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Biomedical subjects

Kevin Spencer

Publications and source records attributed to Kevin Spencer.

32 records · Page 2Linked to original sources
PubMed2004

Maternal serum level of placental growth factor in diabetic pregnancies.

OBJECTIVE: To determine if maternal serum placental growth factor (PlGF) concentration at 11-14 weeks in pregnancies complicated by diabetes, including those with preexisting diabetes and those that developed gestational diabetes subsequently, differed from that in normal, uncomplicated pregnancies. STUDY DESIGN: PlGF concentration was measured in stored maternal serum samples obtained at 11-14 weeks of gestation from 82 women with diabetic pregnancies, including 32 with preexisting diabetes and 50 with gestational diabetes, and 400 normal controls. Gestational diabetes mellitus was diagnosed with the 75-g oral glucose tolerance test and by applying World Health Organization criteria. RESULTS: When expressed as the multiple of the median and adjusted for gestation, the log transformed values of PlGF were significantly higher (P < .05) in the diabetic group (mean multiple of the median, [MoM] 1.14; SD 0.11) as compared to the controls (mean MoM, 1.00; SD, 0.11). On further comparison between the diabetic groups with the controls, significant differences were found in the groups with gestational diabetes (mean MoM, 1.15; SD, 0.12) and non-insulin dependent diabetes (mean MoM, 1.16; SD, 0.09) but not in those complicated by insulin-dependent diabetes (mean MoM, 1.09; SD, 0.10). CONCLUSION: These findings suggest that in the first trimester of pregnancy the level of maternal PIGF was already significantly increased not only in pregnancies complicated by noninsulin dependent diabetes but also in those with gestational diabetes. The implications of these findings remain to be explored.

Adult↗
PubMed2003

Predicting complications of pregnancy with first-trimester maternal serum free-betahCG, PAPP-A and inhibin-A.

OBJECTIVE: To find whether fbetahCG, PAPP-A and inhibin-A levels in maternal serum or fetal nuchal translucency (NT) thickness at the first-trimester screening for trisomy 21 (T21) might detect women at high risk for adverse pregnancy outcomes. METHODS: A retrospective analysis of 1136 women with singleton pregnancy between 10 and 14 weeks. Women with pregnancy complications were allotted to five subgroups: small for gestational age (SGA), large for gestational age (LGA), gestational diabetes (GDM), hypertensive disorders, preterm delivery; women with normal pregnancy represented the control group. NT, maternal serum fbetahCG, PAPP-A and inhibin-A were measured. Mann-Whitney test was used for the comparison of fbetahCG, PAPP-A, inhibin-A and NT between a subgroup of a certain pregnancy complication and the control group. Multivariate logistic regression models were built to explore the relationship among different variables and the occurrence of pregnancy complications. RESULTS: PAPP-A values were significantly lower in women who delivered SGA babies (n=51, 0.76 MoM; p=0.002) and significantly higher in women who delivered LGA babies (n=120, 1.12 MoM; p=0.036). In women with GDM (n=27), fbetahCG, PAPP-A and inhibin-A were insignificantly lower than in controls, whereas in women with hypertensive disorders (n=56) no significant differences between the groups were found. In women with a preterm delivery (<34 weeks) (n=17), inhibin-A levels were significantly higher (1.25 MoM; p=0.015). CONCLUSION: Low PAPP-A level is associated with the delivery of an SGA baby and high PAPP-A with the delivery of an LGA baby. High inhibin-A is associated with preterm delivery before 34 weeks. Feto-placental products in the first trimester do not prove to be useful as a screening tool for predicting pregnancy complications.

Adolescent↗
PubMed2003

Integrated ultrasound and biochemical screening for trisomy 21 using fetal nuchal translucency, absent fetal nasal bone, free beta-hCG and PAPP-A at 11 to 14 weeks.

BACKGROUND: Screening for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) thickness and maternal serum free beta-hCG and pregnancy-associated plasma protein-A (PAPP-A) at 11 to 14 weeks of gestation is associated with a detection rate of 90% for a false-positive rate of 5%. Recent evidence suggests that in about 70% of fetuses with trisomy 21, the nasal bone is not visible at the 11th- to 14th-week scan (Cicero et al., 2001). The aim of this study was to examine whether fetal NT thickness and the level of maternal serum biochemical markers is independent of the presence or absence of the nasal bone, and to estimate the performance of a screening test that integrates the two sonographic and the two biochemical markers. METHODS: This was a retrospective case-control study comprising 100 trisomy 21 and 400 chromosomally normal singleton pregnancies at 11 to 14 weeks of gestation. Ultrasound examination was carried out for measurement of fetal NT and assessment of the presence or absence of the fetal nasal bone. Maternal serum free beta-hCG and PAPP-A were measured using the Kryptor rapid random-access immunoassay analyser (Brahms Diagnostica GmbH, Berlin). The distribution of fetal NT, maternal serum free beta-hCG and PAPP-A in trisomy 21 fetuses with absent and present nasal bone was examined. RESULTS: The nasal bone was absent in 69 and present in 31 of the trisomy 21 fetuses. There were no significant differences in median maternal age, median gestational age, NT delta, free beta-hCG MoM and PAPP-A MoM in trisomy 21 fetuses with and without a visible nasal bone. For a false-positive rate of 5%, it was estimated that screening with the four markers in combination with maternal age would be associated with a detection rate of 97%. For a false-positive rate of 0.5%, the detection rate was 90.5%. CONCLUSIONS: An integrated sonographic and biochemical test at 11 to 14 weeks can potentially identify about 90% of trisomy 21 fetuses for a false-positive rate of 0.5%.

Adult↗
PubMed2003

Increased total cell-free DNA in the serum of pregnant women carrying a fetus affected by trisomy 21.

OBJECTIVE: Analysis of the levels of cell-free fetal and total DNA in serum of women carrying a male fetus affected by trisomy 21, and comparison of these levels with those in women carrying a normal male fetus. METHODS: DNA was extracted from archived second-trimester maternal serum samples collected as part of a prenatal screening program. A total of 10 cases with trisomy 21 male fetuses were compared with 10 controls (male fetuses) with samples matched for duration of storage and gestational age. Real-time quantitative PCR of the SRY and albumin genes was used to quantify fetal and total DNA respectively. RESULTS: The median fetal DNA level in the group of 10 pregnancies with trisomy 21 was 31.98 cell-equivalents per mL compared to 34.06 in the control group. The difference was not significant. The median total DNA level in women with a trisomy 21 fetus was significantly higher (P = 0.029) than that in controls (36 152.6 vs 5832.81 cell-equivalents per mL). CONCLUSIONS: Although we could not confirm previous studies of an increased amount of fetal DNA in pregnancies affected by trisomy 21, we did find increased levels of total DNA. The possible reasons for these observations are discussed with respect to previous findings. Larger studies are needed to elucidate the true value, if any, of measurement of fetal and total DNA in maternal serum in the context of prenatal screening for chromosomal abnormalities.

Adolescent↗
PubMed2003

Maternal weight correction of maternal serum PAPP-A and free beta-hCG MoM when screening for trisomy 21 in the first trimester of pregnancy.

OBJECTIVE: To assess the suitability of either the log-linear or reciprocal-linear regression procedure for maternal weight correction of biochemical marker MoMs in the first trimester. METHODS: Data from two prospective first-trimester OSCAR screening programmes including 32,010 women with first-trimester maternal serum-free beta-hCG and PAPP-A measured by the Kryptor analyser was analysed by regression analysis to provide parameters for the log-linear and reciprocal-linear MoM correction procedures. Assessment was made by goodness of fit to the data. The impact on detection rate and false-positive rate of the different correction procedures was assessed using statistical modelling with biochemical markers alone. RESULTS: Both log-linear and reciprocal-linear correction were shown to fit the data well. For free beta-hCG, the log-linear procedure was marginally superior to the reciprocal-linear procedure (r2=0.986 v 0.980), whilst for PAPP-A the reciprocal-linear procedure was marginally better (r2=0.991 v 0.985). Log-linear correction reduced the variance for both markers more than did the reciprocal-linear procedure. For free beta-hCG, the sd was reduced from 0.2675 to 0.2605 and for PAPP-A, it was reduced from 0.2545 to 0.2336. Correcting for maternal weight was shown to reduce the population false-positive rate from 7.0 to 6.5%, whilst maintaining the same detection rate at a risk cut-off of 1 in a 100. At individual levels, a two-fold variation in risk was demonstrated depending upon the individual's weight. CONCLUSIONS: To provide accurate individual patient-specific risks for trisomy 21, maternal weight must be taken into account and should be a mandatory data item for screening programmes. Maternal weight correction in the first trimester using free beta-hCG and PAPP-A can be best achieved using the log-linear procedure.

Adult↗
PubMed2003

The influence of different sample collection types on the levels of markers used for Down's syndrome screening as measured by the Kryptor Immunosassay system.

BACKGROUND: In a rapid point-of-care screening programme for chromosomal anomalies, analysis of biochemical markers in maternal blood can now be accomplished in a rapid time frame (less than 20 min). The need to leave whole blood samples some 10 min for coagulation and a further 5 min for centrifugation adds additional processing time. METHODS: The possibilities for reducing this processing time were investigated using various anticoagulated blood collection systems and the Kryptor analytical platform. Plasma levels of alpha-fetoprotein (AFP), pregnancy-associated plasma protein-A (PAPP-A) and free human chronic gonadotrophin beta-subunit (beta-hCG) were compared with those in maternal serum. RESULTS: From the mean results from ten patients it was shown that use of heparin plasma resulted in a statistically significant reduction in levels of PAPP-A and that EDTA plasma reduced the levels of PAPP-A dramatically. For AFP, levels in citrated plasma and EDTA plasma were also significantly reduced, whereas levels of free beta-hCG were not affected. CONCLUSION: Use of alternative sample types for PAPP-A is not possible. The sample of choice for first trimester screening using the Kryptor platform is maternal serum.

Chemistry, Clinical↗
PubMed2003

Screening for trisomy 21 in twins using first trimester ultrasound and maternal serum biochemistry in a one-stop clinic: a review of three years experience.

OBJECTIVE: To evaluate the performance of screening for fetal trisomy 21 in the first trimester of twin pregnancies by a combination of maternal serum biochemistry and ultrasonography. DESIGN: Three year retrospective review of screening performance. SETTING: District General Hospital maternity unit. POPULATION: All women booked to receive routine antenatal care at Harold Wood Hospital between 1 June 1998 and 30th September 2001. The population included 13,940 women of all ages presenting with pregnancies between 10 weeks 3 days and 13 weeks 6 days gestation. Of these, 230 had a twin pregnancy. METHODS: Women booked into the clinic were offered screening using a combination of maternal serum free beta-hCG and pregnancy-associated plasma protein-A (PAPP-A) and fetal nuchal translucency thickness. Women at increased risk of carrying a fetus with trisomy 21 or trisomy 13/18 (>/=1 in 300 at sampling) were offered counselling and an invasive diagnostic procedure. Follow up of the outcome of all pregnancies was carried out. For women who on examination were at 14 weeks of gestation or greater, or for women presenting as late bookers beyond 14 weeks, screening was performed in the same time frame using only maternal serum free beta-hCG and alpha-fetoprotein. MAIN OUTCOME MEASURES: The first trimester detection rate for trisomy 21 and all aneuploides, false positive rate, uptake of screening, uptake of invasive testing in women identified at increased risk and fetal loss rates after invasive testing. RESULTS: Overall, 97.4% of the women with twins (224/230) accepted first trimester screening. The rate of detection of trisomy 21 was 75% (3/4). Fetal death at presentation was found in 3.4% of fetuses (16/460). Of women who accepted screening, 4.3% (10/230) presented too late for fetal nuchal translucency measurement and 10.0% of women (23/230) presented too early. A risk for trisomy 21 was calculated for each fetus based on the individual fetal nuchal translucency thickness and the maternal biochemistry. The false positive rate among those eligible for first trimester screening was 9.0% (19/206) of pregnancies and 6.9% of fetuses (28/412). Uptake of invasive testing was 59% (10/17) with chorionic villus sampling in eight cases and amniocentesis in two. No fetal loss occurred within 28 days of chorionic villus sampling and no loss occurred after amniocentesis. One case of trisomy 21 was identified for every three invasive procedures. CONCLUSIONS: First trimester screening for trisomy 21 in twin pregnancies is both theoretically possible and practically achievable using a combination of nuchal translucency thickness and maternal serum biochemistry. However, dilemmas for the mother and health professionals when both nuchal translucency thickness measurements are normal might suggest that greater reliance be placed on the nuchal translucency thickness risk alone when counselling women about invasive testing.

Adult↗
PubMed2003

Screening for chromosomal abnormalities in the first trimester using ultrasound and maternal serum biochemistry in a one-stop clinic: a review of three years prospective experience.

OBJECTIVE: To evaluate the performance of a one-stop multidisciplinary clinic of screening for fetal chromosomal anomalies in the first trimester of pregnancy by a combination of maternal serum biochemistry and ultrasonography. DESIGN: Retrospective review of screening performance. SETTING: District General Hospital maternity unit. POPULATION: All women booked for routine antenatal care at Harold Wood Hospital between 1 June 1998 and 31 May 2001. The population included 12,339 women with singleton pregnancies presenting at 10-14 weeks of gestation. METHODS: Women were offered screening using a combination of maternal serum free beta-hCG and pregnancy associated plasma protein-A (PAPP-A) and fetal nuchal translucency thickness. Those with an estimated risk of >/=1 in 300 of carrying a fetus with trisomy 21 or trisomy 18 or trisomy 13 were offered the option of an invasive diagnostic test. Follow up of the outcome of all pregnancies was carried out. MAIN OUTCOME MEASURES: Uptake of screening and invasive testing, detection rate for fetal chromosomal abnormalities and false positive rate. RESULTS: The uptake of first trimester screening was 97.5% and the uptake of invasive testing in the increased risk group was 77%. The rate of detection of trisomy 21 was 92% (23 of 25), of trisomy 13 or 18 was 100% (all 15) and of all aneuploidies was 96% (49 of 51). The false positive rate was 5.2%. CONCLUSIONS: First trimester screening for trisomy 21 and other aneuploidies can be delivered in an efficient manner in a one-stop multidisciplinary clinic. The detection rates are far better than can be achieved by second trimester serum screening.

Adult↗
PubMed2002

Accuracy of Down syndrome risks produced in a first-trimester screening programme incorporating fetal nuchal translucency thickness and maternal serum biochemistry.

Over the past three years approximately 12 000 women have been screened in the first trimester through our OSCAR programme, which utilizes fetal NT and maternal serum free beta-hCG and PAPP-A. During this time 30 cases of Down syndrome were identified either prenatally or postnatally. Using an established procedure the accuracy of predicted risk for Down syndrome was assessed in a population of 30 cases of Down syndrome and 11 758 unaffected pregnancies. The correlation between predicted risk and prevalence of Down syndrome was very high (r=0.9995). It is concluded that risks produced by the Fetal Medicine Foundation combined risk algorithm agree very closely with Down syndrome prevalence and can be used with confidence when counselling women of their risk.

Algorithms↗
PubMed2002

A first trimester trisomy 13/trisomy 18 risk algorithm combining fetal nuchal translucency thickness, maternal serum free beta-hCG and PAPP-A.

This study examines 45 cases of trisomy 13 and 59 cases of trisomy 18 and reports an algorithm to identify pregnancies with a fetus affected by trisomy 13 or 18 by a combination of maternal age fetal nuchal translucency (NT) thickness, and maternal serum free beta-hCG and PAPP-A at 11-14 weeks of gestation. In this mixed trisomy group the median MoM NT was increased at 2.819, whilst the median MoMs for free beta-hCG and PAPP-A were reduced at 0.375 and 0.201 respectively. We predict that with the use of the combined trisomy 13 and 18 algorithm and a risk cut-off of 1 in 150 will for a 0.3% false positive rate allow 95% of these chromosomal defects to be identified at 11-14 weeks. Such algorithms will enhance existing first trimester screening algorithms for trisomy 21.

Algorithms↗
PubMed2002

Between pregnancy biological variability of first trimester markers of Down syndrome and the implications for screening in subsequent pregnancies: an issue revisited.

OBJECTIVES: To assess the level of correlation of first trimester biochemical and biophysical markers of Down syndrome between different pregnancies in the same individual. To assess the impact that between pregnancy biological variability has on the likelihood that women who are at increased risk in a first pregnancy being also at increased risk in a subsequent pregnancy. METHODS: During a three period women attending the OSCAR clinic at Harold Wood Hospital have had the opportunity to have first trimester screening for Down syndrome and other aneuploidies using the maternal serum biochemical markers free beta-human chorionic gonadotrophin (hCG) and pregnancy associated plasma protein-A (PAPP-A) in conjunction with fetal nuchal translucency (NT) thickness and maternal age. Of the 111,105 women undergoing such screening, the computer records were examined for women who had more than one pregnancy. The results from 1002 women with two normal singleton pregnancies were available for analysis. Marker correlations (as MoM) were established between the pregnancies and the proportion of women likely to be at increased risk in each pregnancy estimated, as was the likelihood of women being at increased risk in both pregnancies. RESULTS: For fetal NT there was no correlation between NT MoM in the first and second pregnancy (r = 0.0959, p > 0.10). For maternal serum free beta-hCG MoM a significant correlation was found (r = 0.3976, p < 0.001), as was also found for PAPP-A MoM (r = 0.4371, p < 0.001). CONCLUSION: The implication for such between pregnancy marker association is that women who have an increased risk of Down syndrome in one pregnancy are two or three times more likely to repeat this event in their next pregnancy. This information may be useful in counselling women when undergoing first trimester screening in a subsequent pregnancy.

Adolescent↗
PubMed2002

Screening for chromosomal anomalies in the first trimester: does repeat maternal serum screening improve detection rates?

OBJECTIVE: To assess the within person biological variability of first trimester maternal serum biochemical markers of trisomy 21 across the 10-14 week gestational period. To evaluate whether repeat sampling and testing of free beta-hCG and PAPP-A during this period would result in an improved detection rate. METHODS: Women presenting at the first trimester OSCAR clinic have blood collected prior to ultrasound dating and nuchal translucency measurement. All samples are analysed for free beta-hCG and PAPP-A before an accurate estimate of gestation is available. In 10% of cases the gestation is prior to the minimum time for NT measurement (11 weeks) and these women are rebooked for a repeat visit to the clinic at the appropriate time. Our fetal database was interrogated to obtain cases in which two maternal blood samples had been collected and analysed in the 10-14 week period. Using data from the marker correlations and statistical modelling, the impact of repeat testing on detection rate for trisomy 21 at a fixed 5% false positive rate, was assessed. RESULTS: 261 pairs of data were available for analysis collected over a 3 year period. The correlation between free beta-hCG in sample 1 and sample 2 was 0.890 and that for PAPP-A was 0.827. The average within person biological variation for free beta-hCG was 21% and 32% for PAPP-A. The increase in detection rate when using both sets of marker data was 3.5% when using serum biochemistry and maternal age, and 1.3% when using nuchal translucency, serum biochemistry and maternal age. CONCLUSION: Repeat sampling and testing of maternal serum biochemical markers is unlikely to substantially improve first trimester screening performance.

Chorionic Gonadotropin, beta Subunit, Human↗
PubMed2002

Uptake of prenatal screening for chromosomal anomalies: impact of test results in a previous pregnancy.

AIM: To assess whether the uptake of prenatal screening for trisomy 21 in a subsequent pregnancy is influenced by being classified in the 'increased risk' or 'not at increased risk' group in the first pregnancy. SETTING: District General Hospital Maternity Unit. METHODS: Amongst a group of women attending for maternity care at this hospital, the maternity records were examined to find women having at least two pregnancies. Any prenatal screening record for each pregnancy was retrieved from the prenatal screening database. Prenatal screening for trisomy 21 was by a combination of maternal serum alpha-fetoprotein (AFP) and free beta-human chorionic gonadotrophin (beta-hCG) in the second trimester and by maternal serum free beta-hCG and pregnancy-associated plasma protein-A (PAPP-A) and fetal nuchal translucency (NT) thickness in the first trimester. Women were stratified according to their trisomy 21 risk into an 'increased risk' group (1: <250 in the second trimester and 1: <300 in the first trimester) or 'not at increased risk' group based on their first pregnancy. In a second pregnancy, the records were examined to see if the mother accepted prenatal screening in the second pregnancy. The rate of acceptance of screening in a subsequent pregnancy, depending on whether 'at increased risk' or 'not at increased risk' in the first pregnancy, was examined using chi square tests. RESULTS: In the second trimester study, 4601 women were identified with two pregnancies during the study period. Of these, 4559 women had prenatal screening in a subsequent pregnancy. Initially, 273 women were identified in the high-risk group, and of these 252 (92.3%) elected to have prenatal screening in a subsequent pregnancy. This compared with 4307 of 4328 (99.5%) women in the low-risk group. In the first trimester study, 1077 women were identified with two pregnancies during the study period. Of these, 1072 had prenatal screening in a subsequent pregnancy. Initially, 60 women were identified in the high-risk group, and of these 56 (93.3%) elected to have prenatal screening in a subsequent pregnancy. This compared with 1016 of 1017 (99.9%) in the low-risk group. Statistically, there was no difference between the rate of declining prenatal screening in a second pregnancy amongst those in the high-risk group in a first pregnancy or those in the low-risk group (p = 0.429 for second trimester screening and p = 0.794 for first trimester screening). Similarly, no difference could be demonstrated between rates when screening in the first or second trimester (p = 0.961) for those in the high-risk group. CONCLUSION: Despite the understandable anxiety associated with being identified in the high-risk group (as a false positive finding) in a previous pregnancy, this did not seem to deter women from accepting prenatal screening in a subsequent pregnancy.

Adult↗