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Biomedical subjects

T K Lau

Publications and source records attributed to T K Lau.

At least 19 recordsLinked to original sources
PubMed2003

Customizing fetal biometric charts.

OBJECTIVE: To study the effects of maternal and pregnancy characteristics on fetal biometric size using longitudinal ultrasound measurements and to construct customized models for fetal biometric size charts. METHODS: A cohort of 533 healthy pregnant women with normal singleton pregnancies were recruited for regular ultrasound examination for fetal biometry between 24 and 40 weeks' gestation. Multilevel modeling was used to construct models of fetal head size, femur length and abdominal circumference. Variables of maternal and pregnancy characteristics including booking weight and height, age, parity and fetal sex were included in the construction of the customized fetal biometric size charts. RESULTS: Increased fetal head size and abdominal circumference were significantly associated with extremes of maternal age. Maternal height had a statistically significant influence on biparietal diameter. Maternal booking weight had an influence on fetal abdominal circumference and femur length. Fetal sex was found to have a statistically significant influence on the final regression models of biparietal diameter, head circumference and femur length. Parity had an influence on fetal head circumference and abdominal circumference. CONCLUSIONS: Maternal and pregnancy characteristics have a significant influence on in-utero fetal biometry. We produced models to construct customized fetal biometric size charts. Further validation studies are necessary to evaluate the clinical usefulness of such customized fetal biometric size charts.

Adult↗
PubMed2003

A study of teratogenicity of hydrosalpinx fluid using a whole rat embryo culture model.

BACKGROUND: Hydrosalpinx fluid may be toxic to sperm and early embryo growth. Information concerning the effect of hydrosalpinx fluid on embryo development during organogenesis is lacking. METHODS: Rat embryos at gestational day 9.5 were cultured for 48 h with 80% rat serum and 20% of either hydrosalpinx fluid (study group) or lactated Ringer's solution (control group). Embryos were scored for growth and development at the end of the culture period. RESULTS: Hydrosalpinx fluid, collected from 10 patients, was tested for embryotoxicity individually. Median total morphological scores were significantly lower in embryos exposed to hydrosalpinx fluid from three of the 10 patients (43.0 versus 47.0, P = 0.01; 36.0 versus 45.0, P < 0.001; 36.0 versus 46.5, P = 0.003). This was accompanied by a significant reduction in median yolk sac diameter (4.0 versus 5.2 mm, P < 0.001 and 4.0 versus 5.0 mm, P < 0.001) and somite number (17.5 versus 22.5, P < 0.001 and 17.0 versus 21.5, P = 0.008) in the latter two patients. CONCLUSIONS: Hydrosalpinx fluid in some patients may contain toxin(s) that is potentially teratogenic.

Animals↗
PubMed2002

Second-trimester ultrasonographic assessment of the umbilical coiling index.

OBJECTIVE: To determine the relationship between gestational age and the ultrasonic measurement of umbilical coiling index (UCI), and to assess the ability of second-trimester ultrasonic measurements of UCI to predict the true UCI, determined at birth. SUBJECTS/METHODS: Five hundred and thirty-one consecutive women with uncomplicated pregnancies, booking for delivery with a singleton pregnancy, were recruited during a routine second-trimester fetal morphology scan. Multiple ultrasonographic measurements of the intercoil distance were performed between two to three coils of the umbilical cord, along its entire visible length. Three hundred and seventy-four patients (70%) were followed until delivery when the true UCI was measured. RESULTS: An adequate portion of umbilical cord for assessment of coiling was visualized in 99% of cases. Adequate ultrasonographic visibility rates for the fetal, middle and placental regions of the cord were different. All three regions of the umbilical cord could only be visualized adequately in 10% of cases, and two regions were visible in 75%. The UCI progressively decreased along the cord from the fetal insertion to the placental insertion. The mean decrease in UCI with increasing gestational age was similar in all parts of the cord before the 23rd week (160 days) of pregnancy, and plateaued off after this point, except in measurements performed near the fetal insertion. The sensitivity of second-trimester ultrasound examination for predicting hypercoiling at birth was 17.3% and for predicting hypocoiling was 9.1%. DISCUSSION: Whilst UCI can be measured easily and reliably in the second trimester these estimates do not accurately reflect the UCI at term. Our original assumption that umbilical coiling does not alter after the initial formation of coils in the first trimester is incorrect; mixed patterns occurred in about 25% of cases. These patterns develop during the second and third trimesters, presumably due to snarls in the cord, and influence the final coiling number and therefore the relationship between the two measurements of UCI.

Female↗
PubMed2002

Back pain in pregnancy--magnetic resonance imaging correlation.

AIM: To study the relationship of disk abnormality and signal changes of the uterine cervix on magnetic resonance imaging (MRI) with back pain in pregnancy at 36-39 weeks of gestation. MATERIAL AND METHODS: One hundred and five pregnant Chinese women with previous Caesarean section at 36-39 weeks gestation undergoing magnetic resonance pelvimetry performed for a study for trial of vaginal delivery were questionnaired for back pain. Sagittal T2-weighted images were analysed for intervertebral disk abnormality, and signal intensity of the uterine cervix on the same sagittal images. The findings on MRI were correlated with back pain. RESULTS: Seventy-three (70%) of the pregnant women had back pain. Disk bulge or prolapse were infrequent but correlated significantly with the presence of back pain (P=0.02). Women with back pain in the current pregnancy tended to have a higher signal intensity of the uterine cervix compared with those without (P=0.006). Women with a history of back pain also had higher cervical signal intensity compared with those without (P=0.02). CONCLUSION: Disk bulge or prolapse was associated with back pain in pregnancy but were relatively infrequent. The significant correlation of high signal intensity in the uterine cervix and back pain suggested that soft tissue laxity may be a more important cause of back pain in pregnancy than disk bulge or prolapse.

Adult↗
PubMed2002

An in-vivo study on placental transfer of naproxen in early human pregnancy.

BACKGROUND: Naproxen is one of the most common non-steroidal anti-inflammatory drugs used by women of reproductive age. Naproxen is known to be teratogenic in animals. The aim of this study was to investigate the placental transfer of naproxen in the first trimester of human pregnancy, and to determine the amount of the drug in different embryonic compartments. METHODS: Twenty-eight patients who requested surgical termination of pregnancy in the first trimester were given two oral 500 mg doses of naproxen before the surgical procedure. Four biological samples, maternal venous blood, coelomic fluid, amniotic fluid and fetal tissue, were collected from each patient for drug analyses by high performance liquid chromatography. RESULTS: Naproxen was detected in all samples. The mean (+/- SD) concentrations were 69.5 +/- 12.2 microg/ml, 6.4 +/- 2.4 microg/g, 1.85 +/- 1.03 microg/ml and 0.14 +/- 0.11 microg/ml in maternal serum, fetal tissue, coelomic fluid and amniotic fluid respectively. The mean amniotic fluid/maternal drug ratio and fetal/maternal drug ratio were 0.002 (range 0.0005-0.0064) and 0.092 (range 0.022-0.155) respectively. There was a positive correlation between the fetal drug concentration (r = 0.59, P = 0.001), amniotic fluid drug concentration (r = 0.47, P = 0.013), amniotic fluid/maternal ratio (r = 0.536, P = 0.003) and fetal/maternal ratio (r = 0.72, P < 0.001) with advancing gestational age. CONCLUSIONS: Although naproxen can cross the placenta readily in the first trimester of human pregnancy, only a small amount was present in fetal tissues. Since there is no information on whether this small amount of naproxen would be teratogenic or not, women of reproductive age who are taking naproxen regularly should be warned of the possible fetal side-effects.

Amniotic Fluid↗
PubMed2001

The upregulation of angiotensin II receptor AT(1) in human preeclamptic placenta.

The human placenta has been considered to possess a locally generated renin-angiotensin system (RAS), which may play a physiological role in the regulation of uteroplacental blood circulation. The changes in the expression of such a placental RAS during pregnancy could be important for the physiological and pathophysiological aspects of some clinical disorders, such as pregnancy-induced hypertension, preeclampsia. In the present study, the alterations of expression and localization of placental angiotensin II receptor subtypes, namely AT(1) in patients with preeclampsia (elective caesarean delivery) were investigated and compared with controls (vaginal delivery and elective caesarian delivery) using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), Western blot and immunohistochemistry respectively. Results from RT-PCR analysis revealed an upregulated expression of placental mRNA for AT(1) receptor subtype in patients with preeclampsia when compared with those in controls. In addition, there was also a significant activation of placental expression of angiotensinogen mRNA in patients with preeclampsia. Results from Western blot showed that the expression of AT(1) receptor was also upregulated. Immunohistochemical results further demonstrated that increased immunoreactivity for placental AT(1) receptor was predominantly localized to the thin layers of syncytiotrophoblasts and, to a less extent, the capillaries of the term placental villi. These data indicate that upregulation of placental RAS components, notably AT(1) receptor in the syncytiotrophoblasts, could play a pathophysiological role in patients with preeclampsia.

Angiotensinogen↗
PubMed2001

Intracardiac leiomyomatosis. Case report and literature review.

We describe a case of intracardiac leiomyomatosis originating from the uterus, growing up in the inferior vena cava, and extending into the right ventricle. She also found to have lung metastasis. As she declined for further operative intervention, Tamoxifen was given for the control of disease. This case represented an unusual rapid recurrence of intravenous leiomyomatosis which was potentially preventable. To investigate for the appropriate management, a review of the literature concerning this rare condition was made.

Aged↗
PubMed2001

Venous thromboembolism in pregnant Chinese women.

OBJECTIVE: To evaluate the incidence, disease pattern, and risk factors for thromboembolism in pregnant Chinese women. METHODS: We conducted a study from January 1998 to December 2000. Women with thromboembolic diseases were identified and their case records retrieved and reviewed. Demographic characteristics were compared between women with and without thromboembolism. RESULTS: Thirty-two women were diagnosed as having thromboembolic disease during the study period. The total number of deliveries over the study period was 16,993, giving an incidence of 1.88 per 1000 deliveries. There were two cases of pulmonary embolism and one resulted in a maternal death. The others had deep vein thrombosis of which over 80% were limited to calf veins only. The ultrasound examinations requested for suspected deep venous thrombosis before and after the event of maternal death were 1.62 and 10.7 per 1000 deliveries (P <.001); and the corresponding cases of deep venous thrombosis diagnosed were 0.29 and 2.94 per 1000 deliveries, respectively (P <.001). The majority (75%) of cases were diagnosed in the postpartum period, mainly after cesarean delivery. Women with venous thromboembolism were older, had higher body mass index, and a higher incidence of preeclampsia. CONCLUSION: Thromboembolic disease is not uncommon among pregnant Chinese women. The incidence was similar to that of the white population, although the sites of vascular occlusion were different. The long-standing belief that thromboembolism is rare among Chinese is at least partly because of underdiagnosis.

Asian People↗
PubMed2001

Influences of perinatal factors on cord blood thyroid-stimulating hormone level.

BACKGROUND: Cord blood thyroid-stimulating hormone level is affected by various perinatal factors. The aim of this study is to investigate the relative impact of these factors on the cord blood thyroid-stimulating hormone results in singleton pregnancies. METHODS: The study group consisted of 20,086 consecutive singleton deliveries over a 3 year period. The effect of mode of delivery, infant sex, gestation at birth, birth weight, and duration of labor on the incidence of false elevation of cord blood thyroid-stimulating hormone was assessed by univariate analysis and logistic regression. RESULTS: There was an independent positive association between false elevation of cord blood thyroid-stimulating hormone (> or =15.0 mIU/L) and birth weight (p=0.005), male infant sex (p<0.001), and instrumental delivery (p<0.001). Both elective and emergency cesarean section were negatively associated with elevated cord thyroid-stimulating hormone level (p<0.001). When the cutoff level was raised to 40.0 mIU/L, none of the variables examined were significant. The incidence of false positive tests (> or =15.0 mIU/L) was higher in neonates born by cesarean section for failed instrumental delivery and fetal distress than for failure to progress of labor (34.7% vs 4.5% vs 1.3% respectively, p<0.001). CONCLUSIONS: While the incidence of false positive screening was significantly affected by various perinatal factors when the thyroid-stimulating hormone cutoff level is low, it was unaffected at a high cutoff level. The present study also provides further evidence that cord blood thyroid-stimulating hormone level reflects fetal response to perinatal stress events.

Birth Weight↗
PubMed2001

A study of diclofenac-induced teratogenicity during organogenesis using a whole rat embryo culture model.

BACKGROUND: Diclofenac is a non-steroidal anti-inflammatory drug, commonly used by reproductive age women for the treatment of a variety of conditions. However, there is limited information regarding the teratogenic effects of this drug. METHODS: The effect of diclofenac on the developing embryo during the critical period of organogenesis was investigated by using a whole rat embryo culture model. Embryos were exposed to various concentrations of diclofenac and scored for growth and differentiation at the end of the culture period. RESULTS: Total developmental score and score for caudal neural tube, flexion and hindlimb were significantly lower in embryos exposed to high concentrations of diclofenac (7.5 and 15.0 microg/ml), but no difference in these parameters was observed when embryos were exposed to low concentration of diclofenac (1.5, 2.5 and 5.0 microg/ml). No significant differences in yolk sac diameter, crown-rump length and number of somites was found between embryos in the experimental and the control group. CONCLUSIONS: Our study has demonstrated that diclofenac exerts direct teratogenic effects on rat embryos. Until more is known about the effects of diclofenac (especially in moderate to high doses) in women of reproductive age, we suggest its use should be treated with caution.

Abnormalities, Drug-Induced↗
PubMed2001

Comparison of metaraminol and ephedrine infusions for maintaining arterial pressure during spinal anesthesia for elective cesarean section.

BACKGROUND: Although ephedrine is usually recommended as the first-line vasopressor in obstetrics, its superiority over other vasopressors has not been proven in humans. METHODS: In a double-blind study, the authors randomized women having elective cesarean section with spinal anesthesia to receive an intravenous infusion of ephedrine, starting at 5 mg/min (n = 25), or metaraminol, starting at 0.25 mg/min (n = 25), titrated to maintain systolic arterial pressure in the target range 90-100% of baseline. Umbilical cord gases, maternal hemodynamics, uterine artery puLsatility index, and Apgar scores were compared. RESULTS: Systolic arterial pressure was maintained more closely in the target range in the metaraminol group compared with the ephedrine group. In the metaraminol group, umbilical arterial pH was greater (median and interquartile range, 7.31 and 7.31-7.33 vs. 7.24 and 7.14-7.29; P < 0.0001), and umbilical venous pH was greater (7.36 and 7.35-7.38 vs. 7.33 and 7.26-7.34; P < 0.0001) compared with the ephedrine group. No patient in the metaraminol group had umbilical arterial pH less than 7.2, compared with nine patients (39%) in the ephedrine group (P = 0.0005). Apgar scores were similar between groups. Changes in uterine artery pulsatility index were similar between groups. CONCLUSIONS: When used by infusion to maintain arterial pressure during spinal anesthesia for cesarean section, metaraminol was associated with less neonatal acidosis and more closely controlled titration of arterial pressure compared with ephedrine.

Adult↗
PubMed2001

The predictive value of serum 1,5-anhydro-D-glucitol in pregnancies at increased risk of gestational diabetes mellitus and gestational impaired glucose tolerance.

The objective of the study was to determine the efficacy of 1,5-anhydro-D-glucitol (1,5 AG) for the prediction of gestational diabetes and gestational impaired glucose tolerance (GIGT). One hundred and eighty-five pregnant women with epidemiological risk factors of gestational diabetes or GIGT underwent 75 g oral glucose tolerance test and plasma 1,5 AG assay at 26 to 28 weeks of gestation. There was no significant difference in plasma 1,5 AG either before or after an oral glucose load. The area under the receiver operator characteristic curve for 1,5 AG was only 0.485 which implies that 1,5 AG is a poor predictor of GIGT or gestational diabetes.

Adolescent↗
PubMed2001

Levels of cord blood thyroid stimulating hormone after external cephalic version.

OBJECTIVE: To investigate the relationship between breech presentation, external cephalic version and levels of cord blood thyroid stimulating hormone. DESIGN: Case-control study. SETTING: University teaching hospital. POPULATION: The study group consisted of 289 consecutive singleton deliveries at term over a four-year period, all of whom had an attempt at external cephalic version performed near term for breech presentation. The control group included 23,001 singleton term deliveries during the same four-year period. METHODS: Between group differences were compared with the Mann-Whitney U test or chi2 test when appropriate. MAIN OUTCOME MEASURES: Levels of cord blood thyroid stimulating hormone and the incidence of false positive screening results for congenital hypothyroidism. RESULTS: Babies who were born vaginally after prior successful external cephalic version had significantly higher median levels of cord blood thyroid stimulating hormone (6.4 vs 6.0 mlU/L, P = 0.034) and the incidence of false positive screening for thyroid stimulating hormone (12.9% vs 7.2%, P = 0.016, OR 1.9) compared with babies with spontaneous cephalic presentation. In babies with a breech presentation born by elective caesarean section, previous attempts at external cephalic version had no effect on cord blood thyroid stimulating hormone levels. There was also no difference in the levels of cord blood thyroid stimulating hormone between cephalic and breech-presenting fetuses born by elective caesarean section. However, breech-presenting babies born by emergency caesarean section after onset of labour had higher median levels of cord thyroid stimulating hormone than those with cephalic presentation (5.1 vs 4.5 mIU/L, P= 0.008). CONCLUSION: Levels of cord blood thyroid stimulating hormone are elevated in babies born vaginally after a successful external cephalic version. This finding may represent a biological difference in fetal response to the stress of labour in breech-presenting fetuses, which is not correctable by a successful external cephalic version.

Adult↗
PubMed2001

Relationship between birthweight and repeated courses of antenatal corticosteroids.

A retrospective study was conducted in a university teaching hospital to review the association between birthweight and the number of courses of antenatal corticosteroids received in 236 singleton pregnancies. Those pregnancies complicated with pregnancy-induced hypertension, preeclampsia, diabetes mellitus and intrauterine growth restriction were excluded. The results showed that the birthweight ratio (calculated as the baby's birthweight divided by the median birthweight for that gestational age) was negatively correlated with the number of courses of corticosteroids received. Further, exposure to four or more courses of antenatal corticosteroids was associated with a significant reduction in birthweight ratio and a three-fold increase in the risk of being small-for-dates compared to those exposed to one to three courses.

Birth Weight↗
PubMed2001

Circulating fetal RNA in maternal plasma.

The discovery of cell-free nucleic acids in plasma has opened up new possibilities for noninvasive clinical diagnosis. We demonstrate the presence of cell-free fetal RNA in maternal plasma, indicating that plasma fetal RNA might be used as a marker for noninvasive prenatal diagnosis.

Biomarkers↗
PubMed2001

Risk and prediction of preterm delivery in pregnancies complicated by antepartum hemorrhage of unknown origin before 34 weeks.

OBJECTIVE: To assess the timing and risk factors of preterm delivery in pregnancies complicated by antepartum hemorrhage of unknown origin (APHUO) before 34 weeks of gestation, and to formulate a clinical management protocol. METHODS: A retrospective study involving singleton pregnancies with APHUO occurring before the 34th week of gestation was performed over a 4-year period at a university teaching hospital. RESULTS: Seventy-five cases were identified. Fifty-nine (78.7%) did not have any associated uterine contractions, 74.7 and 90.7% of the cases were classified as having mild bleeding according to history and physical examination, respectively. The number of cases delivering before 37 weeks of gestation and before 34 weeks were 28 (37.3%) and 22 (29.3%), respectively. Eighteen cases (24%) delivered within the first week of APHUO, and 4 (5.3%) within the first day. The number of cases delivering within the first week was significantly higher when there were uterine contractions (62.5 vs. 13.6%, p < 0.001). The severity of bleeding was not shown to be related to the time of delivery. CONCLUSION: APHUO that occurs before 34 weeks is associated with a high risk of preterm delivery before 34 weeks (29.3%). The chance of delivery within the first week is 62.5% when there are coexisting uterine contractions. Even if contractions are absent, the risk is still high (13.6%) and persists beyond the first week. We suggest that this group of patients should be managed with a course of steroid injection and hospitalization for 4 days.

Female↗