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.

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