A Cochrane review [Abstract] 1 included 13 studies with a total of 34 980 subjects. There was no difference in antenatal, obstetric and neonatal intervention or morbidity in screened versus control groups T1. Routine late pregnancy ultrasound was not associated with improvements in overall perinatal mortality.
| Outcome | Relative effect (95% CI) | Assumed risk -Control | Corresponding risk - Intervention=Routine ultrasound > 24 weeks (95% CI) | Participants (studies) |
|---|---|---|---|---|
| Perinatal mortality | RR 1.01 (0.67 to 1.54) | 6/1000 | 6 /1000(4 to 9) | 30 675(8) |
| Preterm delivery< 37 weeks' gestation | RR 0.96 (0.85 to 1.08) | 59/1000 | 57 /1000(50 to 64) | 17 151(2) |
| Induction of labour | RR 0.93 (0.81 to 1.07) | 238/1000 | 222/1000(193 to 255) | 22 663(6) |
| Caesarean section | RR 1.02 (0.97 to 1.09) | 139/1000 | 142 /1000(135 to 152) | 27461(6) |
A nationwide, multicentre, cluster randomised trial 2 included 13 046 women with a low risk singleton pregnancy. Small for gestational age at birth was significantly more often detected in the intervention group than in the usual care group (179 of 556 (32%) v 78 of 407 (19%), P<0.001). The incidence of severe adverse perinatal outcomes was 1.7% for the intervention strategy and 1.8% for usual care. After adjustment for confounders, the difference between the groups was not significant (odds ratio 0.88, 95% CI 0.70 to 1.20). The intervention strategy showed a higher incidence of induction of labour (1.16, 1.04 to 1.30) and a lower incidence of augmentation of labour (0.78, 0.71 to 0.85). Maternal outcomes and other obstetric interventions did not differ between the strategies.
A systematic review and cost-effectiveness analysis 3 assessed diagnostic test accuracy reviews of 5 ultrasonic measurements in late pregnancy. Umbilical artery Doppler flow velocimetry, cerebroplacental ratio, severe oligohydramnios and borderline oligohydramnios were all either non-predictive or weakly predictive of the risk of neonatal morbidity (summary positive likelihood ratios between 1 and 2) and were all weakly predictive of the risk of delivering a small for gestational age infant (summary positive likelihood ratios between 2 and 4). Suspicion of fetal macrosomia is strongly predictive of the risk of delivering a large infant, but it is only weakly, albeit statistically significantly, predictive of the risk of shoulder dystocia. Health economic analysis indicated that universal ultrasound for fetal presentation only may be both clinically and economically justified on the basis of existing evidence.
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