David Baptista da Silva Pares

Noninvasive Determination of Fetal Rh Blood Group, D Antigen Status by Cell-Free DNA Analysis in Maternal Plasma: Experience in a Brazilian Population

We evaluated the diagnostic accuracy of Rh blood group, D antigen (RHD) fetal genotyping, using real-time polymerase chain reaction in maternal blood samples, in a racially mixed population. We performed a prospective study conducted between January 2006 and December 2007, analyzing fetal RHD genotype in the plasma of 102 D- pregnant women by real-time polymerase chain reaction, targeting exons 7 and 10 of the RHD gene. Genotype results were compared with cord blood phenotype obtained after delivery or before the first intrauterine transfusion when necessary. Most of the participants (75.5%) were under 28 weeks of pregnancy, and 87.5% had at least one relative of black ancestry. By combining amplification of two exons, the accuracy of genotyping was 98%, sensitivity was 100%, and specificity was 92%. The positive likelihood ratio was 12.5, and the negative likelihood ratio was 0. The two false-positive cases were confirmed to be pseudogene RHD by real-time polymerase chain reaction. There were no differences between the patients with positive or negative Coombs test ( P = 0.479). Determination of fetal RHD status in maternal peripheral blood was highly sensitive in this racially mixed population and was not influenced by the presence of antierythrocyte antibodies.

Prediction of fetal anemia by Doppler of the middle cerebral artery and descending thoracic aorta

SummaryBackgroundDespite significant advances, perinatal hemolytic disease has not been eradicated and is still associated with significant morbidity and mortality, especially in developing countries. An accurate method for antenatal diagnosis and quantification of fetal anemia is a crucial step prior to the performance of invasive procedures, which are not risk-free. The middle cerebral artery peak systolic velocity (MCA-PSV) is currently the most popular non-invasive diagnostic method used to quantify fetal anemia and determine the exact timing for transfusion The combined use of MCA-PSV and descending thoracic aorta mean velocity (DTA-MV) has not been previously evaluated. Since this strategy has the potential to decrease false positive results it could reduce unnecessary cordocenteses, therefore minimizing fetal risks. This study aimed to evaluate the accuracy of MCA-PSV associated with DTA-MV in the prediction of fetal anemia.MethodRetrospective analysis of 90 cordocenteses performed on alloimmunized pregnancies in a single hospital MCA-PSV and DTA-MV were performed immediately before cordocentesis. The Dopplervelocimetry findings were compared with fetal hemoglobin concentration. Sensitivity, specificity, positive and negative predictive values and accuracy of MCA-PSV and DTA-MV in the prediction of moderate/severe fetal anemia were calculated.ResultsThe individual sensitivity of MCA-PSV and DTA-MV was 100 and 95.7%, specificity was 65 and 100% and accuracy was 92.2 and 96.7%, respectively. The combination of both vessels produced a higher overall accuracy (98.6%).ConclusionMCA-PSV is more sensitive and DTA-MV is more specific in the detection of fetal anemia. The highest diagnostic accuracy was obtained by the association of both Doppler evaluations.

Reference range for amniotic fluid index measurements in a Brazilian population

Abstract Objective: The aim of this study was to determine the reference range for amniotic fluid index (AFI) measurements in a large sample of the Brazilian population. Methods: This was a retrospective cross-sectional study on 3837 normal singleton pregnancies between 18+0 and 38+6 weeks of pregnancy. The AFI was measured from the largest vertical pockets of amniotic fluid in the four quadrants of the uterine cavity. To assess the correlation between AFI and gestational age (GA), polynomial equations were calculated, with adjustments using the determination coefficient (R2). Results: The mean maternal age and gestational age were 27.01±6.57 years and 30.43±5.29 weeks, respectively. The mean AFI ranged from 12.2±2.6 cm at 18 weeks to 11.6±6.0 cm at 38 weeks of pregnancy. The correlation between AFI and GA was best represented by a linear equation: AFI=17.78–0.153*GA (R2=0.027). Conclusion: We established the reference range for the AFI in a large sample of the Brazilian population. This reference range can be used to monitor deviations in the volume of amniotic fluid in fetuses at high risk for intrauterine growth disturbances.

Fetal frontomaxillary facial angle between 11 and 13 + 6 weeks of gestation in a Brazilian population: influence of different races.

Abstract Objective: To evaluate the influence of different races over the measurement of the frontomaxillary facial angle between 11 and 13 + 6 weeks of pregnancy in a Brazilian population. Methods: A cross-sectional study was conducted with 332 healthy pregnant women, with a crown-rump length (CRL) between 47 and 84 mm. Such measurements were taken abdominally, using the mid-sagittal plane, and the angle was measured by tracing a line over the palate and a line from the anterosuperior maxillary angle all the way to the external part of the forehead. As for the reference intervals, a simple linear regression between the frontomaxillary facial angle and the CRL was used, as well as Pearson’s correlation coefficient (r). To evaluate the difference between races, a variance analysis was used (ANOVA). To calculate reproducibility, the intraclass correlation coefficient (ICC) was used. Results: The means for the fetal frontomaxillary facial angle in white, black and mixed races were 81.8 ± 6.6; 82.2 ± 6.1 and 81.4 ± 6.2 mm, respectively. There was no statistical difference between races (p = 0.713). A decreasing correlation between the frontomaxillary facial angle and the CRL was observed for the black (r = −0.450) and mixed (r = −0.212) races. Excellent intraobserver reproducibility was observed, as well as a satisfactory interobserver reproducibility, with ICC of 0.858 and 0.605, respectively. Conclusion: There were no significative statistical differences in the measurement of the fetal frontomaxillary facial angle between 11 and 13 + 6 weeks of pregnancy in the different races in a Brazilian population.

Alterações ultra-sonográficas na gravidez Rh negativo sensibilizada avaliada pela espectrofotometria do líquido amniótico e pela dopplervelocimetria da artéria cerebral média

OBJECTIVE: To evaluate and compare existing ultrasound findings in women with Rh-alloimmunized pregnancies with diagnosis of fetal anemia by spectrophotometric analysis of amniotic fluid or Doppler ultrasound of the fetal middle cerebral artery. MATERIALS AND METHODS: This was an observational descriptive study involving 99 patients evaluated between January 1995 and January 2004. Patients were divided into two groups: 74 Rh-isoimmunized women submitted to spectrophotometry of the amniotic fluid (group S) and 25 Rh-isoimmunized women submitted to Doppler ultrasound of fetal middle cerebral artery (group D) to evaluate fetal anemia. Ultrasound findings in the two groups were compared. RESULTS: Placental anomalies, mainly placentomegaly and textural irregularities were more frequently seen in pregnant women followed up with spectrophotometry of the amniotic fluid compared to those followed up with Doppler ultrasound (64% X 32%, p = 6,294). CONCLUSION: The frequency of abnormal ultrasound findings was 2-fold higher in pregnancies evaluated with spectrophotometry of the amniotic fluid compared to those followed up with Doppler ultrasound.

Avaliação do desfecho dos conceptos com risco aumentado de ocorrência de anomalias cromossômicas calculado pela medida da translucência nucal

OBJETIVO: avaliar o desfecho dos fetos que apresentam risco de anomalia cromossomica superior a 1:300, calculado pela medida da translucencia nucal, por meio do programa da Fetal Medicine Foundation. METODOS: nas gestacoes unicas com risco para aneuploidia fetal superior a 1:300 foram avaliadas variaveis como: cariotipo fetal, abortamento espontâneo e provocado, prematuridade, obito fetal, obito neonatal, malformacoes estruturais e recem-nascidos normais. Usamos o teste exato de Fisher para fazer comparacoes de diferencas de proporcoes entre grupos. RESULTADOS: foram observadas 193 (3,6%) gestacoes unicas com risco de aneuploidia fetal acima de 1:300. Somente 165 gestacoes preencheram os criterios. Destas, apenas 32,1% foram submetidas a estudo do cariotipo fetal, com 8,5% de anomalias cromossomicas (85,7% de trissomia do cromossomo 21). Foram os seguintes os desfechos das gestacoes: 4,2% de abortos espontâneos, 4,2% de abortos induzidos, 4,8% de prematuridade, 1,8% de obito neonatal, 1,8% de obito fetal e 4,2% de malformacoes estruturais (85,7% de malformacoes cardiacas). Aproximadamente 85,0% dos casos eram recem-nascidos normais. Pacientes com cariotipo anormal tiveram significativamente mais abortos induzidos (p<0,001) e mais malformacoes (p<0,001) que pacientes com cariotipo normal. Nenhum diagnostico de doenca genica ou perda gestacional relacionada aos procedimentos invasivos foi detectado. Nos fetos com diagnostico no pre-natal de aneuploidia, a gestacao foi interrompida em 66,7%. CONCLUSOES: a translucencia nucal mantem seu papel no rastreamento das cromossomopatias, especialmente nas gestantes de baixo risco. Porem, o aconselhamento das gestantes com risco elevado deve ser prudente, uma vez que, apesar de estes casos apresentarem pior prognostico fetal, a maioria apresenta desfecho favoravel da gestacao.

Validation of Fetal Medicine Foundation algorithm for prediction of pre-eclampsia in the first trimester in an unselected Brazilian population

Abstract Objective: The objective of this study is to evaluate the predictive performance of the Fetal Medicine Foundation (FMF) algorithm for prediction of preeclampsia (PE) between 11 and 14 weeks of gestation in an unselected Brazilian population. Methods: We conducted a prospective cohort study with 617 singleton pregnancies of unselected risk. Biophysical markers (mean pulsatility index, mean arterial pressure) and biochemical markers (placental growth factor (PLGF) and PAPP-A) were inserted into the FMF software and converted into multiples of the median (MoM). The subjects were divided into five groups: early-onset PE, parturition <34 weeks’ gestation; preterm PE, parturition <37 weeks; PE, parturition at any gestational age; gestational hypertension (GH); and control group. Areas under the receiver operating characteristics curve (AUC) were calculated for the outcomes. Results: Among 617 patients, seven developed early-onset PE, 18 developed preterm PE (seven early PE plus 11 delivered between 34 and 36 + 6 weeks gestation), 34 developed PE (18 preterm PE plus 16 delivered after 37-week gestation), 12 pregnant women developed GH, and 517 women comprised the control group. The best predictive performance using the FMF algorithm occurred in the early-onset PE group, with AUC = 0.946 (95% CI 0.919–0.973) and the detection rate of 28.6% and 85.7% for 5% and 10% false-positive (FP), respectively. Conclusions: The FMF algorithm to predict PE was effective in a Brazilian population, mainly in the early-onset form of the disease at 10% FP.

Reference range for the fetal intracranial translucency measurement between 11 and 14 + 2 weeks of gestation in a Brazilian population.

Abstract Objective: To establish a reference range for the fetal intracranial translucency (IT) measurement between 11 and 14 + 2 weeks in a Brazilian population. Methods: A retrospective cross-sectional study was performed with 199 low-risk singleton pregnancies during the first trimester ultrasound exam. The IT (fourth ventricle width) measurement was performed in a mid-sagittal view of fetal profile defined by two echogenic borders – the dorsal part of the brain stem anteriorly and the choroid plexus of the fourth ventricle posteriorly. Polynomial regression was used to obtain the best fit using fetal IT measurements and crown-rump length (CRL). Percentiles 5th, 50th and 95th were determined for each gestational age. Results: The mean of fetal IT ranged from 1.6 mm at CRL 45 to 2.0 mm at CRL 84 mm. A best fit curve was a first-degree polynomial regression: IT measurement = 1.001 + 0.0124 × CRL (R2=0.09). Conclusion: Reference range for the fetal IT measurement between 11 and 14 + 2 weeks of gestation in a Brazilian population was established.

Fetal heart assessment in the first trimester of pregnancy: influence of crown-rump length and maternal body mass index

Objective To evaluate the influence of the crown-rump length and body mass index on sonographic evaluation of the fetal heart using abdominal and vaginal routes in the first trimester of pregnancy. Methods We conducted a cross-sectional study with 57 pregnant women between 12-14 weeks (CRL≤ 84 mm). We evaluated the following fetal cardiac plans using the abdominal and vaginal routes: four-chamber view, right ventricle outflow tract, left ventricle outflow tract and aortic arch. We used the B-mode, color Doppler and four-dimensional ultrasonography (spatio-temporal image correlation). To evaluate the influence of crown-rump length and body mass index in the assessment of fetal cardiac planes, we used the t test unpaired. Results There were no statistically significant differences in the rates of success and failure between abdominal and vaginal routes in relation to body mass index, however, there was a higher failure rate in vaginal assessment using B mode associated with color Doppler (P<0.01). Conclusion The crown-rump length and body mass index had no interference in fetal cardiac assessment in the first trimester of pregnancy.

Evaluation of fetal heart geometry during pregnancy by three-dimensional ultrasound using the STIC rendering mode

To determine fetal heart geometry during pregnancy using three‐dimensional (3D) ultrasound and the spatiotemporal image correlation (STIC) rendering mode.