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In memory of my parents, Drs. Ruth and Raymond Masters, who encouraged me to enjoy
the intellectual challenge of medicine and the love of making a difference in patients’ lives.
CMR
To a lifetime of clinical colleagues, residents, and fellows who have provided me with a
wealth of professional joy. And to my wonderful family, for your love and never-ending support.
SRW
To Cathy, Nicholas, Ben, and Laurie, for all the love and joy you bring to my life. You are
all I could ever hope for.
JWC
To Alex, Becky, and Julie—your love and support made this work possible.
DL
Preface
The fourth edition of Diagnostic Ultrasound is a major
revision. Previous editions have been very well accepted
as a reference textbook and have been the most commonly used reference in ultrasound education and practices worldwide. We are pleased to provide a new update
of images and text with new areas of strength. For the
first time we are including video clips in the majority of
chapters. The display of real-time ultrasound has helped
to capture those abnormalities that require a sweep
through the pathology to truly appreciate the lesion. It
is similar to scrolling through images on a PACS and has
added great value to clinical imaging. Daily we find that
cine or video clips show important areas between still
images that help to make certain a diagnosis or relationships between lesions. Now we rarely need to go back to
reevaluate a lesion with another scan, making patient
imaging more efficient.
We are pleased to announce that a new editor, Deborah
Levine, has joined us, providing expertise in fetal imaging,
in both obstetrical sonography and fetal MRI. Prenatal
diagnosis is one of the frontiers of medicine that continues to grow as a field and has pushed our understanding
of what happens to the fetus before we see a lesion at
birth. These antecedents of disease in children and adults
help us to arrange care for patients long before the
mother goes into labor.
Approximately 90 outstanding new and continuing
authors have contributed to this edition, and all are
recognized experts in the field of ultrasound. We have
replaced at least 50% of the images without increasing
the size of the two volumes, so new value has been added
to all of the chapters, particularly for obstetrics and
gynecology. The fourth edition now includes over
5000 images, many in full color. The layout has been
exhaustively revamped, and there are highly valuable
multipart figures or key figure collages. These images all
reflect the spectrum of sonographic changes that may
occur in a given disease instead of the most common
manifestation only.
The book’s format has been redesigned to facilitate
reading and review. There are again color-enhanced
boxes to highlight the important or critical features of
sonographic diagnoses. Key terms and concepts are
emphasized in boldface type. To direct the readers to
other research and literature of interest, comprehensive
reference lists are organized by topic.
Diagnostic Ultrasound is again divided into two
volumes. Volume I consists of Parts I to III. Part I contains chapters on physics and biologic effects of ultrasound, as well as more of the latest developments in
ultrasound contrast agents. Part II covers abdominal,
pelvic, and thoracic sonography, including interventional procedures and organ transplantation. Part III
presents small parts imaging including thyroid, breast,
scrotum, carotid, peripheral vessels, and particularly
MSK imaging. Newly added is a chapter on musculoskeletal intervention.
Volume II begins with Part IV, where the greatest
expansion of text and images has been on obstetric and
fetal sonography, including video clips for the first time.
Part V comprehensively covers pediatric sonography.
Diagnostic Ultrasound is for practicing physicians, residents, medical students, sonographers, and others interested in understanding the vast applications of diagnostic
sonography in patient care. Our goal is for Diagnostic
Ultrasound to continue to be the most comprehensive
reference book available in the sonographic literature
with a highly readable style and superb images.
Carol M. Rumack
Stephanie R. Wilson
J. William Charboneau
Deborah Levine
Acknowledgments
Our deepest appreciation and sincerest gratitude:
To all of our outstanding authors who have contributed extensive, newly updated, and authoritative text
and images. We cannot thank them enough for their
efforts on this project.
To Sharon Emmerling in Denver, Colorado, whose
outstanding secretarial and communication skills with
authors and editors have facilitated the review and final
revision of the entire manuscript. Her enthusiastic attention to detail and accuracy has made this our best edition
ever.
To Gordana Popovich and Dr. Hojun Yu for their
artwork and schematics in Chapter 8, The Gastrointestinal Tract.
To Dr. Hojun Yu for his schematics on liver anatomy
in Chapter 4, The Liver.
To Lisa Barnes, developmental editor at Elsevier, who
has worked closely with us on this project from the very
beginning of the fourth edition. We also thank the
enthusiastic participation of many other Elsevier experts
including Rebecca Gaertner, Elsevier’s guiding hand
overseeing the project. She has patiently worked with us
through all the final stages of development and production. It has been an intense year for everyone, and we
are very proud of this superb edition of Diagnostic
Ultrasound.
CHAPTER 28
Overview of Obstetric
Imaging
Deborah Levine
Chapter Outline
TRAINING, PERSONNEL, AND
EQUIPMENT
ULTRASOUND GUIDELINES
First Trimester
Second and Third Trimesters
ROUTINE ULTRASOUND
SCREENING
Estimation of Gestational Age
There were more than 4.2 million live births in the
United States in 2008.
ultrasound was used in 68% of pregnancies in 2002, up
from 48% in 1989.
sound use, it is likely that an even higher percentage of
pregnant women undergo ultrasound evaluation currently in the United States. Ultrasound use is even higher
in countries where it is considered a part of routine
obstetric care, as opposed to the United States, where
this is still a contentious issue.
Indications for ultrasound during the first 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 indications related to age, drug use, or history
of prior 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, fetal drainage, 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
1
It is estimated that obstetric
2
Given the upward trend in ultra-
Identification of Twin/Multiple
Pregnancies
Screening and Perinatal Outcomes
Fetal Malformations: Diagnostic
Accuracy
Three- and Four-Dimensional
Ultrasound
Prudent Use of Ultrasound
MAGNETIC RESONANCE
IMAGING
CONCLUSION
nervous system abnormalities, fetal magnetic resonance
imaging (MRI) can help clarify the diagnosis.
Part IV of this textbook focuses on obstetric ultrasound and reviews specific fetal organ system anatomy
and pathology, with chapters also on safety of ultrasound
in pregnancy, assessment of twins, and growth. Fetal MR
and three-dimensional ultrasound images are added
throughout to illustrate the benefit of these techniques
in select cases.
TRAINING, PERSONNEL,
AND EQUIPMENT
Obstetric ultrasound diagnosis is critically dependent
on examiner training and experience.
sonographers performing obstetric ultrasound examinations should have completed appropriate training and
should be appropriately credentialed and boarded.
Accreditation of ultrasound laboratories improves compliance with published minimum standards and guide-
5
Ultrasound practitioners should be knowledgeable
lines.
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 using a
transabdominal and/or transvaginal approach, depending on the gestational age and the region of interest. The
choice of transducer frequency is a trade-off between
beam penetration and resolution. In general, a 3 to
5–MHz transducer frequency provides sufficient resolution with adequate depth penetration in all but the
3,4
Physicians and
1040
Chapter 28 ■ Overview of Obstetric Imaging 1041
INDICATIONS FOR
FIRST-TRIMESTER ULTRASOUND
To confirm the presence of an intrauterine
pregnancy.
To evaluate a suspected ectopic pregnancy.
To define the cause of vaginal bleeding.
To evaluate pelvic pain.
To estimate gestational (menstrual) age.
To diagnose or evaluate multiple gestations.
To confirm cardiac activity.
As an adjunct to chorionic villus sampling, embryo
transfer, and localization, and removal of an
intrauterine device.
To assess for certain fetal anomalies, such as
anencephaly, in high-risk patients.
To evaluate maternal pelvic masses and/or uterine
abnormalities.
To measure nuchal translucency when part of a
screening program for fetal aneuploidy.
To evaluate a suspected hydatidiform mole.
From American College of Radiology. ACR practice
guideline for the performance of antepartum obstetrical
ultrasound. In ACR practice guidelines and technical
standards. Philadelphia, 2007, ACR, pp 1025-1033.
extremely obese patient. During early pregnancy, a 4 to
7–MHz abdominal transducer or a 5 to 10–MHz vaginal
transducer may provide superior resolution while still
allowing adequate penetration. Higher-frequency transducers are most useful in achieving high-resolution
scans, and lower-frequency transducers are useful when
increased penetration of the sound beam is necessary.
Use of Doppler ultrasound and three-dimensional (3-D)
and four-dimensional (4-D) imaging depends on the
specific indication. As in all imaging studies, complete
documentation of the images and a formal written interpretation are essential for quality assurance, accreditation, and medicolegal issues.
INDICATIONS FOR SECOND- AND
THIRD-TRIMESTER ULTRASOUND
Estimation of gestational (menstrual) age
Evaluation of fetal growth
Vaginal bleeding
Abdominal or pelvic pain
Cervical insufficiency
Determination of fetal presentation
Suspected multiple gestation
Adjunct to amniocentesis or other procedure
Significant discrepancy between uterine size and
clinical dates
Pelvic mass
Suspected hydatidiform mole
Adjunct to cervical cerclage placement
Suspected ectopic pregnancy
Suspected fetal death
Suspected uterine abnormality
Evaluation of fetal well-being
Suspected amniotic fluid abnormalities
Suspected placental abruption
Adjunct to external cephalic version
Premature rupture of membranes and/or premature
labor
Abnormal biochemical markers
Follow-up evaluation of a fetal anomaly
Follow-up evaluation of placental location for
suspected placenta previa
History of previous congenital anomaly
Evaluation of fetal condition in late registrants for
prenatal care
To assess for findings that may increase the risk for
aneuploidy
Screening for fetal anomalies
From American College of Radiology. ACR practice
guideline for the performance of antepartum obstetrical
ultrasound. In ACR practice guidelines and technical
standards. Philadelphia, 2007, ACR, pp 1025-1033.
ULTRASOUND GUIDELINES
First Trimester
The current guidelines of the American College of Radiology (ACR) and American Institute of Ultrasound in
Medicine (AIUM) for the performance of first-trimester
obstetric ultrasound examination include documentation of the location of the pregnancy (intrauterine vs.
extrauterine), documentation of the appearance of the
maternal uterus and ovaries (Fig. 28-1), and assessment
of gestational age, either by measurement of mean sac
diameter (before visualization of embryonic pole; Fig.
28-2) or by embryonic/fetal pole crown-rump length
(Fig. 28-3).
yolk sac. An image of the heart rate is taken using
M-mode ultrasound. It is important to use M-mode
6
Another important structure to assess is the
GENERAL SURVEY GUIDELINES FOR
FIRST-TRIMESTER ULTRASOUND
Gestational sac
Location of pregnancy: intrauterine vs.
extrauterine
Gestational age (as appropriate)
Mean sac diameter
Embryonic pole length
Crown-rump length
Yolk sac or embryo/fetus
Cardiac activity on M-mode ultrasound
Fetal number (amnionicity/chorionicity)
Maternal anatomy: uterus and adnexa
Modified from American College of Radiology. ACR
practice guideline for the performance of antepartum
obstetrical ultrasound. In ACR practice guidelines and
technical standards. Philadelphia, 2007, ACR, pp
1025-1033.
1042 PART IV ■ Obstetric Sonography
A
C
FIGURE 28-1. Normal first-trimester ultrasound images: pregnancy location and adnexa. A, Transabdominal
sagittal sonogram shows an intrauterine gestational sac. B, Transverse image to the left of uterus shows normal appearance for the ovary
(arrow). C, Transvaginal color Doppler image shows normal hypervascular rim around corpus luteum.
B
rather than spectral Doppler ultrasound on the embryo
to limit power deposition. Late in the first trimester,
dating can be performed with measurement of the biparietal diameter and head circumference, rather than
crown-rump length. Chapters 30 and 42 discuss the
first-trimester examination and gestational dating in
pregnancy, respectively.
In cases of multiple gestation, first-trimester scans
should document the fetal number as well as the amnionicity and chorionicity (Fig. 28-4). Chapter 32 discusses the assessment of multifetal pregnancies.
It is increasingly common to assess for risk of aneu-
ploidy (e.g., trisomy 21, 18, or 13) by measuring nuchal
translucency between 11 and 14 weeks of gestation (see
FIGURE 28-2. Normal first-trimester ultrasound
images: mean sac diameter. Transvaginal sagittal image
shows sagittal measurement of sac diameter (calipers). Measurements in three orthogonal planes are averaged to calculate the
mean sac diameter. Note yolk sac within the gestational sac.
Fig 28-3, I ). This measurement, in conjunction with
maternal age and serology, can be used to determine an
individualized risk of fetal aneuploidy (see Chapter 31).
Increased use of first- and second-trimester ultrasound
has reduced the number of interventional procedures to
Chapter 28 ■ Overview of Obstetric Imaging 1043
A
B C
D E F
G H I
FIGURE 28-3. First-trimester ultrasound images: embryo and fetus. A, Normal embryo at 6.5 weeks’ gestation. Note
embryonic pole (calipers) adjacent to yolk sac. B, Normal embryo at 8 weeks’ gestation. Note embryo (calipers) and adjacent yolk sac
(arrow). C, M-mode ultrasound from same embryo as in B. Note normal heart rate of 160 beats/min. D, Normal embryo at 9 weeks’
gestational age. Note embryo within amnion (arrow) and umbilical cord (arrowhead). E, Just lateral to image in D, note yolk sac (arrowhead) is located outside the amnion (arrow). F, Sagittal ultrasound at 10.5 weeks’ gestation. G, Sagittal ultrasound at 11.5 weeks’ gestation.
H, Coronal view of face at 13 weeks’ gestation. I, Sagittal ultrasound of nuchal translucency (calipers) at 13 weeks’ gestation.
detect aneuploidy while increasing the prenatal diagnosis
of aneuploidy.
7
Given the increased scanning late in the
first trimester, it is also increasingly common for a
limited anatomic survey to be conducted in the late first
trimester. Anomalies that should be detected this early
include anencephaly (Fig. 28-5) and omphalocele (Fig.
28-6). Although substantial information can be obtained
at this time, first-trimester anatomic survey is unlikely
to replace the second-trimester anatomic survey, since
many structures are difficult to visualize completely early
in the second trimester, particularly the heart, cardiac
outflow tracts, posterior fossa, and distal spine.
Second and Third Trimesters
The current ACR/AIUM guidelines for the performance
of the second- and third-trimester obstetric ultrasound
examinations describe the standard sonographic exami-
6
nation.
It is important to understand that the guidelines
were written to maximize detection of many fetal abnormalities, but are not expected to allow for detection of
all structural abnormalities.
6
The terminology level I and level II examinations
refer to “standard” or “routine” (level I) and “high risk,”
“specialized,” or “detailed” (level II) obstetric ultrasound.
The concept of these two levels of scanning is that the
1044 PART IV ■ Obstetric Sonography
A B
FIGURE 28-4. Multiple gestations. Be sure to examine the entire gestational sac to identify multiple gestations. A, Transabdominal
image of diamniotic dichorionic twins. Note the thick, dividing membrane. B, Transvaginal image of diamniotic monochorionic twins
at 8 weeks’ gestational age (calipers denote crown rump length) with two thin membranes (arrows, amnion) still close to embryonic poles.
A B
FIGURE 28-5. Anencephaly. A, Sagittal ultrasound at 10 weeks’ gestation. B, Sagittal ultrasound in a different fetus at 12 weeks’
gestation. Note the orbits (arrow) with absent ossified cranium above this level with angiomatous stroma.
FIGURE 28-6. Omphalocele at 11 weeks’ gesta-
tional age. Sagittal view of fetus (calipers) shows a large,
abdominal wall defect (arrow).
standard, basic, routine, or level I examination is performed routinely on pregnant patients (Figs. 28-7 to
28-16). The methods to obtain all the required images
are described in detail in subsequent chapters. This
chapter provides a collage of figures as a guide for the
anatomic survey and common additional views obtained
during a fetal survey.
In general, the “standard fetal anatomic survey” refers
to the second-trimester scan, typically performed
between 16 and 22 weeks of gestation. When anatomic
surveys are performed at 20 to 22 weeks’ gestational age,
there is less need for repeat scans to document normal
anatomy compared to studies performed earlier in preg-
8
However, there are practical considerations
nancy.
when determining the optimal timing of studies. In welldated pregnancies in women who are unlikely to want
amniocentesis, a survey at 20 to 22 weeks’ gestation is
optimal. However, if a pregnancy is not well dated, an
earlier scan may be needed both to establish accurate
dates for the pregnancy and to assess the anatomy. Some
centers offer the scan at 16 weeks’ gestation to coincide
with performance of genetic amniocentesis and/or
midtrimester quadruple serum screening.
The level I examination consists of investigation of the
maternal uterus and ovaries, the cervix, and placenta
(Fig. 28-7; Video 28-1), as well as a systematic review
of fetal anatomy. Adnexal cysts are common in pregnant
women. In early pregnancy a cyst is most likely the
corpus luteum. If a cyst appears atypical or enlarges
beyond the middle second trimester, it should be further
assessed. Leiomyoma position and size should be documented. If the myometrium appears thin in the lower
uterine segment (e.g., <
3 mm in woman with prior
cesarean section), the myometrium should be measured
because this puts the woman at risk for uterine dehis-
Chapter 28 ■ Overview of Obstetric Imaging 1045
SURVEY GUIDELINES FOR SECOND-
AND THIRD-TRIMESTER ULTRASOUND
GENERAL SURVEY
Cardiac activity: document with M-mode
Presentation: cephalic, breech, transverse, variable
Fetal number: for multiples, amnionicity/
chorionicity, concordance with size, amniotic
fluid
Maternal anatomy: uterus, adnexa, and cervix
Gestational age and fetal weight assessment
Biparietal diameter
Head circumference
Abdominal circumference
Femur length
Amniotic fluid
Estimate as normal
If abnormal, qualify if high or low
Placenta: position
FETAL ANATOMIC SURVEY
Head, Face, and Neck
Cerebellum
Choroid plexus
Cisterna magna
Lateral cerebral ventricles
Midline falx
Cavum septi pellucidi
Upper lip
Chest
Four-chamber view
Outflow tracts “if technically feasible”
Abdomen
Stomach (presence, size, and situs)
Kidneys, bladder
Umbilical cord insertion site into fetal abdomen
Umbilical cord vessel number
Spine
Cervical, thoracic, lumbar, and sacral
Extremities
Legs and arms: presence or absence
Gender (Sex)
Medically indicated in low-risk pregnancies only for
evaluation of multiple gestations
Modified from American College of Radiology. ACR practice
guideline for the performance of antepartum obstetrical
ultrasound. In ACR practice guidelines and technical
standards. Philadelphia, 2007, ACR, pp 1025-1033.
cence or rupture. It is helpful to begin the examination
with a sagittal midline view to assess the cervix. If the
cervix appears abnormally short or if placenta previa is
suspected, a vaginal scan can then be performed.
Transverse and longitudinal scans of the entire uterine
cavity are then performed for assessment of fetal cardiac
1046 PART IV ■ Obstetric Sonography
A
C D
FIGURE 28-7. Overview of uterus, cervix, and fetal position. A, Sagittal sonogram of uterus shows a normal-appearing
cervix (C) and an anterior placenta (P), with the placental tip far away from the internal cervical os; B, bladder. B, Transverse sonogram
of posterior placenta (P). C, Transabdominal image of normal-appearing cervix (arrow on internal os). Note bladder (B) and fetal head
(H). With the head as the presenting part, the fetus is in cephalic position. D, Transvaginal sonogram of normal-appearing cervix
(calipers).
B
activity, amniotic fluid volume, localization of the placenta, and determination of fetal presentation and situs
(Fig. 28-8). Knowledge of the plane of section across the
maternal abdomen, combined with the position of the
fetal spine and right-sided and left-sided structures
within the fetal body, allows accurate determination
of fetal position and identification of normal and
pathologic anatomy. Some congenital anomalies, such
as dextrocardia, will be recognized only if a structure is
identified as “abnormal” by virtue of its atypical position
related to the lie and presentation of the fetus.
Biometry is performed, both to estimate gestational
age and to estimate fetal weight (Fig. 28-9).
The high-risk, targeted, detailed, or level II scan
should have a specific indication that requires a
detailed fetal sonogram, performed by a clinician with
expertise in obstetric imaging.
9
This high-risk scan is
performed when an anomaly is suspected because of
maternal medical or family history, or if abnormal
results are suspected on a routine scan. Additional
views in routine obstetric sonography include the head
(Fig. 28-10; Video 28-2), face (Fig. 28-11), heart
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