Fetal imaging: executive summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, American Institute of Ultrasound in Medicine, American College of Obstetricians and Gynecologists, American College of Radiology, Society for Pediatric Radiology, and Society of Radiologists in Ultrasound Fetal Imaging Workshop

Given that practice variation exists in the frequency and performance of ultrasound and magnetic resonance imaging (MRI) in pregnancy, the Eunice Kennedy Shriver National Institute of Child Health and Human Development hosted a workshop to address indications for ultrasound and MRI in pregnancy, to discuss when and how often these studies should be performed, to consider recommendations for optimizing yield and cost effectiveness, and to identify research opportunities. This article is the executive summary of the workshop.

Prenatal detection of fetal growth restriction in newborns classified as small for gestational age: correlates and risk of neonatal morbidity

We examined the rate of detecting small for gestational age (SGA; birth weight < 10%) as intrauterine growth restriction (IUGR) prenatally at four centers and determined risks of composite neonatal morbidity (CNM) and mortality among detected versus undetected (no antenatal diagnosis of IUGR). A multicenter cohort study of 11,487 nonanomalous, singleton live births with sonographic exam before 22 weeks was performed. Of 11,487 births, 8% (n = 929) were SGA that met the inclusion criteria, with 25% of them being prenatally detected. The CNM among SGA births that were prenatally detected as IUGR was higher (23.3%) than undetected SGA (9.7%), but this difference was no longer significant following adjustments for confounding factors. Among preterm births (< 37 weeks), undetected SGA had significantly higher CNM (risk ratio [RR] 10.0, 95% confidence interval [CI] 6.3, 16.1) for deliveries at 24 to 33 weeks and RR 3.0, 95% CI 1.7, 5.4 for 34 to 36 weeks). In summary, only a quarter of SGA births were detected prenatally as IUGR and among preterm SGA, the CNM is significantly higher when SGA births are undetected as IUGR.

Orientation of the uterine fundus in reference to the longitudinal axis of the body: a 3-dimensional sonographic study

OBJECTIVES

The aim of this pilot study was to measure the angle of rotation of the uterus at the fundus from horizontal using 3-dimensional sonography in women presenting for annual gynecologic examinations.

METHODS

A total of 51 patients participated in the study. All patients underwent transvaginal sonography, and 3-dimensional volumes were acquired. The cervicouterine angle and the angle of rotation at the fundus were measured.

RESULTS

The uteri were noted to be anteverted in 64.7%, retroverted in 25.5%, and euverted in 9.8%. They were noted to be pointing toward the right side of the pelvis in 49.0%, to the left side in 39.2%, and at the midline in 11.8%. The median cervicouterine angle was 122° (interquartile range [IQR], 105°-137°). The median angle of rotation at the fundus away from horizontal in either a clockwise or counterclockwise direction on the transverse B-plane was 10.4° (IQR, 7.1°-19.0°), with a maximal angle of 43°, and on the coronal C-plane, it was 10.0° (IQR, 3.0°-20.0°), with a maximal angle of 43°. Noneuverted uteri were more likely to be rotated at the fundus.

CONCLUSIONS

Our study reveals that, contrary to traditional thinking, the uterus can be rotated at the fundus in relation to the body (z-axis) along the longitudinal axis of the cervical canal.

Clinical outcomes of mild isolated cerebral ventriculomegaly in the presence of other neurodevelopmental risk factors

OBJECTIVES

The purpose of this study was to evaluate neuropsychological test data in school-aged children whose fetal sonograms revealed mild isolated cerebral ventriculomegaly without asymmetry of the lateral ventricles.

METHODS

Nine of 52 children 6 years and older with sonographic evidence of mild isolated cerebral ventriculomegaly without asymmetry of the lateral ventricles were able to be recruited for follow-up school-aged neuropsychological testing. The children received a half-day battery of neuropsychological tests, including the Wechsler Abbreviated Scales of Intelligence; Beery-Buktenica Developmental Test of Visual Motor Integration, Fifth Edition; Wide Range Achievement Test, Fourth Edition; and Integrated Visual and Auditory Continuous Performance Test. Parents completed the Conners 3 Parent Short Form and the Personality Inventory for Children, Second Edition.

RESULTS

In this small group, other risk factors for neurodevelopmental disorders were often present, including preterm birth, perinatal hypoxia, and a family history of psychiatric disease or substance abuse. Within this sample, the proportion of children with a pattern of test results showing poorer nonverbal intelligence than verbal intelligence scores and poorer math than reading performance, as well as meeting criteria for a diagnosis of attention deficit/hyperactivity disorder, was higher than the basal rates of these problems among children in general.

CONCLUSIONS

Particularly given the complexity of various factors affecting neurodevelopment, follow-up neuropsychological evaluation is warranted in children with sonographic evidence of mild isolated cerebral ventriculomegaly without asymmetry of the lateral ventricle (eg, in the context of poor school performance).

Screening for intrauterine growth restriction in uncomplicated pregnancies: time for action

A randomized clinical trial (RCT) noted that sonographic examination in the third trimester, in conjunction with delivery at term for abnormalities of fetal growth, significantly decreased the likelihood of small-for-gestational-age (SGA) neonates in uncomplicated pregnancies. We identified 15 characteristics of screening tests and attempted to determine if there is evidence to routinely obtain sonographic estimates of fetal weight in the third trimester and decrease rates of SGA. Of the 15 suggested characteristics, currently 10 (67%) are fulfilled, two are uncertain (sonographic examination is cost-effective or reliable), and one (the test must do its job) is possibly valid. Due to the lack of RCTs demonstrating reduction in morbidity, there is potential for lead-time and length bias. To observe a 36% decrease (from 4.1 to 2.6%) decrease in composite perinatal morbidity, 6000 women need to be randomized to at least two sonographic examinations in the third trimester versus routine prenatal care. Such an RCT is warranted and justified.

Society of Maternal-Fetal Medicine annual meeting and a continuing medical education course: results of pre- and postcourse survey

OBJECTIVE

To assess the influence of a continuing medical education (CME) course on knowledge acquired and potential to change clinical management or opinion.

STUDY DESIGN

During the annual Society of Maternal-Fetal Medicine meeting, a survey consisting of 11 knowledge-based, 10 management plan, and 8 opinion questions was administered at the start and completion of the CME course. Chi-square and Fisher exact test were used, and p < 0.05 was considered significant.

RESULTS

The survey was administered electronically to 394 attendees. Questions assessing knowledge showed significant improvement with 91% (10/11) of queries. Purported management changed significantly with 60% (6/10) scenarios and opinions in 62% (5/8) of clinical situations.

CONCLUSION

A survey done at the completion of a course indicates that CME improves knowledge and can change management and opinions. The prolonged benefits of CME need to be investigated.

Intrapartum fetal surveillance: review of three national guidelines

Evidence-based guidelines regarding intrapartum fetal surveillance from three countries (United States, Canada, and Australia/New Zealand) were reviewed. The similarities in the three national guidelines (purported etiology, management of periodic changes, and intermittent auscultation for low-risk women) are understandable. Differences in recommendations (role of fetal admission test, amnioinfusion for variable decelerations, scalp pH, umbilical arterial acid-base status, and education in interpretation of fetal heart tracing) are not explained. The likelihood of recommendations being categorized as level A differed for the countries: United States, 41% (7/17); Canada, 18% (3/17); and Australia and New Zealand, 17% (2/12). Only one publication was cited by all three guidelines. To avoid confusion and possibly enhance their quality, national guidelines should acknowledge the presence of others on the same topic, and if there are differences then provide explanations for dissimilarities.

Severe small size for gestational age and cognitive function: catch-up phenomenon possible

OBJECTIVE

We sought to compare cognitive functioning in children born with birthweight <3% vs ≥3% for gestational age (GA) between 9 months and kindergarten.

STUDY DESIGN

Nonanomalous singletons from the Early Childhood Longitudinal Study-Birth Cohort were included. Associations between weight for GA and cognitive functioning were examined using a series of confounder-adjusted general linear models.

RESULTS

Of 3633 cohorts, 585 (16%) were <3% for GA. At 9 months, cognitive performance of newborns <3% was about 12 percentile points lower than their normal counterparts (P < .001). By 2 years, however, no significant cognitive differences between these groups were observed (P = .668). Academic performance at preschool age (around 3.5 years) was not different for reading (P = .245) or math (P = .880), nor different at kindergarten age.

CONCLUSION

Newborns <3% for GA exhibit catch-up cognitive functioning by 2 years, with relatively no decrements in academic functioning observed by kindergarten.

A study of the cost, accuracy, and benefits of 3-dimensional sonography compared with hysterosalpingography in women with uterine abnormalities

OBJECTIVES

We conducted a prospective blinded study to evaluate the costs, accuracy, risks, and benefits of 3-dimensional (3D) transvaginal sonography compared to hysterosalpingography.

METHODS

A total of 101 women aged 26 to 44 years with evidence of uterine anomalies were enrolled. All participants had routine hysterosalpingography as part of their infertility evaluation as well as 3D transvaginal sonography as part of the study. Surgical findings were used as the standard for final diagnosis.

RESULTS

A total of 6 normal uteri and 119 uterine anomalies were classified: 30 congenital uterine anomalies (3 arcuate, 1 unicornuate, 4 bicornuate, 2 didelphys, and 20 septate uteri) and 89 acquired anomalies (38 polyps, 30 fibroids, 17 synechiae, and 4 adenomyosis). Congenital anomalies were correctly identified in 30 of 30 cases by 3D sonography but from 10 to 30 of 30 cases by hysterosalpingography. The detection rates for acquired uterine anomalies were lower for both techniques: 44 to 89 of 89 cases for 3D sonography and 22 to 74 of 89 cases for hysterosalpingography. Only 7 of the 20 septi would have been surgically corrected if patients only had hysterosalpingography. On the contrary, 30 of 30 patients with congenital uterine anomalies, 2 of 4 patients with adenomyosis, and all 6 patients with normal uteri were spared from surgery with diagnoses by 3D sonography. No adverse effects were reported after sonography, and only 6 minor ones were reported after hysterosalpingography.

CONCLUSIONS

Three-dimensional transvaginal sonography provides visualization and evaluation of the uterine cavity with similar or better accuracy than standard hysterosalpingography in the office setting, with lower cost and morbidity.

Collaborative study on 3-dimensional sonography for the prenatal diagnosis of central nervous system defects

OBJECTIVES

Prenatal diagnosis of central nervous system (CNS) anomalies by 2-dimensional sonography is challenging because of difficulties in obtaining complete visualization of the fetal brain during routine examinations, which is necessary for identification of its axial, coronal, and sagittal planes. Three-dimensional (3D) sonography has been introduced as a tool for studying the fetal CNS because of its ability to facilitate examinations of the fetal brain. The objective of this study was to determine inter-center agreement in diagnosing CNS defects by review of 3D volume data sets.

METHODS

This study included 11 centers with expertise in 3D fetal neurosonography. A total of 217 fetuses with and without confirmed CNS defects were scanned after 18 weeks' gestation, and their volume data sets were uploaded onto a centralized file transfer protocol server and later analyzed by all of the centers. Intercenter agreement was determined using a κ statistic for multiple raters.

RESULTS

All volumes were made anonymous and sent to the centers for blinded analysis with the exception of the data sets they had themselves previously uploaded. For identification of fetuses with CNS defects, the sensitivity, specificity, positive and negative predictive values, and false-positive and -negative rates were 93.3%, 96.5%, 96.5%, 93.3%, 3.5%, and 6.7%, respectively. No differences were found in the efficacy of the diagnostic indices according to either the route of acquisition (transabdominal or trans-vaginal) or the gestational age at diagnosis (18-24 or >24 weeks). Intercenter agreement was excellent (κ = 0.92; 95% confidence interval, 0.88-0.97).

CONCLUSIONS

Among centers with technical expertise, remote review of 3D sonographic volumes of the fetal CNS resulted in an accurate and reliable method for diagnosis of fetal brain malformations.

Time and number of displays impact critical signal detection in fetal heart rate tracings

Interest in centralized monitoring in labor and delivery units is growing because it affords the opportunity to monitor multiple patients simultaneously. However, a long history of research on sustained attention reveals these types of monitoring tasks can be problematic. The goal of the present experiment was to examine the ability of individuals to detect critical signals in fetal heart rate (FHR) tracings in one or more displays over an extended period of time. Seventy-two participants monitored one, two, or four computer-simulated FHR tracings on a computer display for the appearance of late decelerations over a 48-minute vigil. Measures of subjective stress and workload were also obtained before and after the vigil. The results showed that detection accuracy decreased over time and also declined as the number of displays increased. The subjective reports indicated that participants found the task to be stressful and mentally demanding, effortful, and frustrating. The results suggest that centralized monitoring that allows many patients to be monitored simultaneously may impose a detrimental attentional burden on the observer. Furthermore, this seemingly benign task may impose an additional source of stress and mental workload above what is commonly found in labor and delivery units.

Electronic fetal heart rate monitoring and its relationship to neonatal and infant mortality in the United States

OBJECTIVE

To examine the association between electronic fetal heart rate monitoring and neonatal and infant mortality, as well as neonatal morbidity.

STUDY DESIGN

We used the United States 2004 linked birth and infant death data. Multivariable log-binomial regression models were fitted to estimate risk ratio for association between electronic fetal heart rate monitoring and mortality, while adjusting for potential confounders.

RESULTS

In 2004, 89% of singleton pregnancies had electronic fetal heart rate monitoring. Electronic fetal heart rate monitoring was associated with significantly lower infant mortality (adjusted relative risk, 0.75); this was mainly driven by the lower risk of early neonatal mortality (adjusted relative risk, 0.50). In low-risk pregnancies, electronic fetal heart rate monitoring was associated with decreased risk for Apgar scores <4 at 5 minutes (relative risk, 0.54); in high-risk pregnancies, with decreased risk of neonatal seizures (relative risk, 0.65).

CONCLUSION

In the United States, the use of electronic fetal heart rate monitoring was associated with a substantial decrease in early neonatal mortality and morbidity that lowered infant mortality.

The role of 3-dimensional ultrasonography and magnetic resonance imaging in the diagnosis of müllerian duct anomalies: a review of the literature

OBJECTIVE

The purpose of this article is to review the published literature and determine the roles that magnetic resonance imaging (MRI) and endovaginal 3-dimensional ultrasonography (3DUS) play in the diagnosis of müllerian duct anomalies (MDAs).

METHODS

A PubMed search was performed to identify all of the articles pertaining to the use of MRI or 3DUS for the evaluation or diagnosis of MDAs. Clinical studies, review articles, case reports, and descriptive studies were reviewed.

RESULTS

Magnetic resonance imaging and 3DUS are highly sensitive and specific in identifying women with MDAs. Magnetic resonance imaging is 100% to 28.6% sensitive and 100% to 66% specific in correctly categorizing MDAs. Three-dimensional ultrasonography is 100% to 98% sensitive and 100% specific in correctly categorizing MDAs.

CONCLUSIONS

In experienced hands, both MRI and 3DUS are adequate modalities for identifying women with MDAs. There is a lack of studies comparing MRI with 3DUS for the diagnosis and categorization of MDAs. However, it seems likely that 3DUS is more sensitive and specific than MRI in categorizing specific types of MDAs. The high sensitivity and specificity of 3DUS make it an ideal tool for identifying women with MDAs that are amenable to hysteroscopic resection. Therefore, we believe that as practitioners become more experienced, 3DUS will emerge as the reference standard for the diagnosis of MDAs.

Detection of transient postoperative changes in the endometrial cavity by 3-dimensional ultrasonography after hysteroscopic correction of various uterine anomalies

OBJECTIVE

The purpose of this series was to prospectively evaluate early postoperative intrauterine changes by 3-dimensional ultrasonography (3DUS) in patients undergoing hysteroscopic correction of various uterine anomalies.

METHODS

Thirty consecutive patients with a diagnosis of an anomaly of the uterine cavity who underwent hysteroscopic correction were studied. Patients had transvaginal 3DUS to display the midcoronal view of the uterus immediately before and 1 and 2 months after hysteroscopy. The presence of postoperative changes and the pregnancy outcomes (either spontaneous or after assisted reproduction) in the subsequent 6 months after hysteroscopy were recorded.

RESULTS

Postoperative changes 1 month after hysteroscopy were detected by 3DUS in 20% (6/30) of these patients. The changes detected consisted of intrauterine cystic loculations in 3 patients and endometrial irregularities/possible mucus accumulations in the other 3. These loculations and irregularities were sometimes larger and more complex in nature than the original lesions and always coincided with the resection site. These changes resolved spontaneously after the second postoperative month and did not interfere with embryo implantation or cause pregnancy loss in patients attempting to conceive during the study period.

CONCLUSIONS

Patients who underwent hysteroscopic correction of various anomalies of the uterine cavity had immediate postoperative findings when imaged by 3DUS that were transient and of no clinical relevance. These transient and self-resolving ultrasonographic changes did not affect the patients' reproductive capacity.

Monitoring simulated maternal-fetal heart rate signals

The present study represents the first in a series aimed at examining how individuals monitor maternal-fetal heart rate signals over an extended period of time. Seventy-two undergraduate students monitored simulated maternal-fetal heart rate signals for late decelerations of either high or low amplitude for 48 minutes. The results showed that the ability to detect late decelerations was quite good and did not decline over time. Although the findings regarding detections are encouraging, the participants also made a lot of false alarms. Collectively, these results suggest that the observers still struggled to distinguish critical patterns from the background fetal heart activity.

Clinical implications of the echo enhancement artifact in volume sonography of the uterus

OBJECTIVE

The purpose of this report is to present a 3-dimensional (3D) imaging artifact, the echo enhancement artifact, which may have important clinical implications in the display of the midcoronal plane of the uterus in volume sonography and to suggest a technologic modification to current 3D equipment that may help the user in the identification of such an artifact.

METHODS

Three coronal planes were retrieved out of a 3D volume of a uterus obtained during the luteal phase of the menstrual cycle by standard postprocessing techniques. The effect of the echo enhancement artifact on the display of the coronal planes was compared.

RESULTS

Coronal planes, obtained in the posterior myometrium, below the endometrial cavity, appeared to show what looked like endometria and could potentially be confused with the anatomic midcoronal plane of the uterus by an inexperienced operator because of the echo enhancement artifact.

CONCLUSIONS

Physicians reviewing diagnostic images retrieved out of a sonographic volume should be aware of this artifact and should review the anatomic plane that corresponds to the retrieved image before a clinical diagnosis is rendered. A technologic modification to current 3D equipment is suggested.

The Z technique: an easy approach to the display of the mid-coronal plane of the uterus in volume sonography

OBJECTIVE

The purpose of our study was to evaluate the ease of learning and clinical applicability of a technique (Z technique) for display of the mid-coronal plane of the uterus in volume sonography.

METHODS

Eight physicians were randomly assigned to 2 groups, A and B, after being instructed on the basic principles of post processing of sonographic volumes. Physicians in group A were asked to individually display the mid-coronal plane of the uterus in each of five 3-dimensional volumes of uteri. Physicians in group B were instructed on the Z technique and were then asked to individually display the mid-coronal plane of the uterus in the same volumes as group A. The time needed for display of the mid-coronal plane of the uterus and the quality of the mid-coronal plane image retrieved were recorded for each volume.

RESULTS

The mean time required to display the mid-coronal plane of the uterus for all volumes was 47.7 seconds in group B compared with 110.7 seconds in group A (P=.002). Furthermore, a significant improvement in time performance was seen for physicians in group A after learning the Z technique (23.2 seconds after compared with 110.7 seconds before; P=.0001). The quality of the image produced was notably better for all physicians after learning the Z technique.

CONCLUSIONS

The Z technique is an easy technique to learn. Physicians who learn this technique are able to retrieve the mid-coronal plane of the uterus faster and improve its image quality in volume sonography.