Validation of an oscillometric electronic sphygmomanometer in an obstetric population

Use of an automated electronic sphygmomanometer will allow us to minimize the errors inherent in mercury sphygmomanometry. We conducted this validation according to the 1990 protocol of the British Hypertensive Society. We recruited 87 subjects from the antenatal population of Kandang Kerbau Hospital and took three sequential readings using simultaneously both manual and electronic sphygmomanometry. A total of 261 readings from either method were thus collected and the results analyzed to compare the accuracy of electronically read blood pressure with that assessed manually. We found that 89.9% of the electronically read pressures differed from the manually read pressures by 5 mm Hg or less and 98.9% of the electronic readings differed from manual readings by 10 mm Hg or less; only 0.4% of readings had a difference of more than 15 mm Hg. The accuracy of the device was not affected either by the blood pressure or the arm circumference.

Suppression of multidrug resistance via inhibition of heat shock factor by quercetin in MDR cells

MDR1 promoter has been shown to contain heat shock elements (HSE), and it has been reported that FM3A/M and P388/M MDR cells show a constitutively activated heat shock factor (HSF), suggesting that HSF might be an important target for reversing the multidrug resistance. Therefore, it was examined whether quercetin, which has been shown to interfere with the formation of the complex between HSE and HSF, and to downregulate the level of HSF1, can sensitize MDR cells against anticancer drugs by inhibition of HSF DNA-binding activity. In this study, quercetin appeared to inhibit the constitutive HSF DNA-binding activity and the sodium arsenite-induced HSF DNA-binding activity in the MDR cells. The basal and sodium arsenite-induced MDRCAT activities were remarkably suppressed by the treatment of quercetin. These results were well consistent with the finding that the treatment of quercetin decreased the expression level of P-gp, MDR1 gene product, in dose-dependent manner, and markedly increased the sensitivity of MDR cells to vincristine or vinblastine. These results suggest that quercetin can decrease the expression of P-gp via inhibition of HSF DNA-binding activity, and might be useful as a chemosensitizer in MDR cells.

Umbilical cord blood gas analysis at delivery

BACKGROUND

Umbilical cord blood gas values are better indicators of perinatal asphyxia than Apgar scores. However, the reported normal range of umbilical blood gas values vary greatly in the literature. The aim of this prospective study was to establish the normal range of umbilical cord blood gas values in our labour ward.

METHODS AND RESULTS

Umbilical cord blood gas from 153 vaginal deliveries and 52 Caesarean sections for indication other than fetal distress were evaluated. In our labour ward, the mean and standard deviation of umbilical artery pH were 7.21 and 0.08 for vaginal deliveries and 7.22 and 0.07 for Caesarean sections respectively. The mean and standard deviation for umbilical artery base deficit were 5.08 and 3.85 for vaginal deliveries and 4.09 and 3.07 for Caesarean sections respectively.

CONCLUSION

In conclusion, pH of 7.05 is the statistical lower limit of umbilical artery pH in our labour ward and is a good cut-off value to indicate perinatal asphyxia. Five cases with abnormal umbilical artery pH (< 7.05) were also analysed and discussed.

Down syndrome screening in Singapore--the effectiveness of a second trimester serum screening policy modelled on 29,360 pregnancies in KK Women's and Children's Hospital

AIM OF STUDY

To assess the effectiveness of a proposed second trimester Down syndrome serum screening policy in Singapore.

METHOD

Auditing the effectiveness of an age-only policy and comparing it against a serum screening policy modelled on the same maternal population of KK Women's and Children's Hospital in 1994 and 1995.

RESULTS

KK Women's and Children's Hospital's (KKH) maternal age distribution is similar to the national age distribution of mothers. Sixteen percent (16.7%) of mothers in KKH, in 1994 and 1995, were 35 years or older at delivery. Based on our hospital birth defect registry, 66% (35/53) of Down Syndrome pregnancies occurred in mothers who were 35 years or older at delivery and 43% (23/53) in the oldest 6.5% of mothers (38 years or older at delivery). Using various models on KKH's population structure to estimate the expected number of Down Syndrome livebirths expected, 52%-55% and 34%-36% of Down Syndrome livebirths were expected to occur in the oldest 16.7% and 6.5% of mothers respectively. These simulated figures are much lower than the figures from the data and needs further study, assuming that the Western Down Syndrome risk model to be applicable to our population. The overall uptake of amniocentesis irrespective of gestational age at booking was 28%. In mothers who were 35 years or older at delivery and booked before 22 weeks gestation, the uptake rate of amniocentesis was 49%. There was a substantial difference in the uptake rate when the counselling was done by trained counsellers compared to those who were not.

CONCLUSION

We would expect that for a fixed amniocentesis rate of 6.5% and 16.7%, serum screening would be able to detect 71% and 85% respectively of the Down syndrome pregnancies. This is more efficient than figures published from Western populations as our patients are older.

Cervicovaginal foetal fibronectin in the prediction of preterm labour in a low-risk population

The aim of this study was to evaluate the role of cervicovaginal fibronectin as a screening test in a low-risk population. Swabs were taken from the posterior fornix at 28 weeks gestation and foetal fibronectin levels were assayed using enzyme immunoassay. Eighteen patients (7.7%) delivered at less than 37 weeks of gestation, and 6 (2.4%) at less than 34 weeks of gestation. Five patients (2.1%) had a positive fibronectin test result. The sensitivity, specificity, positive predictive value and negative predictive value in the prediction of delivery less than 37 weeks of gestation were 16.7%, 99.1%, 60.0% and 93.4%, respectively. The sensitivity of foetal fibronectin in the prediction of delivery less than 34 weeks of gestation was higher (50%) compared with the prediction of delivery less than 37 weeks of gestation (16.7%). The low sensitivity of this test suggests a limited role for cervicovaginal fibronectin in the low-risk population. Further studies need to be carried out to assess whether multiple testing of cervicovaginal fibronectin at different gestational ages will further increase the sensitivity.

Computerised analysis of foetal heart rate variation: prediction of adverse perinatal outcome in patients undergoing prostaglandin induction of labour at term

The aim of this study was to determine the value of antenatal numerical assessment of foetal heart rate variation in the prediction of adverse perinatal outcome in patients undergoing prostaglandin induction of labour at term. Two hundred and seven patients who underwent prostaglandin cervical ripening after 37 weeks gestation for the indications of pregnancy-induced hypertension, foetal growth retardation or post-dates pregnancy were included in this study. Prior to commencement of cervical ripening, a 30-minute cardiotocography tracing was recorded on the System 8000 machine and the long-term and short-term variations were calculated. Forty-three patients (20.8%) had a long-term variation of less than 30 ms; 9 (4.3%) had a short-term variation of less than 3 ms. The sensitivity and positive predictive values of long-term variation in the prediction of admission to neonatal special care unit were 25.6% and 23.2%, respectively. Corresponding values for short-term variation were 2.6% and 11.1%, respectively. The sensitivity and positive predictive values of long-term variation in the prediction of caesarean section for foetal distress were 33.3% and 9.3%, respectively. Corresponding values for short-term variation were 8.3% and 11.1%, respectively. Long-term and short-term variations appeared to be both poor predictors of adverse perinatal outcome. However, of 4 foetuses with both reduced antenatal heart rate variation and who were subsequently delivered by caesarean section for foetal distress in labour, all 4 were admitted to neonatal special care unit (NSCU). Foetuses with intrapartum evidence of foetal distress were more likely to be admitted to NSCU when antenatal foetal heart rate variation was reduced.

Cloning and sequencing of complement component C9 and its linkage to DOC-2 in the pufferfish Fugu rubripes

The Japanese pufferfish Fugu rubripes has a 400 Mb genome with high gene density and minimal non-coding complexity, and is therefore an ideal vertebrate model for sequence comparison. The identification of regions of conserved synteny between Fugu and humans would greatly accelerate the mapping and ordering of genes. Fugu C9 was cloned and sequenced as a first step in an attempt to characterize the region in Fugu homologous to human chromosome 5p13. The 11 exons of the Fugu C9 gene share 33% identity with human C9 and span 2.9 kb of genomic DNA. By comparison, human C9 spans 90 kb, representing a 30-fold difference in size. We have also determined by cosmid sequence scanning that DOC-2, a tumour suppresser gene which also maps to human 5p13, lies 6-7 kb from C9 in a head-to-head or 5' to 5' orientation. These results demonstrate that the Fugu C9/DOC-2 locus is a region of conserved synteny. Sequence scanning of overlapping cosmids has identified two other genes, GAS-1 and FBP, both of which map to human chromosome 9q22, and lie adjacent to the Fugu C9/DOC-2 locus, indicating the boundary between two syntenic regions.

Diagnosis of ectopic pregnancy--why we need a protocol

OBJECTIVE

To audit the management after instituting a screening programme for ectopic pregnancy in an institution with a protocol utilising ultrasound examination and serial human chorionic gonadotropin (hCG) and to examine the risk of missed diagnosis with deviation from the protocol.

MATERIAL AND METHOD

A retrospective analysis of the management of 145 symptomatic patients in early pregnancies without intrauterine gestational sacs from ultrasound examinations, during the period April to June 1994 in Kandang Kerbau Hospital. Patients underwent serial hCG tests over 48 hours with or without repeat ultrasound scans before definitive treatment unless clinical indications for emergency surgery was necessary.

RESULTS

There were 35 ectopic pregnancies (24%), 16 were viable intrauterine pregnancies (11%), 87 were non-viable pregnancies (60%) and 7 were of unknown outcome. There were much practice deviations from the protocol. Forty-four percent (64 cases) of the management decisions were made based on the initial clinical and ultrasound findings, and another 14% (21 cases) after a repeat assessment within the next day by either a repeat scan or serial serum hCG over one day. Among them, two of the 29 operated for suspected ectopic pregnancy were not ectopic (7%) and two of the 56 thought not to be ectopic, turned out to be ectopic (4%) (p < 10(-8)). Six percent (8 cases) defaulted after the initial assessments and one of them was found to be ectopic subsequently. Thirty percent (43 cases) adhered to the protocol. They had serial serum hCG done over two days. Seven of them requiring further repeats of serial serum hCG before management decisions were made. Four patients who were operated on were confirmed ectopic and 39 patients not operated on were not ectopic. Three percent (5 cases) were managed by serial hCG over 3 to 5 days and another 3% (4 cases) by repeating scan over one to two weeks without serial hCG. None of these was ectopic. The percentage change of hCG levels over two days gave indications of the likely diagnosis.

CONCLUSION

Adhering to a protocol utilising the principle of ultrasound scan, serial hCGs and selective repeat ultrasound scans are highly recommended for the diagnosis of ectopic pregnancy. Any deviation from protocol is dangerous, with a 4% risk of missing an ectopic and a 7% risk of unnecessary operation for suspected ectopic pregnancy.

Optimising management of stillbirths in modern Singapore

OBJECTIVE

To conduct a critical analysis of stillbirths in Kandang Kerbau Hospital with emphasis on epidemiological factors, related causes and investigation strategies.

DESIGN

A prospective study.

SETTING

Kandang Kerbau Hospital.

PATIENTS

Case records containing antenatal and post-partum details of all 136 stillbirths were obtained from the medical records office and reviewed by 3 obstetricians. Epidemiological data, antenatal history, intrapartum progress, post-partum investigation, post-mortem findings (where applicable) were reviewed and recorded.

RESULTS

The incidence of stillbirths was 4.48/ 1,000 in 1994. 73.1% of the stillbirths were macerated. Significantly higher stillbirth rates were noted in the Malays and unbooked or late booking cases. The causes of stillbirths were unexplained in 29.4%. Fetal anomalies constituted 18.4%, followed by asphyxia, abruptio, and cord accidents. Maternal obstetrical problems contributed to the rest.

CONCLUSION

A comprehensive management strategy to reduce stillbirths include community and patient education, early or shared antenatal care, careful prenatal surveillance, optimum investigations as well as a careful audit with adequate bereavement and counselling.

Three cases of fatal pulmonary embolism in obstetrics

We conducted a retrospective analysis of maternal deaths in our hospital from January 1992 to December 1995. Cases of fatal pulmonary embolism were identified and analysed with respect to their past history, antenatal and peripartum progress, clinical presentation and investigation. There were 7 maternal deaths during this period and autopsies were performed in all cases. Pulmonary embolism was the leading cause of maternal mortality, responsible for 3 deaths. The incidence of fatal pulmonary embolism was 4.9 per 100,000 maternities. One case occurred antepartum and 2 occurred postpartum. The antepartum case occurred after a period of immobilisation, and both postpartum cases occurred after emergency Caesarean sections. Dyspnoea and sudden cardiovascular collapse were the commonest presentations. Electrocardiograph and arterial blood gases were abnormal in both patients in whom the tests were performed. Death occurred within 11 hours of presentation of symptoms in all 3 cases. Pulmonary embolism was more common among our population than previously reported, and was the leading cause of maternal mortality in our institution over the last 4 years. Immobilisation and Caesarean section were the major risk factors. Identification of high risk situation, antithrombotic prophylaxis and a high degree of suspicion were the key to reducing the incidence of fatal pulmonary embolism in obstetric patients.

Holoprosencephaly and chromosomal anomalies

Holoprosencephaly is a rare cerebral malformation resulting from failure or incomplete cleavage of the forebrain. The sonographic diagnosis consists of monoventricle, fused thalami and absent cavum septum pellucidi. Chromosomal anomalies, diabetes mellitus, alcohol, autosomal recessive inheritance and toxins have been implicated. We describe seven cases of holoprosencephaly diagnosed in the antenatal and postnatal periods. The chromosomal anomalies included trisomy 13, triploidy, trisomy 13 with an unbalanced 13; 14 translocation and isochromosome of the long arm of 18. The clinicopathological findings and chromosomal anomalies are correlated.

Impaired glucose tolerance in pregnancy--is it of consequence?

This study was done to determine if impaired glucose tolerance in pregnancy was associated with increased maternal and neonatal morbidity and if so, whether the increased morbidity was due to the confounding factors of increased maternal age and maternal obesity. It was a retrospective analysis to compare 944 women with impaired glucose tolerance (IGT) in pregnancy with 10,065 women without abnormal glucose tolerance. The incidence of impaired glucose tolerance in pregnancy was 8.6% in this study. Even when maternal age and obesity were excluded, the IGT group had significantly higher risks of labour induction (relative risk, RR, 1.15); Caesarean section (RR: overall 1.43, elective 1.72, emergency 1.31); Caesarean section for dystocia/no progress (RR 1.60); macrosomia (RR 1.69, 1.76, 1.61 for birth-weight > = 97th, 95th, 90th percentiles respectively) and shoulder dystocia (RR 2.84) when compared to the nondiabetics (NDM). The risks of hypertensive disease (RR 1.22) and Caesarean section for fetal distress/thick meconium-stained liquor (RR 1.53) were also higher in the IGT group but these increases were not statistically significant when maternal age and obesity were excluded. There was no significant difference in the rates of low Apgar scores at 1 and 5 minutes between the 2 groups.

Reference charts of foetal biometry in Asians

OBJECTIVES

To construct reference ranges for foetal biometry measurements of biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), humerus length (HL) and mandible length (ML) for the Asian population in Singapore.

DESIGN

A prospective, cross-sectional study.

SETTING

The obstetric ultrasound services and the labour ward of the department of Obstetrics and Gynaecology in Singapore General Hospital.

SUBJECTS

The foetuses of 6,374 women whose delivery date was within 2 weeks of their estimated date of delivery (EDD) as calculated from the last menstrual period.

METHOD

During the period August 1, 1989 and December 31, 1993, 17,005 obstetric ultrasound scans were retrieved from the computerised database. These ultrasound scans were cross-referenced with the delivery database and the earliest ultrasound scan of 6,374 women who delivered within 2 weeks of their EDD were retrieved for analysis. Different growth models were fitted using regression analysis to estimate the mean and standard deviations as functions of gestational age. Centiles were then derived after confirming a normal distribution of measurements at each gestation.

RESULTS

A total of 6,131 measurements of the BPD, 6,117 measurements of the HC, 6,017 measurements of the AC, 6,078 measurements of the FL, 2,863 measurements of the HL and 2,029 measurements of the ML were obtained. Regression analysis using the linear-cubic formula was used to model the mean values; a separate linear regression analysis was used to model the standard deviations.

CONCLUSION

These are the regressed reference charts from 6,374 Asian foetuses using parametric analysis of cross-sectional data. The authors encourage their use in Asian foetuses.

The role of discriminant functions in screening for beta-thalassaemia traits during pregnancy

INTRODUCTION

The mean red cell volume (MCV) has been shown to be useful in a 2-stage screening process for beta-thalassaemia traits among pregnant women though associated with a large number of false positive results. We tested prospectively the ability of 5 discriminant functions (DF), (England & Fraser, Shine & Lal, Mentzer, Srivistava and Klee et al) to reduce the number of false positives when used as additional screening determinants for beta-thalassaemia in antenatal patients with red cell microcytosis.

METHODS

The diagnostic performance of each DF was compared in 493 patients with microcytosis and known beta-thalassaemia status. Truth table analysis and Receiver Operation Characteristic curves for each function were determined.

RESULTS

11.4% of the patients with microcytosis were diagnosed to have beta-thalassaemia traits. DFs incorporating the red cell indices: haemoglobin or total red cell count are unsuitable during pregnancy. Shine & Lal's index [(0.01 x MCH x (< MCV)2] reduced the number of people recalled for confirmatory testing by 31.1% and increased the diagnostic yield to 38.7% while maintaining a negative predictive value for the test of 0.993.

CONCLUSION

We conclude that a 3-stage screening process for beta-thalassaemia among pregnant women in Singapore involving the MCV, Shine & Lal's index and a confirmatory test to be both valid and cost-effective.

An analysis of risk factors for the prediction of shoulder dystocia in 16,471 consecutive births

This paper is a univariate analysis of the demographic, antepartum and intrapartum risk factors in a series of 16,471 consecutive deliveries in a tertiary obstetric and gynaecological unit in Singapore. In total, 12,229 term vaginal cephalic deliveries with 77 cases of shoulder dystocia were entered into the study for analysis. The incidence of shoulder dystocia was found to be 0.63% of all term vaginal cephalic deliveries. There is a direct relationship between increasing infant birthweight and incidence of shoulder dystocia. The critical birthweight for the prediction of shoulder dystocia is 3600 g. In order of decreasing relative risks, the factors which appear to be predictive of shoulder dystocia are a birthweight in excess of 3600 g, diabetes in pregnancy, lower social class, of Indian origin, maternal weight in excess of 70 kg, parity more than 4, and the use of oxytocics during labour. The local birthweight distribution is very different from the West. A policy for elective caesarean section for birthweights in excess of 4000 g (97% tile) would prevent 44% of shoulder dystocias, increase the caesarean section rate by 2% and half the perinatal mortality among births with shoulder dystocia.

A ten-year review of uterine rupture in modern obstetric practice

The aim of this paper is to determine the antecedent factors, clinical presentation, complications and management of uterine rupture in the context of modern obstetric practice in Singapore. We conducted a retrospective study of 26 proven cases of uterine rupture in Kandang Kerbau Hospital, Singapore between January 1983 to December 1992. These cases were analysed with regards to their past history, clinical presentation, complications, management and outcome. The incidence of uterine rupture was 1 in 6331 deliveries. The ratio of cases with scarred uteri against those with unscarred uteri was 3:1. The commonest antecedent factor was previous lower segment caesarean section for the scarred group and cephalo-pelvic disproportion in the unscarred group. Overall, 46.2% of the patients had augmentation with oxytocin. The major clinical presentations were abnormal cardiotocogram (25%) and blood-stained amniotic fluid (20%) in the scarred group, and postpartum haemorrhage (50%) and shock (33%) in the unscarred group. Repair of the uterus with or without tubal ligation was performed in 95% of the patients with scarred uteri, whereas 67% of the patients with unscarred uteri underwent total abdominal hysterectomy with or without salpingo-oophorectomy. There was 1 (3.8%) maternal death. Maternal morbidity included bladder injuries, broad ligament haematoma, disseminated intravascular coagulation and gastrointestinal bleeding. The overall incidence of fetal loss was 7.4%. When compared to a previous study on uterine rupture in the same hospital, there was an improvement in obstetric performance.

Eclampsia--are we doing enough?

OBJECTIVES

This paper reviews the cases of eclampsia managed at the Kandang Kerbau Hospital with respect to incidence, management, maternal and perinatal outcome.

METHOD

A retrospective analysis of eclampsia occurring over a 4-year period from January 1990 to December 1993.

RESULTS

There were 27 cases of eclampsia among 59,599 deliveries during the study period, giving an overall incidence of 45.3 per 100,000 deliveries. Sixteen patients were nulliparous and the mean age was 29 years. Two-thirds of the cohort were booked patients and more than half of the cohort (55.6%) had their first seizure despite being in hospital. The majority (86.2%) of all seizures recorded occurred in the antepartum and intrapartum period. Eleven of the patients (40.7%) were asymptomatic prior to the first fit while headache was the commonest symptom of impending eclampsia in the remainder. Fifteen patients (55.6%) had significant proteinuria and this was associated with significant neonatal morbidity. The mean gestational age was 35.9 weeks and the mean birth weight was 2,328g. Major areas of substandard management included failure to administer anticonvulsant prophylaxis and antihypertensive agents when indicated, failure to assess for proteinuria, and failure to closely monitor the hypertensive and proteinuric patient. Seven patients developed convulsions despite anticonvulsant prophylaxis. Twenty-four patients were delivered by Caesarean section. There were 26 live born infants (singletons) and one abortus. There was no perinatal mortality. Neonatal morbidity was frequent and attributable to prematurity (51.9%) and birth asphyxia (29.6%). The majority of infants were well neurologically on long term follow-up. There was no maternal mortality but significant morbidity was present in 8 patients (29.6%). High uric acid levels were associated with intrauterine death, prematurity and intrauterine growth retardation. Seven patients remained hypertensive on follow-up. Residual neurological deficits persisted in 3 patients.

CONCLUSIONS

The incidence of eclampsia at Kandang Kerbau Hospital shows an unsteady decline over the past 4 years. It carries significant foetal mortality (3.7%) as well as neonatal (74.1%) and maternal (29.6%) morbidity. The observation that neither the occurrence of antenatal office visits nor hospitalisation prevents eclampsia, and that substandard management was identified in most of the cases (77.8%) shows that there is no room for complacency and that more needs to be done. Improvement in patient assessment, institution of appropriate preventive therapy, a high index of suspicion even in apparently low-risk patients coupled with a disease notification system and regular audit may be the key strategies to reduce the incidence of this dreaded obstetric complication.

Using glucose tolerance test results to predict insulin requirement in women with gestational diabetes

This study was done to test the clinical impression that the result of the oral glucose tolerance test could be used to predict which patients with gestational diabetes did not need insulin therapy. If this was true, a full blood sugar profile assessment could be avoided in many of these women. The second analysis was to test the clinical impression that the fasting glucose level was the best predictor of insulin requirement in women with gestational diabetes. The results of the study showed that none of the 3 readings of the oral glucose tolerance test could be used to predict reliably which patients did not need insulin therapy. Hence, blood sugar profile assessment of all patients with gestational diabetes is still necessary. The receiver-operator characteristic curves also showed that the 2-hour postload glucose level during the 75 g load glucose tolerance test was a better predictor of insulin requirement than the fasting glucose level.

Second trimester colour Doppler imaging of the uterine artery: reproducibility of the resistance index

Second trimester assessment of uterine blood flow has been advocated as a predictor of subsequent adverse perinatal outcome. The reproducibility of uterine artery resistance index, as assessed using colour Doppler imaging, was investigated. Two observers, both of whom were experienced in colour Doppler assessment of uterine artery flow velocity waveforms, performed the measurements. One-way analysis of variance was used to evaluate intraobserver variability and the limits of agreement method was used to determine the 95% prediction interval for interobserver differences. The intraobserver standard deviation was small for both observers. The limits of agreement for interobserver differences were wide (-0.24, 0.16), similar in magnitude to those reported by other workers who assessed the uterine vessel using continuous wave Doppler. The poor reproducibility of the resistance index suggests that second trimester Doppler assessment of uterine artery flow velocity waveforms may be better described using other semiquantitative methods such as the presence or absence of a diastolic notch.

Birth defects--the state of awareness amongst mothers

Birth defects have in recent years become the major cause of perinatal morbidity and mortality. The incidence of birth defects is between 2% to 6% of all live births. However, from a survey carried out in Singapore General Hospital (SGH), the majority of mothers enter pregnancy without realising the risks that they or their offspring may face. Only 20% to 25% of mothers were aware of the actual incidence of birth defects, and only 2.5%-10% knew that the risk of Down Syndrome (DS) increases with maternal age. However, the use of ultrasound is now well accepted and is considered a necessary investigation by 90% of the mothers surveyed.

Racial differences in fetal morphometry in Singapore

A systematic collection of fetal morphometric measurements was started seven years ago in 1987 with the prospective entry of data into personal computer-based stations in the Department of Obstetrics and Gynaecology, Singapore General Hospital. A cross-sectional study was done, comparing 2392 Chinese fetuses with 2117 Malay fetuses and 459 Indian fetuses from 18 to 40 weeks. The mean values of the head circumference (HC), abdominal circumference (AC) and femur length (FL) of the 3 ethnic groups were analysed. There were no statistical significant differences in the head circumference and abdominal circumference of Chinese, Malay and Indian fetuses in Singapore. The Chinese and Malay fetal femur length appeared similar but were apparently shorter than the Indian femur length. Nomograms of head circumference, abdominal circumference and femur length were constructed for application to fetuses of all 3 ethnic groups.

Screening for beta thalassaemia and HbE traits with the mean red cell volume in pregnant women

Both beta thalassaemia and HbE disease are microcytic red cell disorders. Pregnancy however induces macrocytosis which makes screening with the mean cell volume (MCV) difficult in antenatal patients. In addition, population screening for HbE has not been widely reported in the literature and the screening criteria for beta thalassaemia may not necessarily apply. A study of the value of the MCV for routine screening for both beta thalassaemia and HbE traits in 3696 antenatal patients of different gestational ages was carried out. All patients with an MCV < or = 80 fL received confirmatory tests for haemoglobinopathies. The MCV rose by only 2.0% in pregnancy. A total of 494 patients (13.4% of the general population) had an MCV < or = 80 fL. Of these microcytic patients, 11.3% (56) and 4.7% (23) were eventually confirmed to have beta thalassaemia and HbE traits respectively. The mean MCV for the 3696 antenatal patients was 87.8 fL (SD 7.5) compared to patients with beta thalassaemia and HbE traits, which were 67.5 fL (SD 4.5) and 75.7 fL (SD 4.1). HbE traits were less microcytic than beta thalassaemia traits and overlapped significantly with the general population. Beta thalassaemia trait and HbE trait detected by this screening method constituted 1.52% and 0.62% respectively of the total antenatal population screened. The MCV remains a valid screening parameter in pregnancy for beta thalassaemia trait. As for HbE trait, applying a discriminant value of 80 fL to the MCV in the population screening would miss a significant proportion of the HbE traits.(ABSTRACT TRUNCATED AT 250 WORDS)

Birth defects--the state of awareness

As doctors and nurses are the primary sources of medical information, a simple survey was conducted in 1992 among doctors and nurses to determine their level of awareness of the incidence of and risk of having an abnormal as well as their knowledge of the use of ultrasound in pregnancy. Only 10% of doctors and 23% of nurses were aware that the general risk of having an abnormal baby is greater than 1%. Only 37% and 17% of doctors and nurses respectively were aware that the best time to screen for structural abnormalities was indeed at approximately 20 weeks gestation.

The effect of prenatal diagnosis on the incidence of Down syndrome livebirths in the Singapore General Hospital

During a 3-year-period between January 1988 and December 1990, there were 12 Down Syndrome (DS) livebirths out of 13,794 livebirths at the Department of Obstetrics and Gynaecology, Singapore General Hospital, giving an incidence of 1 in 1,150 livebirths or 0.87 per thousand. There were 1569 mothers who were 35 years or older at the expected date of delivery (EDD) and 5 of these 12 DS livebirths were from these older mothers. Although only 11.5% of all mothers were 35 years or more, as a group, these older mothers contributed to 42% of the DS livebirths. There were 5 DS fetuses diagnosed prenatally and 4 were aborted electively. The fifth DS fetus which was diagnosed prenatally was allowed to continue to term because of the mother's religious objection to an induced abortion. The failure to offer prenatal diagnosis and selective procreation to all mothers 35 years or older had resulted in 4 unnecessary DS births, reducing our DS detection rate by a factor of 33%. All these 4 cases were booked late for antenatal care.