Showing papers in "Ultrasound in Obstetrics & Gynecology in 2002"

Temporal sequence of abnormal Doppler changes in the peripheral and central circulatory systems of the severely growth-restricted fetus

Abstract: Objective To identify the temporal sequence of abnormal Doppler changes in the fetal circulation in a subset of early and severely growth-restricted fetuses Methods This was a prospective observational study in a tertiary care/teaching hospital Twenty-six women who were diagnosed with growth-restricted fetuses by local standards before 32 weeks' gestation and who had abnormal uterine and umbilical artery Doppler velocimetry were enrolled onto the study To compare Doppler changes as a function of time, pulsed-wave Doppler ultrasound was performed on five vessels in the fetal peripheral and central circulations Doppler examinations were performed twice-weekly and on the day of delivery if the fetal heart rate tracing became abnormal Doppler indices were scored as abnormal when their values were outside the local reference limits on two or more consecutive measurements Biometry for assessment of fetal growth was performed every 2 weeks Computerized fetal heart rates were obtained daily Delivery was based on a non-reactive fetal heart rate tracing and not on Doppler information Patients with a severely growth-restricted fetus who were delivered for maternal indications such as pre-eclampsia were excluded Perinatal outcome endpoints included: intrauterine death, gestational age at delivery, newborn weight, central nervous system damage of grade 2 or greater, intraventricular hemorrhage and neonatal mortality Results Mean gestational age and newborn weight at delivery were 29 (standard deviation (SD), 2) weeks and 818 (SD, 150) g, respectively The sequence of Doppler velocimetric changes was described by onset time cumulative curves that showed two time-related events First, for each vessel there was a progressive increase in the percent of fetuses developing a Doppler abnormality Second, severely growth-restricted fetuses followed a progressive sequence of acquiring Doppler abnormalities which were categorized into ‘early’ and ‘late’ Doppler changes Early changes occurred in peripheral vessels (umbilical and middle cerebral arteries; 50% of patients affected 15–16 days prior to delivery) Late changes included umbilical artery reverse flow, and abnormal changes in the ductus venosus, aortic and pulmonary outflow tracts (50% of patients affected 4–5 days prior to delivery) The time interval between the occurrence of early and late changes was significantly different (P < 00001) and late changes were significantly associated with perinatal death (P < 001) Conclusions Doppler velocimetry abnormalities develop in different vessels of the severely growth-restricted fetus in a sequential fashion Late changes in vascular adaptation by the severely growth-restricted fetus are the best predictor of perinatal death Copyright © 2002 ISUOG

One-stop clinic for assessment of risk for trisomy 21 at 11-14 weeks: a prospective study of 15 030 pregnancies

Abstract: Objective To evaluate the performance of a one-stop clinic for assessment of risk (OSCAR) for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) thickness and maternal serum free β-human chorionic gonadotropin (hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11–14 weeks of gestation. Method Screening for trisomy 21 was carried out by OSCAR in 15 030 singleton pregnancies with live fetuses at 11–14 weeks. The estimated risk for trisomy 21 was calculated, and the women were counseled regarding this risk and the option of invasive testing or expectant management. Follow-up of the outcome of all pregnancies was carried out. The detection and false-positive rates for different risk cut-offs were calculated. Results Fetal NT and maternal serum free β-hCG and PAPP-A were successfully measured in all cases. Pregnancy outcome, including karyotype results or the birth of a phenotypically normal baby, was obtained from 14 383 cases. The median maternal age of these cases was 34 (range 15–49) years and in 6768 (47.1%) the age was 35 years or greater. The median gestation at screening was 12 (range 11–14) weeks and the median fetal crown–rump length was 64 (range 45–84) mm. The estimated risk for trisomy 21 based on maternal age, fetal NT and maternal serum free β-hCG and PAPP-A was 1 in 300 or greater in 6.8% (967 of 14 240) normal pregnancies, in 91.5% (75 of 82) of those with trisomy 21 and in 88.5% (54 of 61) of those with other chromosomal defects. For a fixed false-positive rate of 5% the respective detection rates of screening for trisomy 21 by maternal age alone, maternal age and serum free β-hCG and PAPP-A, maternal age and fetal NT, and by maternal age, fetal NT and maternal serum biochemistry were 30.5%, 59.8%, 79.3% and 90.2%, respectively. Conclusion Screening for trisomy 21 by a combination of maternal age, fetal NT and maternal serum biochemistry at 11–14 weeks can be provided in an OSCAR setting and is associated with a detection rate of about 90% for a false-positive rate of 5%.

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

Abstract: 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 ≥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° 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° 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° 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. Copyright © 2002 ISUOG

Uterine and fetal cerebral Doppler predict the outcome of third‐trimester small‐for‐gestational age fetuses with normal umbilical artery Doppler

Abstract: Objective To assess the value of different admission tests in predicting the outcome of small-for-gestational age (SGA) fetuses with normal Doppler waveforms in the umbilical artery. Methods Criteria for admission into this retrospective study included: singleton pregnancy with a birth weight < 10th centile; absence of severe maternal complications; no evidence of fetal anomalies on the sonogram; normal umbilical artery Doppler; and availability of complete follow-up. At the first antenatal sonogram classifying the fetus as SGA, Doppler analysis of the uterine and middle cerebral arteries was performed and amniotic fluid volume was assessed. Outcome variables included adverse perinatal outcome (perinatal death, severe morbidity) and emergency Cesarean section for fetal distress. Results Two hundred and thirty-one pregnancies were included in the study. The mean ± standard deriation birth weight and gestational age at delivery were 2222 ± 502 g and 37.3 ± 2.9 weeks, respectively. In 37 cases (16%), an emergency Cesarean section was performed. There was one intrauterine death and three fetuses delivered by emergency Cesarean section developed severe morbidity. Logistic regression demonstrated that abnormal velocimetry of the uterine arteries and fetal middle cerebral artery were independently correlated with the occurrence of Cesarean section. Conclusions SGA fetuses with normal umbilical artery Doppler waveforms and abnormal uterine arteries and fetal middle cerebral artery waveforms have an increased risk of developing distress and being delivered by emergency Cesarean section. Particularly when both uterine and fetal cerebral waveforms are altered at the same time, the risk is exceedingly high (86%) and delivery as soon as fetal maturity is achieved seems advisable. On the other hand, when both vessels have normal waveforms, the chances of fetal distress are small (4%) and expectant management is the most reasonable choice.

A systematic review of the accuracy of ultrasound in the diagnosis of endometriosis.

Abstract: Objective To evaluate transvaginal and transabdominal ultrasound scanning, with or without Doppler, as a diagnostic test for the accurate diagnosis of pelvic endometriosis Methods The MEDLINE (1966–2001) and EMBASE (1980–2001) databases were searched for relevant studies, published in English Only studies fulfilling predefined criteria were selected An assessment of quality was made for each study, and data were then reanalyzed using likelihood ratios to determine the usefulness of the test Results In total, 67 papers were identified using the search strategy, of which 17 described relevant studies Of these, seven fulfilled the inclusion criteria All seven related to the use of transvaginal gray-scale imaging in the diagnosis of ovarian endometriomata specifically, rather than endometriosis The positive likelihood ratios ranged from 76 to 298, and the negative likelihood ratios ranged from 01 to 04 Confidence intervals were wide One paper addressed the use of conventional color Doppler with ultrasound: the positive likelihood ratio was 12, with a negative likelihood ratio of 04 One paper assessed the use of color Doppler energy imaging, and showed a positive likelihood ratio of 335 and a negative likelihood ratio of 01 Conclusions Transvaginal ultrasound appears to be a useful test both to make and to exclude the diagnosis of an ovarian endometrioma Copyright © 2002 International Society of Ultrasound in Obstetrics and Gynecology

The three vessels and trachea view (3VT) in fetal cardiac scanning

Abstract: Objective Comprehensive evaluation of the fetal heart has become a major part of targeted organ scanning to rule out fetal malformations. Evaluation of the mediastinal major vessels seems to be the most difficult and time-consuming part of fetal heart examination. Our aim was to define and evaluate the three vessels and trachea (3VT) view, a novel and simple method to examine the great vessels in the mediastinum, and its applicability in the clinical practice of fetal echocardiography, while establishing nomograms for cardiac vessel measurements obtained in this view. Methods The three vessels and trachea view was examined in 379 low-risk gravidae between 14+0 and 23+6 weeks' gestation. Six parameters in this plane were measured to establish nomograms. In another group of 984 mixed high- and low-risk patients we compared the time required to identify the aortic arch using the 3VT view as compared to the long-axis view. Results The 3VT view was readily and satisfactorily demonstrated in all but two of the 1363 cases examined. In 17 cases (out of a total of 982) more than 10 min were required to identify the aortic arch using the 3VT view and in 71 patients when employing the long-axis view (P < 0.001). Conclusion The clinical applicability of the 3VT view to evaluate the anatomy of the major vessels in the mediastinum is demonstrated. Although a wide variation in the six parameters of the 3VT view used here precludes their use in diagnosing great vessel anomalies, some of the ratios between them have promising potential in the evaluation of great vessel malformations. Further, the 3VT view seems to be more efficient in identifying the aortic arch than does the long-axis view. Copyright © 2002 International Society of Ultrasound in Obstetrics and Gynecology

Congenital diaphragmatic hernia: evaluation of prenatal diagnosis in 20 European regions

Abstract: Objective To evaluate prenatal diagnosis of congenital diaphragmatic hernia by ultrasound in well-defined European populations Design Data from 20 registries of congenital malformations in 12 European countries were included The prenatal ultrasound screening programs in the countries ranged from no routine screening to three ultrasound investigations per patient being routinely performed Results There were 187 cases with congenital diaphragmatic hernia, with an overall prenatal detection rate of 59% (110/187) There was considerable variation in prenatal detection rate between regions There was a significant difference in the detection rate of isolated congenital diaphragmatic hernia (59/116, 51%) compared with congenital diaphragmatic hernia associated with multiple malformations, karyotype anomalies or syndromes (51/71, 72%) (P = 001) Termination of pregnancy was performed in 39 cases (21%) of which 14 cases were isolated congenital diaphragmatic hernia Mean gestational age at discovery was 242 weeks (range, 11–38 weeks) Conclusions The overall prenatal detection rate of congenital diaphragmatic hernia is high (59%) but varies significantly between European regions The gestational age at discovery was greater than 24 weeks in half of the prenatally diagnosed cases Copyright © 2002 ISUOG

The fetal mandible: a 2D and 3D sonographic approach to the diagnosis of retrognathia and micrognathia.

Abstract: Objective To define parameters that enable the objective diagnosis of anomalies of the position and/or size of the fetal mandible in utero. Design Fetuses at 18–28 gestational weeks were examined by two- and three-dimensional ultrasound. The study included normal fetuses and fetuses with syndromes associated with known mandible pathology: Pierre Robin sequence or complex (n = 8); hemifacial microsomia (Treacher–Collins syndrome, n = 3); postaxial acrofacial dysostosis (n = 1). Fetuses with Down syndrome (n = 8) and cleft lip and palate without Pierre Robin sequence or complex (n = 18) were also studied. Retrognathia was assessed through the measurement of the inferior facial angle, defined on a mid-sagittal view, by the crossing of: 1) the line orthogonal to the vertical part of the forehead at the level of the synostosis of the nasal bones (reference line); 2) the line joining the tip of the mentum and the anterior border of the more protruding lip (profile line). Micrognathia was assessed through the calculation of the mandible width/maxilla width ratio on axial views obtained at the alveolar level. Mandible and maxilla widths were measured 10 mm posteriorly to the anterior osteous border. Results In normal fetuses, the inferior facial angle was constant over the time span studied. The mean (standard deviation) value of the inferior facial angle was 65.5 (8.13)°. Consequently, an inferior facial angle value below 49.2° (mean—2 standard deviations) defined retrognathism. All the fetuses with syndromes associated with mandible pathology had inferior facial angle values below the cut-off value. Using 49.2° or the rounded-up value of 50° as a cut-off point, the inferior facial angle had a sensitivity of 1.0, a specificity of 0.989, a positive predictive value of 0.750 and a negative predictive value of 1.0 to predict retrognathia. In normal fetuses, the mandible width/maxilla width ratio was constant over the time interval studied. The mean (standard deviation) value was 1.017 (0.116). Consequently, a mandible width/maxilla width ratio <0.785 defined micrognathism. Mandible width/maxilla width ratio values were below this cut-off point in eight and in the normal range in four fetuses with syndromes associated with mandible pathology. Conclusions Retrognathia and micrognathia are conditions that can be separately assessed. The use of inferior facial angle and mandible width/maxilla width ratio should help sonographic recognition and characterization of fetal retrognathic and micrognathic mandibles in utero. Copyright © 2002 ISUOG

Fetal cardiac abnormalities identified prior to 14 weeks' gestation

Abstract: Objective An increasing number of patients are presenting at early gestational age as being at high risk for congenital heart disease, as a result of ultrasound screening by nuchal translucency. The feasibility and accuracy of fetal echocardiography was assessed in a series of pregnancies studied before 14 weeks’ gestation. Methods Echocardiography was attempted in 478 fetuses of crown–rump length 40.0–85.0 mm (median, 60.3 mm) with increased nuchal translucency, suspected abnormalities on routine scan or a family history of heart defect. The findings were related to results of autopsy, karyotyping, later scans and postnatal follow-up. Results Satisfactory images were obtained transabdominally in 402/478 (84.1%) and transvaginally in a further 13 patients. Cardiac defects were confidently identified in 60 fetuses and abnormalities of uncertain significance (isolated ventricular or great artery disproportion, or tricuspid regurgitation) were observed in a further 49. Defects were suspected in an additional 20 fetuses, and 286 were passed as normal. The karyotype was subsequently demonstrated to be abnormal in 70/286 (24.5%) fetuses with normal echocardiograms, and in 94/129 (72.9%) with abnormal or suspicious cardiac findings. Validation of the scan findings was possible in 241 fetuses. Normal heart structure was confirmed in 204 fetuses, and previously unsuspected cardiac abnormalities revealed in nine. Heart defects were verified in 28 fetuses, but five of these had important additional findings. There were false positive findings in three fetuses. Conclusions Fetal echocardiography is feasible prior to 14 weeks’ gestation. Cardiac defects, when present, may be identified or suspected in the majority of cases. In the risk group studied, heart defects were frequently a manifestation of chromosomal abnormality.

First-trimester trisomy screening: nuchal translucency measurement training and quality assurance to correct and unify technique.

Abstract: Objective To describe the process of training for measuring nuchal translucency at five clinical centers in North America and to evaluate methods of quality assurance and feedback. Design Throughout a period of 18 months, the performance of sonographers in measuring fetal nuchal translucency was monitored using qualitative and quantitative methods of review. After 12 months, different approaches (written and personal feedback) were used to inform sonographers of technical aspects that needed to or could be improved. Results On initial qualitative review, discrepancies in judgment from different reviewers coincided with suboptimal magnification, failure to visualize the amniotic membrane and/or use of cross-shaped calipers. At subsequent global review, 13 (29%) images of nuchal translucency measurements were considered unacceptable. Quantitative assessment revealed that, during the first part of the study, the means from four sonographers were significantly smaller and the mean from the fifth sonographer was significantly larger than expected on the basis of findings from The Fetal Medicine Foundation (P < 0.0001). Following feedback, sonographers who underestimated nuchal translucency and who received a written report only did not change measurements overall ( P = 0.9759). In contrast, those who received additional intervention showed a marked difference ( P < 0.0001). Conclusions Global qualitative review of images from one sonographer may be preferable to assessment of individual aspects of images. Results from global qualitative review correspond well with findings from quantitative analysis, indicating that the latter can be applied for ongoing audit. Observation of divergent results should prompt extensive personal feedback, rather than a written report, to prevent sonographers from settling in their own, inappropriate technique.

Anomalies of the fetal aortic arch: a novel sonographic approach to in-utero diagnosis.

Abstract: Objective To describe a novel, sonographic approach for in-utero evaluation of normal and abnormal aortic arch. Methods Aortic arch was evaluated by imaging of the axial view of the upper fetal mediastinum. The normal left aortic arch was defined by the V-shaped appearance of the junction between the ductus arteriosus and aortic arch, with the trachea situated posteriorly. Right and double aortic arches were diagnosed when the great vessels appeared U-shaped, with intermediate location of the trachea. Results Between 1997 and 1999, 18 347 women were scanned in three prenatal centers, and pathological findings were prospectively recorded. In a retrospective analysis of the records, we identified 19 fetuses (0.1%) with atypical, U-shaped appearance, and no other structural abnormalities present. With the exception of one fetus with a ventricular septal defect, no congenital cardiac defects were present. Right aortic arch was found in 18 cases, while color Doppler made it possible to diagnose one case with double aortic arch, and one fetus was demonstrated as having Kommerell's diverticulum. In all 18 cases, a left descending aorta and left ductus arteriosus were present, the latter coursing to the left of the trachea, forming a loose partial vascular ring. All were asymptomatic at birth and early infancy. The fetus with double aortic arch that had a true vascular ring underwent early infantile correction. Conclusions It is possible to diagnose right and double fetal aortic arch using prenatal ultrasound. The use of color Doppler facilitated in-utero evaluation of possible complications, such as true vascular ring. Copyright © 2002 International Society of Ultrasound in Obstetrics and Gynecology

Quantitative transvaginal two‐ and three‐dimensional sonography of the ovaries: reproducibility of antral follicle counts

Abstract: Objective To assess the intra- and interobserver reproducibilities in addition to the between-method reliability of antral follicle counts using two (2D)- and three (3D)-dimensional transvaginal sonography (TVS). Methods Two groups of women with regular menstrual cycles were studied. One group consisted of healthy volunteers with proven fertility and the other group consisted of patients visiting the general infertility clinic. In each woman, 2D or 3D TVS was performed in the early follicular phase (day 2, 3 or 4) of the menstrual cycle to measure the number of antral follicles (2–10 mm). Results Intraobserver reproducibility was calculated from follicle counts using 3D TVS in 41 women. The intraclass correlation coefficient was 0.99 and the 95% coverage interval of the difference (CID) was −3.2 to +3.2. Interobserver reproducibility was assessed from both 2D (n = 37) and 3D (n = 49) TVS-based follicle counts. An interclass correlation coefficient of 0.98 was found for both methods. The 95% CID was −5.0 to +4.1 for 2D and −5.6 to +5.7 for 3D measurements. The latter CID appeared to increase in the higher range of counts. Finally, the degree of agreement between 2D and 3D TVS counts (n = 76) was characterized by a 95% CID of −5.3 to +8.3. This coverage interval widened when higher numbers of follicles were counted. With the exception of the between-method analysis, kappa values indicated overall that follicle counts will hardly change from one category to another when repeatedly carried out.

Fetal ovarian cysts: prenatal diagnosis, management and postnatal outcome

Abstract: Objective In female fetuses ovarian cysts represent the most important differential diagnosis for intra-abdominal masses. Analyzing our own patient population we investigated whether there was a connection between sonographic parameters and postnatal course, especially with regard to the need for surgical intervention. Patients and methods This was a retrospective analysis of cases from the years 1986–1999. The pre- and postnatal data of 64 fetuses who were suspected prenatally to have an ovarian cyst were analyzed. The postnatal outcome was known for all the children. Results The diagnosis was made in all cases in the third trimester (median, 35; range, 26–40 weeks' gestation). In 34 of the 64 (53%) cases, resolution of the cyst occurred either prenatally (n = 18, 53%) or postnatally (n = 16, 47%). The cystic structure in the cases with resolution was isolated, smooth-walled (n = 29) or heterogeneous (n = 5). Postnatal surgery was performed in 30 of the 64 (47%) children. In 18 of the 30 children a fenestration of the ovary was performed (60%). In this group there were 13 children with an isolated, smooth-walled ovarian cyst and five children with a heterogeneous cyst. Twelve of the 30 (40%) children underwent an ovariectomy. Among these 12 children there were eight cases with a heterogeneous cystic structure and four cases with an isolated, smooth-walled cystic structure. Of the 30 cases that underwent surgery, 29 had a follicular cyst and one had an ovarian teratoma (with a heterogeneous internal structure). In three fetuses aspiration of cyst fluid was undertaken and subsequent resolution occurred in one case. The other two cases had to undergo postnatal fenestration. Conclusions When an ovarian cyst is suspected prenatally, serial ultrasound monitoring should follow and delivery should take place in a perinatal center. The prenatal findings should also be checked postnatally by ultrasound. Prenatal aspiration of the cyst seems to be of no advantage and should be carried out only in special individual cases. Copyright © 2002 International Society of Ultrasound in Obstetrics and Gynecology

Impaired uteroplacental blood flow in pregnancies complicated by falciparum malaria.

Abstract: Objective In endemic areas, maternal malaria infection is usually asymptomatic. However, it is known that infected maternal erythrocytes sequester in the intervillous space of the placenta. There is a strong association between placental malaria infection and both low birth weight (LBW) and severe maternal anemia. We aimed to determine whether impaired uteroplacental blood flow might account for the low infant birth weight associated with maternal falciparum malaria infection. Methods This observational study was carried out during a large double-blind, randomized, controlled trial of an antimalarial drug intervention for primigravidae. Nine hundred and ninety-five women were recruited from the antenatal clinic at a district hospital on the Kenya coast and had at least one Doppler ultrasound scan. Uterine artery resistance index and the presence or absence of a diastolic notch were recorded. In the third trimester, blood was taken for hemoglobin and malaria film. Results Malaria infection at 32–35 weeks of gestation was associated with abnormal uterine artery flow velocity waveforms on the day of blood testing (relative risk (RR) 2.11, 95% confidence interval (CI) 1.24–3.59, P = 0.006). This association persisted after controlling for pre-eclampsia. Impaired uteroplacental blood flow in the women studied was also predictive of poor perinatal outcome, including low birth weight, preterm delivery and perinatal death. The risk of preterm delivery in women with histological evidence of past placental malaria infection was more than twice that of women without infection (RR 2.33, 95% CI 1.31–4.13, P = 0.004). Conclusions Uteroplacental hemodynamics are altered in the presence of maternal falciparum malaria infection. This may account for some of the excess of LBW babies observed in malaria endemic areas. Strategies that prevent or clear placental malaria may confer perinatal benefit through preservation of placental function. Copyright © 2002 ISUOG

The development of the fetal vermis: an in‐utero sonographic evaluation

Abstract: Objective To establish a nomogram for fetal penile length during gestation. Design A prospective, cross-sectional study of normal singleton pregnancies. Subjects Four hundred and nineteen male fetuses between 14 and 38 weeks were studied. Methods Measurements of fetal penis length were performed by high resolution transvaginal ultrasonography between 14 and 17 weeks of gestation, and by transabdominal ultrasonography beyond 18 weeks of gestation. Results Adequate penile length measurements were obtained in all 419 fetuses. Penile length as a function of gestational age was expressed by the regression equation: (square root) penile length (mm) = 0.277 + 0.121 × gestational age (weeks). The correlation coefficient, r = 0.967 was found to be highly statistically significant (P < 0.0001). The normal mean and the 90% prediction limits were defined. During the study period, we identified three fetuses with abnormalities involving penile development. Using the above reference data range, it has been shown that their penile length was below the lower limit. Conclusions The present data provide a normal range of fetal penile length from early stages of gestation that may allow intrauterine assessment of the development of the male external genitalia. Copyright © 2001 International Society of Ultrasound in Obstetrics and Gynecology

Sonographic features of phyllodes tumors of the breast

Abstract: Objective The aim of this study was to examine the sonographic features of phyllodes tumors of the breast. Methods Retrospective analysis of prospectively recorded sonographic features was performed on 2268 patients with phyllodes tumors or fibroadenomas during 1995–98. Data from 110 phyllodes tumors (76 benign, 11 borderline, 23 malignant) and 2204 fibroadenomas were analyzed. Results The patients with phyllodes tumors were older than the patients with fibroadenoma (mean ± standard error, 39.7 ± 1.1 years vs. 33.4 ± 0.3 years; P < 0.0001). Sixty-four percent of patients with phyllodes tumors were aged 31–50 years, while 68.5% of those with fibroadenoma were aged 21–40 years. Phyllodes tumors were larger than fibroadenomas (5.90 ± 0.43 cm vs. 1.95 ± 0.03 cm; P < 0.0001). The ratio of length to anteroposterior diameter of phyllodes tumors was smaller than the ratio of length to anteroposterior diameter of fibroadenomas (1.72 ± 0.06 vs. 1.89 ± 0.02; P = 0.0105). Seventy-seven percent of phyllodes tumors were lobulated and 79.5% of fibroadenomas were oval. Lobulated shape of the tumor, heterogeneous echo pattern and absence of microcalcification are significant independent sonographic features in multiple logistic regression analysis to distinguish between phyllodes tumors and fibroadenoma. Benign, borderline and malignant phyllodes tumors displayed no significant differences in tumor size or the ratio of length to anteroposterior diameter. Conclusions There is a substantial overlap in the sonographic characteristics between phyllodes tumors and fibroadenoma of the breast. If lobulation and heterogeneous hypoechoic internal echoes are observed and calcifications are absent, a diagnosis of phyllodes tumors should be considered. Sonography cannot distinguish between malignant, borderline and benign phyllodes tumors. Copyright © 2002 International Society of Ultrasound in Obstetrics and Gynecology

Umbilical venous volume flow in the normally developing and growth‐restricted human fetus

Abstract: Objective To determine the reproducibility of measurement of umbilical venous volume flow components and to calculate umbilical venous volume flow in normal and growth-restricted (small-for-gestational age) fetuses in a cross-sectional study. Method Using Labview and Imaq-vision software, the cross-sectional inner area of the umbilical vein was traced. Vessel area (mm2) and Doppler-derived time-averaged flow velocity (mm/s) were multiplied to calculate volume flow (mL/min) including flow per kg fetal weight. The coefficient of variation for vessel area and flow velocity scans and tracings were determined (n = 13; 26–35 weeks). Normal charts for components and volume flow were constructed (n = 100; 20–36 weeks) and related to data from growth restricted fetuses (birth weight <5th centile) (n = 33; 22–36 weeks). In growth-restricted fetuses the umbilical artery pulsatility index was also obtained. Results Reproducibility: The coefficient of variation was 5.4% (vessel area) and 7.3% (time-averaged velocity) for scans and 6.6% and 10.5% for measurements, resulting in a coefficient of variation of 8.1% (scans) and 11.9% (measurements) for volume flow. A gestational age-related increase exists for vessel area, time-averaged flow velocity and umbilical venous volume flow from 33.2 (SD, 15.2) mL/min at 20 weeks to 221.0 (SD, 32.8) mL/min at 36 weeks of gestation, but there is a reduction from 117.5 (SD, 33.6) mL/min to 78.3 (SD, 12.4) mL/min for volume flow per kg fetal weight. In small-for-gestational age fetuses, the values were below the normal range in 31 of 33 cases for volume flow and in 21 of 33 cases for volume flow per kg fetal weight. Umbilical artery pulsatility index was significantly different between the subsets with normal and those with reduced volume flow per kg fetal weight. Conclusions Measurements of umbilical venous vessel area and time-averaged velocity resulted in acceptable reproducibility of volume flow calculations, which show a seven-fold increase at 20–36 weeks of gestation. In growth-restricted fetuses, volume flow is significantly reduced. When calculated per kg/fetus, the values were reduced in 21 (63.6%) out of 33 cases. Copyright © 2002 ISUOG

How successful is fetal echocardiographic examination in the first trimester of pregnancy

Abstract: Objective Transvaginal echocardiography is still rarely incorporated into the first-trimester ultrasound examination, despite the fact that heart defects are the most frequently encountered congenital malformation. This study was undertaken to explore the possibilities of fetal echocardiography in the late first trimester. Methods In 85 women with uncomplicated singleton pregnancies, three transvaginal ultrasound examinations between 11+0 and 13+6 weeks' gestation were performed. The examinations were carried out at weekly intervals and visualization of several echocardiographic planes was attempted (four-chamber view, aortic root, long axis of the aorta, pulmonary trunk with three-vessel view, cross-over of the great arteries). The diameter of the aorta and pulmonary trunk were measured to establish reference ranges. Results The success rate of visualization of the different parameters increased with gestational age. The ability to perform a full cardiac examination increased from 20% in week 11 to 92% in week 13. Longitudinally derived growth curves of the aorta and the pulmonary trunk were constructed and both showed a linear increase with gestational age. Conclusions The best time in the first trimester to perform transvaginal echocardiography is at 13+0 to 13+6 weeks' gestation. In this period, a full cardiac examination is possible in 92% of cases. The increase of success rate compared to earlier studies is likely to result from the use of better resolution, high-frequency transvaginal probes. First-trimester echocardiography provides an opportunity to examine the fetal heart early in gestation, especially in patients at risk for cardiac malformations because of a positive family history or in fetuses with increased nuchal translucency. Copyright © 2002 International Society of Ultrasound in Obstetrics and Gynecology

The reproducibility of endometrial volume acquisition and measurement with the VOCAL-imaging program.

Abstract: Objectives To determine the intraobserver reproducibility of volume acquisition and repeatability of endometrial volume measurements using the VOCAL™-imaging program (Virtual Organ Computer-aided AnaLysis). Methods Ten three-dimensional (3D) ultrasound datasets of the same endometrium were obtained from one patient during one scan session. For every 3D dataset, the endometrial volume was calculated by four different measurement techniques; three rotational methods and one conventional method. A single observer acquired each dataset and conducted all measurements. For the rotational technique, the manual mode was used to trace the myometrial‐endometrial border through three different predefined rotations of 30 ϒ , 15 ϒ and 9 ϒ . Endometrial volume was also measured in a conventional manner by scrolling through one of the multiplanar images and outlining the contour in another. Ten consecutive measurements were taken for each of the four measurement techniques so that 40 endometrial volume readings were obtained for each of the 10 3D-ultrasound datasets. Results Endometrial volume measurements were more reproducible with the rotational technique. Rotational methods employing a rotation step of less than 30 ϒ were associated with coefficients of variation below 1% and intraclass correlation coefficients above 0.94. Within each of the 10 different scans, the homogeneity of the variance of measurements was significantly different according to the method of measurement ( P = 0.022 to < 0.001). Post-hoc tests revealed that both the conventional and 30 ϒ rotational methods resulted in a significantly smaller mean endometrial volume than both the 15 ϒ and the 9 ϒ rotational methods. Conclusions Endometrial volume acquisition is reproducible and endometrial volume measurements are repeatable but they depend upon the technique of volume calculation in so much as rotational methods employing a rotation step of less than 30 ϒ are associated with a significantly smaller variance in measurements and a significantly greater mean endometrial volume.

Brains and faces in holoprosencephaly: pre- and postnatal description of 30 cases.

Abstract: Objective To investigate the prenatal appearance of the holoprosencephaly spectrum. Methods A database of 1750 fetuses with congenital anomalies identified by ultrasound was prospectively collected from 1987 to 2000. Among them, 30 cases (1.7%) with holoprosencephaly were prenatally identified and described. Results The prevalence of holoprosencephaly in the Health Region of the National Center for Fetal Medicine in Norway was 1.26: 10 000; the sex distribution (male: female) was 1.4: 1. Holoprosencephaly was found in one dichorionic twin pregnancy and one pair of conjoined twins. Among the 30 cases of holoprosencephaly, 18 were alobar, five were semilobar, two were lobar, two were lobar variants, and three were anencephalic. The facial features varied considerably. Sixty-seven per cent (20/30) had associated structural anomalies that were not related to the cerebral and facial holoprosencephaly condition. Thirty-seven per cent (11/30) had detectable chromosome aberrations and 23% (7/30) had nonchromosomal syndromal origin. The size or shape of the head was abnormal in 83% (25/30) of holoprosencephaly cases. Conclusion This study indicates that holoprosencephaly represents a heterogeneous entity with different etiologies and clinical appearances. The fact that holoprosencephaly features are found associated with particular conditions such as fronto-nasal dysplasia (2/30; 6.7%), agnathia-otocephaly (3/30; 10%), and anencephaly (3/30; 10%), suggests that these may be underreported conditions in other large holoprosencephaly series. Copyright © 2002 ISUOG

Absent or hypoplastic thymus on ultrasound: a marker for deletion 22q11.2 in fetal cardiac defects

Abstract: Objective Congenital heart defects (CHD), particularly conotruncal anomalies, may be associated with deletion of chromosome 22q11.2. Thymic aplasia or hypoplasia is known to be a typical feature in this condition. We aimed to establish (i) the prevalence of del22q11.2 in fetal CHD and (ii) whether ultrasound assessment of an absent or hypoplastic fetal thymus helps in preselection of a group who are at high risk for this deletion. Study design In fetuses (> 16 weeks) with CHD, karyotyping and fluorescence in situ hybridization for 22q11.2 were offered and the fetal thymus was evaluated sonographically. Results One hundred and forty-nine fetuses with CHD and normal karyotype were analyzed. Seventy-six fetuses had conotruncal anomalies. 22q11.2 deletion was present in 10 cases (6.7%), all of which had conotruncal anomalies (13.1%). Thymic hypoplasia or absence was suspected in 11 cases with conotruncal anomaly. Nine of these 11 had the deletion; two cases were false positive. One fetus with a normal-sized thymus had deletion of 22q11.2 (sensitivity 90%, specificity 98.5%, positive predictive value 81.8%, and negative predictive value 99.2%). By subtype of cardiac anomaly, there was deletion in four of six fetuses with interruption of the aortic arch, two of four with absent pulmonary valve syndrome, three of nine with truncus arteriosus and one of 11 cases of tetralogy of Fallot. Pulmonary atresia with ventricular septal defect (n = 7), right-sided aortic arch (n = 4), transposition of the great arteries (n = 14), double outlet right ventricle (n = 13) and other complex malpositions of the great vessels (n = 8) were not associated with the deletion. Conclusion Thymic hypoplasia or aplasia may reliably be diagnosed during fetal echocardiography. The technique allows identification of a group at high risk for 22q11.2 deletion and is more specific and sensitive than by subtype of cardiac anomaly alone. Copyright © 2002 International Society of Ultrasound in Obstetrics and Gynecology

Flecainide in the intrauterine treatment of fetal supraventricular tachycardia.

Abstract: Objectives To assess the efficacy of flecainide in the intrauterine treatment of fetal supraventricular tachycardia (SVT) with 1: 1 atrioventricular conduction. Design Twenty fetuses (21–35 weeks of gestation) with SVT ranging between 215 and 280 bpm were analyzed retrospectively. Fetuses received flecainide and digoxin as either first, second or third line therapy. Intracardiac blood flow, venous Doppler waveforms and cardiotocograms were evaluated before and after drug induced conversion to sinus rhythm. Results After initiation of combined flecainide and digoxin therapy, the median time interval until final conversion to sinus rhythm was 5 days (range, 0–14 days). The majority of fetuses (n = 15; 75%) converted to sinus rhythm within 7 days of treatment, whereas the remaining five (25%) showed initial reduction of the heart rate to 160–215 bpm over several days, with restoration of a triphasic venous blood flow pattern before late conversion within 7–14 days after initiation of flecainide treatment. One of these fetuses showed a decrease in fetal heart rate to 160–190 bpm without conversion to sinus rhythm but with resolution of hydrops. All fetuses survived. Conclusions Flecainide is safe and highly effective in the intrauterine treatment of hydropic fetuses with supraventricular tachycardia. Conversion into sinus rhythm can be expected 72 h after initiation of therapy but may take up to 14 days. Therefore therapy should be continued beyond 72 h, especially when an initial decrease of fetal heart rate is observed which may represent an early therapeutic response. Copyright © 2002 ISUOG

An algorithm including results of gray-scale and power Doppler ultrasound examination to predict endometrial malignancy in women with postmenopausal bleeding

Abstract: OBJECTIVE: To determine if power Doppler ultrasound examination of the endometrium can contribute to a correct diagnosis of endometrial malignancy in women with postmenopausal bleeding and endometrium >/= 5 mm. METHODS: Eighty-three women with postmenopausal bleeding and endometrium >/= 5 mm underwent gray-scale and power Doppler ultrasound examination using predetermined, standardized settings. Suspicion of endometrial malignancy at gray-scale ultrasound examination (endometrial morphology) was noted, and the color content of the endometrium at power Doppler examination was estimated subjectively (endometrial color score). Computer analysis of the most vascularized area of the endometrium was done off-line in a standardized manner. Stepwise multivariate logistic regression analysis was carried out to determine which subjective and objective ultrasound and power Doppler variables satisfied the criteria to be included in a model to calculate the probability of endometrial malignancy. RESULTS: Endometrial thickness, vascularity index (vascularized area/endometrial area), and use of hormone replacement therapy (HRT) satisfied the criteria to be included in the model used to calculate the 'objective probability of endometrial malignancy'. Endometrial morphology, endometrial color score and HRT use satisfied the criteria to be included in the model to calculate the 'subjective probability of malignancy'. Endometrial thickness >/= 10.5 mm had a sensitivity with regard to endometrial cancer of 0.88 and a specificity of 0.61. At a fixed sensitivity of 0.88, the specificity of the 'objective probability of malignancy' (0.81) was superior to all other ultrasound and power Doppler variables (P = 0.001-0.02). The 'objective probability of malignancy' detected more malignancies at endometrium 5-15 mm than endometrial morphology (5/7 vs. 1/7, i.e. 0.71 vs. 0.14; P = 0.125) with a similar specificity (49/57 vs. 51/57, i.e. 0.86 vs. 0.89). CONCLUSION: Power Doppler ultrasound can contribute to a correct diagnosis of endometrial malignancy, especially if the endometrium measures 5-15 mm. The use of regression models including power Doppler results to estimate the risk of endometrial cancer deserves further development. (Less)

Blood redistribution in the fetal brain during chronic hypoxia

Abstract: Background Studies on blood flow velocity in the fetal middle cerebral artery have revealed signs of brain sparing in chronic hypoxia. These signs of brain sparing can disappear in the terminal case, but whether this applies to the whole brain or only parts of it is unknown. Methods Velocity waveforms of the middle cerebral, anterior cerebral and posterior cerebral arteries were recorded in 221 pregnancies complicated by pregnancy-induced hypertension. The presence of brain sparing (pulsatility index < 2 standard deviations) was noted and correlated to outcome of pregnancy, including emergency operative intervention and/or neonatal distress. Results Signs of brain sparing in the anterior cerebral artery were found in 90 fetuses, and in the middle cerebral and posterior cerebral arteries in 52 and 65, respectively. Signs of brain sparing in the anterior cerebral artery showed the strongest relationship to adverse perinatal outcome. The anterior cerebral artery was the only vessel in which signs of brain sparing were predictive of perinatal mortality. Conclusions Velocimetry of the anterior cerebral artery appears to be superior to that of the middle cerebral and posterior cerebral arteries as a means to predict adverse perinatal outcome. Anterior cerebral artery brain sparing may therefore be less transitory than sparing in the middle cerebral and posterior cerebral arteries, possibly suggesting that the frontal lobes are spared longer than the lateral and occipital regions of the fetal brain.

Limitations of transvaginal sonography for the diagnosis of adenomyosis, with histopathological correlation

Abstract: Objectives To evaluate the accuracy of transabdominal sonography (TAS) and transvaginal sonography (TVS) for the diagnosis of adenomyosis, and to determine the diagnostic relevance of various sonographic criteria. Subjects and methods A total of 129 women scheduled for hysterectomy were enrolled into this prospective study. Group 1 (n = 23) consisted of patients with menometrorrhagia who were free of myoma and endometrial disorders on TAS. Group 2 consisted of all the other patients (n = 106). TAS and TVS findings were compared to histopathological results. Results The prevalence of adenomyosis in Groups 1 and 2 was 91.3% and 24.5%, respectively. TAS had limited value for the diagnosis of adenomyosis in both groups. The sensitivity, specificity, and positive and negative predictive values of TVS in Groups 1 and 2 were 80.9% and 38.4%, 100% and 97.5%, 100% and 83.3%, and 40% and 82.9%, respectively. The accuracy of combined TAS and TVS in Groups 1 and 2 was 91.3% and 83%, respectively. The presence of myometrial cysts was the most specific ultrasound diagnostic criterion for adenomyosis. Hypoechoic linear myometrial striations related to the presence of myometrial hypertrophy correlated to hormonal status with a sensitivity of 66.6% and a specificity of 100% in Group 1. Conclusions Our results show that TAS has a limited diagnostic capacity for adenomyosis but also that TVS alone was poor in patients with an enlarged uterus. In these cases a combination of TVS and TAS should be used. Copyright © 2002 International Society of Ultrasound in Obstetrics and Gynecology

Fetal learning: a prospective randomized controlled study.

Abstract: Objectives To examine whether prenatal exposure to a music stimulus alters fetal behavior and whether this continues into the newborn period. Subjects and methods A prospective randomized control trial was conducted using an exposure learning model in 20 normal term pregnancies. Music was played to ten fetuses via a headphone on the maternal abdomen. Ten controls had the headphone without sound. All fetal studies took place within 72 h prior to elective delivery. All 20 newborns were exposed to the same music on days 3–5. Computerized assessment of fetal heart rate and activity was documented and neonatal behavioral states were recorded. Nonparametric statistical analysis was used. Results For the first hour of study, exposed fetuses had higher mean heart rates (FHR) and spent more time exhibiting high FHR variation compared to unexposed fetuses, but neither of these differences was statistically significant. However, by the fourth hour the exposed fetuses not only demonstrated these two features but also exhibited more state transitions (P = 0.01) and higher FHR variation (P = 0.04) compared to unexposed fetuses. These effects were carried over into the neonatal period with prenatally exposed newborns manifesting more state transitions (P = 0.01) and spending a higher proportion of time in awake states (P = 0.05) when exposed to the same music stimulus. Conclusion Prenatal music exposure alters the fetal behavioral state and is carried forward to the newborn period. This suggests that a simple form of fetal programming or learning has occurred. Copyright © 2002 International Society of Ultrasound in Obstetrics and Gynecology

Chorionicity determination in twin pregnancies: how accurate are we?

Abstract: Objectives To determine the accuracy of antenatal prediction of chorionicity in twin pregnancies in our institution. Methods Antenatal chorionicity was determined using the number of placental masses, the presence or absence of a twin peak sign and the fetal sex. The gestational age at assessment was documented. Postnatal diagnosis of chorionicity was determined by neonatal sex and placental pathology. Results Chorionicity was correctly determined in 95% of cases (n = 131); 91% of the monochorionic and 96% of the dichorionic pregnancies were correctly determined. If chorionicity was assessed prior to 14 weeks' gestation (n = 96) the correct diagnosis was made in all except one case. Conclusions Ultrasound assessment of chorionicity has a high sensitivity and specificity. This is further improved if the assessment is performed prior to 14 weeks' gestation. Copyright © 2002 ISUOG

A normal second‐trimester ultrasound does not exclude intracranial structural pathology

Abstract: Objective To report the prenatal diagnosis and management of 34 fetuses with various intracranial structural pathologies diagnosed following a normal second-trimester ultrasound examination. Methods We retrospectively reviewed the images of 203 abnormal central nervous system ultrasound examinations performed between 13 and 37 weeks of gestation at our prenatal diagnosis unit. In 34 (16.7%) of them at least one previous second-trimester ultrasound examination had been performed and considered normal. These 34 fetuses represent the study group. Results The following intracranial pathologies were diagnosed: dysgenesis of the corpus callosum, ventriculomegaly, cerebral cysts or hemorrhage, migrational disorders, vermian dysgenesis, arachnoid cysts, macrocephaly, enlarged subarachnoid space, brain calcifications and microcephaly. Conclusion A normal second-trimester ultrasound scan does not rule out significant intracranial anomalies. Parents and physicians should be informed about the limitations of second-trimester sonography as far as brain diagnosis is concerned. A repeat third-trimester scan may enable more accurate diagnosis and counseling. Copyright © 2002 International Society of Ultrasound in Obstetrics and Gynecology

Transvaginal sonographic examination of the cervix in asymptomatic pregnant women: review of the literature.

Abstract: Different strategies have been developed to refine the prediction of the risk of preterm delivery in asymptomatic patients. Transvaginal sonography has been used for this reason to measure and examine the length and shape of the cervix. In this review, we focus on clinical studies involving transvaginal sonographic assessment of the cervix in asymptomatic women at high risk of preterm delivery and in the general pregnant population. Three ultrasound signs are suggestive of cervical incompetence, namely, dilatation of the internal os, sacculation or prolapse of the membranes into the cervix (with shortening of the functional cervical length) either spontaneously or induced by transfundal pressure, and short cervix in the absence of uterine contractions. Transvaginal sonography has clearly demonstrated that cerclage leads to a measurable increase in cervical length which may contribute to the success of this procedure in reducing the risk of preterm delivery. Several non-randomized interventional studies among patients with cervical incompetence have been published. They have defined a new group of patients requiring cerclage when the women show progressive cervical modifications on transvaginal sonography, while in other studies, cerclage performed on the basis of cervical changes on transvaginal sonography did not prevent premature delivery. One prospective randomized trial in asymptomatic high-risk women has shown two benefits of cerclage following indications for transvaginal sonography: (1) it would generate fewer prophylactic cerclages in high-risk women; (2) therapeutic cerclage before 27 weeks may reduce the incidence of premature delivery before 34 weeks. The risk of preterm delivery is inversely correlated with cervical length. Routine transvaginal sonography of the cervix performed between 18 and 22 weeks can help identify patients at risk of preterm delivery. However, given the low prevalence of preterm births, screening would generate either a high false-positive rate or a low sensitivity. One non-randomized interventional study among patients with a short cervix on routine ultrasound examination found a lower risk of delivery before 32 weeks in the cerclage group than in the expectant management group. However, to date, there have been no prospective randomized trials in a general population. Although evidence is still lacking, there does appear to be a benefit in performing a cerclage rather than continuing with expectant management in cases with sonographic appearance of cervical incompetence in asymptomatic women at high risk of preterm delivery. Ultrasound can be offered to reduce the indications of cerclage for cases in which the situation is uncertain. Within the general obstetric population, transvaginal sonography might help in the selection of asymptomatic but high-risk women. However, the benefit associated with cerclage for sonographic indication has not been demonstrated.

Determination of gestational age after the 24th week of gestation from fetal kidney length measurements

Abstract: Objective To evaluate the application of kidney length measurement to the determination of gestational age between the 24th and 38th weeks and to compare its accuracy with that of other fetal biometric indices Study design Seventy-three women with singleton uncomplicated pregnancies underwent standard ultrasound fetal biometry and kidney length measurement every 2 weeks between 24 and 38 weeks' gestation These measurements were used to date the pregnancies relative to crown–rump length dating between 8 and 10 weeks' gestation Linear regression models for estimation of gestational age were derived from the biometric indices and kidney length In addition, stepwise regression models were constructed to determine the best model for determining gestational age between 24 and 38 weeks Comparisons were then made between the accuracy of these models in the determination of gestational age Results The best model for estimating gestational age in late pregnancy included the variables kidney length, biparietal diameter, head circumference, femur length and abdominal circumference This model accurately predicted gestational age with a standard error of ±848 days A model including kidney length, biparietal diameter, head circumference and femur length accurately predicted gestational age with a standard error of ±857 days These models were slightly more accurate than models derived from the biometric indices of biparietal diameter, head circumference and femur length (±987 days), biparietal diameter, head circumference, femur length and abdominal circumference (±945 days) and biparietal diameter and femur length (±99 days) Kidney length and femur length were the most accurate single parameters for predicting gestational age using simple linear regression models (±1029 and 1096 days, respectively); the abdominal circumference was the least accurate (±1454 days) Conclusion Kidney length is a more accurate method of determining gestational age than the fetal biometric indices of biparietal diameter, head circumference, femur length and abdominal circumference between 24 and 38 weeks' gestation When combined with biparietal diameter, head circumference and femur length, the precision of dating is improved by 2 days This measurement is easy to make and could therefore be easily incorporated into the model for dating pregnancies after 24 weeks of gestation, in particular when measurements of the biparietal diameter and head circumference are difficult Copyright © 2002 ISUOG