OBSTETRIC ULTRASONOGRAPHY - 11/09/11
Résumé |
Diagnostic ultrasonography is an imaging technique widely used in modern perinatal care. In some European countries pregnant women receive one or more ultrasound scans as a matter of routine during pregnancy, but in the United States the standard of care is for ultrasound to be used for specific medical indications.3, 4 Nonetheless, the majority of low-risk patients in the United States eventually develop an indication for ultrasonography during pregnancy.16, 23
The radiology model for the performance of obstetric ultrasound scans is for sonographers, who are not physicians, to perform the ultrasound scan, to record representative images, and to collect fetal biometric data. A radiologist then reviews the images and validates the information collected and generates a report to be sent to the referring physician. Practicing clinicians such as obstetricians, family physicians, and advanced practice nurses, however, often perform, record, interpret, and report the ultrasound scan themselves. The clinician's clinical information and familiarity with the patient strongly complement the examination process and the clinical application of information obtained.
Terminology describing obstetric ultrasound examinations has undergone evolution and is discussed briefly. An old terminology categorizes obstetric ultrasound scans as level I or level II and so forth.6 This terminology arose from the British maternal serum alphafetoprotein (MSAFP)screening program in which patients with an abnormal MSAFP had a level I scan performed by a nonphysician that included only fetal biometry to verify gestational age. If the patient's dates were confirmed, indicating that her abnormal MSAFP was a true abnormal instead of false-positive, a level II scan then was performed by a physician, directed at fetal anatomy, primarily to rule out anomalies that would cause the elevated MSAFP. Modern practice dictates that essentially all obstetric ultrasound scans adhere to standard examination content that includes fetal biometry and an anatomic survey. The content of this examination has been agreed on widely by the American Institute of Ultrasound in Medicine, 4 the American College of Obstetricians and Gynecologists,3 and the American College of Radiology. If the standard examination yields questions requiring further analysis, a consultative or targeted examination may be performed by a subspecialist, often using more sophisticated equipment. Under specific circumstances, a limited examination might be appropriate, such as a scan in labor and delivery to clarify the fetal lie or to assess amniotic fluid or placental location. In this article, the modern terminology is adopted, and the types of obstetric ultrasound scans described include limited labor and delivery scans and the standard antepartum obstetric ultrasound examination as described by the American Institute of Ultrasound in Medicine/American College of Obstetricians and Gynecologists/American College of Radiology guidelines.
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Vol 24 - N° 2
P. 407-431 - juin 1997 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
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