Safety

Kieler H, Ahlsten G, Haglund B, Salvesen K, Axelsson O.
Routine ultrasound screening in pregnancy and the children's subsequent neurologic development.
Obstetrics and Gynecology 1998; 5(1): 750-6, Abstract.

A follow up study of 3265 children aged 8-9 whose mothers participated in a randomised controlled trail of ultrasound screening during pregnancy. There was no significant difference in the frequency of impaired neurological development in either exposed or non exposed groups.

Dating Pregnancies

Evans J.
Fetal crown rump length values in the first trimester based upon ovulation timing using lutenizing hormone surge.
1991; 98(1): 48-51, Abstract

Fetal crown rump length (CRL) was measured weekly in 33 singleton pregnancies conceived after in vitro fertilization, gamete intrafallopian transfer or natural intercourse in monitored infertility treatment cycles. There was no difference in the CRL between different infertility groups. However the CRL was found to be smaller than the CRL measurement from pregnancies where the gestational age was based on the last menstrual period.

Chervenak KA, Skupski DW, Romero R, Myers MK, Smith-Levitin, Rosrnwaks Z, Thaler HT.
How accurate is fetal biometry in the assessment of fetal age?
American Journal of Obstetrics and Gynecology. 1998; 178: 678-87, Abstract

Retrospective study of 152 singleton, 67 twin and 19 triplet gestations resulting from in vitro fetilization, comparing gestational age as defined by fetal biometry at 14-22 weeks and a gestation age prediction equation. Fetal biometry proved accurate and head circumference was the most accurate parameter.

Taipale P, Hilesmaa,V.
Prediction delivery date by ultrasound and last menstrual period by early gestation.
Obstetrics and Gynecology 2001; 97: 189-194, Abstract

Early Pregnancy Ultrasound

Neilson JP.
Ultrasound for fetal assessment in early pregnancy (Cochrane Review).
In: The Cochrane Library, Issue 4, 2001. Oxford: Update Software, Abstract.

A review of 9 trials of women scanned routinely in early pregnancy (usually before 20 weeks) compared to those with scans for specific indications. Those scanned routinely had better detection of gestational age, earlier detection of clinically unsuspected fetal malformations and earlier detection of multiple pregnancy. The odds ratio of undiagnosed twins in the routinely scanned group at 26 weeks was 0.08 (95% CI 0.04-0.16).

Nuchal Translucency

Snijders RJ, Nobel P, Sebire N, Souka A, Nicolaides KH. (1998)
UK multicentre project on the assessment of risk of trisomy 21 by maternal age and fetal nuchal translucency thickness at 10-14 weeks of gestation.
Lancet.352(9125):343-6, Abstract

Multicentre study of 96127 women, investigated for their risk of Trisomy 21 by a combination of maternal age and nuchal translucency thickness at 10-14 weeks gestation. Risk was calculated by maternal age, gestational-age-related prevalence and multiplied by a likelihood ratio derived from the deviation from normal of the Nuchal translucency measurement. The sensitivity of a cut off risk of 1 in 300 was investigated. Phenotype was derived from fetal karyotype or clinical examination of liveborn infants. The estimated Trisomy 21 risk was > 1in 300 for 8.3% of normal pregnancies, 82.2% of those with Trisomy 21 and 77.9% of those with other chromosomal defects. 80% of affected pregnancies were identified using the above screening method to determine -those offered invasive testing.

20-Week Anomaly Scan

Whitlow BJ, Chatzipapas IK, Lazanakis ML, Kadir RA, Economides DL.(1999)
The value of sonography in early pregnancy for the detection of fetal abnormalities in an unselected population.
British Journal of Obstetrics and Gynaecology 106(9):923-36, Abstract.

Prospective cross sectional study of 6634 sequential unselected women. All underwent transabdominal sonography and if the anatomy scan was considered incomplete they also underwent transvaginal scan. Nuchal translucency was also performed. The overall detection rate for structurally abnormal fetuses was 59% in early pregnancy (11-14 weeks) and 81% in combination with a second trimester scan.

Ultrasound Screening for Fetal Abnormalities Report of the RCOG Working Party, July 2000
http://www.rcog.org.uk/mainpages.asp?PageID=439#20week
Includes details of the detection rate for anomalies of each system at the anomaly scan.

Later Pregnancy Scans

Routine:
Bricker L, Neilson JP.
Routine ultrasound in late pregnancy (after 24 weeks gestation) (Cochrane Review).
In: The Cochrane Library, Issue 1, 2002. Oxford: Update Software, Abstract.

A review of 7 studies of 25036 women. There was no difference in obstetric, antenatal or neonatal interventions between those women undergoing routine Doppler ultrasound compared with those who did not. Likewise there was no difference in outcome measures and long term safety was not assessed.

Targeted:
Harding K, Evans S, Newham J (1995).
Screening for the small fetus: a study of the relative efficiency of ultrasound biometry and symphysiofundal height. Aust N Z Obstet Gynaecol; 35(2):160-4, Abstract.

1135 women were screened for birthweight <10th centile using 3 different methods alone and in combination; symphysiofundal height measurement, amniotic fluid index and ultrasound imaging at 18, 24, 28, 34 and 38 weeks. The best test was fetal abdominal circumference measurement by ultrasound. Selecting at risk pregnancies by symphysiofundal height measurement first prior to ultrasound reduces the false positive rate at the expense of sensitivity.

Neilson JP, Alfirevic Z.
Doppler ultrasound for fetal assessment in high risk pregnancies (Cochrane Review).
In: The Cochrane Library, Issue 4, 2001. Oxford: Update Software, Abstract

A review of 11 randomised studies involving nearly 7000 women. Doppler ultrasound compared with no Doppler ultrasound in high risk pregnancy was associated with a trend in reduction in perinatal deaths. There was also a reduction in induction of labour and admissions to hospital. There was no difference in fetal distress in labour or Caesarean section rate between the two groups.

Placenta Praevia: Diagnosis and Management
RCOG Green Top Guidelines Number 27.
http://www.rcog.org.uk/guidelines.asp?PageID=106&GuidelineID=17
Evidence based review of diagnosis and management.

Diagnostic Tests for Chromosomal Anomalies

RCOG Green Top Guideline no. 8 - Amniocentesis
http://www.rcog.org.uk/guidelines.asp?PageID=106&GuidelineID=2
Evidence based guideline detailing the complications, procedure and training requirements of amniocentesis.

Alfirevic Z, Gosden CM, Neilson JP
Chorion villus sampling versus amniocentesis for prenatal diagnosis (Cochrane Review)
In: The Cochrane Library, Issue 1, 2002. Oxford: Update Software, Abstract

A review of 3 studies involving over 9000 women concluded that the pregnancy loss rate following CVS was greater than second trimester amniocentesis.

Alfirevic Z
Early amniocentesis versus transabdominal chorion villus sampling for prenatal diagnosis (Cochrane Review)
In: The Cochrane Library, Issue 1, 2002. Oxford: Update Software, Abstract

Early (<14 weeks) amniocentesis was associated with a greater miscarriage rate and incidence of neonatal talipes than CVS. However it had less technical difficulties.

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