RESUMEN

OBJECTIVE: To investigate the potential value of biophysical and biochemical markers at 30-34 weeks' gestation in the prediction of adverse perinatal outcome. METHODS: This was a screening study in 8268 singleton pregnancies at 30-34 weeks' gestation. Estimated fetal weight (EFW), uterine artery (UtA) pulsatility index (PI), umbilical artery (UA) PI, fetal middle cerebral artery (MCA) PI, mean arterial pressure (MAP), serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) were measured. The detection rate (DR) and false-positive rate (FPR) of screening by each biomarker were estimated for stillbirth, pre-eclampsia, delivery of small-for-gestational-age (SGA) neonate, Cesarean section for fetal distress before or during labor, umbilical arterial cord blood pH ≤7.0 or umbilical venous cord blood pH ≤7.1, 5-min Apgar score < 7 and admission to the neonatal unit (NNU). RESULTS: Multivariable regression analysis demonstrated that significant prediction of PE was provided by PlGF, sFlt-1, MAP and MCA-PI, with a DR of 98% for PE delivering < 37 weeks' gestation and 56% for those delivering ≥ 37 weeks, at a 10% FPR. Prediction of SGA was provided by EFW, PlGF, sFlt-1, UtA-PI, UA-PI and MCA-PI, with a DR of 88% for SGA delivering < 37 and 51% for those delivering ≥ 37 weeks' gestation, at a 10% FPR. Prediction of stillbirth was provided by EFW, UtA-PI and MCA-PI, with DR of 30% at 10% FPR. Prediction of Cesarean section for fetal distress before labor was provided by EFW, sFlt-1, UtA-PI and UA-PI, with a DR of 90% at a 10% FPR. Prediction of fetal distress in labor was provided by EFW and sFlt-1, with a DR of 16% at a 10% FPR. There were no significant differences from the normal outcome group in any of the biomarkers for low cord blood pH, low Apgar score or NNU admission for cases other than those with PE and/or SGA. CONCLUSION: At 30-34 weeks' gestation, biomarkers of impaired placentation and fetal hypoxemia provide good prediction of PE, SGA and fetal distress before labor, but poor or no prediction of stillbirth and adverse events in labor or after birth.

Asunto(s)

Complicaciones del Trabajo de Parto/diagnóstico , Complicaciones del Embarazo/diagnóstico , Resultado del Embarazo , Tercer Trimestre del Embarazo/fisiología , Adulto , Puntaje de Apgar , Presión Arterial , Biomarcadores/análisis , Cesárea/estadística & datos numéricos , Reacciones Falso Positivas , Femenino , Sangre Fetal/química , Sufrimiento Fetal/diagnóstico , Sufrimiento Fetal/etiología , Peso Fetal , Feto/irrigación sanguínea , Edad Gestacional , Humanos , Concentración de Iones de Hidrógeno , Recién Nacido , Recién Nacido Pequeño para la Edad Gestacional , Edad Materna , Arteria Cerebral Media/diagnóstico por imagen , Análisis Multivariante , Complicaciones del Trabajo de Parto/etiología , Factor de Crecimiento Placentario , Preeclampsia/diagnóstico , Preeclampsia/etiología , Valor Predictivo de las Pruebas , Embarazo , Complicaciones del Embarazo/etiología , Proteínas Gestacionales/sangre , Estudios Prospectivos , Flujo Pulsátil , Análisis de Regresión , Mortinato , Ultrasonografía Prenatal/métodos , Arterias Umbilicales/diagnóstico por imagen , Arteria Uterina/diagnóstico por imagen , Receptor 1 de Factores de Crecimiento Endotelial Vascular/sangre

RESUMEN

OBJECTIVE: To investigate the potential value of biophysical and biochemical markers at 35-37 weeks' gestation in the prediction of adverse perinatal outcome. METHODS: This was a screening study in 3953 singleton pregnancies at 35-37 weeks' gestation. Estimated fetal weight (EFW), uterine artery pulsatility index (UtA-PI), umbilical artery (UA)-PI, fetal middle cerebral artery (MCA)-PI, mean arterial pressure (MAP), serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) were measured. The detection rate (DR) and false-positive rate (FPR) of screening by each biomarker were estimated for pre-eclampsia (PE), delivery of small-for-gestational-age (SGA) neonates, Cesarean section for fetal distress before or during labor, umbilical arterial cord blood pH ≤ 7.0 or umbilical venous cord blood pH ≤ 7.1, 5-min Apgar score < 7 and admission to the neonatal unit (NNU). RESULTS: Multivariable regression analysis demonstrated that significant prediction of PE was provided by PlGF, sFlt-1 and MAP, with a DR of 73% at a 10% FPR. Prediction of SGA was provided by EFW, PlGF and UtA-PI, with a DR of 63% at a 10% FPR. Prediction of Cesarean section for fetal distress before labor was provided by EFW and UA-PI with DR of 100% at 10% FPR. Prediction of fetal distress in labor was provided by EFW and sFlt-1, with a DR of 15% at a 10% FPR. There were no significant differences between those with a normal outcome and those with low cord blood pH, low Apgar score or NNU admission for any of the biomarkers assessed. CONCLUSION: At 35-37 weeks' gestation biomarkers of impaired placentation and fetal hypoxemia provide good prediction of PE, SGA and fetal distress before labor, but poor or no prediction of adverse events in labor or after birth.

Asunto(s)

Complicaciones del Trabajo de Parto/diagnóstico , Complicaciones del Embarazo/diagnóstico , Resultado del Embarazo , Tercer Trimestre del Embarazo/fisiología , Adulto , Puntaje de Apgar , Presión Arterial , Biomarcadores/análisis , Cesárea/estadística & datos numéricos , Femenino , Sangre Fetal/química , Sufrimiento Fetal/diagnóstico , Sufrimiento Fetal/etiología , Peso Fetal , Feto/irrigación sanguínea , Edad Gestacional , Humanos , Concentración de Iones de Hidrógeno , Recién Nacido , Recién Nacido Pequeño para la Edad Gestacional , Edad Materna , Arteria Cerebral Media/diagnóstico por imagen , Análisis Multivariante , Complicaciones del Trabajo de Parto/etiología , Factor de Crecimiento Placentario , Preeclampsia/diagnóstico , Preeclampsia/etiología , Valor Predictivo de las Pruebas , Embarazo , Complicaciones del Embarazo/etiología , Proteínas Gestacionales/sangre , Estudios Prospectivos , Flujo Pulsátil , Análisis de Regresión , Mortinato , Ultrasonografía Prenatal/métodos , Arterias Umbilicales/diagnóstico por imagen , Arteria Uterina/diagnóstico por imagen , Receptor 1 de Factores de Crecimiento Endotelial Vascular/sangre

RESUMEN

OBJECTIVE: To investigate the potential value of uterine artery (UtA) Doppler at 30-34 weeks' gestation in the prediction of adverse perinatal outcome. METHODS: This was a screening study in 30 780 singleton pregnancies at 30-34 weeks. UtA pulsatility index (UtA-PI) was measured and the values were converted to multiples of the median (MoM) after adjustment for variables relating to maternal characteristics and medical history that affect the measurements. Multivariable logistic regression analysis was used to determine if measuring UtA-PI improved the prediction of adverse perinatal outcome provided by screening with maternal characteristics, medical history and obstetric factors. The detection rate (DR) and false-positive rate (FPR) of screening by UtA-PI were estimated for stillbirth, Cesarean section for fetal distress, umbilical arterial cord blood pH ≤ 7.0 or umbilical venous cord blood pH ≤ 7.1 and 5-min Apgar score < 7. RESULTS: The incidence of adverse perinatal outcome was higher in small-for-gestational-age (SGA) fetuses than in non-SGA fetuses, but the majority of cases with each adverse outcome were in the non-SGA group, including about 70% of stillbirths and more than 80% with Cesarean section for fetal distress, low cord blood pH and low Apgar score. The performance of UtA-PI > 95(th) percentile in screening for each adverse outcome was poor with DR of 6-16% and a FPR of 5-6%. The DR of adverse outcome when screening by high UtA-PI was greater in pregnancies complicated by SGA than in non-SGA pregnancies; 24% vs 13% for stillbirth, 15% vs 5% for Cesarean section for fetal distress, 30% vs 9% for low cord blood pH and 20% vs 3% for low 5-min Apgar score, respectively. CONCLUSION: High UtA-PI at 30-34 weeks' gestation may be useful in the prediction of adverse perinatal outcome in pregnancies with a SGA fetus, however, in the absence of SGA, UtA-PI is a poor predictor of adverse outcome. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Asunto(s)

Sufrimiento Fetal/diagnóstico por imagen , Mortinato , Ultrasonografía Prenatal/métodos , Arteria Uterina/diagnóstico por imagen , Adulto , Femenino , Humanos , Valor Predictivo de las Pruebas , Embarazo , Tercer Trimestre del Embarazo/fisiología , Estudios Prospectivos , Flujo Pulsátil/fisiología , Ultrasonografía Doppler en Color/métodos

RESUMEN

OBJECTIVE: Effective screening for pre-eclampsia resulting in delivery < 37 weeks' gestation (preterm PE) is provided by assessment of a combination of maternal factors, mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF) at 11-13 or 19-24 weeks' gestation. This study explores the possibility of carrying out routine screening for preterm PE by maternal factors and MAP in all pregnancies and reserving measurements of UtA-PI and PlGF for a subgroup of the population, selected on the basis of the risk derived from screening by maternal factors and MAP alone. METHODS: Study data were derived from prospective screening for adverse obstetric outcomes in women attending their routine hospital visit at 11-13 and/or 19-24 weeks' gestation. Bayes' theorem was used to derive the a-priori risk for preterm PE from maternal factors and MAP. The posterior risk was obtained by the addition of UtA-PI and PlGF. We estimated the detection rate (DR) of preterm PE, at an overall false-positive rate (FPR) of 10%, from a policy in which first-stage screening by a combination of maternal factors and MAP defines screen-positive, screen-negative and intermediate-risk groups, with the latter undergoing second-stage screening by UtA-PI and PlGF. RESULTS: At 11-13 weeks' gestation, the model-based DR of preterm PE, at a 10% FPR, when screening the whole population by maternal factors, MAP, UtA-PI and PlGF was 74%. A similar DR was achieved by two-stage screening, with screening by maternal factors and MAP in the first stage and reserving measurement of UtA-PI and PlGF for the second stage and for only 50% of the population. If second-stage screening was offered to 30% of the population, there would be only a small reduction in DR from 74% to 71%. At 19-24 weeks, the model-based DR of preterm PE, at a 10% FPR, when screening the whole population by maternal factors, MAP, UtA-PI and PlGF was 84%. A similar DR was achieved by two-stage screening with measurements of UtA-PI and PlGF in only 70% of the population; if second-stage screening was offered to 40% of the population, the DR would be reduced from 84% to 81%. CONCLUSIONS: High DR of preterm PE can be achieved by two-stage screening in the first and second trimesters with maternal factors and MAP in the whole population and measurements of UtA-PI and PlGF in only some of the pregnancies. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Asunto(s)

Factor de Crecimiento Placentario/sangre , Preeclampsia/diagnóstico , Arteria Uterina/fisiología , Presión Arterial , Teorema de Bayes , Femenino , Edad Gestacional , Humanos , Embarazo , Diagnóstico Prenatal/métodos , Estudios Prospectivos

RESUMEN

OBJECTIVE: To investigate the value of combined screening by maternal characteristics and medical history, fetal biometry and biophysical and biochemical markers at 19-24 weeks' gestation, for prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE), and examine the potential value of such assessment in deciding whether the third-trimester scan should be at 32 and/or 36 weeks' gestation. METHODS: This was a screening study in 7816 singleton pregnancies, including 389 (5.0%) that delivered SGA neonates with birth weight < 5(th) percentile (SGA < 5(th) ), in the absence of PE. Multivariable logistic regression analysis was used to determine if screening by a combination of maternal factors, fetal biometry, uterine artery pulsatility index (UtA-PI) and maternal serum concentrations of placental growth factor (PlGF) and α-fetoprotein (AFP) had significant contribution in predicting SGA neonates. A model was developed for selecting the gestational age for third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks. RESULTS: Significant independent contributions to the prediction of SGA < 5(th) were provided by maternal factors, fetal biometry, UtA-PI and serum PlGF and AFP. The detection rate (DR) of such combined screening at 19-24 weeks was 100%, 78% and 42% for SGA < 5(th) delivering < 32, at 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. In a hypothetical model, it was estimated that if the desired objective of prenatal screening is to predict about 80% of the cases of SGA < 5(th) , it would be necessary to select 11% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 44% to be reassessed at 36 weeks; 57% would not require a third-trimester scan. CONCLUSION: Prenatal prediction of a high proportion of SGA neonates necessitates the undertaking of screening in the third trimester of pregnancy, in addition to assessment in the second trimester, and the timing of such screening, at 32 and/or 36 weeks, should be contingent on the results of the assessment at 19-24 weeks.

Asunto(s)

Recién Nacido Pequeño para la Edad Gestacional/metabolismo , Proteínas Gestacionales/sangre , Embarazo/sangre , alfa-Fetoproteínas/metabolismo , Adulto , Biomarcadores/sangre , Femenino , Retardo del Crecimiento Fetal/sangre , Retardo del Crecimiento Fetal/diagnóstico por imagen , Edad Gestacional , Humanos , Recién Nacido , Masculino , Factor de Crecimiento Placentario , Valor Predictivo de las Pruebas , Atención Prenatal/métodos , Diagnóstico Prenatal/métodos , Estudios Prospectivos , Ultrasonografía Doppler de Pulso/métodos , Ultrasonografía Prenatal/métodos , Arteria Uterina/diagnóstico por imagen

RESUMEN

OBJECTIVE: To investigate the value of maternal serum concentrations of placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), pregnancy-associated plasma protein-A (PAPP-A), free ß-human chorionic gonadotropin (ß-hCG) and α-fetoprotein (AFP) at 19-24 weeks' gestation, in combination with maternal factors and fetal biometry, in the prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE) and examine the potential value of such assessment in deciding whether the third-trimester scan should be performed at 32 and/or 36 weeks' gestation. METHODS: This was a screening study in 9715 singleton pregnancies, including 481 (5.0%) that delivered SGA neonates with birth weight < 5(th) percentile (SGA < 5(th) ), in the absence of PE. Multivariable logistic regression analysis was used to determine if screening by a combination of maternal factors, Z-scores of fetal head circumference, abdominal circumference and femur length, and log10 multiples of the median (MoM) values of PlGF, sFlt-1, PAPP-A, free ß-hCG or AFP had a significant contribution to the prediction of SGA neonates. A model was developed in selecting the gestational age for third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks. RESULTS: Compared to the normal group, the mean log10 MoM value of PlGF was lower, AFP was higher and sFlt-1, PAPP-A and free ß-hCG were not significantly different in the SGA < 5(th) group that delivered < 37 weeks. The detection rate (DR) of combined screening by maternal factors, fetal biometry and serum PlGF and AFP at 19-24 weeks was 100%, 76% and 38% for SGA < 5(th) delivering < 32, 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. In a hypothetical model, it was estimated that, if the desired objective of prenatal screening is to predict about 80% of the cases of SGA < 5(th) , it would be necessary to select 11% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 46% to be reassessed at 36 weeks; 54% would not require a third-trimester scan. CONCLUSION: Prenatal prediction of a high proportion of SGA neonates necessitates the undertaking of screening in the third trimester of pregnancy, in addition to assessment in the second trimester, and the timing of such screening, at 32 and/or 36 weeks, should be contingent on the results of the assessment at 19-24 weeks.

Asunto(s)

Retardo del Crecimiento Fetal/diagnóstico , Recién Nacido Pequeño para la Edad Gestacional , Pruebas de Detección del Suero Materno , Segundo Trimestre del Embarazo/sangre , Adulto , Biomarcadores/sangre , Técnicas de Apoyo para la Decisión , Reacciones Falso Positivas , Femenino , Retardo del Crecimiento Fetal/sangre , Humanos , Recién Nacido , Modelos Logísticos , Embarazo , Estudios Prospectivos , Curva ROC

RESUMEN

OBJECTIVE: To investigate the potential value of serum placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), pregnancy-associated plasma protein-A (PAPP-A), free ß-human chorionic gonadotropin (ß-hCG) and α-fetoprotein (AFP) at 30-34 weeks' gestation in the prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE). METHODS: This was a screening study in singleton pregnancies at 30-34 weeks' gestation, including 490 that delivered SGA neonates and 9360 cases that were unaffected by SGA, PE or gestational hypertension (normal outcome). Multivariable logistic regression analysis was used to determine if screening by serum PlGF, sFlt-1, PAPP-A, free ß-hCG and AFP, individually or in combination, improved the prediction of SGA neonates provided by screening with maternal characteristics and medical history (maternal factors), and estimated fetal weight (EFW) from fetal head circumference, abdominal circumference and femur length. RESULTS: Compared to the normal group, the mean log10 multiples of the median (MoM) values of PlGF and AFP were significantly lower and the mean log10 MoM values of sFlt-1 and free ß-hCG were significantly higher in the SGA group with a birth weight < 5(th) percentile (SGA < 5(th)) delivering < 5 weeks following assessment. The best model for prediction of SGA was provided by a combination of maternal factors, EFW and serum PlGF. Such combined screening, predicted, at a 10% false-positive rate, 85%, 93% and 92% of SGA neonates delivering < 5 weeks following assessment with birth weight < 10(th), < 5(th) and < 3(rd) percentiles, respectively; the respective detection rates of combined screening for SGA neonates delivering ≥ 5 weeks following assessment were 57%, 64% and 71%. CONCLUSION: Combined screening by maternal factors, EFW and serum PlGF at 30-34 weeks' gestation can identify a high proportion of pregnancies that subsequently deliver SGA neonates.

Asunto(s)

Gonadotropina Coriónica Humana de Subunidad beta/metabolismo , Recién Nacido Pequeño para la Edad Gestacional/metabolismo , Proteínas Gestacionales/sangre , Diagnóstico Prenatal/métodos , Receptor 1 de Factores de Crecimiento Endotelial Vascular/metabolismo , Adulto , Biomarcadores/sangre , Femenino , Enfermedades Fetales/sangre , Enfermedades Fetales/diagnóstico por imagen , Edad Gestacional , Humanos , Recién Nacido , Factor de Crecimiento Placentario , Preeclampsia/diagnóstico , Valor Predictivo de las Pruebas , Embarazo , Proteína Plasmática A Asociada al Embarazo/metabolismo , Estudios Prospectivos , Ultrasonografía Prenatal/métodos , alfa-Fetoproteínas/metabolismo

RESUMEN

OBJECTIVE: To investigate the potential value of uterine artery (UtA) pulsatility index (PI) and mean arterial pressure (MAP) at 19-24 weeks' gestation, in combination with maternal characteristics and medical history and fetal biometry in the prediction of delivery of small-for-gestational-age (SGA) neonates in the absence of pre-eclampsia (PE) and to examine the potential value of such assessment in deciding whether the third-trimester scan should be performed at 32 and/or 36 weeks' gestation. METHODS: This was a screening study in 63 975 singleton pregnancies, including 3702 (5.8%) that delivered SGA neonates with birth weight < 5(th) percentile (SGA < 5(th) ) in the absence of PE. Multivariable logistic regression analysis was used to determine if screening by a combination of maternal factors, fetal head circumference (HC), abdominal circumference (AC), femur length (FL), UtA-PI and MAP had significant contribution in predicting SGA neonates. A model was developed to select gestational age for the third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks. RESULTS: The detection rates (DRs) of combined screening by maternal factors, fetal biometry and UtA-PI at 19-24 weeks were 90%, 68% and 44% for SGA < 5(th) delivering < 32, 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. The performance of screening was not improved by the addition of MAP. The DR of SGA < 5(th) delivering at 32-36 weeks improved from 68% to 90% with screening at 32 rather than at 19-24 weeks. Similarly, the DR of SGA < 5(th) delivering ≥ 37 weeks improved from 44% with screening at 19-24 weeks to 59% and 76% when screening at 32 and 36 weeks, respectively. In a hypothetical model, it was estimated that if the desired objective of prenatal screening is to predict about 80% of the cases of SGA < 5(th) , it would be necessary to select 17% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 38% to be reassessed at 36 weeks; 62% would not require a third-trimester scan. CONCLUSION: Prenatal prediction of a high proportion of SGA neonates necessitates the undertaking of screening in the third trimester of pregnancy in addition to assessment in the second trimester, and the timing of such screening, at 32 and/or 36 weeks, should be contingent on the results of the assessment at 19-24 weeks.

Asunto(s)

Presión Arterial , Retardo del Crecimiento Fetal/diagnóstico por imagen , Recién Nacido Pequeño para la Edad Gestacional , Segundo Trimestre del Embarazo , Ultrasonografía Doppler , Ultrasonografía Prenatal/métodos , Arteria Uterina/diagnóstico por imagen , Adulto , Toma de Decisiones Clínicas , Técnicas de Apoyo para la Decisión , Reacciones Falso Positivas , Femenino , Retardo del Crecimiento Fetal/fisiopatología , Humanos , Recién Nacido , Modelos Logísticos , Embarazo , Tercer Trimestre del Embarazo , Estudios Prospectivos , Flujo Pulsátil , Arteria Uterina/fisiología

RESUMEN

OBJECTIVE: To investigate the potential value of cerebroplacental ratio (CPR) at 36 weeks' gestation in the prediction of adverse perinatal outcome. METHODS: This was a screening study in 6178 singleton pregnancies at 35-37 weeks' gestation. Umbilical artery (UA) and fetal middle cerebral artery (MCA) pulsatility index (PI) were measured and the values were converted to multiples of the median (MoM) after adjustment from variables in maternal characteristics and medical history that affect the measurements. CPR was calculated by dividing MCA-PI MoM by UA-PI MoM. Multivariable logistic regression analysis was used to determine if measuring CPR improved the prediction of adverse perinatal outcome provided by maternal characteristics, medical history and obstetric factors. The detection rate (DR) and false-positive rate (FPR) of screening by CPR were estimated for stillbirth, Cesarean section for fetal distress, umbilical arterial cord blood pH ≤ 7.0, umbilical venous cord blood pH ≤ 7.1, 5-min Apgar score < 7 and admission to the neonatal unit (NNU) and neonatal intensive care unit (NICU). RESULTS: There was a linear association between CPR and both birth-weight Z-score and arterial or venous umbilical cord blood pH, but the steepness of the regression lines was inversely related to the interval from assessment to delivery. The performance of low CPR < 5(th) percentile in screening for each adverse outcome was poor, with DRs of 6-15% and a FPR of about 6%. In the small subgroup of the population delivering within 2 weeks of assessment, the DRs improved to 14-50%, but with a simultaneous increase in FPR, to about 10%. CONCLUSION: The performance of CPR in routine screening for adverse perinatal outcome at 36 weeks' gestation is poor.

Asunto(s)

Arteria Cerebral Media/diagnóstico por imagen , Ultrasonografía Prenatal/métodos , Arterias Umbilicales/diagnóstico por imagen , Adulto , Peso al Nacer , Femenino , Sangre Fetal/química , Edad Gestacional , Humanos , Embarazo , Resultado del Embarazo , Análisis de Regresión

RESUMEN

OBJECTIVE: To investigate the potential value of cerebroplacental ratio (CPR) at 30-34 weeks' gestation in the prediction of adverse perinatal outcome. METHODS: This was a screening study in 30 780 singleton pregnancies at 30-34 weeks' gestation. Umbilical artery (UA) and fetal middle cerebral artery (MCA) pulsatility index (PI) were measured and the values were converted to multiples of the median (MoM) after adjustment from variables in maternal characteristics and medical history that affect the measurements. CPR was calculated by dividing MCA-PI MoM by UA-PI MoM. Multivariable logistic regression analysis was used to determine if measuring CPR improved the prediction of adverse perinatal outcome provided by screening with maternal characteristics, medical history and obstetric factors. The detection rate (DR) and false-positive rate (FPR) of screening by CPR were estimated for stillbirth, Cesarean section for fetal distress, umbilical arterial cord blood pH ≤ 7.0, umbilical venous cord blood pH ≤ 7.1, 5-min Apgar score < 7 and admission to the neonatal unit (NNU) and neonatal intensive care unit (NICU). RESULTS: There was a significant association between CPR and birth-weight Z-score. In addition to maternal characteristics, medical history and obstetric factors, measuring CPR provided a significant contribution to the prediction of arterial cord blood pH ≤ 7.0, venous cord blood pH ≤ 7.1 and admission to NNU. The performance of CPR in screening for each adverse outcome was poor, with DR of 5-11% and a FPR of about 5%. In the small subgroup of the population delivering within 2 weeks following assessment, the DR improved to 20-50%, but with a simultaneous increase in FPR to 10-23%. CONCLUSION: The performance of CPR in routine screening for adverse perinatal outcome at 30-34 weeks' gestation is poor.

Asunto(s)

Arteria Cerebral Media/diagnóstico por imagen , Resultado del Embarazo , Arterias Umbilicales/diagnóstico por imagen , Adulto , Femenino , Sangre Fetal/química , Sufrimiento Fetal/diagnóstico por imagen , Feto/irrigación sanguínea , Edad Gestacional , Humanos , Valor Predictivo de las Pruebas , Embarazo , Estudios Prospectivos , Flujo Pulsátil/fisiología , Ultrasonografía Doppler en Color , Ultrasonografía Prenatal/métodos

RESUMEN

OBJECTIVE: To investigate the value of fetal biometry at 19-24 weeks' gestation in the prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE), and examine the potential value of such assessment in deciding whether the third-trimester scan should be at 32 and/or 36 weeks' gestation. METHODS: This was a screening study in 88,187 singleton pregnancies, including 5003 (5.7%) that delivered SGA neonates with birth weight < 5(th) percentile (SGA < 5(th)). Multivariable logistic regression analysis was used to determine if screening by a combination of maternal characteristics and medical history and Z-scores of fetal head circumference (HC), abdominal circumference (AC) and femur length (FL) had significant contribution in predicting SGA neonates. A model was developed for selecting the gestational age for third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks. RESULTS: Combined screening by maternal factors and fetal biometry at 19-24 weeks, predicted 76%, 58% and 44% of SGA < 5(th) delivering < 32, 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. The detection rate (DR) of SGA < 5(th) delivering at 32-36 weeks improved from 58% to 82% with screening at 32 weeks rather than at 19-24 weeks. Similarly, the DR of SGA < 5(th) delivering ≥ 37 weeks improved from 44% with screening at 19-24 weeks to 61% and 76% with screening at 32 and 36 weeks, respectively. In a hypothetical model, it was estimated that if the desired objective of prenatal screening is to predict about 80% of the cases of SGA < 5(th), it would be necessary to select 28% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 41% to be reassessed at 36 weeks; in 59% of pregnancies there would be no need for a third-trimester scan. CONCLUSION: Prenatal prediction of a high proportion of SGA neonates necessitates the undertaking of screening in the third trimester of pregnancy, in addition to assessment in the second trimester, and the timing of such screening, either at 32 and/or 36 weeks, should be contingent on the results of the assessment at 19-24 weeks.

Asunto(s)

Biometría/métodos , Retardo del Crecimiento Fetal/diagnóstico por imagen , Recién Nacido Pequeño para la Edad Gestacional , Diagnóstico Prenatal/métodos , Adulto , Peso al Nacer , Femenino , Retardo del Crecimiento Fetal/patología , Peso Fetal , Edad Gestacional , Humanos , Recién Nacido , Preeclampsia/diagnóstico por imagen , Valor Predictivo de las Pruebas , Embarazo , Estudios Prospectivos , Ultrasonografía Prenatal/métodos

RESUMEN

Nine large-scale symmetry reaction center mutants were constructed in Rhodobacter capsulatus by replacing segments of the M subunit gene with the homologous region of the L subunit gene. Between them, the mutations resulted in symmetrization of essentially the entire region from the carboxy terminal portion of the C helix through most of the E helix. The amino acids in this region define about 80% of the environment of the reaction center cofactors. These studies show that roughly 80% of the amino acids that come in close contact with the cofactors involved in initial electron transfer can be made symmetric in a piecewise manner without loss of the ability to grow photoheterotrophically. However, the amino acid regions near the quinones and iron atom are much more sensitive to symmetrization and most of the large-scale changes in this region resulted in the loss of photosynthetic viability, probably due to loss of stable reaction centers from the photosynthetic membrane. More detailed analysis of the isolated photosynthetic membranes from these mutants showed that in all cases but one, there was some amount of charge separation occurring in the mutant reaction centers. This bank of mutants serves as a useful starting point for more detailed studies of the differential molecular interactions which occur between the two reaction center subunits and their associated cofactors.

Asunto(s)

Proteínas Bacterianas , Fotosíntesis/genética , Proteínas del Complejo del Centro de Reacción Fotosintética/metabolismo , Rhodobacter capsulatus/genética , Secuencia de Aminoácidos , Fluorescencia , Genes Bacterianos , Luz , Datos de Secuencia Molecular , Mutagénesis , Proteínas del Complejo del Centro de Reacción Fotosintética/genética , Proteínas del Complejo del Centro de Reacción Fotosintética/efectos de la radiación , Potenciometría , Espectrofotometría , Relación Estructura-Actividad , Supresión Genética

RESUMEN

Munchausen syndrome by proxy is a form of abuse in which the child suffers from a factitious illness induced by a parent. A case report of an 18-month-old boy who suffered from intractable diarrhea because of the surreptitious administration of laxatives by his mother is presented. The evolution of this case is discussed, as are the legal and ethical considerations in the diagnosis of Munchausen syndrome by proxy.

Asunto(s)

Relaciones Madre-Hijo , Síndrome de Munchausen/diagnóstico , Grabación en Video , Maltrato a los Niños/diagnóstico , Diarrea Infantil/etiología , Humanos , Lactante , Masculino