Ultrasonography in pregnancy and fetal abnormalities: screening or diagnostic test? IPIMC 1986-1990 register data. Indagine Policentrica Italiana sulle Malformazioni Congenite

Antenatal screening for fetal structural anomalies - Routine or targeted practice?

Antenatal screening with ultrasound identifies fetal structural anomalies in 3-6% of pregnancies. Identification of anomalies during pregnancy provides an opportunity for counselling, targeted imaging, genetic testing, fetal intervention and delivery planning. Ultrasound is the primary modality for imaging the fetus in pregnancy, but magnetic resonance imaging (MRI) is evolving as an adjunctive tool providing additional structural and functional information. Screening should start from the first trimester when more than 50% of severe defects can be detected. The mid-trimester ultrasound balances the benefits of increased fetal growth and development to improve detection rates, whilst still providing timely management options. A routine third trimester ultrasound may detect acquired anomalies or those missed earlier in pregnancy but may not be available in all settings. Targeted imaging by fetal medicine experts improves detection in high-risk pregnancies or when an anomaly has been detected, allowing accurate phenotyping, access to advanced genetic testing and expert counselling.

The Performance of First-Trimester Anatomy Scan: A Decision Analysis

Introduction First-trimester ultrasound (US) for anatomy assessment may improve anomaly detection, but it may also increase overall US utilization. We sought to assess the utility of first-trimester US for evaluation of fetal anatomy. Materials and Methods A decision analytic model was created to compare first- plus second-trimester anatomy scans to second-trimester scan alone in four populations: general, normal weight women, obese women, and diabetics. Probability estimates were obtained from the literature. Outcomes considered were number of: major structural anomalies detected, US performed, and false-positive US. Multivariable sensitivity analyses were performed to evaluate the consistency of the model with varying assumptions. Results A strategy of first- plus second-trimester US detected the highest number of anomalies but required more US examinations per anomaly detected. The addition of a first-trimester anatomy US was associated with a small increase in the false-positive US (< 10/10,000). In populations with higher anomaly prevalence and lower second-trimester US sensitivity (i.e., diabetes, obesity), the number of additional US performed per anomaly detected with the first-trimester US was < 60. Discussion In high-risk populations, a first-trimester US in addition to a second-trimester US may be a beneficial approach to detecting anomalies.

The Ultrasonic Microsurgical Anatomical Comparative Study of the CHD Fetuses and Their Clinical Significance

The aim of our study was to increase the detection rate of fetal cardiac malformations for congenital heart disease (CHD). The ultrasonic and microanatomical methods were combined to study the CHD cases firstly, which could provide the microsurgical anatomical basis to the prenatal ultrasonic diagnosis which was used in suspected CHD and help the sonographer to improve the quality of fetal cardiac diagnosis. We established the ultrasonic standard section of the 175 complex CHD cases and collected the fetal echocardiography image files. The induced/aborted fetuses were fixed by 4% paraformaldehyde and dissected by the ultrasonic microsurgical anatomy. This research could obtain the fetal cardiac anatomic cross-sectional images which was consistent with the ultrasonic standard section and could clearly show the internal structure of the vascular malformation that optimized the ultrasound examination individually. This method could directly display the variation of the CHD fetal heart clearly and comprehensively help us to understand the complex fetal cardiac malformation from the internal structure of the vascular malformation which was consolidated by the anatomical basis of the fetal heart. This study could improve the integrity and accuracy of the prenatal cardiac ultrasound examination tremendously.

Prenatal diagnosis of cloacal malformations

INTRODUCTION

Prenatal diagnosis of anorectal malformations currently occurs in 0-15.9% of screened cases. In cloacas, these numbers are unknown. We speculate that some images from prenatal ultrasound studies may suggest the diagnosis of cloaca, but are not recognized because of a lack of suspicion for this diagnosis.

METHODS

A retrospective review of the medical records of 489 patients born with cloaca was performed; 95 of them had prenatal ultrasound reports that represent the material analyzed for this study. A literature review was performed, finding 31 publications, with 68 cloaca patients detected by prenatal images. The abnormal findings of our patients were compared with those described in the literature to determine the most common abnormal prenatal images found in patients with cloaca.

RESULTS

The 95 ultrasound reports found in our patients described 270 abnormalities, the most frequent were: abdominal/pelvic cystic/mass (39), hydronephrosis (36), oligohydramnios (23), distended bowel/bowel obstruction (19), ascites (15), 2 vessel cord (14), dilated bladder (14), dilated ureter (14), polyhydramnios (10), echogenic bowel (8), multicystic kidney (8), "ambiguous genitalia" (7), hydrops fetalis (7), hydrocolpos (4), absent kidney (3), abnormal spine (3), and anorectal atresia (3). In spite of these findings, the radiologists who interpreted the studies only suspected a cloaca in 6 cases (6%). The literature review showed 212 abnormalities in 68 demonstrated cloaca patients. The most frequent were: abdominal/pelvic cystic/mass (46), hydronephrosis (44), ascites (21), oligohydramnios (20), distended bowel (11), multicystic dysplastic kidney (7), ambiguous genitalia (6), non-visualization of the bladder (6), two-vessel cord (5), dilated bladder (5), intraabdominal calcification (4), polyhydramnios (4), enterolithiasis (4), hydrometrocolpos (3), and dilated ureter (3).

CONCLUSION

We conclude that it is possible to suspect the diagnosis of cloaca, prenatally, more frequently than what currently occurs, looking at the same images but with an increased index of suspicion for cystic abdominal masses and a combination of gastrointestinal and urological abnormalities.

Diagnostic performance of routine ultrasound screening for fetal abnormalities in an unselected Swedish population in 2000-2005

OBJECTIVES

To determine the detection rate of fetal malformations and chromosomal abnormalities and the rate of false-positive ultrasound diagnoses at routine ultrasound examinations carried out by specially trained midwives in an unselected pregnant population from 2000 to 2005, and to describe the consequences of true-positive and false-positive ultrasound diagnoses of fetal malformations.

METHODS

A retrospective analysis was undertaken of all babies born in Malmö, Sweden, between January 2000 and December 2005 by mothers residing in Malmö and of all fetuses with an ultrasound diagnosis of malformation made in the same time interval at the two units performing all routine pregnancy scans in Malmö. All women underwent two routine scans, at 18 and 32 weeks, including scrutiny of the fetal anatomy. Detection rates and false-positive rates were calculated per fetus.

RESULTS

The prevalence of chromosomally abnormal fetuses was 0.31% (52/16 775); that of chromosomally normal fetuses with major and minor malformations was 1.80% (302/16 775) and 1.32% (222/16 775), respectively. The detection rate of fetuses with major malformations but normal chromosomes was 68% (205/302), with a detection rate at < 22 weeks of 37% (112/302). In addition, 46% (24/52) of all chromosomally abnormal fetuses were diagnosed before birth because a malformation was detected at ultrasound imaging, 33% (17/52) being detected at < 22 gestational weeks. In all, 68 pregnancies were terminated because of an ultrasound diagnosis of fetal malformation (0.4% of all pregnancies and 47% of the pregnancies in which a fetal malformation was detected by ultrasound examination before 22 weeks). A false-positive ultrasound diagnosis of malformation was made in 0.19% (31/16 180) of the normally formed fetuses and in 20 (0.12%) fetuses the abnormal finding persisted during pregnancy. No fetus assigned a false-positive diagnosis was lost by termination of pregnancy, but most were subjected to one or more unnecessary interventions before birth (e.g. amniocentesis), at birth (e.g. Cesarean section) or after birth (e.g. electrocardiogram, X-ray, ultrasound examination or treatment with antibiotics).

CONCLUSIONS

In a screening program consisting of one fetal anomaly scan at 18 weeks and another at 32 weeks the detection rate of major malformations in chromosomally normal fetuses was 68% with a detection rate of 37% at < 22 weeks. The corresponding detection rates of chromosomally abnormal fetuses were 46% and 33%. Fewer than one in 500 screened fetuses had an ultrasound diagnosis of an anomaly that was not confirmed after birth.

Prenatal diagnosis of isolated limb defects: an updated review

Abnormalities of bone segments, either isolated or in combination with others, may affect any single bone. Given the relatively low incidence of such defects and the relevance of the clinical issues involved, it could be useful to evaluate all the diagnostic and procedural aspects that should be considered at prenatal diagnosis, when obstetricians are confronted with an event that is certainly unfamiliar to most of them: a fetus with an isolated limb defect. In fact, with comparatively infrequent abnormalities investigators often tend to neglect some diagnostic aspects that could be useful both in terms of prenatal counseling and of optimum management of the affected fetus. Therefore, a multidisciplinary approach is required that supplements ultrasound diagnostics with additional tests and examinations, even of the invasive type, depending on the complexity of the condition. This updated review may represent a useful tool to reach the stated objectives.

Increasing detection rates of birth defects by prenatal ultrasound leading to apparent increasing prevalence. Lessons learned from the population-based registry of birth defects of Barcelona

OBJECTIVE

To assess the evolving trends in prenatal ultrasound detection of birth defects and to suggest a method to avoid the bias generated by an increasing detection rate, when comparing different time periods.

METHODS

In the population-based registry of birth defects of Barcelona (REDCB), 1976 cases with birth defects (1462 newborns and 514 terminations of pregnancy) were observed among 99 753 pregnancies, from 1992 to 1999. Detection rates for isolated birth defects by anatomical systems were evaluated. Since an increasing prevalence was observed in some birth defects systems, adjustment for detection rates was suggested.

RESULTS

A rise in prevalence was observed in isolated birth defects involving internal organs (central nervous, respiratory, digestive, and urinary systems). Ultrasound detection rates increased in all system groups of isolated birth defects during the study period, except for cardiovascular defects. Early detection rates (before 23 weeks of pregnancy) increased in all but three systems (cardiovascular, genital and tegument).

CONCLUSIONS

The apparent rise in the observed prevalence of certain birth defects may be largely due to improvements in prenatal detection methods. Population-based registries are able to measure the impact of evolving prenatal diagnosis in order to avoid biases and establish the prevalence of birth defects more accurately.

Prenatal ultrasonographic detection of gastrointestinal obstruction: results from 18 European congenital anomaly registries

OBJECTIVES

We evaluated the prenatal detection of gastrointestinal obstruction (GIO, including atresia, stenosis, absence or fistula) by routine ultrasonographic examination in an unselected population all over Europe.

METHODS

Data from 18 congenital malformation registries in 11 European countries were analysed. These multisource registries used the same methodology. All fetuses/neonates with GIO confirmed within 1 week after birth who had prenatal sonography and were born during the study period (1 July 1996 to 31 December 1998) were included.

RESULTS

There were 670 793 births in the area covered and 349 fetuses/neonates had GIO. The prenatal detection rate of GIO was 34%; of these 40% were detected < or = 24 weeks of gestation (WG). A total of 31% (60/192) of the isolated GIO were detected prenatally, as were 38% (59/157) of the associated GIO (p=0.26). The detection rate was 25% for esophageal obstruction (31/122), 52% for duodenal obstruction (33/64), 40% for small intestine obstruction (27/68) and 29% for large intestine obstruction (28/95) (p=0.002). The detection rate was higher in countries with a policy of routine obstetric ultrasound. Fifteen percent of pregnancies were terminated (51/349). Eleven of these had chromosomal anomalies, 31 multiple malformations, eight non-chromosomal recognized syndromes, and one isolated GIO. The participating registries reflect the various national policies for termination of pregnancy (TOP), but TOPs after 24 WG (11/51) do not appear to be performed more frequently in countries with a liberal TOP policy.

CONCLUSION

This European study shows that the detection rate of GIO depends on the screening policy and on the sonographic detectability of GIO subgroups.

Ultrasound in prenatal diagnosis: polemics around routine ultrasound screening for second trimester fetal malformations

Ultrasound for routine fetal malformation screening has been polemical from its early beginning because of the very broad range of diagnosis rates disclosed, i.e. from 13% to 82%, average 27.5%. A review of available studies is proposed to assess objectively the efficacy of ultrasound, considering also economical, ethical and methodological aspects as influential factors for choosing a routine screening policy. The utility of fetal malformation diagnosis before birth is brought forward, including second opinion, karyotyping, poly-disciplinary case discussion prior to management. Method and material of reviewed studies considerably vary and might influence the sensitivity results, as the choice of the population sample and selection of pregnant women, gestation age at screening, distribution of malformation among systems or tracts, exclusion of some fetal malformation and the routine practice of autopsy. Efficiency of screening studies is compared, and among them Radius and Eurofetus studies. Average sensitivity is finally considered as satisfactory in the daily practice when operated by trained personnel. The importance of additional factors for successful screening are emphasized such as education, equipment quality and fetal ultrasound examination at different gestation age for a better understanding of natural history of fetal morphology.

Evaluation of the prenatal diagnosis of limb reduction deficiencies. EUROSCAN Study Group

Ultrasound scans in the mid-trimester of pregnancy are now a routine part of antenatal care in most European countries. Using data from registries of congenital anomalies a study was undertaken in Europe. The objective of the study was to evaluate prenatal detection of limb reduction deficiencies (LRD) by routine ultrasonographic examination of the fetus. All LRDs suspected prenatally and all LRDs (including chromosome anomalies) confirmed at birth were identified from 20 Congenital Malformation Registers from the following 12 European countries: Austria, Croatia, Denmark, France, Germany, Italy, Lithuania, Spain, Switzerland, The Netherlands, UK and Ukrainia. These registries are following the same methodology. During the study period (1996-98) there were 709,030 births, and 7,758 cases with congenital malformations including LRDs. If more than one LRD was present the case was coded as complex LRD; 250 cases of LRDs with 63 (25.2%) termination of pregnancies were identified including 138 cases with isolated LRD, 112 with associated malformations, 16 with chromosomal anomalies and 38 non chromosomal recognized syndromes. The prenatal detection rate of isolated LRD was 24.6% (34 out of 138 cases) compared with 49.1% for associated malformations (55 out of 112; p<0.01). The prenatal detection of isolated terminal transverse LRD was 22.7% (22 out of 97), 50% (3 out of 6) for proximal intercalary LRD, 8.3% (1 out of 12) for longitudinal LRD and 0 for split hand/foot; for multipli-malformed children with LRD those percentages were 46.1% (30 out of 65), 66.6% (6 out of 9), 57.1% (8 out of 14) and 0 (0 out of 2), respectively. The prenatal detection rate of LRDs varied in relation with the ultrasound screening policies from 20.0% to 64.0% in countries with at least one routine fetal scan.

Prenatal diagnosis of gastrointestinal anomalies with ultrasound. What have we learned?

The use of routine obstetric ultrasound has been shown to accurately diagnose fetal gastrointestinal anomalies, both during and after the midtrimester. These are among the most accurately diagnosed of all anomalies, comprising 5-7% of all fetal anomalies. From a review of the literature it is clear that the use of routine ultrasound allows: (1) the detection of multiple anomalies that are often present and affect outcome significantly, (2) preparation for delivery at a tertiary center where neonatal surgical experience will allow optimal outcome, and (3) decisions about mode and timing of delivery in cases where this is important, i.e., cases of omphalocele and gastroschisis.

Evaluation of prenatal diagnosis of congenital gastro-intestinal atresias

Prenatal diagnosis performed by fetal ultrasound scan is now a routine part of antenatal care in many countries. That an increasing number of fetal anomalies may be detected on prenatal ultrasound is beyond doubt. However what is theoretically possible is not, always done in practice specially when gastrointestinal atresias (GIA) are concerned and when whole antenatal populations are screened rather than high risk groups. Thanks to our registry of congenital anomalies a retrospective study was undertaken to evaluate the prenatal detection of GIA by ultrasound scan in 118,265 consecutive pregnancies of known outcome. Only 31 out of 129 malformed fetuses with GIA were detected (24.0%). The sensitivity of detection varied from 51.4% for atresia of the small intestine to 24.2% for esophageal atresia and 8.2% for ano-rectal atresia. No isolated case with esophageal atresia and ano-rectal atresia were diagnosed. Our results stress the need to perform scans at > or = 18 weeks gestation and to train sonographers in order to improve prenatal detection of GIA.