Audit of a screening service for fetal abnormalities using early ultrasound scanning and maternal serum alpha-fetoprotein estimation combined with selective detailed scanning

Another Case of De Novo 3q26.33q27.3 Microdeletion and Its Medicolegal Sequel

A new case of a de novo 3q26.33q27.3 microdeletion is reported. The fetus had a sonographically undiagnosable polymalformative syndrome. The case highlights the difficulties of echographic diagnosis of such syndromes and leads to reflection on the difficulties of appropriate counselling in cases of uncertainty.

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.

Cardiac findings in fetal and pediatric autopsies: a five-year retrospective review

This review aims to determine the spectrum of cardiac findings in our fetal and pediatric postmortem population and provide an analysis of associated extracardiac malformations and genetic abnormalities. Pediatric autopsy reports from 2003 to 2007 inclusive were reviewed and cases with cardiac pathology selected for analysis. Over the 5-year period, 119 cases (10.8%) with abnormal cardiac findings were identified from a total of 1102 postmortem examinations. Of these cardiac cases, 42% were after termination of pregnancy for fetal anomaly, 29% after fetal demise, 14% after neonatal unit death, 3% after hospital inpatient death, and 11% after sudden unexpected death. Structural abnormality cases numbered 107 (90%), with ventricular septal defect as the most common individual defect. Nonstructural abnormality cases, such as myocarditis, numbered 12 (10%). Extracardiac malformations were identified in 78%. Chromosome or gene aberrations were detected in 37%. This review highlights the potential benefit of introducing routine fetal anomaly scanning, the need for cardiac pathology training for pediatric pathologists, and the importance of examination of the heart and associated vessels in all cases to provide parents with as much information as possible and aid identification of the etiology and associations of cardiac pathology.

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.

Clinical follow-up of high mid-trimester maternal serum intact human chorionic gonadotrophin concentrations in singleton pregnancies

Mid-trimester biochemical screening of 38 143 pregnancies in south-east Scotland revealed 127 cases (0.34 per cent) in which the maternal serum (MS) intact human chorionic gonadotrophin (hCG) concentration was > or = 4 multiples of the median in singleton pregnancies (MOM). Three were lost to follow-up but in 72 (58 per cent) complications developed or there were associated fetal abnormalities. This percentage was greatest at very high hCG concentrations, 92 per cent with hCG > or = 10 MOM (n = 12) compared with 48 per cent with hCG concentrations of 4-4.99 MOM (n=69). 22 cases had an MS alpha-fetoprotein > or = 2 MOM in addition to an MS hCG > or = 4 MOM, and in only 3 of these was the pregnancy uneventful; 86 per cent were associated with abnormalities or pregnancy complications.

A six year study of the antenatal detection of fetal abnormality in six Scottish health boards

OBJECTIVE

To assess the sensitivity of prenatal diagnosis by ultrasound and biochemical methods, to evaluate the reasons for non-detection and to make appropriate recommendations.

DESIGN

Six year observational study, during which biochemical screening for trisomy 21 was introduced and there was an increase in routine ultrasound scanning at 18-22 weeks.

SETTING

Six health boards in Scotland.

POPULATION

264,481 pregnancies, of which 862 were terminated because of fetal abnormality, and 2123 delivered with prenatally detectable major fetal abnormalities.

MAIN OUTCOME MEASURES

The prenatal detection of trisomies 13, 18 and 21, and 12 major structural abnormalities, which the average ultrasonographer with average skills using average equipment would be expected to detect.

RESULTS

Serum biochemical screening improved detection of trisomy 21 from 33% to 57%. The detection rate for the major abnormalities was 62% (815/1320) and 73% (598/818) when the trisomies were excluded. 18-22 weeks scanning yielded a 92% detection rate. Of the 505 undetected cases, 15% declined prenatal screening, 46% were unscreened because they were ineligible for testing, unbooked, booked too late or scanned too early for a diagnosis to be made, 2% had findings suspicious of a chromosomal abnormality but testing was not undertaken and 37% had a negative scan at a gestation when the abnormality was potentially detectable.

CONCLUSIONS

A policy of first trimester scanning followed by serum alpha-fetoprotein screening and additional scanning as clinically indicated is effective in detecting major structural abnormalities, but scanning at 18-22 weeks and serum biochemical screening for trisomy 21 improved the detection rates. Supervised training and adequate equipment are essential. Present prenatal diagnostic tests will not detect all abnormalities and patients must be made aware of this.

Correlation of prenatal ultrasound diagnosis and pathologic findings in fetal anomalies

This retrospective study compared the prenatal ultrasound (US) diagnosis with autopsy findings in 61 intact fetuses following induced abortion and 36 fragmented fetuses from dilatation and evacuation (D&E). In intact fetuses, complete agreement between US diagnosis and autopsy findings was achieved in 65.6% of cases in the central nervous system (CNS) and 47.5% in other somatic organ systems (SOS). There were major differences between US and autopsy findings involving the CNS in 6.5% of cases and SOS in 27.9%. Correlation was better for evaluation of renal anomalies (complete agreement in 63.6% of 11 suspected cases, 2 false-positive and no false-negative cases) than congenital heart disease (complete agreement in 27.3% of 11 suspected cases, 5 false-positive and 3 false-negative cases). In D&E specimens, a prenatal diagnosis of neural tube defect (NTD) was confirmed in 90% of cases. However, due to fragmentation of fetal parts, the US diagnosis in the CNS could not be confirmed totally (69.4%) or partially (2.8%) in fetuses with chromosomal abnormalities (ChA) or multiple congenital anomalies (MCA). Nonetheless, the US diagnosis of SOS was confirmed in six cases on D&E, including Meckel-Gruber syndrome, cystic hygroma, renal agenesis with contralateral renal dysplasia, cardiac defect, fetal hydrops, and tracheal atresia. Our results show that a thorough autopsy of an intact fetus after abortion is necessary to confirm prenatal diagnosis and allow proper management and counseling. The pathologic examination of D&E specimens can reliably confirm the US diagnosis of NTD, but it is very limited in identifying other fetal anomalies.

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.

Routine ultrasound screening of congenital anomalies. An overview of the European experience

Results from ultrasound in low-risk pregnant women are significant when routine screening is performed on a large population because the anomalies are rare. Professionals expect from routine ultrasound objective information that cannot usually be obtained by clinical procedures. Parents seek reassurance about the absence of fetal congenital anomalies and overall fetal health. Therefore, Europeans view routine ultrasound as a part of obstetrical care, capable of filling important gaps by delivering much key information for improving obstetrical practice. Fetal anomalies screening (FAS) requires higher education and qualifications than obstetrical ultrasound. The health insurance systems support ultrasound screening and allow its spread in most European countries; approximately 98% of pregnant women are examined by ultrasound and, frequently, two to three times (usually once per trimester). Detection rate of congenital anomalies is about 28% in geographical areas (private practice and hospitals), 60 to 80% in Ob/Gyn's ultrasound labs. Routine ultrasound screening policy has not proved to result in an immoderate use of ultrasound; on the contrary, chaotic use of routine ultrasound can lead to an unproductive and excessive number of scans. New trends in FAS, such as the early detection of fetal defects and chromosomal anomalies, bring more arguments for routine screening. Effectiveness should increase by enhancing education and training and the systematic referral for FAS to accredited laboratories.

Ultrasound screening for fetal abnormalities

Ultrasound screening for fetal abnormalities is increasingly becoming part of routine antenatal care in Europe and the UK. However, there has been very little formal evaluation of this practice. In this article reports of routine ultrasound screening are reviewed and the advantages and disadvantages discussed. The majority of routine anomaly scanning is done in the second trimester but there may be a case for screening at other times in pregnancy and alternative anomaly screening policies are discussed.