WITHDRAWN: Routine ultrasound in late pregnancy (after 24 weeks' gestation)

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.

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.