Diagnostic ultrasound ( PDFDrive )

PART FOUR: Obstetric and Fetal Sonography
CHAPTER
28
Overview of Obstetric Imaging
Deborah Levine
SUMMARY OF KEY POINTS
• Ultrasound allows for accurate prediction of gestational
age.
• The appropriate training and skills are necessary for
safely performing and accurately interpreting obstetric
ultrasound
• There are many options for screening pregnant women,
most of which include ultrasound.
• Routine obstetric ultrasound has speciic recommended
views that allow for depiction of many, but not all, fetal
anomalies.
• Three-dimensional ultrasound, fetal Doppler examinations,
and fetal magnetic resonance imaging may be used when
additional information is needed beyond that available with
routine gray-scale ultrasound.
CHAPTER OUTLINE
TRAINING, PERSONNEL, AND
EQUIPMENT
ULTRASOUND GUIDELINES
First Trimester
Second and Third Trimesters
ROUTINE ULTRASOUND SCREENING
Estimation of Gestational Age
Identiication of Twin/Multiple
Pregnancies
Screening and Perinatal Outcomes
Fetal Malformations: Diagnostic
Accuracy
Three-Dimensional Ultrasound
Prudent Use of Ultrasound
MAGNETIC RESONANCE IMAGING
CONCLUSION
There were more than 3.9 million live births in the United
States in 2013. 1 Ultrasound is the most frequently used
imaging modality for assessment of pregnancy. With care being
taken to keep exposure to ultrasound limited to medically needed
information, and with imaging performed at the appropriate
power settings, ultrasound is safe for use in pregnancy.
Indications for ultrasound during the irst trimester include
pregnancy dating, assessment of women with bleeding or pain,
and assessment of nuchal translucency in screening for aneuploidy.
In the second trimester, ultrasound is used for pregnancy dating,
assessment of interval growth, assessment of patients with
abnormal pain or bleeding, assessment of size-to-dates discrepancy,
routine survey of fetal anatomy, and assessment of maternal
complications due to conditions such as age, drug use, or history
of previous abnormalities.
In cases of multiple gestations, ultrasound is used to assess
growth and complications of twinning. In women with history
of cervical incompetence, ultrasound is used to screen for cervical
changes that put a patient at risk for preterm delivery. In the
third trimester, ultrasound is predominantly used to assess fetal
growth and well-being. Ultrasound is increasingly used for fetal
procedures such as testing for aneuploidy, drainage of abnormal
fetal luid collections, and guidance for fetal surgery. Ultrasound
is well recognized as the screening modality of choice, but
additional information may be needed beyond that available
with ultrasound. In many of these cases, especially those with
fetal central nervous system abnormalities, fetal magnetic resonance
imaging (MRI) can help clarify the diagnosis.
Part IV of this textbook focuses on obstetric ultrasound and
reviews speciic fetal organ system anatomy and pathology, with
chapters also on safety of ultrasound in pregnancy, assessment
of twins, and growth. Fetal magnetic resonance (MR) and threedimensional
(3D) ultrasound images are added throughout to
illustrate the beneit of these techniques in select cases.
TRAINING, PERSONNEL,
AND EQUIPMENT
Obstetric ultrasound diagnosis is critically dependent on examiner
training and experience. 2,3 Physicians and sonographers performing
obstetric ultrasound examinations should have completed
appropriate training and should be appropriately credentialed
and/or boarded. Accreditation of ultrasound laboratories improves
compliance with published minimum standards and guidelines. 4
Ultrasound practitioners should be knowledgeable regarding the
basic physical principles of ultrasound, equipment, record-keeping
requirements, indications, and safety of using ultrasound in
pregnancy. Studies should be conducted with real-time scanners
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