Umbilical Cord — Assessment of the Number of Umbilical Cord Vessels at the Time of Nuchal Translucency Screening
Citation(s)
Abu-Rustum RS, Daou L, Abu-Rustum SE Role of ultrasonography in early gestation in the diagnosis of congenital heart defects. J Ultrasound Med. 2010 May;29(5):817-21.
ACOG Committee on Practice Bulletins ACOG Practice Bulletin No. 77: screening for fetal chromosomal abnormalities. Obstet Gynecol. 2007 Jan;109(1):217-27.
Becker R, Wegner RD Detailed screening for fetal anomalies and cardiac defects at the 11-13-week scan. Ultrasound Obstet Gynecol. 2006 Jun;27(6):613-8.
Cuckle H, Nanchahal K, Wald N Birth prevalence of Down's syndrome in England and Wales. Prenat Diagn. 1991 Jan;11(1):29-34.
Dugoff L Ultrasound diagnosis of structural abnormalities in the first trimester. Prenat Diagn. 2002 Apr;22(4):316-20. Review.
Economides DL, Whitlow BJ, Braithwaite JM Ultrasonography in the detection of fetal anomalies in early pregnancy. Br J Obstet Gynaecol. 1999 Jun;106(6):516-23. Review.
Heifetz SA Single umbilical artery. A statistical analysis of 237 autopsy cases and review of the literature. Perspect Pediatr Pathol. 1984 Winter;8(4):345-78.
Heifetz SA The umbilical cord: obstetrically important lesions. Clin Obstet Gynecol. 1996 Sep;39(3):571-87. Review.
Hill LM, Wibner D, Gonzales P, Chenevey P Validity of transabdominal sonography in the detection of a two-vessel umbilical cord. Obstet Gynecol. 2001 Nov;98(5 Pt 1):837-42.
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.
