1. The screening ultrasound at 16 to 20 weeks should evaluate 8 markers, 5 of which (thickened nuchal fold, echogenic bowel, mild ventriculomegaly, echogenic focus in the heart, and choroid plexus cyst) are associated with an increased risk of fetal aneuploidy, and in some cases with nonchromosomal problems, while 3 (single umbilical artery, enlarged cisterna magna, and pyelectasis) are only associated with an increased risk of nonchromosomal abnormalities when seen in isolation (II-2 B).
2. Identification of soft markers for fatal aneuploidy requires correlation with other risk factors, including history, maternal age, and maternal serum testing results (II-1 A).
3. Soft markers identify a significant increase in fatal risk for genetic disease. Timely referral for confirmation, counselling, and investigation is required to maximize management options (III-B).
Periodic health examination, 1992 update: 2. Routine prenatal ultrasound screening. Canadian Task Force on the Periodic Health Examination. Can Med J 1992;147(5):627-633.
- Guidelines for the performance of ultrasound examination in obstetrics and gynaecology.J Soc Obstet Gynaecol Can. 1995; 17: 263-266
- Obstetric/gynaecologic ultrasound [policy statement].J Soc Obstet Gynaecol Can. 1997; 65: 871-872
- Ultrasound screening and perinatal mortality: controlled trial on systematic one-stage screening in pregnancy. The Helsinki Ultrasound Trial.Lancet. 1990; 336: 387-391
- Cost-effectiveness of one-stage ultrasound screening in pregnancy: a report from the Helsinki ultrasound trial.Ultrasound Obstet Gynecol. 1996; 7: 309-314
- A comparative study of routine versus selective fetal anomaly ultrasound scanning.J Med Screen. 1998; 5: 6-10
- Ultrasonographically detectable markers of fetal aneuploidy.Lancet. 1992; 340: 704-707
- The genetic sonogram: a method of risk assessment for Dawn syndrome in the second trimester.J Ultrasound Med. 2002; 21: 1087-1096
- Risk for chromosome abnormality at amniocentesis following a child with a non-inberited chromosome aberration.Prenatal Diagn. 1984; 4: 81-95
- Genetic Factors Influencing Aneuploidy Frequency.in: Dellarco VL Voytek PK Hollaender A Aneuploidy: etiology and mechanisms. Plenum, New York1985: 133-148
- Guidelines for health care providers involved in prenatal screening and diagnosis.SOGC Clinicat Practice Guidelines. 1998; : 75
- Periodic health examination, 1996 update: 1. Prenatal screening for and diagnosis of Dawn syndrome. Canadian Task Force on the Periodic Health Examination.Can Med J. 1996; 154: 465-479
- Second-rtimester genetic sonography in patients with advanced maternal age and normal triple screen.Obstet Gynecol. 2002; 99: 993-995
- Combined use of genetic sonography and maternal serum triple marker screening: an effective method for increasing the detection of trisomy 21 in women younger than 35 years.J Ultrasound Med. 2001; 20: 645-654
- Combined second-trimester biochemical and ultrasound screening for Dawn syndrome.Obstet Gynecol. 2002; 100: 1168-1176
- An 8-center study to evaluate the utility of mid-term genetic sonograms among high-risk pregnancies.J Ultrasound Med. 2003; 22: 33-38
- The role of ultrasonographic markers for trisomy 21 in women with positive serum biochemistry.Br J Obstet Gynaecol. 1998; 105: 63-67
- Abnormal biochemical serum screening versus 2nd rtimester ultrasounddetected minor anomalies as predictors of aneuploidy in low-risk patients.Fetal Diagn Ther. 1996; 11: 301-305
- Canadian Task Force on the Periodic Health Exam. Canadian Communication Group, Ottawa1994