Ultrasound screening in pregnancy: a randomised controlled trial

How safe is it to use ultrasound in prenatal medicine? Facts and contradictions - Part 2 - Laboratory experiments regarding non-thermal effects and epidemiological studies

The first part of this CME article (issue 5/20) provided a detailed examination of the biophysical effects of ultrasound waves, the exposure values, and in particular the thermal effect. In vivo and in vitro measurements have shown that the temperature increase in tissue associated with B-mode ultrasound is far too low to pose a potential risk. Even experiments with exposure values in the range of pulsed Doppler have shown that temperature increases of over 1.5 °C can only occur in areas in direct contact with the probe, thus making a limited exposure time particularly in the case of transvaginal application advisable. The second part of this CME article describes various laboratory and animal experiments for evaluating non-thermal effects and also presents the most important epidemiological studies in the last 30 years in the form of an overview and review. In addition to direct insonation of isolated cells to examine possible mutagenic effects, the blood of patients exposed in vivo to ultrasound was also analyzed in multiple experiments. Reproducible chromosome aberrations could not be found in any of the studies. In contrast, many experiments on pregnant rodents showed some significant complications, such as abortion, deformities, and behavioral disorders. As in the case of thermal effects, the results of these experiments indicate the presence of an intensity- or pressure-dependent effect threshold. Numerous epidemiological studies examining possible short-term and long-term consequences after intrauterine ultrasound exposure are available with the most important studies being discussed in the following. In contrast to information presented incorrectly in the secondary literature and in the lay press, health problems could not be seen in the children observed in the postpartum period in any of these studies.

Routine ultrasound for fetal assessment before 24 weeks' gestation

BACKGROUND

Ultrasound examination of pregnancy before 24 weeks gestation may lead to more accurate dating and earlier diagnosis of pathology, but may also give false reassurance. It can be used to monitor development or diagnose conditions of an unborn baby. This review compares the effect of routine or universal, ultrasound examination, performed before 24 completed weeks' gestation, with selective or no ultrasound examination.  OBJECTIVES: To assess the effect of routine pregnancy ultrasound before 24 weeks as part of a screening programme, compared to selective ultrasound or no ultrasound, on the early diagnosis of abnormal pregnancy location, termination for fetal congenital abnormality, multiple pregnancy, maternal outcomes and later fetal compromise. To assess the effect of first trimester (before 14 weeks) and second trimester (14 to 24 weeks) ultrasound, separately.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, and the World Health Organization's International Clinical Trials Registry Platform (ICTRP) on 11 August 2020. We also examined the reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), quasi-RCTs, cluster-RCTs and RCTs published in abstract form. We included all trials with pregnant women who had routine or revealed ultrasound versus selective ultrasound, no ultrasound, or concealed ultrasound, before 24 weeks' gestation. All eligible studies were screened for scientific integrity and trustworthiness.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for eligibility and risk of bias, extracted data and checked extracted data for accuracy. Two review authors independently used the GRADE approach to assess the certainty of evidence for each outcome MAIN RESULTS: Our review included data from 13 RCTs including 85,265 women. The review included four comparisons. Four trials were assessed to be at low risk of bias for both sequence generation and allocation concealment and two as high risk. The nature of the intervention made it impossible to blind women and staff providing care to treatment allocation.  Sample attrition was low in the majority of trials and outcome data were available for most women. Many trials were conducted before it was customary for trials to be registered and protocols published. First trimester routine versus selective ultrasound: four studies, 1791 women, from Australia, Canada, the United Kingdom (UK) and the United States (US). First trimester scans probably reduce short-term maternal anxiety about pregnancy (risk ratio (RR) 0.80, 95% confidence interval (CI) 0.65 to 0.99; moderate-certainty evidence). We do not have information on whether the reduction was sustained.  The evidence is very uncertain about the effect of first trimester scans on perinatal loss (RR 0.97, 95% CI 0.55 to 1.73; 648 participants; one study; low-certainty evidence) or induction of labour for post-maturity (RR 0.83, 95% CI 0.50 to 1.37; 1474 participants; three studies; low-certainty evidence). The effect of routine first trimester ultrasound on birth before 34 weeks or termination of pregnancy for fetal abnormality was not reported. Second trimester routine versus selective ultrasound: seven studies, 36,053 women, from Finland, Norway, South Africa, Sweden and the US. Second trimester scans probably make little difference to perinatal loss (RR 0.98, 95% CI 0.81 to 1.20; 17,918 participants, three studies; moderate-certainty evidence) or intrauterine fetal death (RR 0.97, 95% CI 0.66 to 1.42; 29,584 participants, three studies; low-certainty evidence). Second trimester scans may reduce induction of labour for post-maturity (RR 0.48, 95% CI 0.31 to 0.73; 24,174 participants, six studies; low-certainty evidence), presumably by more accurate dating. Routine second trimester ultrasound may improve detection of multiple pregnancy (RR 0.05, 95% CI 0.02 to 0.16; 274 participants, five studies; low-certainty evidence). Routine second trimester ultrasound may increase detection of major fetal abnormality before 24 weeks (RR 3.45, 95% CI 1.67 to 7.12; 387 participants, two studies; low-certainty evidence) and probably increases the number of women terminating pregnancy for major anomaly (RR 2.36, 95% CI 1.13 to 4.93; 26,893 participants, four studies; moderate-certainty evidence). Long-term follow-up of children exposed to scans before birth did not indicate harm to children's physical or intellectual development (RR 0.77, 95% CI 0.44 to 1.34; 603 participants, one study; low-certainty evidence). The effect of routine second trimester ultrasound on birth before 34 weeks or maternal anxiety was not reported. Standard care plus two ultrasounds and referral for complications versus standard care: one cluster-RCT, 47,431 women, from Democratic Republic of Congo, Guatemala, Kenya, Pakistan and Zambia. This trial included a co-intervention, training of healthcare workers and referral for complications and was, therefore, assessed separately. Standard pregnancy care plus two scans, and training and referral for complications, versus standard care probably makes little difference to whether women with complications give birth in a risk appropriate setting with facilities for caesarean section (RR 1.03, 95% CI 0.89 to 1.19; 11,680 participants; moderate-certainty evidence).  The intervention also probably makes little to no difference to low birthweight (< 2500 g) (RR 1.01, 95% CI 0.90 to 1.13; 47,312 participants; moderate-certainty evidence). The evidence is very uncertain about whether the community intervention (including ultrasound) makes any difference to maternal mortality (RR 0.92, 95% CI 0.55 to 1.55; 46,768 participants; low-certainty evidence). Revealed ultrasound results (communicated to both patient and doctor) versus concealed ultrasound results (blinded to both patient and doctor at any time before 24 weeks): one study, 1095 women, from the UK. The evidence was very uncertain for all results relating to revealed versus concealed ultrasound scan (very low-certainty evidence).

AUTHORS' CONCLUSIONS

Early scans probably reduce short term maternal anxiety.  Later scans may reduce labour induction for post-maturity. They may improve detection of major fetal abnormalities and increase the number of women who choose termination of pregnancy for this reason. They may also reduce the number of undetected twin pregnancies. All these findings accord with observational data.  Neither type of scan appears to alter other important maternal or fetal outcomes, but our review may underestimate the effect in modern practice because trials were mostly  from relatively early in the development of the technology, and many control participants also had scans. The trials were also underpowered to show an effect on other important maternal or fetal outcomes.

Postpartum Hemorrhage in Pregnancy beyond 40 Weeks of Gestation in a Tertiary Care Hospital: A Descriptive Cross-sectional Study

INTRODUCTION

Postpartum hemorrhage is defined as a blood loss of 500ml or more within 24 hours after birth. It is the leading cause of maternal mortality in low-income countries and the primary cause of nearly one-quarter of all maternal deaths globally. It occurs in up to 18% of total births. Post-dated pregnancy is a high-risk pregnancy with increased maternal morbidity. This study aims to determine the prevalence of postpartum hemorrhage in pregnancy beyond 40 weeks of gestation in a tertiary care hospital.

METHODS

A descriptive cross-sectional study was conducted among pregnant women beyond 40 weeks in Dhulikhel hospital from October 2016 to March 2017. The study was conducted after ethical clearance from the hospital research committee (reference number#128/16). The sample size was calculated and convenient sampling was done. Statistical Package for the Social Sciences is used for analysis. Point estimate at 95% confidence interval was calculated along with frequency and percentage for binary data.

RESULTS

Out of 465 ladies enrolled in this study postpartum hemorrhage was seen in 6 (1.29%) (95% Confidence Interval = 0.267-2.31), and the mean age was 24.25+4.8. About 346 (74.4%) had a normal delivery, 104 (22.36%) had cesarean section and 15 (3.22%) had instrumental delivery.

CONCLUSIONS

Postpartum haemorrhage prevalence is low among the pregnant women beyond 40 weeks compared to the standard study. Postpartum hemorrhage is the common leading cause of maternal mortality. So high-risk cases should be identified and active management should be done to reduce morbidity and mortality.

Biochemical tests of placental function versus ultrasound assessment of fetal size for stillbirth and small-for-gestational-age infants

BACKGROUND

Stillbirth affects 2.6 million pregnancies worldwide each year. Whilst the majority of cases occur in low- and middle-income countries, stillbirth remains an important clinical issue for high-income countries (HICs) - with both the UK and the USA reporting rates above the mean for HICs. In HICs, the most frequently reported association with stillbirth is placental dysfunction. Placental dysfunction may be evident clinically as fetal growth restriction (FGR) and small-for-dates infants. It can be caused by placental abruption or hypertensive disorders of pregnancy and many other disorders and factorsPlacental abnormalities are noted in 11% to 65% of stillbirths. Identification of FGA is difficult in utero. Small-for-gestational age (SGA), as assessed after birth, is the most commonly used surrogate measure for this outcome. The degree of SGA is associated with the likelihood of FGR; 30% of infants with a birthweight < 10th centile are thought to be FGR, while 70% of infants with a birthweight < 3rd centile are thought to be FGR. Critically, SGA is the most significant antenatal risk factor for a stillborn infant. Correct identification of SGA infants is associated with a reduction in the perinatal mortality rate. However, currently used tests, such as measurement of symphysis-fundal height, have a low reported sensitivity and specificity for the identification of SGA infants.

OBJECTIVES

The primary objective was to assess and compare the diagnostic accuracy of ultrasound assessment of fetal growth by estimated fetal weight (EFW) and placental biomarkers alone and in any combination used after 24 weeks of pregnancy in the identification of placental dysfunction as evidenced by either stillbirth, or birth of a SGA infant. Secondary objectives were to investigate the effect of clinical and methodological factors on test performance.

SEARCH METHODS

We developed full search strategies with no language or date restrictions. The following sources were searched: MEDLINE, MEDLINE In Process and Embase via Ovid, Cochrane (Wiley) CENTRAL, Science Citation Index (Web of Science), CINAHL (EBSCO) with search strategies adapted for each database as required; ISRCTN Registry, UK Clinical Trials Gateway, WHO International Clinical Trials Portal and ClinicalTrials.gov for ongoing studies; specialist abstract and conference proceeding resources (British Library's ZETOC and Web of Science Conference Proceedings Citation Index). Search last conducted in Ocober 2016.

SELECTION CRITERIA

We included studies of pregnant women of any age with a gestation of at least 24 weeks if relevant outcomes of pregnancy (live birth/stillbirth; SGA infant) were assessed. Studies were included irrespective of whether pregnant women were deemed to be low or high risk for complications or were of mixed populations (low and high risk). Pregnancies complicated by fetal abnormalities and multi-fetal pregnancies were excluded as they have a higher risk of stillbirth from non-placental causes. With regard to biochemical tests, we included assays performed using any technique and at any threshold used to determine test positivity.

DATA COLLECTION AND ANALYSIS

We extracted the numbers of true positive, false positive, false negative, and true negative test results from each study. We assessed risk of bias and applicability using the QUADAS-2 tool. Meta-analyses were performed using the hierarchical summary ROC model to estimate and compare test accuracy.

MAIN RESULTS

We included 91 studies that evaluated seven tests - blood tests for human placental lactogen (hPL), oestriol, placental growth factor (PlGF) and uric acid, ultrasound EFW and placental grading and urinary oestriol - in a total of 175,426 pregnant women, in which 15,471 pregnancies ended in the birth of a small baby and 740 pregnancies which ended in stillbirth. The quality of included studies was variable with most domains at low risk of bias although 59% of studies were deemed to be of unclear risk of bias for the reference standard domain. Fifty-three per cent of studies were of high concern for applicability due to inclusion of only high- or low-risk women.Using all available data for SGA (86 studies; 159,490 pregnancies involving 15,471 SGA infants), there was evidence of a difference in accuracy (P < 0.0001) between the seven tests for detecting pregnancies that are SGA at birth. Ultrasound EFW was the most accurate test for detecting SGA at birth with a diagnostic odds ratio (DOR) of 21.3 (95% CI 13.1 to 34.6); hPL was the most accurate biochemical test with a DOR of 4.78 (95% CI 3.21 to 7.13). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.88 and median prevalence of 19%, EFW, hPL, oestriol, urinary oestriol, uric acid, PlGF and placental grading will miss 50 (95% CI 32 to 68), 116 (97 to 133), 124 (108 to 137), 127 (95 to 152), 139 (118 to 154), 144 (118 to 161), and 144 (122 to 161) SGA infants, respectively. For the detection of pregnancies ending in stillbirth (21 studies; 100,687 pregnancies involving 740 stillbirths), in an indirect comparison of the four biochemical tests, PlGF was the most accurate test with a DOR of 49.2 (95% CI 12.7 to 191). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.78 and median prevalence of 1.7%, PlGF, hPL, urinary oestriol and uric acid will miss 2 (95% CI 0 to 4), 4 (2 to 8), 6 (6 to 7) and 8 (3 to 13) stillbirths, respectively. No studies assessed the accuracy of ultrasound EFW for detection of pregnancy ending in stillbirth.

AUTHORS' CONCLUSIONS

Biochemical markers of placental dysfunction used alone have insufficient accuracy to identify pregnancies ending in SGA or stillbirth. Studies combining U and placental biomarkers are needed to determine whether this approach improves diagnostic accuracy over the use of ultrasound estimation of fetal size or biochemical markers of placental dysfunction used alone. Many of the studies included in this review were carried out between 1974 and 2016. Studies of placental substances were mostly carried out before 1991 and after 2013; earlier studies may not reflect developments in test technology.

Knowledge of Safety, Training, and Practice of Neonatal Cranial Ultrasound: A Survey of Operators

OBJECTIVES

Ultrasound can lead to thermal and mechanical effects in interrogated tissues. This possibility suggests a potential risk during neonatal cranial ultrasound examinations. The aim of this study was to explore safety knowledge and training of neonatal cranial ultrasound among Australian operators who routinely perform these scans.

METHODS

An online survey was administered on biosafety and training in neonatal cranial ultrasound, targeting all relevant professionals who can perform neonatal cranial ultrasound examinations in Australia: namely, radiologists, neonatologists, sonographers, and pediatricians. The survey was conducted between November 2013 and May 2014.

RESULTS

A total of 282 responses were received. Twenty of 208 (10%) answered all ultrasound biosafety questions correctly, and 49 of 169 (29%) correctly defined the thermal index. Two-thirds (134 of 214 [63%]) of respondents failed to recognize that reducing the overall scanning time is the most effective method of reducing the total power exposure. Only 13% (31 of 237) indicated that a predetermined fixed period of training or that a specified minimum number of supervised scans was used during training. The reported number of supervised scans during training was highly variable. Almost half of the participants (82 of 181 [45%]) stated that they had received supervision for 10 to 50 scans (median, 20 scans).

CONCLUSIONS

There is a need to educate operators on biosafety issues and approaches to minimize power outputs and reduce the overall duration of cranial ultrasound scans. Development of standardized training requirements may be warranted.

Ultrasound for fetal assessment in early pregnancy

BACKGROUND

Diagnostic ultrasound is a sophisticated electronic technology, which utilises pulses of high-frequency sound to produce an image. Diagnostic ultrasound examination may be employed in a variety of specific circumstances during pregnancy such as after clinical complications, or where there are concerns about fetal growth. Because adverse outcomes may also occur in pregnancies without clear risk factors, assumptions have been made that routine ultrasound in all pregnancies will prove beneficial by enabling earlier detection and improved management of pregnancy complications. Routine screening may be planned for early pregnancy, late gestation, or both. The focus of this review is routine early pregnancy ultrasound.

OBJECTIVES

To assess whether routine early pregnancy ultrasound for fetal assessment (i.e. its use as a screening technique) influences the diagnosis of fetal malformations, multiple pregnancies, the rate of clinical interventions, and the incidence of adverse fetal outcome when compared with the selective use of early pregnancy ultrasound (for specific indications).

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 March 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

Published, unpublished, and ongoing randomised controlled trials that compared outcomes in women who experienced routine versus selective early pregnancy ultrasound (i.e. less than 24 weeks' gestation). We have included quasi-randomised trials.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We used the Review Manager software to enter and analyse data.

MAIN RESULTS

Routine/revealed ultrasound versus selective ultrasound/concealed: 11 trials including 37,505 women. Ultrasound for fetal assessment in early pregnancy reduces the failure to detect multiple pregnancy by 24 weeks' gestation (risk ratio (RR) 0.07, 95% confidence interval (CI) 0.03 to 0.17; participants = 295; studies = 7), moderate quality of evidence). Routine scans improve the detection of major fetal abnormality before 24 weeks' gestation (RR 3.46, 95% CI 1.67 to 7.14; participants = 387; studies = 2,moderate quality of evidence). Routine scan is associated with a reduction in inductions of labour for 'post term' pregnancy (RR 0.59, 95% CI 0.42 to 0.83; participants = 25,516; studies = 8), but the evidence related to this outcome is of low quality, because most of the pooled effect was provided by studies with design limitation with presence of heterogeneity (I² = 68%). Ultrasound for fetal assessment in early pregnancy does not impact on perinatal death (defined as stillbirth after trial entry, or death of a liveborn infant up to 28 days of age) (RR 0.89, 95% CI 0.70 to 1.12; participants = 35,735; studies = 10, low quality evidence). Routine scans do not seem to be associated with reductions in adverse outcomes for babies or in health service use by mothers and babies. Long-term follow-up of children exposed to scan in utero does not indicate that scans have a detrimental effect on children's physical or cognitive development.The review includes several large, well-designed trials but lack of blinding was a problem common to all studies and this may have an effect on some outcomes. The quality of evidence was assessed for all review primary outcomes and was judged as moderate or low. Downgrading of evidence was based on including studies with design limitations, imprecision of results and presence of heterogeneity.

AUTHORS' CONCLUSIONS

Early ultrasound improves the early detection of multiple pregnancies and improved gestational dating may result in fewer inductions for post maturity. Caution needs to be exercised in interpreting the results of aspects of this review in view of the fact that there is considerable variability in both the timing and the number of scans women received.

Routine ultrasound in late pregnancy (after 24 weeks' gestation)

BACKGROUND

Diagnostic ultrasound is used selectively in late pregnancy where there are specific clinical indications. However, the value of routine late pregnancy ultrasound screening in unselected populations is controversial. The rationale for such screening would be the detection of clinical conditions which place the fetus or mother at high risk, which would not necessarily have been detected by other means such as clinical examination, and for which subsequent management would improve perinatal outcome.

OBJECTIVES

To assess the effects on obstetric practice and pregnancy outcome of routine late pregnancy ultrasound, defined as greater than 24 weeks' gestation, in women with either unselected or low-risk pregnancies.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 May 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

All acceptably controlled trials of routine ultrasound in late pregnancy (defined as after 24 weeks).

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy.

MAIN RESULTS

Thirteen trials recruiting 34,980 women were included in the systematic review. Risk of bias was low for allocation concealment and selective reporting, unclear for random sequence generation and incomplete outcome data and high for blinding of both outcome assessment and participants and personnel. There was no difference in antenatal, obstetric and neonatal outcome or morbidity in screened versus control groups. Routine late pregnancy ultrasound was not associated with improvements in overall perinatal mortality. There is little information on long-term substantive outcomes such as neurodevelopment. There is a lack of data on maternal psychological effects.Overall, the evidence for the primary outcomes of perinatal mortality, preterm birth less than 37 weeks, induction of labour and caesarean section were assessed to be of moderate or high quality with GRADE software. There was no association between ultrasound in late pregnancy and perinatal mortality (risk ratio (RR) 1.01, 95% confidence interval (CI) 0.67 to 1.54; participants = 30,675; studies = eight; I² = 29%), preterm birth less than 37 weeks (RR 0.96, 95% CI 0.85 to 1.08; participants = 17,151; studies = two; I² = 0%), induction of labour (RR 0.93, 95% CI 0.81 to 1.07; participants = 22,663; studies = six; I² = 78%), or caesarean section (RR 1.03, 95% CI 0.92 to 1.15; participants = 27,461; studies = six; I² = 54%). Three additional primary outcomes chosen for the 'Summary of findings' table were preterm birth less than 34 weeks, maternal psychological effects and neurodevelopment at age two. Because none of the included studies reported these outcomes, they were not assessed for quality with GRADE software.

AUTHORS' CONCLUSIONS

Based on existing evidence, routine late pregnancy ultrasound in low-risk or unselected populations does not confer benefit on mother or baby. There was no difference in the primary outcomes of perinatal mortality, preterm birth less than 37 weeks, caesarean section rates, and induction of labour rates if ultrasound in late pregnancy was performed routinely versus not performed routinely. Meanwhile, data were lacking for the other primary outcomes: preterm birth less than 34 weeks, maternal psychological effects, and neurodevelopment at age two, reflecting a paucity of research covering these outcomes. These outcomes may warrant future research.

Handedness in the helsinki ultrasound trial

OBJECTIVES

To determine whether exposure to prenatal ultrasound increases non-right-handedness in boys.

METHODS

The association between exposure to prenatal ultrasound and handedness was tested, using logistic regression analysis, in the Helsinki Ultrasound Trial data. We applied an intention-to-treat approach in this analysis of a subset of 4150 subjects whose parents answered a follow-up questionnaire on handedness when the children were aged 13-15 years.

RESULTS

The odds ratio for non-right-handedness of children who had been exposed to prenatal ultrasound was 1.16 (0.98-1.37) for all subjects, 1.12 (0.89-1.41) for boys and 1.24 (0.97-1.58) for girls.

CONCLUSIONS

We could not confirm the hypothesis that prenatal ultrasound exposure and handedness are associated. Our findings were independent of the particular definition of handedness used, whether it was considered according to the writing hand alone or defined using a laterality quotient.

Ultrasonic imaging: safety considerations

Modern ultrasound imaging for diagnostic purposes has a wide range of applications. It is used in obstetrics to monitor the progress of pregnancy, in oncology to visualize tumours and their response to treatment, and, in cardiology, contrast-enhanced studies are used to investigate heart function and physiology. An increasing use of diagnostic ultrasound is to provide the first photograph for baby's album-in the form of a souvenir or keepsake scan that might be taken as part of a routine investigation, or during a visit to an independent high-street 'boutique'. It is therefore important to ensure that any benefit accrued from these applications outweighs any accompanying risk, and to evaluate the existing ultrasound bio-effect and epidemiology literature with this in mind. This review considers the existing laboratory and epidemiological evidence about the safety of diagnostic ultrasound and puts it in the context of current clinical usage.

Ultrasound for fetal assessment in early pregnancy

BACKGROUND

Diagnostic ultrasound is a sophisticated electronic technology, which utilises pulses of high frequency sound to produce an image. Diagnostic ultrasound examination may be employed in a variety of specific circumstances during pregnancy such as after clinical complications, or where there are concerns about fetal growth. Because adverse outcomes may also occur in pregnancies without clear risk factors, assumptions have been made that routine ultrasound in all pregnancies will prove beneficial by enabling earlier detection and improved management of pregnancy complications. Routine screening may be planned for early pregnancy, late gestation, or both. The focus of this review is routine early pregnancy ultrasound.

OBJECTIVES

To assess whether routine early pregnancy ultrasound for fetal assessment (i.e. its use as a screening technique) influences the diagnosis of fetal malformations, multiple pregnancies, the rate of clinical interventions, and the incidence of adverse fetal outcome when compared with the selective use of early pregnancy ultrasound (for specific indications).

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (September 2009).

SELECTION CRITERIA

Published, unpublished, and ongoing randomised controlled trials that compared outcomes in women who experienced routine versus selective early pregnancy ultrasound (i.e. less than 24 weeks' gestation). We have included quasi-randomised trials.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data for each included study. We used the Review Manager software to enter and analyse data.

MAIN RESULTS

Routine/revealed ultrasound versus selective ultrasound/concealed: 11 trials including 37505 women. Ultrasound for fetal assessment in early pregnancy reduces the failure to detect multiple pregnancy by 24 weeks' gestation (risk ratio (RR) 0.07, 95% confidence interval (CI) 0.03 to 0.17). Routine scan is associated with a reduction in inductions of labour for 'post term' pregnancy (RR 0.59, 95% CI 0.42 to 0.83). Routine scans do not seem to be associated with reductions in adverse outcomes for babies or in health service use by mothers and babies. Long-term follow up of children exposed to scan in utero does not indicate that scans have a detrimental effect on children's physical or cognitive development.

AUTHORS' CONCLUSIONS

Early ultrasound improves the early detection of multiple pregnancies and improved gestational dating may result in fewer inductions for post maturity. Caution needs to be exercised in interpreting the results of aspects of this review in view of the fact that there is considerable variability in both the timing and the number of scans women received.

WITHDRAWN: Ultrasound for fetal assessment in early pregnancy

BACKGROUND

Advantages of early pregnancy ultrasound screening are thought to be more accurate calculation of gestational age, earlier identification of multiple pregnancies, and diagnosis of non-viable pregnancies and certain fetal malformations.

OBJECTIVES

The objective of this review was to assess the use of routine (screening) ultrasound compared with the selective use of ultrasound in early pregnancy (ie before 24 weeks).

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register (up to June 2001) were searched.

SELECTION CRITERIA

Adequately controlled trials of routine ultrasound imaging in early pregnancy.

DATA COLLECTION AND ANALYSIS

One reviewer assessed trial quality and extracted data. Study authors were contacted for additional information.

MAIN RESULTS

Nine trials were included. The quality of the trials was generally good. Routine ultrasound examination was associated with earlier detection of multiple pregnancies (twins undiagnosed at 26 weeks, odds ratio 0.08, 95% confidence interval 0.04 to 0.16) and reduced rates of induction of labour for post-term pregnancy (odds ratio 0.61, 95% confidence interval 0.52 to 0.72). There were no differences detected for substantive clinical outcomes such as perinatal mortality (odds ratio 0.86, 95% confidence interval 0.67 to 1.12). Where detection of fetal abnormality was a specific aim of the examination, the number of terminations of pregnancy for fetal anomaly increased.

AUTHORS' CONCLUSIONS

Routine ultrasound in early pregnancy appears to enable better gestational age assessment, earlier detection of multiple pregnancies and earlier detection of clinically unsuspected fetal malformation at a time when termination of pregnancy is possible. However, the benefits for other substantive outcomes are less clear.

Safety of ultrasonography in pregnancy: WHO systematic review of the literature and meta-analysis

OBJECTIVE

In the context of the planned International Society of Ultrasound in Obstetrics and Gynecology-World Health Organization multicenter study for the development of fetal growth standards for international application, we conducted a systematic review and meta-analysis to evaluate the safety of human exposure to ultrasonography in pregnancy.

METHODS

A systematic search of electronic databases, reference lists and unpublished literature was conducted for trials and observational studies that assessed short- and long-term effects of exposure to ultrasonography, involving women and their fetuses exposed to ultrasonography, using B-mode or Doppler sonography during any period of pregnancy, for any number of times. The outcome measures were: (1) adverse maternal outcome; (2) adverse perinatal outcome; (3) abnormal childhood growth and neurological development; (4) non-right handedness; (5) childhood malignancy; and (6) intellectual performance and mental disease.

RESULTS

The electronic search identified 6716 citations, and 19 were identified from secondary sources. A total of 61 publications reporting data from 41 different studies were included: 16 controlled trials, 13 cohort and 12 case-control studies. Ultrasonography in pregnancy was not associated with adverse maternal or perinatal outcome, impaired physical or neurological development, increased risk for malignancy in childhood, subnormal intellectual performance or mental diseases. According to the available clinical trials, there was a weak association between exposure to ultrasonography and non-right handedness in boys (odds ratio 1.26; 95% CI, 1.03-1.54).

CONCLUSION

According to the available evidence, exposure to diagnostic ultrasonography during pregnancy appears to be safe.

Screening for Congenital Abnormalities

Improvements in nutrition, sanitation, housing, and medical care have been associated with reductions in infectious diseases of infancy, such as diarrhea, and, concomitantly, with a decline in infant mortality. Although deaths from congenital abnormalities have also decreased, the rate of their decline has not kept pace with the overall rate. Thus in the United States they have become the most frequent cause of infant death (58). For abnormalities detected in the newborn period, which comprise 3% of all births, about 8 per cent are due to single gene disorders, 6 to 12% to chromosome abnormalities, and less than 5% to viral infections of the mother (39,69). Little is known about underlying causes in the remainder; polygenic factors, environmental agents, and, probably the most common, genetic-environmental interactions, account for them. Congenital abnormalities also contribute substantially to childhood hospitalizations in several developed countries (17). One chromosome disorder, Down's syndrome, accounts for about 16 to 30% of all severe mental retardation, with other genetic and chromosome disorders contributing another 15 to 20% (58). Although the incidence of congenital abnormalities differs to some extent geographically (39), it seems likely that as any country develops, the proportion of infant mortality and childhood disability due to congenital abnormalities will increase.

Inter- and intra-observer variability in Sonographic measurements of the cross-sectional diameters and area of the umbilical cord and its vessels during pregnancy

BACKGROUND

The purpose of the study was to evaluate inter- and intra-observer variability in sonographic measurements of the cross-sectional area of the umbilical cord and the diameters of its vessels in low-risk pregnancies of 12 to 40 weeks of gestation.

METHODS

A prospective cross sectional study was performed in 221 pregnant women at different gestational ages. Measurements were carried out also by a second observer to evaluate inter-observer variability and repeated once again by the first observer to assess intra-observer variability. The linear correlation between the measurements (Spearman's coefficient of correlation) and their reliability through the intraclass correlation coefficient (ICC), the Cronbach's alpha coefficient and the limits of agreement proposed by Bland and Altman were evaluated.

RESULTS

The results showed that inter-observer and intra-observer variability did not show any significant difference between examiners. A good linear correlation between the measurements and reliability was obtained, with values of R, ICC and Cronbach's alpha all above the standard limits.

CONCLUSION

It is possible to conclude that inter- and intra-observer variability in the measurements of the umbilical cord and its vessels was small; their reliability and agreement were good.

Routine ultrasound in late pregnancy (after 24 weeks' gestation)

BACKGROUND

Diagnostic ultrasound is used selectively in late pregnancy where there are specific clinical indications. However, the value of routine late pregnancy ultrasound screening in unselected populations is controversial. The rationale for such screening would be the detection of clinical conditions which place the fetus or mother at high risk, which would not necessarily have been detected by other means such as clinical examination, and for which subsequent management would improve perinatal outcome.

OBJECTIVES

To assess the effects on obstetric practice and pregnancy outcome of routine late pregnancy ultrasound, defined as greater than 24 weeks' gestation, in women with either unselected or low-risk pregnancies.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (February 2008).

SELECTION CRITERIA

All acceptably controlled trials of routine ultrasound in late pregnancy (defined as after 24 weeks).

DATA COLLECTION AND ANALYSIS

All three review authors were involved in assessing trial quality and data extraction.

MAIN RESULTS

Eight trials recruiting 27,024 women were included. The quality of trials overall was satisfactory. There was no difference in antenatal, obstetric and neonatal intervention or morbidity in screened versus control groups. There was a slightly higher caesarean section rate in the screened group, but this difference did not reach statistical significance. Routine late pregnancy ultrasound was not associated with improvements in overall perinatal mortality. Placental grading as an adjunct to third trimester examination scan was associated with a significant reduction in the stillbirth rate in the one trial that assessed it. There is little information on long-term substantive outcomes such as neurodevelopment. There is a lack of data on maternal psychological effects.

AUTHORS' CONCLUSIONS

Based on existing evidence, routine late pregnancy ultrasound in low-risk or unselected populations does not confer benefit on mother or baby. It may be associated with a small increase in caesarean section rates. There is a lack of data about the potential psychological effects of routine ultrasound in late pregnancy, and limited data about its effects on both short- and long-term neonatal and childhood outcome. Placental grading in the third trimester may be valuable, but whether reported results are reproducible remains to be seen, and future research of late pregnancy ultrasound should include evaluation of placental textural assessment.

WITHDRAWN: Routine ultrasound in late pregnancy (after 24 weeks' gestation)

BACKGROUND

Diagnostic ultrasound is used selectively in late pregnancy where there are specific clinical indications. However, the value of routine late pregnancy ultrasound screening in unselected populations is controversial. The rationale for such screening would be the detection of clinical conditions which place the fetus or mother at high risk, which would not necessarily have been detected by other means such as clinical examination, and for which subsequent management would improve perinatal outcome.

OBJECTIVES

To assess the effects on obstetric practice and pregnancy outcome of routine late pregnancy ultrasound, defined as greater than 24 weeks gestation, in women with either unselected or low risk pregnancies.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group Specialised Register of Controlled Trials and the Cochrane Controlled Trials Register were searched.

SELECTION CRITERIA

All acceptably controlled trials of routine ultrasound in late pregnancy (defined as after 24 weeks).

DATA COLLECTION AND ANALYSIS

The principal reviewer assessed trial quality and extracted data, under supervision of the co-reviewer.

MAIN RESULTS

Seven trials recruiting 25,036 women were included. The quality of trials overall was satisfactory. There was no difference in antenatal, obstetric and neonatal intervention or morbidity in screened versus control groups. Routine late pregnancy ultrasound was not associated with improvements in overall perinatal mortality. Placental grading as an adjunct to third trimester examination scan was associated with a significant reduction in the stillbirth rate in the one trial that assessed it. There is a lack of data with regard to long term substantive outcomes such as neurodevelopment. There is a lack of data on maternal psychological effects.

AUTHORS' CONCLUSIONS

Based on existing evidence, routine late pregnancy ultrasound in low risk or unselected populations does not confer benefit on mother or baby. There is a lack of data about the potential psychological effects of routine ultrasound in late pregnancy, and the effects on both short and long term neonatal and childhood outcome. Placental grading in the third trimester may be valuable, but whether reported results are reproducible remains to be seen, and future research of late pregnancy ultrasound should include evaluation of placental textural assessment.

Information, knowledge and expectations of the routine ultrasound scan

OBJECTIVE

To examine the current provision of pre-ultrasound information to women; to determine if the information provided was related to women's knowledge of the routine second trimester ultrasound; and to describe women's expectations of the scan.

DESIGN

A descriptive survey, before and after design.

SETTING

Tertiary referral centre in the Republic of Ireland.

PARTICIPANTS

A convenience sample of pregnant women attending for routine second trimester ultrasound scan.

MEASUREMENTS

Self-report questionnaires were used to explore the availability of information about the test, the extent of women's knowledge and expectations of the examination, and the degree to which expectations were achieved.

FINDINGS

Most women received little information from health professionals about the capability and limitations of the scan, and had expectations that exceeded the purpose and ability of the examination. Most women, however, stated that their expectations were met in most cases. Although the routine ultrasound in the study site is not a targeted fetal anatomical survey, most women were concerned with this aspect of the test.

KEY CONCLUSIONS

If women are to have realistic expectations of the routine ultrasound scan, then improvements are required in the provision of pre-ultrasound information, particularly in relation to the technological limitations of the examination. Consideration should be given to the context of the high appeal associated with visualising the fetus for women when unachievable expectations are reported as having been met.

IMPLICATIONS FOR PRACTICE

Any development of prenatal screening programmes that will uncover fetal abnormalities needs to be considered in context, in particular when termination of pregnancy is not available within the jurisdiction. Women had expectations of the examination that could not, because of technological limitations, have been met by the examination, but which they perceived to have been met. Knowledge of the purpose, capabilities and limitations of the routine second trimester ultrasound scan was not influenced by the mode of information provision.

Epidemiological prenatal ultrasound studies

Epidemiological studies have indicated no association between diagnostic ultrasound exposure during pregnancy and childhood malignancies. Diagnostic ultrasound imaging does not seem to influence birth weight, whereas frequent Doppler ultrasound was associated with reduced birth weight in one study. Most experts do not believe that ultrasound exposure during pregnancy is associated with reduced birth weight. There are no confirmed statistically significant associations between ultrasound and dyslexia and neurological development during childhood. However, two randomised controlled trials and two cohort studies have been unable to rule out a possible association between ultrasound and left-handedness among males.

Rapporteur report: Epidemiology

Three talks were presented in the session on "Epidemiology". The first talk was a review of prenatal studies. The second talk presented epidemiological evidence from prenatal studies. The third talk presented general issues regarding the planning of an epidemiological study. It was noted that epidemiological studies of prenatal exposures use data from the early 1980s when ultrasound was first introduced for foetal scans. These studies did not show associations between prenatal ultrasound scanning and childhood cancer, reduced birth weight, impaired childhood growth or neurological development in childhood. However, there was a possible association between prenatal ultrasound scanning and left-handedness in boys. The aetiology of this association remains uncertain.

Routine ultrasound screening in the third trimester: a population-based study

BACKGROUND

No population-based study has evaluated the effects of third trimester ultrasound screening on prognosis.

OBJECTIVE

To study the effects of routine ultrasound screening in the third trimester on perinatal/infant mortality, prevalence of small for gestational age infants (SGA) and low Apgar score.

STUDY DESIGN

Two university clinics using routine ultrasound screening in the third trimester were compared with seven county or district hospitals with no routine screening. Deliveries between 1985 and 1996 were included. In all, 16 municipalities including 56 371 pregnancies with routine screening were compared with 59 municipalities and 153 355 pregnancies without third trimester screening. An observational design was applied, using data stored during pregnancy, delivery, and during the first year (infant mortality) at the Swedish Medical Birth Registry, The National Board of Health and Welfare. Odds ratio with 95% confidence interval was used in the evaluation. End-points included incidence of SGA, perinatal/infant mortality, Apgar score at 5 min, cesarean section and instrumental delivery in areas with versus without routine third trimester screening.

RESULTS

No significant difference was seen in the prevalence of the most extreme SGA (< -3 SD from the mean), perinatal complications including cesarean section or instrumental delivery, or perinatal/infant mortality between units with versus without routine ultrasound screening in the third trimester.

CONCLUSION

Added to the findings of previous small randomized studies, it seems as if routine third trimester ultrasound screening in an unselected population does not reduce perinatal mortality or early neonatal morbidity, expressed as Apgar scores or SGA.

Is an excessive number of prenatal echographies a risk for fetal growth?

AIM

To assess whether a very high number of prenatal ultrasonographies affects birthweight.

POPULATION AND METHODS

We studied 1203 consecutive women who delivered in Siena Hospital. Exclusion criteria were the following: twin pregnancy, maternal smoke or alcohol ingestion in pregnancy, gestational diabetes, placenta or umbilical cord defects, gestational age at birth <37 weeks, and major malformations. We analysed birthweights in relation to the number of ultrasound examinations. 120 women had undergone a minimum number (three or less-base group) and 167 a maximum number (nine or more-intensive group) of fetal US scans. We compared the birthweight of the children born in these two groups and the correlation between number of US scans and birthweight in the whole population.

RESULTS

Mean birthweights of the base and the intensive groups were 3389.5+/-434 g and 3268+/-438 g, respectively (p=0.0206). Nevertheless, the regression study did not show a significant correlation between birthweight and number of US scans. The mean age of the base group was 30.1+/-5.3 years and that of the intensive group was 32.09+/-4.99 years (p=0.0018). Eighteen women of base group underwent amniocenteses vs. 71 in the intensive group (p<0.001). In the base group 57.5% of the mothers had low school level vs. 24.4% in the intensive group (p<0.01).

CONCLUSION

More studies are needed to confirm or exclude any relationship between an intensive use of prenatal ultrasounds and birthweight, and to exclude other effects of ultrasounds on children's health. Moreover, our study shows an excess of prenatal diagnostic procedures, the causes of which should be investigated.

The evolving role of ultrasound in obstetrics/gynecology practice

The value of ultrasound examinations depends heavily on the preparation of the personnel carrying out the examination and the technical capabilities of the equipment they use. Only well-organized regional or national programs are able to provide high level, cost-effective care based on certification of quality. Such certification must include the training of professionals, the definition of competence levels, accreditation of laboratories and the establishment of professional protocols. Together, these factors can guarantee the standard of care and provide legal protection for practitioners. It is worth carrying out routine screening in each pregnancy because the majority of abnormalities occur in pregnancies with low risk. Abnormalities detected on screening cases and the examination of high risk groups should be referred to higher level centers. Here, appropriate technical background and qualified personnel are present to provide cost-effective care. At the same time, necessary invasive interventions can also be performed. A minimum of three screening tests should be performed during pregnancy. The first should be performed at the fetal age of 10-14 weeks to detect abnormalities and pathological conditions in early pregnancy. The second one has to be performed between the fetal ages of 18 and 22 weeks to assess detailed fetal anatomy and rate of development. The third should be performed between the fetal age of 30 and 34 weeks to assess fetal anatomy, rate of development, placentation and circulation. It is worth considering a fourth screening at approximately 36-38 weeks to assess the intrauterine condition of the fetus and determine the appropriate method of delivery. Finally, besides improving the standard of living, education, and hygienic conditions in developing countries, developed countries also have to help improve the standard of pregnancy care. Within this context, the dissemination of diagnostic ultrasound must be given special emphasis.

EFSUMB: safety tutorial: epidemiology of diagnostic ultrasound exposure during pregnancy-European committee for medical ultrasound safety (ECMUS)

The present paper summarizes some of the epidemiological studies of in utero ultrasound exposure and subsequent childhood development. Emphasis is placed on birth weight, childhood malignancies, neurological development, handedness and speech development. The epidemiological evidence does not indicate any association between diagnostic ultrasound exposure during pregnancy and reduced birth weight, childhood malignancies or neurological development. However, a statistically significant association between ultrasound and left-handedness among males has been found in three studies. Thus, there is still need for more research.

Discrepancies among megatrials

The validity of meta-analyses has recently been examined by comparing their results with those of megatrials on the same topic. We investigated the reliability of this gold standard by identifying megatrials, defined as ones involving more than 1000 subjects, in the recent issue of the Cochrane Library and in the article by LeLorier et al. (N Engl J Med 1997;337:536-42). In the former set, 289 pairs of megatrials were identified which studied the same patient-intervention-outcome combinations. Of these, 210 (73%, 95% CI: 67-77%) reported odds ratios or weighted mean differences that were not statistically significantly different from each other. The agreement of statistical conclusions regarding outcomes was a quadratic weighted kappa of 0.40 (95% CI: 0.29-0.51). The article by LeLorier et al. yielded 133 comparisons, of which 97 (73%, 95% CI: 64-79%) reported mutually compatible odds ratios. The agreement of statistical conclusions was a kappa of 0.33 (95% CI: 0.18-0.47). Agreement among megatrials was approximately as large as that reported between meta-analyses and megatrials. These findings suggest that taking megatrials as the gold standard can be problematic and that there is no substitute for clear and hard thinking for any study, be it a meta-analysis or a megatrial.

A discrepancy between gestational age estimated by last menstrual period and biparietal diameter may indicate an increased risk of fetal death and adverse pregnancy outcome

OBJECTIVE

To determine if the discrepancy between gestational age estimated by last menstrual period and by biparietal diameter (GALMP - GABPD) is associated with adverse pregnancy outcome.

DESIGN

Population-based follow up study.

POPULATION

Singleton pregnancies were studied when a reliable date of last menstrual period and biparietal diameter measured between 12 and 22 weeks of gestation was available (n = 16,469).

METHODS

Logistic regression analysis and Kaplan-Meier survival analysis were used to analyse the association between GALMP - GABPD and adverse pregnancy outcome.

MAIN OUTCOME MEASURES

Adverse outcome was defined as abortion after 12 weeks of gestation, still-birth or postnatal death within one year of birth, delivery < 37 weeks of gestation, a birthweight < 2,500 g or a sex-specific birthweight lower than 22% below the expected.

RESULTS

The risk of death was more than doubled if GALMP - GABPD of > or = 8 days was compared with GALMP - GABPD of < 8 days (OR 2.2; 95% CI 1.6-3.1). The risk of death was a factor of 6.1 higher if GALMP - GABPD of > or = 8 days was combined with increased (> 2 x multiple of median) maternal alpha-fetoprotein measured in the 2nd trimester.

CONCLUSIONS

A discrepancy between GALMP and GABPD generally reflects the precision of the two methods used to predict term pregnancy. However, a positive discrepancy of more than seven days, particularly with high maternal alpha-fetoprotein, might indicate intrauterine growth retardation and an increased risk of adverse perinatal outcome.

Ultrasound for fetal assessment in early pregnancy

BACKGROUND

Advantages of early pregnancy ultrasound screening are thought to be more accurate calculation of gestational age, earlier identification of multiple pregnancies, and diagnosis of non-viable pregnancies and certain fetal malformations.

OBJECTIVES

The objective of this review was to assess the use of routine (screening) ultrasound compared with the selective use of ultrasound in early pregnancy (ie before 24 weeks).

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register (up to July 1998) were searched.

SELECTION CRITERIA

Adequately controlled trials of routine ultrasound imaging in early pregnancy.

DATA COLLECTION AND ANALYSIS

One reviewer assessed trial quality and extracted data. Study authors were contacted for additional information.

MAIN RESULTS

Nine trials were included. The quality of the trials was generally good. Routine ultrasound examination was associated with earlier detection of multiple pregnancies (twins undiagnosed at 26 weeks, odds ratio 0.08, 95% confidence interval 0.04 to 0.16) and reduced rates of induction of labour for post-term pregnancy (odds ratio 0. 61, 95% confidence interval 0.52 to 0.72). There were no differences detected for substantive clinical outcomes such as perinatal mortality (odds ratio 0.86, 95% confidence interval 0.67 to 1.12). Where detection of fetal abnormality was a specific aim of the examination, the number of terminations of pregnancy for fetal anomaly increased.

REVIEWER'S CONCLUSIONS

Routine ultrasound in early pregnancy appears to enable better gestational age assessment, earlier detection of multiple pregnancies and earlier detection of clinically unsuspected fetal malformation at a time when termination of pregnancy is possible. However the benefits for other substantive outcomes are less clear.

Routine ultrasound in pregnancy

The interest in studying routine ultrasound in pregnancy has provided useful results that can be applied to practice. There is no consistent evidence of risk caused by ultrasound, neither biologic risk for the fetus nor increased use of health services as a result of ascertained conditions. There is also no consistent benefit to routine ultrasound in terms of important health outcomes. In the United States, this finding may be related to the excellent care provided to women in the usual-care arm of trials and possibly also to practice patterns. For example, with a high background induction rate in the United States, the prevalence of perinatal morbidity from post-term pregnancy may be so low that differences could not be ascertained between routine-ultrasound and usual care arms of the RADIUS study. The evidence from the use of ultrasound to screen for anomalies reveals substantial concern regarding interobserver variability, as might be expected when using a test for screening that requires considerable skill. The range of observed sensitivities underscores the disadvantages of performing basic ultrasound on a routine basis rather than on selected patients. Because routine ultrasound can reduce perinatal deaths in a population of women who would consider pregnancy termination, pretest counseling may identify a subset of women for whom screening may be effective in improving health outcomes. This remains to be demonstrated in the United States.

Ultrasound during pregnancy and birthweight, childhood malignancies and neurological development

The present paper summarizes some of the epidemiological studies of in utero ultrasound exposure and subsequent childhood development. Emphasis is placed on birthweight, childhood malignancies and neurological development. A meta-analysis, including neurological outcomes such as handedness, speech development, motor development, hearing and vision, is presented. The epidemiological evidence does not indicate any association between diagnostic ultrasound exposure during pregnancy and reduced birthweight, childhood malignancies or neurological maldevelopment. The possible association between ultrasound and nonrighthandedness among boys needs further evaluation.

Obstetric sonography. Who to scan, when to scan, and by whom

Most patients in the United States have an indication for and receive sonography during pregnancy. The issue of routine sonography for low-risk women continues to be contentious even though the randomized trials have not been able to demonstrate a clear benefit. Clinics that routinely offer sonography for all pregnancies usually schedule such a procedure at 16 to 20 weeks of gestation. Although great progress is being made in the first-trimester diagnoses of congenital anomalies, most targeted studies are performed at 18 to 20 weeks of gestation. Although many private obstetricians perform in-office sonography, the highest rates of detection of congenital anomalies are seen in tertiary care settings such as a university medical center. In difficult or otherwise high-risk cases, a consulting perinatologist is commonly the physician most likely to integrate the ultrasound findings with a rational management plan for the remainder of the pregnancy and for delivery.

Can decision analysis help us decide whether ultrasound screening for fetal anomalies is worth it?

Decision analysis is a widely used tool to improve clinical decision making when randomized controlled trials are infeasible, underpowered, or lack generalizability. We performed an exploratory decision analysis of routine second trimester ultrasound to detect fetal anomalies, focusing on the assumptions that would have the greatest impact. Six outcome categories were considered: (1) abnormal ultrasound, anomalous child, (2) abnormal ultrasound, elective abortion of anomalous fetus, (3) abnormal ultrasound, healthy child, (4) abnormal ultrasound, elective abortion of healthy fetus, (5) normal ultrasound, healthy child, and (6) normal ultrasound, anomalous child. Live birth and fetal death rates for nine sonographically detectable anomalies were obtained from the California Birth Defects Monitoring Program. The sensitivity and specificity of ultrasound were estimated through meta-analysis of recent series. Plausible ranges for the probabilities of cesarean delivery and elective abortion, by anomaly, were determined through review of the literature. Standard gamble, willingness-to-pay, and human capital estimates of utility were rescaled for comparability. We found that routine ultrasound appears to be the preferred strategy for most women. This choice is sensitive primarily to the specificity of ultrasound and women's willingness-to-pay for the reassurance of a normal ultrasound.

Routine obstetric ultrasound examinations in South Africa: cost and effect on perinatal outcome--a prospective randomised controlled trial

OBJECTIVE

To compare routine midtrimester with selective obstetric ultrasonography concerning the Health Service cost and the effect on perinatal outcome.

DESIGN

A randomised controlled trial.

SETTING

Urban area served by Tygerberg Hospital, a tertiary referral centre in South Africa.

PARTICIPANTS

Pregnant patients without risk factors for congenital anomalies referred for ultrasonography between 18 and 24 weeks of gestation.

INTERVENTION

Between 18 and 24 weeks, a level one ultrasound examination was performed on study patients only. Except for the routine scan, both groups received the same antenatal care and could be referred later for additional scans as judged by their clinicians.

MAIN OUTCOME MEASURES

Overall adverse perinatal outcome and use of antenatal and neonatal services.

RESULTS

The groups did not differ significantly in their use of antenatal and neonatal services except for a greater number of ultrasound scans in the study group. More suspected postdate pregnancies occurred in control patients, as well as more amniocenteses for confirmation of lung maturity. More babies of low birthweight were born in the study group. The incidence of overall or major adverse perinatal outcome was comparable. Routine ultrasonography was accompanied by a considerable increase in costs.

CONCLUSION

Selective use of obstetric ultrasonography did not increase the use of antenatal and neonatal services. Not routinely performing ultrasonography has led to considerable Health Service savings without increasing the risk for adverse perinatal outcome. It saved 75% of selected patients a referral to an ultrasound unit. Specific problems related to inaccurate gestational age determination need to be addressed.

Standards for ultrasound fetal growth velocity

OBJECTIVES

An ultrasound study to establish the nature and limits of fetal growth in a low risk population from 22 weeks of gestation until term.

DESIGN

Prospective, longitudinal ultrasound study of 274 low risk pregnancies involving organised scanning schedules with all measurements performed by one observer using the same equipment.

RESULTS

Growth velocity charts have been created for a number of ultrasound parameters including estimated fetal weight, by applying appropriate statistical methods to the serial data. The rates of growth of the biparietal diameter, femur length, abdominal area and estimated weight each have characteristic patterns demonstrating maximal growth rates at different gestations.

CONCLUSIONS

Appropriately derived and calculated ultrasound fetal growth velocity standards have been established. These data are suitable for the evaluation of ultrasonically estimated fetal growth rates in the prediction of adverse perinatal outcome and the further investigation of the role of the intrauterine environment in the origin of adult disease.

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

The aim of the present study was to assess the sensitivity of ultrasound diagnosis used as a screening test in detecting major congenital anomalies in the prenatal period in a large nation-based multicentre setting. Data from the IPIMC register were collected in the period 1986-1990. One hundred and thirty-five hospitals, located in 17 out of the 20 regions in Italy, participated in the register. Study cases were 3479 infants with major congenital anomalies diagnosed at birth or in the first week of life. Subjects with chromosomal anomalies or multiple defects were excluded. The sensitivity of ultrasound prenatal diagnosis was 49.5 per cent for central nervous system anomalies, 3.8 per cent for congenital heart diseases, 17.1 per cent for gastrointestinal tract defects, 46.6 per cent for abdominal wall defects, 74.8 per cent for urinary tract anomalies, and 22.9 per cent for skeletal abnormalities. The detection rate for diaphragmatic hernia was 24.2 per cent. Overall, only 18 per cent of the defects diagnosed in utero were detected before 24 weeks' gestation. The sensitivity of prenatal diagnosis was 30.1 and 19.0 per cent in the northern, central, and southern regions, respectively. In light of its low sensitivity, ultrasonography as a screening test in the general population should be abandoned, although some improvement in its performance should be expected following adequate training of the ultrasound staff and the use of good technical equipment.

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.

Routine obstetric ultrasound

A detailed review of the literature reveals that routine obstetric ultrasound has value in providing more accurate gestational dating and in the diagnosis of fetal anomalies. The recent RADIUS study, which has concluded that routine obstetric ultrasound is of no clinical benefit, is critically analyzed, focusing on four areas: the applicability of the results to the general population, the appropriateness of the outcome parameters, the quality of the ultrasound provided, and the issue of excessive cost. Finally, an ethical analysis of the role of routine obstetric ultrasonography is provided, focusing on the principles of beneficence and respect for autonomy. The offering obstetric ultrasound is necessary in both beneficence-based and autonomy-based ethical analyses, and the use of routine ultrasound is supported from an analysis of the scientific data.

Prediction of birth weight by ultrasound-estimated fetal weight: a comparison between single and repeated estimates

OBJECTIVES

Ultrasound estimation of fetal weight is used for diagnosing intrauterine growth retardation. The aim of the present study was to assess the accuracy of birth weight prediction by use of a single or repeated estimations of fetal weight in the third trimester.

STUDY DESIGN

1000 pregnant women considered at risk were scheduled to ultrasound estimation of fetal weight, using Warsof's formula, at 28, 31, 34 and 37 weeks of gestation. The 421 pregnancies with term delivery and complete set of ultrasound examinations and 57 pregnancies with preterm delivery with ultrasound examination at 16 and 28 weeks and once more before delivery were included in the present analysis.

RESULTS

The accuracy of birth weight prediction improved significantly for every three weeks from 28 to 37 weeks of gestation in the term infants. Prediction based on the average of repeated weight estimates or linear extrapolation from two estimates or extrapolation by a second order polynomium fitted to four estimates did not improve accuracy compared to prediction based on the last estimate before delivery.

CONCLUSION

When more than one ultrasound estimation of fetal weight are available, prediction of birth weight in relation to gestational age should be based on the last ultrasound examination only.

The accuracy of prenatal ultrasonography in detecting congenital anomalies

OBJECTIVES

The purpose of this study was to evaluate the accuracy of prenatal ultrasonography in detecting congenital anomalies.

STUDY DESIGN

We studied all singleton births or fetal deaths with one or more congenital defects delivered during the study period who had had one or more ultrasonographic examinations performed at or after 16 weeks' gestation and a random sample of defect-free newborns similarly examined by ultrasonography. Congenital anomalies reported on either the infants' postdelivery medical record or the fetal autopsy report were our standard. Prenatal ultrasonographic findings reported during gestation and therefore "blind" to the postdelivery outcome were then compared with the standard.

RESULTS

The overall sensitivity of ultrasonography in detecting defects was 53%. The overall specificity was 99%. Ultrasonography proved to be highly sensitive (89%) for prevalent lethal malformations. However, serious cardiac defects, microcephalus, and many musculoskeletal deformities were missed by ultrasonography.

CONCLUSION

Ultrasonography is sensitive in detecting many lethal malformations. However, a negative prenatal ultrasonographic examination does not provide absolute assurance that a fetus is defect free.

The value of sonographic diagnosis of fetal malformations: different results between indication-based and screening-based investigations

The advantages of a routine screening or indication-based ultrasound investigation during pregnancy are still under debate. This is the first study where both methods are compared in two different time periods. More malformations were diagnosed before the 24th week of gestation by means of screening-based than indication-based investigation (18 per cent vs. 5 per cent, P < 0.005), and before 28 weeks in 26 per cent compared with 15 per cent respectively (P < 0.01). Twenty-six per cent of all malformations were detected by means of screening-based investigations as opposed to 15 per cent by means of indication-based scans. Primary fetal malformations were also diagnosed much earlier (25 weeks vs. 30 weeks). Except for the fetal head, the detection rate of malformations was higher in nearly all other body regions of the fetus in the screening-based investigation. The most important advantage of a screening-based ultrasound investigation during pregnancy is to detect the malformations early enough in pregnancy for possible intrauterine treatment or to offer safe termination of pregnancy for the woman, at least for those anomalies that are lethal or significantly handicapping.

The value of routine early pregnancy ultrasound in the antenatal booking clinic

The value of routine antenatal booking ultrasound as an adjunct to, or as an alternative to the 18 to 20 week ultrasound, is not known. A study into the possible benefits of routine antenatal booking ultrasound was undertaken. One year's experience, involving 1,372 scans is described. The main medical benefits include the establishment or correction of gestational age (41.7% of all pregnancies) and the identification of multiple pregnancies (0.7%), nonviable pregnancies (1.4%) and other pregnancies requiring specialist antenatal clinic referral (0.7%), resulting in a total of 44.5% of patients in whom some benefit was obtained.

Techniques in current use in prenatal diagnosis

Prenatal diagnosis is now offered to the majority of pregnant women in Europe and the United States. Advances in obstetric and laboratory techniques mean that increasing numbers of conditions can be diagnosed prenatally; indeed, gene carriers can be identified before pregnancy in some cases. Current obstetric and laboratory techniques for prenatal screening and diagnosis of genetic disorders are discussed.

A randomized controlled trial in a hospital population of ultrasound measurement screening for the small for dates baby

Poor fetal growth is an important cause of perinatal mortality and morbidity. Based on the hypothesis that early diagnosis of fetal growth problems leads to more appropriate management and therefore, improved outcome, a randomized controlled trial of ultrasound measurement was performed on 1,528 women booked through a hospital antenatal clinic. This compared a number of perinatal outcomes between the group who had a routine 2-stage examination (early dating and 34-week scan) and a group who had only a dating scan and then additional scans as generated by their clinical situations. No significant differences could be found between the groups when these perinatal outcomes were considered. These results mirror previously published randomized controlled trials. Selection of women for third trimester ultrasound examination for suspected fetal growth problems should be based on careful clinical assessment and should not be routine.

Effects of frequent ultrasound during pregnancy: a randomised controlled trial

Despite widespread application of ultrasound imaging and Doppler blood flow studies, the effects of their frequent and repeated use in pregnancy have not been evaluated in controlled trials. From 2834 women with single pregnancies at 16-20 weeks gestation, 1415 were selected at random to receive ultrasound imaging and continuous-wave Doppler flow studies at 18, 24, 28, 34, and 38 weeks gestation (the intensive group) and 1419 to receive single ultrasound imaging at 18 weeks (the regular group). Outcome data was obtained from 99% of women who entered the study. The only difference between the two groups was significantly higher intrauterine growth restriction in the intensive group, when expressed both as birthweight < 10th centile (relative risk 1.35; 95% confidence interval 1.09 to 1.67; p = 0.006) and birthweight < 3rd centile (relative risk 1.65; 95% confidence intervals 1.09 to 2.49; p = 0.020). While it is possible that this finding was a chance effect, it is also plausible that frequent exposure to ultrasound may have influenced fetal growth. Repeated prenatal ultrasound imaging and Doppler flow examinations should be restricted to those women to whom the information is likely to be of clinical benefit.

A randomized trial of prenatal ultrasonographic screening: impact on maternal management and outcome. RADIUS (Routine Antenatal Diagnostic Imaging with Ultrasound) Study Group

OBJECTIVES

This randomized clinical trial of 15,530 women was designed to test the hypothesis that screening ultrasonography in low-risk pregnancies would improve perinatal outcome. A secondary hypothesis addressed in this article was that screening ultrasonography would have a favorable impact on maternal management or outcome.

STUDY DESIGN

Pregnant women without a specific indication for ultrasonographic examination in early pregnancy were randomly assigned to have either two screening sonograms or conventional obstetric care. Pregnancy interventions and maternal outcomes were compared in the two groups.

RESULTS

No significant differences were found in maternal outcomes. Use of ultrasonography was markedly higher in the screened group. The rates of induced abortion, amniocentesis, tests of fetal well-being, external version, induction, and cesarean section and the distribution of total hospital days were similar in the two groups. Use of tocolytics and the rate of postdate pregnancy were both slightly lower in the screened group.

CONCLUSION

Screening ultrasonography resulted in no clinically significant benefit.