Lai Wa Law

Prediction of birth weight by fetal crown-rump length and maternal serum levels of pregnancy-associated plasma protein-A in the first trimester

To determine whether the first trimester crown–rump length (CRL), maternal serum levels of pregnancy‐associated plasma protein A (PAPP‐A) and free beta‐human chorionic gonadotropin (fβ‐hCG) are independent predictors of birth weight.

Which ultrasound or biochemical markers are independent predictors of small-for-gestational age?

To investigate which ultrasound or biochemical markers in both the first and the second trimesters are the best predictors for fetal growth and small‐for‐gestational age (SGA).

First trimester combined screening for Trisomy 21 in Hong Kong: outcome of the first 10,000 cases

Objective.u2003To examine the effectiveness of first trimester fetal Trisomy 21 (T21) screening using a combination of maternal age, nuchal translucency, maternal serum levels of free β-hCG and PAPP-A in a predominantly Chinese population in Hong Kong. Methods.u2003Consecutive women who underwent the combined screening for T21 between 11 and 13 + 6 weeks of gestation between 2003 and 2007 were recruited. Risk of T21 was calculated using Fetal Medicine Foundation algorithm and karyotyping was advised when the risk was 1:300 or above. All women were followed up for pregnancy and fetal outcome. Results.u200310,363 fetuses underwent screening. 99% of the women were Chinese and 27.4% were at or above 35 years old. 618 fetuses were screened positive (5.9%), which included 31 cases of T21, 14 cases of T18, 7 cases of T13, 10 cases of 45XO and 7 cases of other chromosomal abnormalities. Among the 9745 screened negative fetuses all but 50 (0.5%) had a known outcome, which included three T21 and four other chromosomal abnormalities. All were subsequently identified at the morphology scan except for one case of T21. The detection rate and false positive rates for T21 were 91.2% and 5.4%, respectively and the positive predictive value for all chromosomal abnormalities was 1 in 9. Conclusions.u2003Combined screening for T21 is highly effective among Chinese women. Training, quality control, regular auditing and follow up are essential to maintain screening standards.

De novo 16p13.11 microdeletion identified by high-resolution array CGH in a fetus with increased nuchal translucency

Objectiveu2002 We investigated the application of high‐resolution microarray‐based comparative genomic hybridisation (array CGH) on a fetus showing increased nuchal translucency (NT).

Effect of long-term storage on placental growth factor and fms-like tyrosine kinase 1 measurements in samples from pregnant women

Objective.u2003To assess the effect of storage time on the stability of placental growth factor (PlGF) and fms-like tyrosine kinase 1 (sFlt-1) levels in frozen serum samples from pregnant women. Methods.u2003This is a matched case–control study using fresh and stored serum samples collected at 6, 12, 18, 24, 30 and 36 months prior to the collection of the fresh samples and frozen at –80°C. Forty-eight samples from each of the seven time-groups were matched for non-smoking Chinese, maternal weight, singleton-term pregnancy without major obstetric complications and extracted for PlGF and sFlt-1 assays. Multivariate analysis was performed to assess residual effects of the case-matching procedure. ANOVA was used to assess the effects of storage time. Results.u2003Multivariate analysis of the 336 samples indicated that log10PlGF was positively correlated with parity (pu2009=u20090.014) and gestational age (pu2009=u20090.029), while log10sFlt-1 was inversely correlated with parity (pu2009=u20090.018). After correcting for the residual effect of gestation and parity, ANOVA showed no significant difference in PlGF and sFlt-1 levels between the fresh samples and all stored samples (pu2009=u20090.410 and pu2009=u20090.158, respectively). Conclusions.u2003Serum PlGF and sFlt-1 levels are stable for at least 3 years when stored at –80°C. Parity is an independent factor of PlGF and sFlt-1 levels. PlGF levels are lower and sFlt-1 levels are higher in nulliparous women compared to multiparous.

Medians and correction factors for biochemical and ultrasound markers in Chinese women undergoing first‐trimester screening for trisomy 21

To establish normative values and distribution parameters of first‐trimester maternal serum free β‐human chorionic gonadotropin (β‐hCG), pregnancy‐associated plasma protein‐A (PAPP‐A) and fetal nuchal translucency (NT) thickness in Chinese women and to examine the effects of covariates on their levels.

Comparison of first‐trimester contingent screening strategies for Down syndrome

To assess the relative performance of a multi‐stage first‐trimester screening protocol for fetal Down syndrome.

Use of Hemostatic Gel in Postpartum Hemorrhage Due to Placenta Previa

BACKGROUND: Hemostasis for placenta previa is notoriously difficult because of the poor contractility of the lower segment. A hemostatic gel offers a new type of hemostatic matrix, which may have advantages. CASE: A 35-year-old woman had a postpartum hemorrhage despite the use of uterotonics 2 hours after cesarean delivery for major placenta previa. On relaparotomy, heavy oozing from the placental site was found. Difficult accessibility and profuse bleeding prompted the consideration of alternative treatment with the topical application of hemostatic gel over the lower segment, which achieved hemostasis within minutes. CONCLUSION: Hemostatic gel is easily applicable and provides quick and effective hemostatic control in the lower segment, where surgical intervention may be difficult.

Maternal hepatitis B surface antigen status and incidence of pre-eclampsia

The relationship between chronic hepatitis B virus (HBV) infection with atherosclerosis and cardiovascular disorders remains unclear, and the impact of maternal HBV infection on the development of pregnancy‐induced hypertension (PIH) and pre‐eclampsia (PE) is also controversial. This retrospective cohort study was conducted to examine the relationship between maternal hepatitis B surface antigen (HBsAg) status with PIH and PE in singleton pregnancies that delivered at 24 weeks of gestation and beyond. Among the 86 537 cases in the cohort, 10% were HBsAg positive, and overall 2.0% had PIH, of whom 56.3% developed PE. HBsAg‐positive women had higher weight and body mass index (BMI), but lower incidences of advanced age, nulliparity, PIH (1.6% vs 2.0%, P = 0.007) and PE (0.8% vs 1.1%, P = 0.005). On multiple logistic regression analysis adjusting for the effects of nulliparity, advanced age, high BMI, and underlying renal, cardiac and autoimmune diseases, HBsAg carriage was associated with significantly reduced incidence of PIH (aOR 0.79, 95% CI 0.66–0.95) and PE (aOR 0.71, 95% CI 0.56–0.91). Our results indicate that maternal HBsAg carriage is independently associated with reduced PE. As chronic HBV infection alters the immune response of the individual, our observation could be related to enhanced maternal immunotolerance of the foetus and hence a reduction in the incidence of PE. The implications of our findings on the long‐term health outcome of the infected women, from cardiovascular morbidity to malignancies, warrant further studies.

Prediction of intrapartum Cesarean delivery for non‐reassuring fetal status after a successful external cephalic version by a low pre‐version pulsatility index of the fetal middle cerebral artery

To determine whether a pre‐version Doppler assessment of fetal cerebral and umbilical blood flow can predict the ultimate need for intrapartum Cesarean delivery after a successful external cephalic version (ECV).