Middle cerebral artery pulsatility index: reliability at different sampling sites.

OBJECTIVES: To analyze the interobserver reliability of measurement of the middle cerebral artery (MCA) pulsatility index (PI) at two different sampling sites. METHODS: This study included 100 consecutive singleton pregnancies between 24 and 40 weeks with normal fetal growth. The PI was calculated by two independent operators at proximal and distal sampling sites of the near-field MCA. Reliability analyses were performed between observers at each sampling site by means of the intraclass correlation coefficient (ICC) for agreement. Differences between observers were explored and agreement limits calculated by means of the Bland-Altman test. RESULTS: Satisfactory flow velocity waveforms were obtained successfully in each fetus at both sampling sites. Peak systolic, end-diastolic and time-averaged maximum velocities were significantly higher at the proximal compared with the distal sampling site. Conversely, PI was significantly higher at the distal compared with the proximal site. ICCs for PI were 0.3 and 0.33 at the proximal and the distal sampling sites, respectively. The 95% interval of the PI differences between observers were +0.91 and -1.14 at the proximal and +1.03 and -1.08 at the distal sampling sites. In about 30% of the cases the PI difference between observers was greater than 0.5 at both sampling sites. CONCLUSIONS: Moderate interobserver reliability in the measurement of end-diastolic and time-averaged maximum MCA flow velocities results in limited agreement of the PI calculation at both proximal and distal sampling sites. These results may preclude its clinical applicability.     

Repeatability of the sonographic assessment of fetal sucking and swallowing movements.

OBJECTIVE: To test the repeatability of sonography in the assessment of fetal sucking and swallowing movements. METHODS: Eighty normal fetuses of pregnant women with no systemic abnormalities were examined sonographically at 30-38 weeks of gestation. Sucking and swallowing movements were observed for 15 min and the face was visualized in frontal and lateral views. The examinations were recorded for later analysis by two independent observers and the 95% limits of agreement (Bland and Altman) method was used for inter- and intraobserver comparison. RESULTS: The mean +/- SD number of swallowing movements, sucking bursts and total sucking movements recorded by Observer 1 were 8.3 +/- 4.7, 9.9 +/- 9.3 and 35.8 +/- 48.0 and the equivalent values for Observer 2 were 8.2 +/- 4.8, 9.8 +/- 9.3 and 36.4 +/- 49.0, respectively. The mean (95% limits of agreement) interobserver difference was 0.1 (-1.4; 1.6), 0.1 (-2.2; 2.3) and -0.6 (-9.0; 7.9), and the mean (95% limits of agreement) intraobserver difference was 0.4 (-3.1; 3.9), 0.1 (-2.0; 2.2) and 1.0 (-10.7; 12.7) for swallowing movements, sucking bursts and total sucking movements, respectively. CONCLUSIONS: The high degree of intra- and interobserver repeatability disclosed in the sonographic analysis of fetal sucking and swallowing movements supports the applicability of sonographic assessment in normal fetuses.     

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.     

Intrapartum assessment of fetal head engagement: comparison between transvaginal digital and transabdominal ultrasound determinations.

OBJECTIVE: To test the null hypothesis that no correlation exists between transvaginal digital examination and the gold standard technique of intrapartum transabdominal ultrasound determination of fetal head engagement, and secondarily to compare the performance of attending physicians and senior residents in depicting fetal head engagement by transvaginal digital examination. METHODS: Two hundred and twenty-two consecutive patients in labor > 37 weeks' gestation with normal singleton cephalic-presenting fetuses and with either ruptured or intact membranes were included. Of these, 119 were nulliparous and 103 were multiparous. Transvaginal digital examinations were performed by either attending physicians or senior residents and were followed immediately by transverse suprapubic sonographic assessments by a single sonographer. The fetal head was considered engaged on transvaginal digital examination if the leading part of the fetal head was positioned at least at maternal ischial spine station 0, and on transverse suprapubic ultrasound if the fetal biparietal diameter was below the maternal pelvic inlet. Examiners were blinded to each other's findings and the effect of examiner experience on the rate of agreement between the two techniques was assessed. The effect of several other independent variables upon the rate of agreement between the two modalities was also assessed. RESULTS: Overall, transvaginal digital examinations were consistent with ultrasound determinations with a raw percent agreement rate of 85.6% (95% confidence interval (CI), 80.8-90.3); kappa = 69.5% (95% CI, 59.4-73.9; P < 0.001). When stratified according to parity, the raw percent agreement rate for nulliparous patients was 81.5% (95% CI, 73.4-88.0); kappa = 60.7% (95% CI, 45.9-64.1; P < 0.001), and for multiparous patients it was 90.3% (95% CI, 84.1-95.9); kappa = 80.4% (95% CI, 63.0-87.5; P < 0.001). Maternal age, gravidity, maternal body mass index, gestational age, cervical dilatation, effacement, membrane status, ischial spine station of the fetal head, fetal head position at ultrasound assessment, birth weight and mode of delivery did not significantly affect rate of agreement. Parity did not affect examination consistency in multiparous patients, but in the whole group increasing parity increased the rate of agreement between modalities. Presence of combined spinal epidural anesthesia significantly increased the rate of agreement in the complete group and among multiparous but not among nulliparous patients. CONCLUSION: These data demonstrate a high rate of agreement (85.6%) between ultrasound determination and transvaginal digital assessment of fetal head engagement. Examiner experience had no effect. These data support the use of intrapartum transabdominal assessment of fetal head engagement.     

Frontomaxillary facial angle at 11+0 to 13+6 weeks' gestation-reproducibility of measurements.

OBJECTIVE: To assess the intra- and interobserver reproducibility in the measurement of the frontomaxillary facial (FMF) angle at 11+0 to 13+6 weeks' gestation and to investigate the effect of deviations from the exact mid-sagittal view on these measurements. METHODS: Three-dimensional (3D) volumes of the fetal face were used by two operators to measure the FMF angle in 50 chromosomally normal and 50 trisomy 21 fetuses. The measurements were taken in the exact mid-sagittal view and repeated after lateral rotation of the head by 5 degrees, 10 degrees and 15 degrees away from the vertical position of the occipitofrontal diameter axis. Mean difference and 95% limits of agreement between paired measurements of FMF angle by the same and by two different sonographers were determined. RESULTS: In the mid-sagittal plane the maxillary bone was rectangular shaped. Rotation away from this plane became easily recognizable because at a mean of 7 degrees (range, 4-10 degrees) the shape of the maxilla changed with the appearance of the zygomatic process of the maxilla and at a mean of 8 degrees (range, 4-12 degrees) the tip of the nose became invisible. In both the normal and trisomy 21 fetuses the FMF angle measured at 5-15 degrees was not significantly different from the one measured in the mid-sagittal plane. In 95% of the cases, the difference between paired measurements of the FMF angle by the same sonographer at the mid-sagittal plane was between -2.3 degrees and 3.0 degrees and at 15 degrees it was -1.0 degrees to 6.8 degrees. At the mid-sagittal plane, the difference in measurements between two sonographers was -3.1 to 3.0 degrees. CONCLUSION: The landmarks that define the mid-sagittal plane of the fetal face are the tip of the nose and the rectangular shaped maxilla. Measurement of the FMF angle is highly reproducible.     

Assessment of lung area in fetuses with congenital diaphragmatic hernia.

OBJECTIVE: To compare the intra- and interobserver agreement of three different methods of measuring lung area in fetuses with congenital diaphragmatic hernia (CDH). METHODS: In 71 fetuses with isolated CDH at 21-33 weeks' gestation, the area of the contralateral lung was assessed by firstly, manual tracing of lung borders, secondly, multiplication of the longest diameter of the lung by its widest perpendicular diameter, and thirdly, multiplication of the anteroposterior (AP) diameter of the lung at the mid-clavicular line by the perpendicular diameter at the midpoint of the AP diameter (AP method). In 30 fetuses the measurements were made by two observers and Bland-Altman analysis was used to compare the measurement agreement and bias for each observer and between the two observers. RESULTS: The area obtained by the AP method was similar to that obtained by the manual tracing method, but the area by the longest diameter approach was bigger by 34.4% (95% CI, - 2.4% to 71.1%). The 95% confidence intervals of the difference in paired measurements of lung areas by the same observer and by two different observers were narrower in the manual tracing method than in the multiplying diameters methods. CONCLUSIONS: In CDH the most reproducible measurement of fetal lung area is provided by manual tracing of the limits of the lungs, rather than by multiplication of lung diameters.     

Intrapartum fetal head position II: comparison between transvaginal digital examination and transabdominal ultrasound assessment during the second stage of labor.

OBJECTIVE: To test the null hypothesis that no correlation exists between transvaginal digital examination compared with the gold standard technique of transabdominal suprapubic ultrasound assessment of fetal head position during the second stage of labor. A secondary objective was to compare the performance of attending physicians vs. senior residents in depicting fetal head position by transvaginal digital examination in comparison with ultrasound assessment. METHODS: Consecutive patients in the second-stage of labor at term with normal singleton cephalic-presenting fetuses and ruptured membranes were included. Transvaginal digital examinations were performed by either attending physicians or senior residents and were followed immediately by transverse suprapubic transabdominal sonographic assessments performed by a single sonographer. Examiners were blinded to each other's findings. Power analysis dictated sample size. Exact binomial confidence intervals around observed rates were compared with chi 2 and Cohen's kappa-tests. Logistic regression was applied. P < 0.05 was considered significant throughout. RESULTS: One hundred and twelve patients were studied. The absolute error of transvaginal digital examinations was recorded in 65% of patients (95% confidence interval, 56-74%). Parity, pelvic station, combined spinal epidural anesthesia, length of first or second stages of labor, use of oxytocin augmentation, gestational age, mode of delivery, birth weight, and examiner experience did not significantly affect examination accuracy. Stratification, when the transvaginal digital examination was recorded as correct if occurring within +/- 45 degrees of the ultrasound assessment, reduced the error of the transvaginal digital examinations to 39% (95% confidence interval, 30-49%). Independent variables again did not affect examination accuracy in this assessment modality. Rates of agreement between the two methods for attending physicians compared with residents were not significantly different. The overall degrees of agreement were 40% (95% confidence interval, 26-55%) and 68% (95% confidence interval, 53-80%) (kappa = 0.25 and 0.30) for the absolute agreement and +/- 45 degrees assessment modalities, respectively, for attending physicians, and 31% (95% confidence interval, 20-44%) and 55% (95% confidence interval, 42-68%) (kappa = 0.14 and 0.12) for senior residents. CONCLUSION: Using ultrasound assessment as the gold standard, our data demonstrate a high rate of error (65%) in transvaginal digital determination of fetal head position during the second stage of labor. The performance of senior residents in transvaginal digital examinations did not differ significantly from that of attending physicians. Intrapartum ultrasound increases the accuracy of fetal head position assessment during the second stage of labor.     

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.     

Intra- and interobserver reproducibility of ultrasound measurements of cervical length and width in the second and third trimesters of pregnancy.

OBJECTIVES: To determine intra- and interobserver reproducibility of ultrasound measurements of cervical length and width in the second and third trimesters of pregnancy. DESIGN: Twenty healthy women in the second or third trimester of pregnancy underwent transvaginal ultrasound examination of the cervix by two examiners. Three replicate meaurements of cervical length and width were taken by each observer for each woman. Intraobserver repeatability was expressed as the difference between the highest and lowest measurement value obtained by one observer, and as the repeatability coefficient and intraclass correlation coefficient. Interobserver reproducibility was expressed as the difference between the mean of the three measurements of each observer, limits of agreement, and interclass correlation coefficient. The repeatability coefficient/limits of agreement define the range within which 95% of the differences between two measurements by the same observer/two observers are likely to fall. RESULTS: Intra- and interobserver differences did not vary in any systematic way over the range of values measured. For cervical length measurements the repeatability coefficient was +/- 5.4 mm for Observer 1 and +/- 5.9 mm for Observer 2. The intraclass correlation coefficient for cervical length measurements was 0.93 for both observers. The corresponding coefficients for cervical width measurements were +/- 3.9 mm and +/- 7.3 mm, and 0.97 and 0.91. The interclass correlation coefficient for cervical length measurements was 0.76, the mean interobserver difference was 0.4 mm, and the limits of agreement were -10.0 mm to 10.8 mm. For cervical width measurements the interclass correlation coefficient was 0.74, the mean interobserver difference was -0.02 mm, and the limits of agreement were -12.4 mm to 12.4 mm. There was no systematic difference between the first, second and third cervical length measurements and no systematic bias between the two observers, and the results were not affected by which of the two examiners started the examination (three-way analysis of variance). The same was true of cervical width measurements. CONCLUSIONS: Our results do not support the contention that the first measurement of cervical length is the longest. There is substantial intra- and interobserver variability in the results of measurements of cervical length and width, even when experienced observers perform the measurements under standardized conditions. It is important to consider the possibility of 'measurement error' when ultrasound measurements of cervical length and width are used in clinical practice to monitor women at high risk of delivering preterm or to screen for preterm birth.     

Contribution of three-dimensional volume contrast imaging to the sonographic assessment of the fetal uterus.

OBJECTIVE: To investigate the contribution of volume contrast imaging (VCI) in assessing the fetal uterus in normally developed female fetuses. METHODS: The pelvis of 38 normal female fetuses was examined at 20-22 and 32-34 weeks' gestation using both conventional two-dimensional (2D) ultrasound and VCI on the same transverse or oblique longitudinal view of the fetal pelvis. Two experienced sonographers evaluated the ability of both techniques to image the fetal uterus. Results were compared by kappa index to evaluate the interobserver variability. RESULTS: A clear picture of the fetal uterus was obtained in 50% and 82-87% of the cases at 20-22 weeks' gestation and in 80-85% and 95-100% of the cases at 32-34 weeks' gestation using conventional 2D ultrasound and VCI, respectively. There was moderate to good agreement of uterus visualization between the two observers, with kappa values ranging from 0.43 to 0.65. The lower level of agreement was obtained for conventional 2D ultrasound during the second trimester. CONCLUSIONS: Our results suggest that VCI may be successfully applied to prenatal ultrasonography of the fetal pelvis anatomy. By enhancing the contrast between the intrapelvic organs, VCI provides a clearer picture of the fetal uterus.     

Intrapartum fetal head position I: comparison between transvaginal digital examination and transabdominal ultrasound assessment during the active stage of labor.

OBJECTIVE: To test the null hypothesis that no correlation exists between transvaginal digital and the gold standard technique of transabdominal suprapubic ultrasound assessments of fetal head position during labor. A secondary objective was to compare the performance of attending physicians vs. senior residents in depicting fetal head position by transvaginal digital examination in comparison with ultrasound, respectively. METHODS: Consecutive patients in active labor at term with normal singleton cephalic-presenting fetuses were included. All participants had ruptured membranes, cervical dilation > or = 4 cm and fetal head at ischial spine station -2 or lower. Transvaginal sterile digital examinations were performed by either senior residents or attending physicians and followed immediately by transverse suprapubic transabdominal ultrasound assessments. Examiners were blinded to each other's findings. Power-analyses dictated number of subjects required. Statistical analyses included Chi-square, Cohen's Kappa test and logistic regression analysis. P < 0.05 was considered statistically significant. RESULTS: One hundred and two patients were studied (n = 102). In only 24% of patients (n = 24), transvaginal digital examinations were consistent with ultrasound assessments (P = 0.002, 95% confidence interval, 16-33). Logistic regression revealed that cervical effacement (P = 0.03) and ischial spine station (P = 0.01) significantly affected the accuracy of transvaginal digital examination. Parity, gestational age, combined spinal epidural anesthesia, cervical dilation, birth weight and examiner experience did not significantly affect accuracy of the examination. The accuracy of the transvaginal digital exams was increased to 47% (n = 48) (95% confidence interval, 37-57) when fetal head position at transvaginal digital examination was recorded as correct if reported within +/- 45 degrees of the ultrasound assessment. The rate of agreement between the two assessment methods for attending physicians vs. residents was 58% vs. 33%, respectively (P = 0.02) with the +/- 45 degrees analysis. CONCLUSIONS: Using ultrasound assessment as the gold standard, our data demonstrate an overall high rate of error (76%) in transvaginal digital determination of fetal head position during active labor, consistent with the null hypothesis. Attending physicians exhibited an almost two-fold higher success rate in depicting correct fetal head position by physical examination vs. residents in the +/- 45 degrees analysis. Intrapartum ultrasound increases the accuracy of fetal head position assessment during active labor and may serve as an educational tool for physicians in training.     

The use of inversion mode and 3D manual segmentation in volume measurement of fetal fluid-filled structures: comparison with Virtual Organ Computer-aided AnaLysis (VOCAL)

OBJECTIVE: Volume measurements by three-dimensional (3D) ultrasonography are considered more accurate than those performed by two-dimensional (2D) ultrasonography. The purpose of this study was to compare the agreement of three techniques, as well as the inter- and intraobserver agreements for volume measurements of fetal fluid-filled structures. METHODS: Fifty 3D volume datasets of fetal stomachs and bladders were explored. Volume measurements were performed independently by two observers using: (1) Virtual Organ Computer-aided AnaLysis (VOCAL); (2) inversion mode; and (3) 'manual segmentation'. Reliability was evaluated using intraclass correlation coefficient (ICC), and Bland-Altman plots were generated to examine bias and agreement. The time required to complete the measurements was compared using Student's t-test or the Wilcoxon Signed Rank Test, and P-values < 0.025 or < 0.05 were considered statistically significant. RESULTS: All volume datasets could be measured using the three techniques. A high degree of reliability was observed between: (1) VOCAL and inversion mode (ICC, 0.995; 95% CI, 0.992-0.997); (2) VOCAL and manual segmentation (ICC, 0.997; 95% CI, 0.995-0.998); and (3) inversion mode and manual segmentation (ICC, 0.995; 95% CI, 0.992-0.997). There was good agreement between VOCAL and inversion mode (mean, - 2.4%; 95% limits of agreement, - 20.1 to 15.3%), VOCAL and manual segmentation (mean, - 8.3%; 95% limits of agreement, - 28.8 to 12.2%) as well as between inversion mode and manual segmentation (mean, 5.9%, 95% limits of agreement: - 14.3 to 26%). Manual segmentation and inversion mode measurements were obtained significantly faster than those by VOCAL. CONCLUSIONS: Volume measurements of fetal fluid-filled structures of relatively regular shape with inversion mode and manual segmentation are feasible. Both techniques have good agreement with VOCAL and are significantly faster than VOCAL. Inversion mode is a reliable method for volume calculations of fluid-filled organs, whereas manual segmentation can be used when volume measurements by VOCAL or inversion mode are technically difficult to obtain, such as solid structures with poorly defined borders as the volume dataset is rotated, like the uterine cervix.     

Reliability and validity of tissue volume measurement by three-dimensional ultrasound: an experimental model.

OBJECTIVE: To determine the validity and the intra- and interobserver reliability of volume measurements of an endometrium-like model using a three-dimensional (3D) ultrasound rotational technique. METHODS: A 3D ultrasound dataset was obtained from a sample of bovine liver containing a portion of chicken chest muscle (CCM). The process was repeated seven times using pieces of CCM of different sizes, resulting in seven datasets. Each portion of CCM was then placed in a water-filled volume-scaled tube and the 'actual' volumes were calculated by water displacement. For each dataset, ten volumes were calculated by each of two observers using a (VOCAL) with a 15 degrees rotational step. Reliability was assessed by calculating intraclass correlation coefficients (ICC) and validity by examining the percentage difference from the actual volume using limits of agreement. RESULTS: The volume measurement of organic tissues using the 3D ultrasound rotational method was highly reliable (intraobserver ICC, 0.998 for Observer 1 and 0.997 for Observer 2; interobserver ICC, 0.997) and valid (the bias and 95% limits of agreement of the percentage difference from the actual volume was only 0.57 (-3.07 to 4.21) % for Observer 1 and - 0.17 (-4.34 to 4.0) % for Observer 2). CONCLUSIONS: The 3D sonographic measurement, using VOCAL with a 15 degrees rotational step, of small and irregular tissues is reliable and valid, suggesting that it is a useful technique for measurement of the endometrial volume and other volumes of similar size.     

Three-dimensional ultrasound fetal lung volume measurement: a systematic study comparing the multiplanar method with the rotational (VOCAL) technique.

OBJECTIVES: This study was designed to compare a conventional multiplanar technique for three-dimensional (3D) ultrasound measurement of fetal lung volume with a rotational method using VOCAL trade mark (Virtual Organ Computer-aided AnaLysis). METHODS: Thirty-two fetuses with a variety of conditions at risk for pulmonary hypoplasia were studied. 3D volume data sets of the fetal lungs were acquired using a commercially available ultrasound system. The right and left lung volumes were calculated separately using VOCAL and the multiplanar technique. The level of agreement between two independent observers in categorizing the 3D volume data set as measurable or non-measurable was determined. The interobserver and intermethod variabilities were also evaluated for both methods. RESULTS: The intermethod variability was excellent (correlation r = 0.93 and r = 0.96 for the left and right lung, respectively), and there was substantial agreement between the results of both approaches (limits of agreement - 4.4 to 8.9 and - 3.4 to 4.8 mL for the right and left lung, respectively). Fetal lung estimation with VOCAL had a significantly higher interobserver variability than the multiplanar technique. Interobserver agreement in categorizing lung volume data sets as measurable or non-measurable was lower when VOCAL was used. CONCLUSION: Fetal lung volume measurements can be undertaken interchangeably using the multiplanar technique or the rotational method with VOCAL. However, the latter was less reproducible (lower degree of agreement and significantly higher interobserver variability) than the former.     

Objective evaluation of sylvian fissure development by multiplanar 3-dimensional ultrasonography.

OBJECTIVE: Evaluation of fetal cerebral cortex sulcation is important for the pre-natal diagnosis of neuronal migration disorders. Although abnormal sylvian fissure morphologic features are frequently observed in these conditions, the diagnosis of an abnormal sylvian fissure relies on subjective interpretation of ultrasonographic images. This study was performed to develop an objective ultrasonographic parameter for sylvian fissure evaluation. METHODS: This cross-sectional study included 202 normal singleton pregnancies without fetal anomalies. Using multiplanar, 3-dimensional ultrasonography, the sylvian fissure midpoint was identified. The sylvian fissure-to-parietal bone distance (SPB) was measured from the midpoint to the inner surface of the parietal bone, perpendicular to the falx cerebri. Bland-Altman plots were used to determine intraobserver and interobserver agreement. Regression analysis was used to evaluate the correlation between SPB measurements and gestational age. RESULTS: Two hundred (99%) of 202 pregnancies had a visible sylvian fissure, identifiable as early as 12 weeks of gestation. The mean SPB values at 12 and 41 weeks were 2.1 and 14.3 mm, respectively. Intraobserver and interobserver mean differences between paired measurements were 0.01 mm (95% limits of agreement, -0.41 to 0.43 mm) and 0.05 mm (95% limits of agreement, -1.79 to 1.90 mm), respectively. A linear correlation was observed between the SPB and gestational age (multiple R=0.91; R2=0.82 [SPB = -2.85 + 0.42 x gestational age]). CONCLUSIONS: (1) The SPB can be reproducibly measured from 12 weeks of gestation to term; and (2) a strong positive correlation was observed between the SPB and gestational age.     

Reproducibility of ductus venosus Doppler flow measurements at 11-14 weeks of gestation.

OBJECTIVES: To assess the intra- and interobserver repeatabilities of fetal ductus venosus Doppler measurements at 11-14 weeks of gestation. DESIGN: Flow velocity waveforms were recorded transabdominally. Intraobserver repeatability was studied in 22 fetuses in whom four repeated measurements were performed by the same observer. Interobserver repeatability was assessed in 54 fetuses in each of whom two observers performed two repeated measurements. The pulsatility index for veins (PIV), peak velocity during ventricular systole (S wave), peak velocity during atrial contraction (A wave) and time-averaged maximum velocity (TAMV) were recorded. Reproducibility of the Doppler measurements was analyzed by calculating repeatability coefficient, coefficient of variation (CV), intraclass correlation coefficient (ICC), mean differences and their limits of agreement. Cohen's k-coefficient was used for categorical data. RESULTS: Intraobserver repeatability was good with a CV of 10%, 13%, 22% and 13% and an ICC of 0.85, 0.94, 0.94 and 0.95, respectively, for PIV, S wave, A wave and TAMV. Interobserver repeatability was also good, and no bias between the observers was detected. A CV of 8.8%, 14%, 27% and 15% and an ICC of 0.86, 0.84, 0.87 and 0.84, respectively, for PIV, S wave, A wave and TAMV were obtained. There was 100% agreement for the detection of normal/abnormal blood flow. CONCLUSIONS: Intra- and interobserver repeatability of all parameters was acceptable, allowing for the detection of moderate to large changes in Doppler measurements.     

Fractional moving blood volume estimation in the fetal lung using power Doppler ultrasound: a reproducibility study.

OBJECTIVE: To evaluate the reproducibility of fractional moving blood volume (FMBV) estimation in the fetal lung using power Doppler ultrasound (PDU). METHODS: The lung blood perfusion of 20 normally grown singleton fetuses at 32-35 weeks of gestation was evaluated by two experienced observers using PDU. Each observer recorded two consecutive sequences of images from the posterior part of the fetal lung and calculated FMBV offline. FMBV expresses the percentage of blood movement within a defined region of interest (ROI). Repeatability and agreement were evaluated by means of the intraclass (intraCC) and interclass (interCC) correlation coefficients. RESULTS: FMBV was successfully evaluated in 17/20 fetuses by both observers (kappa index 0.82; 95% CI 0.51-0.93). The intraCC for repeatability for Observer A was 0.92 (95% CI 0.78-0.96), and for Observer B 0.90 (95% CI 0.74-0.96). The mean difference between the first and the second measurement was 0.7% (SD 4.5%). The interCC for repeatability over time and between the operators was 0.70 (95% CI 0.56-0.76) and the mean difference between the observers was 0.6% (SD 4.65%). The interCC for agreement was 0.92 (95% CI 0.84-0.95) and the mean difference in FMBV results when both observers analyzed the same sequences offline was 0.6% (SD 3.85%). CONCLUSION: In the hands of experienced operators, using a well-defined ROI and standard settings, FMBV estimation is a reproducible method of quantifying power Doppler signals recorded from fetal lung blood perfusion.     

Investigation of occiput posterior delivery by intrapartum sonography.

OBJECTIVE: To investigate if occiput posterior delivery is the consequence of persistence of an initial occiput posterior position or malrotation from an initial occiput anterior or transverse position. METHODS: This was a cross-sectional study involving transabdominal sonography to determine fetal occipital position in 918 singleton pregnancies with cephalic presentation in active labor at 37-42 weeks of gestation. The relationship between occipital position in labor and at delivery was examined. RESULTS: The occiput was posterior in 33.0% (149/452), 33.9% (101/298) and 19.0% (32/168) of fetuses at the respective cervical dilatations of 3-5, 6-9 and 10 cm and this persisted at delivery in 21.5% (32/149), 31.7% (32/101) and 43.8% (14/32) of cases. In 70% (32/46), 91% (32/35) and 100% (14/14) of occiput posterior deliveries there was persistence from this position at 3-5, 6-9 and 10 cm of cervical dilation. CONCLUSIONS: The majority of occiput posterior positions during labor rotate to the anterior position even at 10 cm of cervical dilatation. However, the vast majority of occiput posterior positions at delivery are a consequence of persistence of this position during labor rather than malrotation from an initial occiput anterior or transverse position.     

Reproducibility of the measurement of submucous fibroid protrusion into the uterine cavity using three-dimensional saline contrast sonohysterography.

OBJECTIVE: To determine the intraobserver and interobserver reproducibility of measurement of the percentage of protrusion of submucous fibroids into the uterine cavity using three-dimensional saline contrast sonohysterography (3D-SCSH). METHODS: Women diagnosed with submucous uterine fibroids on B-mode two-dimensional (2D) ultrasound scan were invited to join the study and 3D-SCSH was carried out. 3D volume datasets were stored digitally and were examined later using the technique of planar reformatted sections. The reproducibilities of the measurement of fibroid diameter and protrusion ratio into the uterine cavity (ratio of the size of the segment of the fibroid protruding into the cavity to the total diameter of the fibroid) were examined by two independent observers who were unaware of the initial 2D scan findings. Interobserver reproducibility was assessed by calculating the difference between measurements taken by the two operators (limits of agreement) and interclass correlation coefficient. Intraobserver repeatability was assessed by calculating the difference between two measurements for each variable (limits of agreement) and further expressed as an intraclass correlation coefficient. RESULTS: Thirty-three 3D ultrasound volumes were examined. There was a good agreement between the observers in classifying the fibroids as greater or less than 50% confined to the myometrium (Cohen's kappa 0.81). There was no bias in measurements for both variables either between observers or with repeated measurements by each observer. For fibroid diameter and protrusion ratio the inter- and intraclass correlation coefficients were high (0.984-0.995), with narrow limits of agreement. CONCLUSION: 3D-SCSH is a reproducible method for the quantification of the percentage of a submucous fibroid protruding into the uterine cavity.     

The interobserver reliability and validity of volume calculation from three-dimensional ultrasound datasets in the in vitro setting.

OBJECTIVES: The primary aim of this validation study was to determine the interobserver reliability and validity of measurements of phantom objects of known volume using conventional and rotational techniques of volume calculation according to measurement technique. METHODS: Two observers each acquired a single three-dimensional ultrasound dataset of three water-filled objects of different size and shape. The same two observers measured all six datasets using both the conventional technique and the newer rotational technique (Virtual Organ Computer-aided AnaLysis, VOCAL( trade mark )) of volume calculation. Reliability was assessed by calculating intraclass correlation coefficients (ICC) and validity by examining the percentage difference from the 'true' volume, as determined by a water displacement technique, by the limits of agreement method. RESULTS: All of the techniques were highly reliable (ICC: 0.9962-0.9997) and valid to within 4% of the 'true' volumes. There were no significant differences in reliability according to measurement plane or between observers. Measurements made with the 6 degrees rotation step were significantly more reliable than those made by all other techniques with the exception of the 9 degrees rotation step (P < 0.05) and significantly more valid than those made with the 30 degrees rotation step or conventional technique (P < 0.05). CONCLUSIONS: Volume calculation in the in vitro setting is both reliable and valid but is dependent upon the technique applied, with rotational measurements of volume proving superior to conventional techniques.