Free fetal DNA levels in patients at risk of preterm labour.

OBJECTIVES: Our main goals were to evaluate the capability of ffDNA to increase the accuracy in prediction of preterm labour by cervical length and to explore potential mechanisms of disease associated with this pathology. METHODS: Fifty-six women, with male fetus, with cervical length assessment at between 22 and 24 weeks were included in the study and divided in 1) Short cervix (<15 mm) delivered at term (T = 20); 2) Short cervix delivered before 37 weeks (PT = 14); and 3) Patients who delivered at term with normal cervical length (N = 22). Maternal plasma samples were collected between 22 and 24 weeks of gestational age. PCR using primers against DYS14 gene were used to quantified ffDNA in plasma samples. Statistical analysis was done using ANOVA test and spearman´s correlation. RESULTS: The median gestational age at delivery for short cervix groups was 26 + 1 for PT and 39 + 3 for T. The control group delivered at a median gestational age of 39 + 6 weeks. ffDNA was detectable in all cases. There was no significant difference between the 3 groups. Similarly, no significant correlation was observed between ffDNA and gestational age at delivery (r = -0.23; p = 0.07). CONCLUSIONS: ffDNA does not increase the accuracy of short cervix at between 22 and 24 weeks for the prediction of preterm labour.

Reference values for Doppler parameters of the fetal anterior cerebral artery throughout gestation.

AIM: To construct normal reference values for Doppler parameters in 2 anatomical segments of the fetal anterior cerebral artery (ACA) throughout pregnancy. METHODS: The ACA was evaluated in 373 normally growing fetuses from 20 to 40 weeks of gestation. The first segment of the ACA (ACA-S1) was recorded just after its origin from the internal carotid artery in the same plane as the middle cerebral artery (MCA). The second segment (ACA-S2) was recorded distal to the outlet of the anterior communicating artery. RESULTS: The ACA pulsatility index (PI) behaved similarly in both segments, with a constant increase until 28 weeks followed by a decrease until the end of pregnancy [ACA-S1 PI = 3.49 - 0.37 x gestational age (GA) - (0.0063 x GA(2)), SD = 0.6 - 0.061 x GA - (0.001 x GA(2)); ACA-S2 PI = 1.54 - 0.22 x GA - (0.0037 x GA(2)), SD = 0.206 + (0.0037 x GA)]. Peak systolic velocities in both segments showed a constant increase from 20 to 40 weeks of gestation. No significant differences were found between the 2 segments with regard to any Doppler parameter. However, the angle of insonation and the time spent on examination were significantly lower and reproducibility was better for ACA-S1. CONCLUSION: Despite showing similar Doppler values, ACA-S1 has a higher reliability than ACA-S2 and can be recorded in the same anatomical projection as the MCA.

Increased free fetal DNA levels in early pregnancy plasma of women who subsequently develop preeclampsia and intrauterine growth restriction.

OBJECTIVE: To determine if maternal plasma ffDNA is increased early in pregnancies which subsequently develop preeclampsia (PE) and intrauterine growth restriction (IUGR). METHODS: Blood was obtained at 11-14 weeks and plasma stored. Among those who delivered a male infant and had a birth weight under the tenth centile and/or PE, we divided them into those who delivered before 35 weeks (9) and those who delivered after this gestation (15). A third group with uncomplicated pregnancies was used as controls (24). Real time-polymerase chain reaction (RT-PCR) was carried out to detect the multi-copy Y chromosome associated DSY14 gene. RESULTS: There were no differences between the ffDNA levels in the group delivered after 35 weeks and the control group (2.23ge/mL-1.61ge/mL p = 0.39). However, the levels of ffDNA at 11-14 weeks were statistically, significantly higher in patients that delivered before 35 weeks (4.34ge/mL-1.61ge/mL p = 0.0018). A logistic regression analysis shows that for every unit (1ge/mL) in which ffDNA increases, the likelihood of having PE or a fetus growing under the tenth centile delivered before 35 weeks increases by 1.67 times (CI 1.13-2.47). CONCLUSION: The concentration of ffDNA is significantly higher even during early pregnancy, in patients who subsequently develop PE and/or IUGR and are delivered before 35 weeks.

Changes in regional fetal cerebral blood flow perfusion in relation to hemodynamic deterioration in severely growth-restricted fetuses.

OBJECTIVES: To study regional cerebral blood perfusion with power Doppler ultrasound (PDU) imaging in appropriate-for-gestational age (AGA) fetuses and those with intrauterine growth restriction (IUGR) at different hemodynamic stages of fetal deterioration. METHODS: Brain blood perfusion was studied with PDU imaging, and the fractional moving blood volume (FMBV) was estimated in 56 growth-restricted and 56 AGA matched fetuses at 26-32 weeks of gestation. Fetuses with IUGR were classified according to progression of hemodynamic deterioration as follows: Group 1, abnormal umbilical artery (UA) pulsatility index (PI) (mean > 2 SD, n = 13); Group 2, abnormal UA-PI and middle cerebral artery (MCA) PI (mean < 2 SD, n = 15); Group 3, abnormal UA-PI, MCA-PI and ductus venosus (DV) PI (mean > 2 SD) but atrial (a-wave) flow present (n = 16); and Group 4, absent or reversed DV atrial flow (n = 12). FMBV was calculated in the complete mid-sagittal, frontal, basal ganglia and cerebellar regions. RESULTS: In all growth-restricted fetuses, FMBV was significantly increased in all regions. Fetuses in Group 1 showed considerable increments in FMBV values in the frontal, complete mid-sagittal and cerebellar regions, and a mild increase in the basal ganglia. From Groups 2 to 4, there was a steady reduction (compared with Group 1) in frontal FMBV values (F = 3.25, P = 0.027) together with a significant increment in the basal ganglia values (F = 11.61, P < 0.001). A trend for increasing FMBV values was also observed in the cerebellum, whereas a decreasing trend was noted in the complete mid-sagittal area. CONCLUSIONS: Brain perfusion in growth-restricted fetuses shows clear regional variations, which change with progression of hemodynamic deterioration. After an initial and early increase in the frontal area, progression of fetal deterioration was rapidly associated with a pronounced decrease in frontal perfusion, together with an increase towards the basal ganglia.

Hypertrophic cardiomyopathy-like changes in monochorionic twin pregnancies with selective intrauterine growth restriction and intermittent absent/reversed end-diastolic flow in the umbilical artery.

OBJECTIVE: To evaluate the prevalence of hypertrophic cardiomyopathy-like (HCL) changes in monochorionic twins with selective intrauterine growth restriction (sIUGR) and intermittent absent/reversed end-diastolic flow (iAREDF), also defined as Type III sIUGR, and the clinical relevance of this condition. METHODS: A total of 80 pregnancies with sIUGR were studied, 40 with, and 40 without iAREDF. HCL changes were defined as an increased thickness of either left or right ventricular wall (mean > 2 SD) estimated with M-mode ultrasonography. Data were plotted on normal reference values constructed from 75 uncomplicated monochorionic twin pregnancies (150 fetuses) at 22-34 weeks' gestation. Perinatal outcomes in pregnancies with and without HCL changes were compared. RESULTS: In the group with iAREDF, 8/40 of the larger twins (20%) had HCL changes (five bilaterally, two in the right, and one in the left ventricle) as compared with 1/40 (2.5%) in fetuses without iAREDF (P = 0.03). No differences were observed in the smaller twin (1/40 in both groups). HCL changes were not associated with a significant increment in perinatal mortality as only one large fetus from the group with iAREDF died in utero. In the remaining 10 cases, no differences in the intertwin weight discordance, placental surface discordance, or rate of neonatal neurological damage were observed. However, all 10 presented mildly abnormal neonatal cardiac findings that resolved over time with no apparent short-term impact on cardiac function. CONCLUSIONS: HCL changes in the larger twin should be regarded as part of the spectrum of findings in Type III monochorionic-sIUGR (presenting iAREDF). This finding does not seem to be associated with an increased rate of short-term neurological or cardiac complications.

Doppler changes in the main fetal brain arteries at different stages of hemodynamic adaptation in severe intrauterine growth restriction.

OBJECTIVE: To evaluate changes in the temporal evolution and regional distribution of arterial brain Doppler parameters in relation to different stages of hemodynamic adaptation in fetuses with severe intrauterine growth restriction (IUGR). METHODS: Thirty-six fetuses with severe IUGR ( 2 SD) were evaluated longitudinally with pulsed Doppler ultrasound at four different hemodynamic stages: Stage 1 (n = 36), mean UA-PI > 2 SD or absent UA end-diastolic flow; Stage 2 (n = 34), abnormal middle cerebral artery (MCA) PI (mean < 2 SD); Stage 3 (n = 30), reversed UA end-diastolic flow; Stage 4 (n = 12), absent or reversed atrial flow in the ductus venosus. In addition, 36 normally grown fetuses were studied for comparison. PI and time-averaged maximum velocity (TAMXV) in the MCA and the anterior cerebral (ACA), pericallosal (PER) and posterior cerebral (PCA) arteries were measured. RESULTS: In IUGR fetuses, PI values from all arteries were significantly reduced at Stage 2. At Stages 3 and 4, ACA-PI and PCA-PI did not change further, whereas MCA-PI and PER-PI showed a slight increase. In the ACA, MCA and PER, TAMXV in Stage 2 increased significantly. In Stages 3 and 4, ACA and PER-TAMXV remained unchanged, whereas MCA-TAMXV showed a slight decrease, mirroring the PI values. PCA-TAMXV values were similar to controls at all stages. CONCLUSION: In IUGR fetuses, the brain arteries differ in the magnitude and time sequence of Doppler parameters in relation to systemic hemodynamic adaptation, suggesting the existence of regional brain redistribution processes.

Evaluation of fetal regional cerebral blood perfusion using power Doppler ultrasound and the estimation of fractional moving blood volume.

OBJECTIVE: To standardize the evaluation of regional fetal brain blood perfusion, using power Doppler ultrasound (PDU) to estimate the fractional moving blood volume (FMBV) and to evaluate the reproducibility of this estimation. METHODS: Brain blood perfusion was evaluated in 35 normally grown fetuses at 28-30 weeks of gestation, using PDU. The following cerebral regions were included in the PDU color box: anterior sagittal, complete sagittal, basal ganglia, and cerebellar. Ten consecutive good-quality images of each anatomical plane were recorded and the delimitation of the region of interest (ROI) was performed off-line. FMBV was quantified in the ROI of all images and the mean considered as the final value. Differences between regions, variability, reproducibility and agreement between observers were assessed. RESULTS: Power Doppler images of the described anatomical planes were obtained in all cases, regardless of fetal position. The median time for the acquisition of the images was 7 (range 4-12) min. Mean (range) FMBV values were: anterior sagittal, 16.5 (10.7-22.8)%, inter-patient coefficient of variation (CV) 0.22; complete sagittal, 13.5 (8.8-16.1)%, CV 0.27; basal ganglia, 18.3 (10.7-27.6)%, CV 0.27; and cerebellar, 6.6 (3.0-11.0)%, CV 0.38. There were statistically significant differences in FMBV between cerebellar and complete sagittal ROIs with the frontal and basal ganglia regions. Reproducibility analyses showed an intraclass correlation coefficient of 0.91 (95% CI 0.67-0.97) and an interclass correlation coefficient of 0.87 (95% CI 0.70-0.94). Interobserver agreement showed a mean difference between observers of -0.2 (SD 2.7) with 95% limits of agreement -5.6 to 5.2. CONCLUSIONS: When the regions of interest are well defined, the FMBV estimate offers a method to quantify blood flow perfusion in different fetal cerebral areas. There appear to be regional differences in FMBV within the fetal brain.

Gestational-age-adjusted reference values for the modified myocardial performance index for evaluation of fetal left cardiac function.

OBJECTIVE: It has been shown that the modified myocardial performance index (Mod-MPI) is associated with higher reproducibility than conventional MPI because it uses mitral and aortic valve 'clicks' to calculate each time period. We aimed to construct normal reference values for the Mod-MPI after 19 weeks' gestation. METHODS: The Mod-MPI was calculated in the left ventricle of 557 normal fetuses at 19-39 weeks' gestation. The isovolumetric contraction time (ICT), isovolumetric relaxation time (IRT) and ejection time (ET) were measured using the Doppler signals (clicks) of the opening and closing of the mitral and aortic valves as landmarks. Mod-MPI was calculated as (ICT + IRT)/ET. RESULTS: Throughout gestation, there was a small increase in the Mod-MPI (at 19 weeks it was 0.35 +/- 0.027 (mean +/- SD); at 39 weeks, 0.37 +/- 0.029; Mod-MPI = 0.33 + 0.001x gestational age (GA) (weeks), r(2) = 0.017). Of the three components, ICT remained constant, IRT increased (IRT = 0.028 + 2.52 x GA (weeks)), and ET slightly decreased (ET = 0.184 - 3.65 x GA (weeks)). Fetal heart rate (FHR) had no effect on the Mod-MPI, but the duration of IRT, ICT and ET decreased by 13-15% when FHR increased from 130 to 160 beats per minute. CONCLUSION: The GA-adjusted reference values for the Mod-MPI and the three time periods used for its calculation can be applied to fetal cardiac evaluation in the presence of pregnancy-associated complications.

A modified myocardial performance (Tei) index based on the use of valve clicks improves reproducibility of fetal left cardiac function assessment.

OBJECTIVE: To determine whether a modified myocardial performance index (Mod-MPI) involving assessment of the movements (clicks) of the mitral valve (MV) and aortic valve (AV), improves intra- and interobserver agreement as compared to the previously reported method for MPI estimation. METHODS: The Mod-MPI was recorded by two experienced operators in the left cardiac chambers of 25 normally grown fetuses using pulsed Doppler ultrasonography. The isovolumetric contraction time (ICT) was measured from the closure of the MV to the opening of the AV, the ejection time (ET) from the opening to the closure of the AV, and the isovolumetric relaxation time (IRT) from the closure of the AV to the opening of the MV. The Mod-MPI was calculated as (ICT + IRT)/ET. In addition, the MPI was estimated without using the valve clicks (F-MPI) as previously described. Intra- and interobserver agreement were then analyzed for both modalities. RESULTS: There was a significantly lower intra- and inter-observer variability in the estimation of all time periods with the Mod-MPI than with the F-MPI (ICT: intra-observer, 9.9% vs. 13.9%; interobserver 9.9% vs. 15.6%; IRT: intraobserver, 9.9% vs. 14.8%; interobserver 10.4% vs. 18.3%; and ET: intraobserver, 4.5% vs. 6.1%; interobserver 2.8% vs. 5.2%, respectively). Intraclass correlation coefficient (IntraCC) for the Mod-MPI was 0.8 (95% confidence interval (95% CI), 0.56-0.9) and for the F-MPI, the IntraCC was 0.62 (95% CI, 0.26-0.84); P = 0.01. Agreement between observers using the Mod-MPI showed a mean difference of 0.0 with 95% limits of agreement (LA) -0.09 (95% CI, -0.1 to -0.075) to 0.09 (95% CI, 0.075-0.1) and for the F-MPI the mean difference was -0.01 with 95% LA -0.26 (95% CI, -0.3 to -0.22) to 0.25 (95% CI, 0.21-0.29). CONCLUSION: Calculation of the Mod-MPI based on Doppler echoes of the MV and AV clicks is associated with a lower variation and better inter- and intraobserver agreement than the previously used method for fetal cardiac evaluation.