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Biomedical subjects

Tak Yeung Leung

Publications and source records attributed to Tak Yeung Leung.

18 recordsLinked to original sources
PubMed2006

The utility assessment of Chinese pregnant women towards the birth of a baby with Down syndrome compared to a procedure-related miscarriage.

OBJECTIVE: This study was performed to investigate the preferences of Chinese pregnant women for Down syndrome-affected birth compared to invasive test-related miscarriage, using the standard gamble approach, and to investigate whether there is a difference in Utility Score between general obstetric patients and those who request prenatal screening. METHODS: An interviewer-administered survey was conducted on 67 women who presented to the General Obstetric Clinic for booking visits and 69 women who presented to the first-trimester Combined Screening Clinic for fetal Down syndrome in a University Obstetric Unit. Preferences for Down syndrome-affected birth compared to invasive test-related miscarriage were assessed using the standard gamble approach. The differences in Utility Scores for the two outcomes and difference in scores between the two study groups were compared. RESULTS: There was no significant difference in any of the Utility Scores studied between the two study groups. Therefore the summary statistics were performed using the whole study population. The median Utility Score for a Down syndrome-birth was 0.20 (IQR: 0.10-0.40), which was significantly lower than that of 0.55 (IQR: 0.40-0.80) for a procedure-related miscarriage (p < 0.001). Also, the Utility Scores were neither found to be associated with any particular patient demographic characteristics nor their perception of the functional disability of individuals with Down syndrome. CONCLUSION: The Chinese pregnant women in Hong Kong consider a Down syndrome-affected birth as a much worse health state and life event than a miscarriage. Whether or not to have a screening test appeared to be a result of accessibility and affordability rather than fundamental differences in attitude towards Down syndrome. The findings of the study provide important information on how prenatal screening and diagnosis of fetal chromosomal abnormalities should be offered.

Abortion, Spontaneous↗
PubMed2006

Risk factors for procedure-related fetal losses after mid-trimester genetic amniocentesis.

BACKGROUND: The objective of this study was to determine the institutional pregnancy loss rate following second-trimester genetic amniocentesis and to ascertain whether factors exist which would identify pregnancies at increased risk of having a procedure-related fetal loss. SETTING: University Teaching Hospital METHODS: Details of the procedure and pregnancy outcome of all patients who had amniocentesis planned or performed between 15-22 gestational weeks between January 1997 and June 2004 were extracted from our clinical audit database. The procedure-related fetal loss rate, defined as all unintended abortions, stillbirths and neonatal deaths without major fetal abnormalities or obvious obstetric causes, was determined and compared to a presumed background fetal loss rate of 0.8% based on a cohort of women who did not undergo the procedure. RESULTS: A total of 3468 consecutive amniocentesis were performed in 3440 patients with 3498 fetuses. The mean gestational age at amniocentesis was 17.6 +/- 1.2 weeks. The majority (98.6%) required only one puncture and a transplacental procedure was required in 2.7% cases. A total of 3465 chromosomal studies were performed. Sixty six cases (1.9%) of major chromosomal abnormalities were detected. Pregnancy outcome was ascertained in all except 26 singleton pregnancies (0.74%). There were 3285 (93.9%) livebirths, 103 (2.9%) termination of pregnancies (TOP), 6 (0.17%) fetal demises before the procedure, and 20 (0.61%) unintended fetal losses due to significant fetal abnormalities or obstetric complications. The remaining 58 fetal losses (1.66%) were classified as potentially procedure-related, which could be either background fetal losses or procedure-related. The procedure-related fetal loss rate after correcting for the background loss rate was 0.86%.Potentially procedure-related fetal losses were found to be significantly associated with a procedure at 18 weeks or beyond (odds ratio OR = 1.97), a procedure performed for abnormal second-trimester biochemical screening test (OR = 3.08), a bloody tap (OR = 6.48), and a female fetus (OR = 2.39); but not to the number of punctures (p = 0.66) nor transplacental amniocentesis (p = 0.104). CONCLUSIONS: Mid-trimester amniocentesis is associated with a small but significant risk of fetal loss of 0.86%.

Abortion, Spontaneous↗
PubMed2006

Variation of force applied during external cephalic version with different patients' characteristic and outcome of version.

BACKGROUND: To compare the degree of force applied during external cephalic version, between different patients' characteristic and outcomes of version. METHODS: It is a prospective observational study in a cohort of patients undergoing external cephalic version at or above 36 weeks of gestation. During external cephalic version, the operator wore a pair of pressure-sensing gloves which had ultra-thin piezo-resistive pressure sensors positioned on the palmer surface. Readings from each of the sensors were recorded in real time throughout each version attempt and analyzed by a computer program. The pressure exerted on individual sensors over time, the pressure-time integral (PTI; mmHg s), was calculated for each sensor from the start to the end of each version attempted. The degree of force applied for each attempt (PTI-A) was represented by the sum of pressure-time integrals across all sensors. PTI-A was analyzed in relation to different patients' characteristics and outcome of version. RESULTS: Ninety-two patients were recruited, 73% of whom had a successful external cephalic version. The median PTI-A of the successful attempt in women who completed version after 1 and 2 attempts were 17,180 and 17,736 mmHg s, respectively. They were significantly lower than that of the women who required 3 or more attempts for a successful version (32,351 mmHg s), as well as the highest PTI-A among all attempts received by women who finally had a failed version (31,638 mmHg s) (p <0.05, Kruskal-Wallis Test and Dunn test). Within the same subject, there was no difference in PTI-A between the successful attempt and the preceding failed attempt, suggesting that the failure may not be due to insufficient force but rather to inefficient application of the force. Uterine tone was found to be the only clinical variable that was significantly associated with the degree of applied force during a version (p < 0.05). A tenser uterus was associated with a stronger applied force. CONCLUSION: The degree of force required for a successful version is highly variable, being lowest when version can be completed within 2 attempts, but doubled when 3 or more attempts are required. Failure of version is usually not due to inadequate force but inefficient application of force. Uterine tone is significantly related to the degree of applied force, with stronger force being exerted when the uterus is tense.

Adolescent↗
PubMed2006

Higher median levels of free beta-hCG and PAPP-A in the first trimester of pregnancy in a Chinese ethnic group. Implication for first trimester combined screening for Down's syndrome in the Chinese population.

OBJECTIVE: To study the effect of ethnic Chinese on the medians of free beta-hCG and PAPP-A in the first trimester of pregnancy. METHODS: The data of 943 women undergoing first trimester combined screening for fetal Down syndrome were analysed to derive the Chinese-specific medians. The calculated risk of Down syndrome based on these Chinese-specific medians was compared with that based on the original algorithm of the Fetal Medicine Foundation (FMF). RESULTS: The maternal serum levels of multiples of median of free beta-hCG and PAPP-A were significantly higher among the Chinese than among the Caucasians. The weight-adjusted gestation-specific medians were developed. Without adjustment for ethnicity, the original FMF algorithm underestimated the risk of Down syndrome by a median of 1%. Adjustment by ethnicity increased the false-positive rate by 10% (from 5.3 to 5.9%). CONCLUSION: Ethnic Chinese have a significantly higher maternal serum level of free beta-hCG and PAPP-A in the first trimester, which could not be explained by differences in maternal weight. Adjustment for ethnicity may be necessary for these biochemical markers in a first trimester screening program.

Biomarkers↗
PubMed2006

Dextrocardia in pregnancy: 20 years' experience.

OBJECTIVE: To identify all pregnancies complicated by maternal dextrocardia and report the obstetric performance in these patients. STUDY DESIGN: A retrospective review of all deliveries between May 1984 and December 2004 at Prince of Wales Hospital, Chinese University of Hong Kong. Maternal demographic data as well as information on the antenatal course and delivery outcome were abstracted from the maternal records. Neonatal record review yielded information on the gestational age at delivery, birth weight, Apgar scores, sex and neonatal conditions after delivery. RESULTS: Fifteen singleton pregnancies in 9 patients with dextrocardia were identified. There were 6 pregnancies in 3 patients with situs inversus and 9 pregnancies in 6 patients with isolated dextrocardia. There were no apparent antenatal complications. None of the patients developed any cardiac symptoms antenatally. All the infants had a 5-minute Apgar score > 7. Four small-for-gestational-age (SGA) infants, defined after correcting for parity, gestational age, maternal height and maternal entry weight, occurred in patients with situs inversus. This is significantly different from the 10% expected (p < 0.002). No SGA infants were born to patients with isolated dextrocardia. CONCLUSION: Pregnancies complicated by maternal isolated dextrocardia did not have any detrimental effect on the disease or vice versa. However, SGA infants should be watched in patients with situs inversus.

Adult↗
PubMed2005

Expectation and knowledge of women undergoing first-trimester combined screening for Down syndrome in a Chinese population.

OBJECTIVES: To study the preference of pregnant women regarding the time taken to report the results of first-trimester combined screening for Down syndrome and their knowledge about it. METHODS: A questionnaire survey was conducted on a cohort of 325 pregnant participants who attended our first-trimester combined nuchal translucency and biochemical screening programme for fetal Down syndrome. This service was operated in a one-stop setting and the result of the screening test was available within 1 to 2 h after the collection of blood sample. RESULTS: The majority of participants: (1) could recall the quoted detection rate correctly (96.6%); (2) understood that a negative test does not exclude Down syndrome (91.1%); (3) understood that a positive test does not equate to an affected fetus (91.0%), and (4) could decide on the need for further invasive tests on the basis of the screening test results (98.1%). Twenty-nine percent of participants considered that a one-stop setting was very important because any delay in releasing the results made a significant difference to them, while 48.9% considered it acceptable if the results were available on the same day. The percentage dropped dramatically to 6.3% (within 2 days), 6.7% (within 3 days), 5.7% (within 1 week), and 3.1% (more than 1 week). CONCLUSION: The majority of the pregnant women in our test considered same day reporting of screening test results to be no different from a one-stop clinic. This would have important implications for the organisation and structuring of our service provision, since the operation of a one-stop clinic imposes significant stresses on the clinical staff involved.

Adult↗
PubMed2005

Maternal experience of pain during external cephalic version at term.

BACKGROUND: This study was designed to investigate maternal pain perception during external cephalic version (ECV). METHODS: This prospective study included 97 pregnant women with singleton breech presentation at or above 36 weeks of gestation undergoing ECV. No analgesia or anesthesia were used during ECV. The women were asked to rate the degree of pain on a 10-cm visual analog scale after ECV. RESULTS: Ninety-eight ECVs were performed and the overall success rate was 66%. The median pain score was 5.7 (interquartile range 2.7-6.8). The visual analog pain score was significantly lower among those with a successful ECV than those with a failed procedure (median score 4.6 vs. 6.8, p < 0.001). Similarly, those procedures rated as easy by the operator were associated with a significantly lower pain score (3.4 vs. 6.4, p < 0.001). However, the pain score was not found to be related to the operator, parity or placental site. Among the five subjects with a pain score of 8.5 and beyond, the ECV procedure was still successful in four (80%). CONCLUSION: ECV performed without analgesia was associated with a moderate degree of pain that was well tolerated by the majority of patients because of its short duration.

Adult↗
PubMed2005

Fetal hemodynamic changes after amniotomy.

BACKGROUND: The aim of the study was to assess fetal vascular blood flow after amniotomy. METHODS: This was a prospective observational study. Thirty-five women with singleton pregnancy beyond 36 weeks of gestation, who underwent amniotomy, were recruited. The pulsatility indices of the fetal middle cerebral artery (MCA), the renal artery, and the ductus venosum were measured before and 30 min following amniotomy. The changes in pulsatility index were compared by means of Wilcoxon signed rank test. RESULTS: There was a significant reduction in pulsatility indices of the MCA (median reduction: 0.23; interquantile range (IQR): -0.04, 0.4) and the renal artery (median reduction: 0.12; IQR: -0.12, 0.54) after amniotomy. However, there was no obvious change in the ductus venosum (median reduction: 0.00; IQR: -0.06, 0.1). CONCLUSIONS: Amniotomy is associated with significant reduction in the impedance of the fetal MCA and the renal artery. The former may be a result of fetal stress response and the latter could be related to the release of vasoactive substances after amniotomy.

Adult↗
PubMed2005

Effect of prostaglandin E2 for cervical priming on fetal hemodynamics.

OBJECTIVE: To assess the effect of the prostaglandin E2 (PGE2) on fetal vascular blood flow during cervical priming. STUDY DESIGN: In a prospective, observational study, 32 pregnant women > or =37 weeks of gestation requiring PGE2 for induction of labor were recruited. The resistance indices (RIs) of umbilical artery, middle cerebral artery, renal artery and ductus venosum were measured before, 2 and 4 hours after insertion of a PGE2 vaginal pessary. RESULTS: There were no significant changes in RIs of various fetal vessels during cervical priming with PGE2. CONCLUSION: There was no significant change in fetal hemodynamics after vaginal prostaglandin administration. This finding provides further evidence to support the safety of prostaglandin for normal fetuses.

Administration, Intravaginal↗
PubMed2004

Prediction of successful vaginal delivery in women undergoing external cephalic version at term for breech presentation.

OBJECTIVE: The aim of this study is to evaluate the clinical and sonographic predictors of ultimate successful vaginal delivery in women undergoing external cephalic version. STUDY DESIGN: The study population consisted of women with external cephalic version performed at or after 36 weeks of gestation. They were randomized into group A or B, each consisted of half of the total study population. Logistic regression was performed on group A to identify the significant independent variables in predicting successful cephalic vaginal delivery, which were used to construct a prediction model. The derived regression model was then tested in group B to assess its accuracy. RESULTS: The study included 407 pregnancies. Maternal weight (kg) at the time of version, maternal height (cm), multiparity, engagement of fetal presenting part, and fetal head palpable were significant independent variables of successful version and vaginal delivery (regression coefficients are: -0.084, 0.085, 1.752, -1.271, and 0.725, respectively). A prediction model was constructed based on these independent variables. The weighted average of the overall accuracy in predicting success or failure of version and vaginal delivery was 70.9%. The regression model was then applied to study group B. Using 0.50 as the cutoff value, the sensitivity, specificity, positive, and negative predictive values were 75.4, 58.8, 73.7, and 61.0%, respectively. CONCLUSION: A regression model constructed based on clinical variables failed to provide an accurate predictive tool of successful external cephalic version and vaginal delivery. However, in women who are equivocal about external cephalic version, a high prediction of success would be encouraging.

Adult↗
PubMed2004

Attitudes towards termination of pregnancy among Hong Kong Chinese women attending prenatal diagnosis counselling clinic.

OBJECTIVE: To investigate the attitudes towards termination of pregnancy (TOP) among Hong Kong Chinese women attending the prenatal diagnosis counselling (PDC) clinic under three circumstances: (1) normal fetus, (2) fetal chromosomal anomalies, and (3) fetal abnormalities diagnosed after 24 weeks of gestation, and to determine the association between the attitudes and demographic factors. METHODS: One hundred and twenty-two women were interviewed using a structured questionnaire. RESULTS: Over 50% of our women viewed it as their right to choose an abortion in early pregnancy and only 28.7% agreed that the doctor has the right to make the final decision. Approximately 90% would choose TOP for lethal chromosomal abnormalities and Down syndrome while about 50% would do so for Klinefelter or Turner syndromes. Over 80% were of the opinion that women should be given the right to choose TOP for lethal congenital malformation as well as for Down syndrome after 24 weeks of gestation. This figure dropped to 55.7% for non-lethal structural malformation that requires postnatal treatment. Religious background was a significant factor for a negative attitude towards TOP. CONCLUSION: Our data suggest that our women who attended the PDC clinic had an open attitude towards TOP for fetal abnormalities in general.

Abortion, Induced↗
PubMed2004

Cord blood acid-base status at delivery after successful external cephalic version.

BACKGROUND: This study was designed to evaluate whether cord blood acidosis is more likely in infants born after successful external cephalic version. METHODS: This retrospective cohort study included 89 singleton deliveries with successful version performed over a 2-year period. Their cord blood acid-base parameters were compared to 89 pregnancies with spontaneous cephalic presentation (control group). RESULTS: There was no significant difference between the version and control groups in birthweight and Apgar scores. There was no difference between the version and control groups in cord arterial pH (7.26 vs. 7.26), arterial pCO(2) (7.04 vs. 7.09 kPa), arterial pO(2) (2.34 vs. 2.59 kPa), arterial base excess (-5.59 vs. -5.64 mmol/L), venous pH (7.32 vs. 7.33), venous pCO(2) (5.73 vs. 5.63 kPa), venous pO(2) (3.86 vs. 3.84 kPa), or venous base excess (-5.03 vs. -5.12 mmol/L). There was also no significant difference in the number of fetuses with cord arterial pH <7.20 between the two groups. CONCLUSION: Neonates delivered after successful external cephalic version are not more likely to be born with acidosis. Our study provides further support for the safety of external cephalic version for term breech pregnancies.

Acidosis↗
PubMed2004

External cephalic version induced fetal cerebral and umbilical blood flow changes are related to the amount of pressure exerted.

OBJECTIVE: To correlate the applied pressure during external cephalic version with the changes in fetal middle cerebral arterial and umbilical arterial flow before and after the procedure. DESIGN: A prospective observational study over a two-year period. SETTING: External cephalic version was performed in a university hospital. POPULATION: Sixty-nine women with singleton breech-presenting pregnancy at or above 36 weeks of gestation undergoing external cephalic version. METHODS: During external cephalic version, the operator wore a pair of pressure-sensing gloves which had thin piezo-resistive sensors positioned on the palmar surface. During each version procedure, real-time pressure readings were recorded from all sensors, and then analysed with a computer program. The amount of pressure applied over time was presented by pressure-time integral. The pulsatility indices of both fetal middle cerebral artery and umbilical artery before and after external cephalic version were measured. The changes of pulsatility indices of both middle cerebral artery and umbilical artery were presented as a ratio of the post-external cephalic version pulsatility indices to pre-external cephalic version pulsatility indices, denoted by middle cerebral artery pulsatility index ratio and umbilical artery pulsatility index ratio, respectively. The statistical correlation between pressure-time integral and middle cerebral artery pulsatility index ratio and umbilical artery pulsatility index ratio are analysed using Pearson's correlation test. MAIN OUTCOME MEASURES: Changes in pulsatility indices of fetal middle cerebral and umbilical arteries and fetal heart rate after external cephalic version. RESULTS: The overall success rate of external cephalic version was 77%. There was a significant negative correlation between pressure-time integral and both middle cerebral artery pulsatility index ratio (P= 0.001) and umbilical artery pulsatility index ratio (P= 0.012). When women were categorised according to placental site, pressure-time integral was negatively correlated with middle cerebral artery pulsatility index ratio only when the placenta was posteriorly located (P= 0.003), and with umbilical artery pulsatility index ratio only when the placenta was laterally located (P= 0.03). CONCLUSIONS: The greater the force applied during external cephalic version, the greater the reduction in pulsatility indices of middle cerebral artery and umbilical artery, indicating an increase in blood flow through these arteries. The increase in cerebral blood flow after external cephalic version is more prominent when the placenta is lying posteriorly, while the increase in umbilical flow is more prominent when the placenta is lying laterally. These findings suggest that the vascular changes probably represent a direct effect of force exerted on the fetal head and the placenta.

Adolescent↗
PubMed2003

Quantification of contact surface pressure exerted during external cephalic version.

BACKGROUND: The amount of force exerted on the uterus and fetus during external cephalic version (ECV) may be associated with fetal effects or complications. We have designed an instrument to quantify the contact pressure exerted during the performance of ECV, as an indirect measurement of the applied force. METHODS: We have designed a pair of custom-made gloves. Each glove contains 16 piezo-resistive sensors positioned on the palmer surface of the fingers, thenar and hypothenar areas. Pressure readings were recorded simultaneously from all sensors every 0.22 s during each version procedure. Each recording was analyzed with a computer program written according to specified algorithms to ascertain the number of attempts in a version operation, and the duration and pressure changes of each attempt during the operation. RESULTS: Ten subjects having a singleton breech presentation at term underwent an operation of ECV. The number of attempts of version in each operation ranged from one to four. The median pressure-time integral and the duration of an attempt were 19,227 mmHg s (range 5089-42,597 mmHg s) and 42.5 s (range 11.9-80.3 s), respectively. The median pressure-time integral of a whole version operation was 38,110 mmHg s (range 5089-107,511 mmHg s). Subjects with a failed version operation received a higher pressure-time integral (p < 0.05). The number of attempts of each operation was accurately identified by the program. CONCLUSIONS: Measurement of force applied during ECV can be quantified indirectly in terms of contact surface pressure. The indirect measurement of the applied force may further improve the safety of this procedure by preventing excessive use of force by the operator.

Adult↗
PubMed2002

High incidence of obstetric interventions after successful external cephalic version.

OBJECTIVE: To investigate the delivery outcome after successful external cephalic version (ECV). DESIGN: Case-control study. SETTING: University teaching hospital. POPULATION: The study group consisted of 279 consecutive singleton deliveries at term over a six-year period, all of which had had successful ECV performed. The control group included 28,447 singleton term deliveries during the same six-year period. METHODS: Between group differences were compared with the Mann-Whitney U test or Student's t test where appropriate. Odds ratio and 95% confidence interval (CI) were calculated for categorical variables. Main outcome measures Incidence of and indications for obstetric interventions. RESULTS: The risk of instrumental delivery and emergency caesarean section was higher in the ECV group (14.3% vs 12.8%; OR 1.4; 95% CI 1.0-2.0, and 23.3% vs 9.4%; OR 3.1; 95% CI 2.3-4.1, respectively). The higher caesarean rate was due to an increase in all major indications, namely, suspected fetal distress, failure to progress in labour and failed induction. The higher incidence of instrumental delivery was mainly due to an increase in prolonged second stage. The odds ratio for operative delivery remained significant after controlling for potential confounding variables. There were also significantly greater frequencies of labour induction (24.0% vs 13.4%; OR 2.0; 95% CI 1.5-2.7) and use of epidural analgesia (20.4% vs 12.4%; OR 1.8; 95% CI 1.4-2.4) by women in the ECV group. The higher induction rate is mainly due to induction for post term, abnormal cardiotocography (CTG) and antepartum haemorrhage (APH) of unknown origin. CONCLUSION: The incidence of operative delivery and other obstetric interventions are higher in pregnancies after successful ECV. Women undergoing ECV should be informed about this higher risk of interventions.

Adult↗