mL. Of 59 samples from 23 mothers, 63% were contaminated. This high contamination rate could be due to the Chinese tradition of avoiding bathing for one month after childbirth. Previous studies have shown that feeding EBM rather than premature infant formula milk has advantages in terms of decreased incidence of necrotizing enterocolitis and neonatal sepsis. However, in this population, with such a high incidence of contaminated EBM, this may not be the case. Further studies to compare EBM with premature infant formula in this population are required.

Adult↗
PubMed2003

Cardiac function in fetuses of poorly-controlled pre-gestational diabetic pregnancies--a pilot study.

OBJECTIVE: Cardiac impairment is frequently found in babies of diabetic mothers. It is still controversial whether this is due to poor glucose control. The aim of this study is to compare the cardiac function in fetuses of well- and poorly-controlled pre-gestational diabetic pregnancy in third trimester. METHODS: Women with type 1 pre-gestational diabetes were enrolled at 30-32 weeks. Cardiac size and interventricular septal wall thickness were measured by M-mode at end-diastolic phase. The right and left ventricular ejection fractions were calculated. At the mitral and tricuspid valves inflow, the ratio between early ventricular filling and active atrial filling (E/A) at both atrioventricular valves were measured by Doppler echocardiography. Peak velocities of ascending aorta and pulmonary artery were assessed. The angle of isonation was kept at <20 degrees. Women with poorly-controlled diabetes (HbA1c>6.5%) were compared with those with satisfactorily controlled diabetes (HbA1c < or = 6.5%). RESULTS: A total of 21 women with pre-gestational diabetes were recruited for this study. Eight women with well-controlled diabetes were compared with 9 women who had poorly-controlled diabetes. HbA1c in the poorly-controlled group was 7.3% and in the well-controlled group it was 5.4% (p<0.001). There was no difference between the two groups in cardiac size, interventricular septal wall thickness, ejection fraction, aorta and pulmonary artery peak flow velocities. The right atrioventricular E/A ratio was significantly lower among the poorly-controlled diabetic pregnancies (0.71 vs. 0.54; p<0.05). CONCLUSION: Fetuses of poorly-controlled diabetic mothers had a lower right atrioventricular E/A ratio. This may be due to metabolic acidosis, non-hypertrophic cardiac dysfunction or fetal polycythemia.

Diabetes Mellitus, Type 1↗
PubMed2003

Histopathological findings of the nose of Down syndrome abortuses.

Recent reports of absent nasal bone in fetuses with Down syndrome have sparked much interest in the use of this finding for the screening of Down syndrome. We describe the histopathological findings of nasal bones of two fetuses with Down syndrome, one with absence and the other with normal ossification of the nasal bone. We propose that histopathological examination of the nasal bone could improve the accuracy of diagnosis of nasal hypoplasia among Down syndrome abortuses.

Abortion, Induced↗
PubMed2003

Factors influencing the prenatal detection of structural congenital heart diseases.

OBJECTIVE: To assess the factors influencing the prenatal detection rate of structural congenital heart diseases (CHDs). METHODS: A retrospective study was conducted at a major obstetric hospital in Australia between 1 January 1996 and 30 June 1999. The medical records of all fetuses and infants born with CHD, except those with isolated patent ductus arteriosus or secundum atrial septal defect, were reviewed. Only pregnancies that had prenatal ultrasound scan assessments for morphological surveys were included. The following factors that may influence the detection rate were assessed: complexity of the lesions; experience of the sonographers (performance in tertiary versus non-tertiary institutions); presence of other structural or chromosomal anomalies; and maternal body mass index (BMI). RESULTS: The incidence of structural CHD in this series, excluding cases referred from other hospitals, was 7.0 per 1000 (179/25 529). Of the 179 pregnancies with CHD, 151 had prenatal ultrasound scans and were included in the study. The overall detection rate for CHDs in this series was 40.4%. The detection rate for isolated septal defects was poor (13.7%). The detection rates were significantly higher for complex lesions (54%), for lesions with concomitant septal defects (66.7%), and for lesions with abnormal four-chamber views (62.9%). The detection rate was also higher if the scan was performed in the tertiary institution, and if there were other chromosomal or structural anomalies. Maternal BMI did not affect the detection rate in the current series. Stepwise logistic regression analysis showed that three independent variables affecting the detection rate were complexity of the cardiac lesion, experience of the operator, and the detection of chromosomal anomalies. CONCLUSION: A high detection rate for major CHDs can be achieved in a screening setting but there is still room for improvement in scanning skills in the four-chamber view and great-artery analysis in both tertiary and local centers.

Down Syndrome↗
PubMed2003

Correlates of habitual walking and sports/leisure-time physical activity in older persons in Singapore: interaction effects between educational attainment and gender.

INTRODUCTION: We examined for demographic and psychosocial correlates on the participation of habitual walking and sports/leisure-time physical activity (LTPA) among older persons in Singapore. MATERIALS AND METHODS: In an observational study, 177 Chinese, community/urban-dwelling, ambulant, non-disabled participants > or = 50 years old were recruited from a health promotion programme. The main outcome measures were self-reported participation in habitual walking and sports/LTPA. Variables examined include highest educational attainment, demographic and health characteristics, social contact and health knowledge. Interaction between gender and educational attainment was also examined. RESULTS: The mean age of participants was 62.5 +/- 7.8 years. The effects of educational level were significant on habitual walking (P = 0.02), while that of age, self-rated health and interaction between gender and educational level were significant for sports/LTPA (P = 0.012, P = 0.002 and P = 0.019, respectively). Men with higher education had a higher self-reported sport/LTPA, while in women; those with lower education attainment had a higher participation. CONCLUSION: Unlike findings from Western developed nations, previous studies done in Japan and Singapore found that educational level and health behaviours may not be positively associated. In this study, there is a negative correlation between educational attainment and participation in habitual walking and sports/LTPA, especially among older Singaporean women.

Aged↗
PubMed2002

Fetal bradycardia in the first trimester: an unusual presentation of atrial extrasystoles.

We report a fetus with fetal bradycardia at 13 weeks of gestation secondary to atrial extrasystoles. The fetus subsequently developed paroxysmal supraventricular tachycardia and hydrops fetalis. The cardiac arrhythmia recovered spontaneously without any medical intervention. This case illustrates that atrial ectopic beats can present in the first trimester with fetal bradycardia. Rapidly evolving hydrops fetalis secondary to supraventricular tachycardia can develop, warranting close monitoring with weekly heart rate assessment. Fetal bradycardia secondary to atrial extrasystole should be differentiated from first trimester sinus bradycardia and those associated with major structural cardiac abnormality, which have a high fetal loss rate.

Adult↗
PubMed2002

Routine ultrasound screening in diabetic pregnancies.

OBJECTIVES: To assess the detection rate of congenital fetal malformations and specific problems related to routine ultrasound screening in women with pre-existing diabetes. METHODS: A retrospective study was carried out to assess the performance of routine ultrasound screening in women with pre-existing diabetes (Types 1 and 2) within a tertiary institution. The incidence, type and risk factors for congenital fetal malformations were determined. The detection rate of fetal anomalies for diabetic women was compared with that for the low-risk population. Factors affecting these detection rates were evaluated. RESULTS: During the study period, 12 169 low-risk pregnant women and 130 women with pre-existing diabetes had routine ultrasound screening performed within the institution. A total of 10 major anomalies (7.7%) and three minor anomalies (2.3%) were present in the fetuses of the diabetic women. Central nervous system and cardiovascular system anomalies accounted for 60% of the major anomalies. Periconceptional hemoglobin A1c of more than 9% was associated with a high prevalence of major anomalies (143/1000). Women who had fetuses with major anomalies had a significantly higher incidence of obesity (78% vs. 37%; P < 0.05). Ultrasound examination of these diabetic pregnancies showed high incidences of suboptimal image quality (37%), incomplete examinations, and repeat examinations (17%). Compared to the 'low-risk' non-diabetic population from the same institution, the relative risk for a major congenital anomaly among the diabetic women was 5.9-fold higher (95% confidence interval, 2.9-11.9). The detection rate for major fetal anomalies was significantly lower for diabetic women (30% vs. 73%; P < 0.01), and the mean body mass index for the diabetic group was significantly higher (29 vs. 23 kg/m2; P < 0.001). CONCLUSION: The incidence of congenital anomalies is higher in diabetic pregnancies. Unfortunately, the detection rate for fetal anomalies by antenatal ultrasound scan was significantly worse than that for the low-risk population. This is likely to be related to the maternal body habitus and unsatisfactory examinations. Methods to overcome these difficulties are discussed.

Adult↗
PubMed2002

The relative risk of 'fetal distress' in pregnancy associated with meconium-stained liquor at different gestation.

Pregnancies complicated with meconium-stained liquor are regarded as at risk of fetal distress. Evidence from animal and human studies indicate that passage of meconium may be related to fetal maturity. This retrospective study attempts to quantify the relative risk of non-reassuring cardiotocography or 'fetal distress' in pregnant women complicated by meconium-stained liquor for preterm, term and post-term pregnancies. A total of 9542 singleton pregnancies, delivered in a tertiary obstetric unit in Hong Kong between 1 July 1996 and 31 June 1999, were included in the study. Of these pregnancies, 1946 (20.4%) were identified as having meconium-stained liquor, ranging from thin to thick staining. There was a strong association between incidence of meconium-stained liquor (P < 0.0005) and moderate/thick meconium-stained liquor with advanced gestational age. The incidence of non-reassuring cardiotocography in women presenting with meconium-stained liquor was significantly higher (9.8% vs. 6.4%). The relative risk of non-reassuring cardiotocography in women with meconium-stained liquor increased with more advanced gestation. Close fetal surveillance during labour is required among these pregnancies. Premature labour is associated with higher incidence of fetal distress but the presence of meconium did not pose an additional risk.

Amniotic Fluid↗
PubMed2002

A randomised placebo-controlled trial of vaginal misoprostol for cervical priming before hysteroscopy in postmenopausal women.

OBJECTIVE: To investigate the effectiveness of misoprostol given vaginally for cervical priming before hysteroscopy in postmenopausal women. DESIGN: Double-blind randomised controlled study. SETTING: Regional hospital, Hong Kong. PARTICIPANTS: One hundred women with postmenopausal bleeding scheduled for hysteroscopy from October 1998 to September 2001 were randomly assigned to receive either misoprostol or placebo vaginally before the operation. MAIN OUTCOME MEASURES: The number of women requiring cervical dilatation, outcome of hysteroscopy and side effects of the medication were assessed. RESULTS: Forty-eight women receiving misoprostol and 48 women receiving placebo were compared. The mean degree of endocervical diameter estimated by Hegar's dilator was similar between the treatment group and the control group. A similar number of women in the treatment group and the control group required cervical dilatation. The operative times for both groups were similar. The incidence of side effects was comparable in both groups. The most common side effects for misoprostol were febrile episodes and diarrhoea. There was no cervical tear nor uterine perforation encountered in both groups. The mean duration of hospital stay in both groups were similar. Subanalysis of results were similar in women receiving vaginal medication at least five hours before the operation. CONCLUSION: Vaginal misoprostol was not shown to reduce the need for cervical dilatation in postmenopausal women. It cannot convert diagnostic hysteroscopy from a hospital procedure into an office one in postmenopausal women with tight cervical os.

Administration, Intravaginal↗
PubMed2002

Does sweeping of membranes beyond 40 weeks reduce the need for formal induction of labour?

OBJECTIVE: To assess the efficacy of sweeping of membranes beyond 40 weeks of gestation in reducing the incidence of induction of labour, when induction was planned at 42 weeks. DESIGN: Prospective randomised controlled trial. SETTING: A regional obstetric unit in Hong Kong. POPULATION AND METHODS: A total of 120 women with certain gestational age, determined by early pregnancy ultrasound scan, were recruited from 1st July, 1998 to 31st December, 1999. Sixty women were randomly allocated to sweeping of membranes and the other 60 women acted as control. The satisfaction for women allocated to sweeping of membranes was assessed by a questionnaire after the procedure. The two groups were assessed on intention-to-treat basis. MAIN OUTCOME MEASURES: The incidence of formal induction of labour was compared between the two groups. Possible complications of sweeping of membranes such as rupture of membranes, intrapartum infection, postpartum infection, and neonatal infection were also assessed. Maternal and perinatal outcomes were also assessed. RESULTS: The recruitment to delivery interval was significantly shorter among women who had sweeping of membranes (3.2 versus 4.2 days, P < 0.05). The incidence of induction of labour was comparable (35.5% versus 38%, RR 0.91, 95% CI 0.57 - 1.46). The incidences of caesarean section and assisted vaginal delivery were comparable. The incidences of premature rupture of membranes, intrapartum, and postpartum infection were comparable. The perinatal outcomes were also comparable between the two groups. Up to 70% of women found that this procedure was associated with significant discomfort. One third of these women complained of significant pain. CONCLUSIONS: Sweeping of membranes beyond 40 weeks does not reduce the need for formal induction of labour at 42 weeks. Although it is safe, the majority of women felt uncomfortable during the procedure.

Adult↗