A randomized trial of routine prenatal ultrasound. A randomized controlled trial in a hospital population of ultrasound measurement screening for the small for dates baby. Screening for small for dates fetuses: a controlled trial. Effect of prenatal ultrasound screening on perinatal outcome. RADIUS Study Group. Effects of routine one-stage ultrasound screening in pregnancy: a randomised controlled trial. Routine ultrasound fetal examination in pregnancy: the 'Alesund' randomized controlled trial. Effects of frequent ultrasound during pregnancy: a randomised controlled trial. Is smoking an indication for prenatal ultrasonography? RADIUS Study Group. Ultrasound screening and perinatal mortality: controlled trial of systematic one-stage screening in pregnancy. The Helsinki Ultrasound Trial.
Nine hundred fifteen of 2171 pregnant patients had no indication for ultrasound at their first prenatal visit and were randomly assigned to receive either a single routine screening ultrasound or usual prenatal care. The estimated date of confinement was altered in 24.9% of routine-ultrasound patients and in 11.6% of usual-care patients through ultrasound examinations obtained for a subsequent clinical indication. Of these, 8.3% of routine-ultrasound and 5.2% of usual-care patients had gestational age errors of 2 weeks or more. There were no differences between the groups in inductions for post-dates pregnancy (7.0 versus 7.5%; P = .87), total inductions (22.6 versus 24.9%; P = .61), or adverse perinatal outcomes (6.7 versus 8.3%; P = .63). Both sets of twins were detected in the screened group. In the usual-care group, five of seven pairs of twins (71%) were diagnosed by 24 weeks' gestation. There was no benefit found from routine ultrasound as performed in this study. 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. In the hope of reducing perinatal risks associated with retardation of intrauterine growth a previously described two stage ultrasound screening schedule was evaluated by a controlled trial in 877 women with low risk single pregnancies. The two stages of ultrasound examination were an assessment of gestational age during early pregnancy followed by measurement of length from crown to rump and area of trunk at between 34 and 36 weeks' gestation. The product of crown to rump length and trunk area was calculated. The sensitivity of this schedule in identifying in advance 94% of babies who were small for dates at birth, with 90% specificity, and the speed and simplicity of measurement confirmed the accuracy and feasibility of two stage ultrasonography as a screening procedure. The controlled trial did not, however, show any benefit from its routine application in these low risk pregnancies. Many clinicians advocate routine ultrasound screening during pregnancy to detect congenital anomalies, multiple-gestation pregnancies, fetal growth disorders, placental abnormalities, and errors in the estimation of gestational age. However, it is not known whether the detection of these conditions through screening leads to interventions that improve perinatal outcome.
                We conducted a randomized trial involving 15,151 pregnant women at low risk for perinatal problems to determine whether ultrasound screening decreased the frequency of adverse perinatal outcomes. The women randomly assigned to the ultrasound-screening group underwent one sonographic examination at 15 to 22 weeks of gestation and another at 31 to 35 weeks. The women in the control group underwent ultrasonography only for medical indications, as identified by their physicians. Adverse perinatal outcome was defined as fetal death, neonatal death, or neonatal morbidity such as intraventricular hemorrhage.
                The mean numbers of sonograms obtained per woman in the ultrasound-screening and control groups were 2.2 and 0.6, respectively. The rate of adverse perinatal outcome was 5.0 percent among the infants of the women in the ultrasound-screening group and 4.9 percent among the infants of the women in the control group (relative risk, 1.0; 95 percent confidence interval, 0.9 to 1.2; P = 0.85). The rates of preterm delivery and the distribution of birth weights were nearly identical in the two groups. The ultrasonographic detection of congenital anomalies had no effect on perinatal outcome. There were no significant differences between the groups in perinatal outcome in the subgroups of women with post-date pregnancies, multiple-gestation pregnancies, or infants who were small for gestational age.
                Screening ultrasonography did not improve perinatal outcome as compared with the selective use of ultrasonography on the basis of clinician judgment. 4997 of 7354 pregnant women had no clinical indication for an elective ultrasound examination at 12 weeks' gestation. 2482 of these women were randomly selected for ultrasound screening at 15 weeks and the remainder received the same standard antenatal care without the scan. Labour was less often induced among screened women both for all reasons (5.9% vs 9.1%, p less than 0.0001) and for suspected post-term pregnancy (1.7% vs 3.7%, p less than 0.0001). Earlier detection of twins had no effect on neonatal outcome. Among babies born to screened women, fewer were of birthweight less than 2500 g (59 vs 95, p = 0.005) and mean birthweight was 42 g higher (p 0.008). For babies born to screened women who smoked it was 75 g higher (p 0.012) and for those of non-smokers 26 g (not significant). The reason for the differences in mean birthweight could be that screened women reduced smoking in response to watching their fetus on the scan. To evaluate the possible benefits of the routine use of ultrasound screening in pregnancy.
                A randomized controlled trial was designed to detect a 50% difference in the incidence of induction for apparent post-term pregnancies between women who were screened with ultrasound and unscreened women. A total of 1628 pregnant women from the general population were included. Eight hundred and twenty-five were allocated to an ultrasound examination at the 18th and 32nd week of pregnancy in addition to receiving routine antenatal care. The remaining 803 women received standard antenatal care, but could only be referred for ultrasound examination on clinical indication.
                The incidence of induced labor due to apparent post-term pregnancies was approximately 70% lower in the ultrasound-screened group. Inductions from all causes were also less frequent among ultrasound-screened women. There were six perinatal deaths among the screened and seven among the controls after excluding three lethal malformations among the controls. There was no difference in Apgar score after 1 min, but the proportion with Apgar score less than 8 after 5 min was lower among the screened group (P = 0.04). The need for positive pressure ventilation for more than 1 min was lower among the screened group (P = 0.02). Birth weight was slightly higher in the screened group (39 g), but the difference was not statistically significant. Among the controls three pairs of twins remained undiagnosed until the mothers were admitted to the hospital in labor at between 36 and 38 weeks gestation.
                These results suggest that for women who were screened with ultrasound, obstetricians were less likely to induce labor due to apparent post-term pregnancy, than for women who were not screened. All 10 pairs of twins in the screened group were diagnosed at the routine examination. These data also suggest that perinatal morbidity might be slightly lower in the screened group. 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. To evaluate whether ultrasound screening during pregnancy decreases the frequency of smoking in women who present with a history of smoking.
                The Routine Antenatal Diagnostic Imaging with Ultrasound Study was a multicenter, randomized clinical trial of ultrasound screening during pregnancy. We obtained information on smoking habits during pregnancy from birth certificate records for the subset of women who were delivered of a neonate in Missouri hospitals, and determined the effect of ultrasound screening on smoking habits during pregnancy.
                The study was conducted in multiple practices in six states.
                Women who registered for prenatal care at participating practices.
                Women in the screened group were routinely scheduled for ultrasound screening at 16 to 22 weeks' gestation and at 31 to 35 weeks' gestation. Those in the control group received ultrasound screening only for medical indications, as determined by their physicians.
                Smoking habits were measured by the number of cigarettes smoked per day.
                There was no difference in the rates of smoking cessation between the screened group and the control group. For those who continued smoking, the mean number of cigarettes smoked per day, as reported at the time of delivery, was slightly higher in the screened group.
                Ultrasound screening does not reduce the frequency of smoking during pregnancy. During a 19-month period, 95% of all pregnant women in the greater Helsinki area, Finland, entered a study to compare one-stage ultrasonography screening with selective screening according to antenatal hospital use, obstetric procedures, and fetal outcomes. Of 9310 women who entered the trial, 4691 were randomly allocated to ultrasound screening between the 16th and 20th gestational weeks and 4619 to follow-up only. Screened and control groups otherwise had the same antenatal care, which included ultrasonography according to usual practice. Screened women made fewer visits to the antenatal outpatient clinic than did women in the control group (2.3 vs 2.6). There were no differences in the number of labour inductions or mean birthweights in the two groups. Perinatal mortality was significantly lower in the screened than in the control group (4.6/1000 vs 9.0/1000); this 49.2% reduction was mainly due to improved early detection of major malformations which led to induced abortion. All twin pregnancies were detected before the 21st gestational week in the screening group compared with 76.3% in the control group; perinatal mortality in the small series of twins was 27.8/1000 vs 65.8/1000, respectively.
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.