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Subsequent chapters will discuss the technique and clinical use of colour Doppler
and power Doppler measurements.
Preliminary results raise the possibility of detecting increased vascularity and
new vessel formation in cases of malignant ovarian masses. In general, vessels in
malignant tumours lack the muscle layer and have lower impedance. However,
increased flow may also be seen with pelvic inflammatory processes. The presence of a corpus luteum not only may be misleading in the structural evaluation
of an adnexal mass since the flow measurement values overlap with those found
in ovarian cancer. The corpus luteum is known to have new vessel formation,
which lowers the resistance to flow while present.
Recent studies have suggested a possible role for colour Doppler in the diagnosis of adnexal torsion.
15,23
These studies suggest that, at the site of the torsion,
the diameter of the vessels proximal to the occlusion is increased; the disruption
of flow is identified on colour Doppler. Within the twisted adnexa, there is significantly diminished flow or no flow at all. The cost–benefit ratio of colour flow
studies is still under investigation, and the value of such studies is as yet not fully
determined. Moreover, the technique requires a great deal of training, and measurement remains a subjective process.
SCREENING FOR OVARIAN MASSES
Scanning techniques in obstetrics and gynaecology
Transvaginal sonography, with or without colour flow-directed measurements of
resistance to flow and flow velocities, has been suggested as a means of screening for ovarian cancer.
5,7,24
Although transvaginal sonography is probably the best
means of determining the morphological structure of adnexal masses, its efficacy in screening for ovarian cancer has not been adequately established. Both
modalities – transvaginal sonography and colour flow-directed measurements –
are experimental for these uses.
11,49,59
Several studies are under way to determine whether transvaginal sonography
and colour Doppler in conjunction with biological markers (proteins) can be
used to screen a selected population at high risk for ovarian cancer. Other studies are being done to examine the feasibility of using transvaginal sonography as a
first-line modality for screening. Doubts about the value of colour Doppler in the
diagnosis of ovarian masses have also been expressed.
45-47
TRANSPERINEAL AND TRANSRECTAL SCANNING
This chapter would not be complete without mentioning other scanning
routes. The transperineal route is also called translabial scanning. It is mainly
used if transvaginal scanning is not possible (no transvaginal transducer is
available or a contraindication prevents its use).
transducer is inserted in a glove and applied to the vulvar area in a sagittal
fashion.
The authors' experience is that there are very few contradictions to the use of
transvaginal probes in favour of a transperineal scan. Even in the case of premature
21,41
A linear or curvilinear
53
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rupture of the membranes, it was found that one transvaginal scan can be more
useful than one digital examination to predict premature delivery.
19,37
In cases where transvaginal scanning is not feasible or is contradicted, transrec-
tal scanning can be used.
55
ULTRASOUND-GUIDED PUNCTURE PROCEDURES
There are two kinds of ultrasound-guided puncture procedures: those guided by
a transabdominal transducer and performed transabdominally and those guided
by a transvaginal transducer and performed transvaginally.
Transabdominal puncture procedures can be done using the ‘free hand’ method
or a fixed needle guide. The former requires some degree of experience and good
eye–hand co-ordination.
Transvaginal puncture procedures should always be performed using a fixed
needle guide which is ‘mated’ to the shaft of the transvaginal probe.
Ultrasound in obstetrics and gynaecology
CONCLUSION
The technique and clinical aspects of transabdominal and transvaginal ultrasound
have been discussed. Those who intend to perform hands-on scanning of obstetric and gynaecological patients should familiarize themselves with the described
techniques. In addition, the more specific and detailed texts and published articles
should be read.
Based upon our experience, the evolution of understanding in this imaging
specialty is closely related to advances in the fields of electronics, acoustics and
computer sciences as well as to the ability to miniaturize most components of the
ultrasound equipment.
54
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BA, Kliewer MA, Jordan SG. Sonography
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M, Kupesic-Urek S. Stage I ovarian cancer
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25. Lavery MJ, Benson CB. Transvaginal versus
transabdominal ultrasound. In: TimorTritsch IE, Rottem S (eds) Transvaginal
sonography, 2nd edn. Chapman and Hall,
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27. Mendelson EB, Bohm-Velez M, Joseph
N, Neiman HL. Gynecologic imaging:
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30. Monteagudo A, Reuss ML, Timor-Tritsch
IE. Imaging the fetal brain in the second
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31. Monteagudo A, Timor-Tritsch IE. First
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What can we see now? Current Opin
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32. Moore TR. Superiority of the four-quadrant
sum over the single-deepest-pocket
technique in ultrasonographic identification
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33. Nelson TR, Downey DB, Pretorius DH,
Feuster A. Three-dimensional ultrasound.
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34. Nicolaides KH. Nuchal translucency and
other first-trimester sonographic markers of
chromosomal abnormalities. Am J Obstet
Gynecol 2004;191:45–67
35. Nyberg DA, Hill LM, Bohm-Velez M,
Mendelson EB. Transvaginal ultrasound.
Mosby-Yearbook, St Louis, MO, 1992
36. Odwin CS, Fleischer AC, Kepple DM. Probe
covers and disinfectants for transvaginal
transducers. J Diagn Med Sonogr
1990;6:130–135
37. Rizzo G, Capponi A, Angelini E,
Vlachopoulou A, Grassi C, Romanini C.
The value of transvaginal ultrasonographic
examination of the uterine cervix in
predicting preterm delivery in patients with
preterm premature rupture of membranes.
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38. Rottem S, Thaler I, Goldstein SR, TimorTritsch IE, Brandes JM. Transvaginal
sonographic technique: targeted organ
scanning without resorting to ‘planes.’ J Clin
Ultrasound 1999;18:243–247
39. Rutherford SE, Phelan JP, Smith CV,
Jacobs N. The four-quadrant assessment
of amniotic fluid volume: an adjunct to
antepartum fetal heart rate testing. Obstet
Gynecol 1987;70:353–356
40. Sabbagha RE. Diagnostic ultrasound applied
to obstetrics and gynecology, 3rd edn.
Lippincott, Philadelphia, 1994
41. Scanlan KA, Pozniak MA, Fagerholm M,
Shapiro S. Value of transperineal sonography
in the assessment of vaginal atresia. Am J
Roentgenol 1990;154:545–548
42. Souka AP, Nicolaides KH. Diagnosis of
fetal abnormalities at the 10–14-week scan.
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43. Souka AP, Pilalis A, Kavalakis I et al.
Ultrasound in obstetrics and gynaecology
Assessment of fetal anatomy at the 11–14week ultrasound examination. Ultrasound
Obstet Gynecol 2004;24:730–734
44. Spencer K, Nicolaides KH. Screening
for trisomy 21 in twins using first
trimester ultrasound and maternal serum
biochemistry in a one-stop clinic: a review
of three years experience. Br J Obstet
Gynaecol 2003;110:276–280
45. Tekay A, Jouppila P. Blood flow in benign
ovarian tumors and normal ovaries during
the follicular phase. Obstet Gynecol
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46. Tekay A, Jouppila P. Controversies in
assessment of ovarian tumors with
transvaginal color Doppler ultrasound. Acta
Obstet Gynecol Scand 1996;75:316–329
47. Tekay A, Jouppila P. Intraobserver variation
in transvaginal Doppler blood flow
measurements in benign ovarian tumors.
Ultrasound Obstet Gynecol 1997;9:
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48. Tessler F, Schiller VL, Perrella RR et al.
TAS versus endovaginal pelvic sonography:
prospective study. Radiology 1980;170:
553–556
49. Timmerman D, Valentin L, Bourne TH
et al. Terms, definitions and measurements
to describe the sonographic features of
adnexal tumors: a consensus opinion from
the International Ovarian Tumor Analysis
(IOTA) Group. Ultrasound Obstet Gynecol
2000;16:500–505
50. Timor-Tritsch IE, Bar-Yam Y, Elgali
S, Rottem S. The technique of TVS
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sonography with the use of 6.5 MHz probe.
Am J Obstet Gynecol 1988;158:1019–1024
51. Timor-Tritsch IE, Bashiri A, Monteagudo
A, Arslan AA. Qualified and trained
sonographers in the US can perform
early fetal anatomy scans between 11
and 14 weeks. Am J Obstet Gynecol
2004;191:1247–1252
52. Timor-Tritsch IE, Haratz-Rubinstein N,
Monteagudo A, Lerner JP, Murphy K.
Transvaginal color Doppler sonography
of the ureteral jets: a potential method to
detect ureteral obstruction. Obstet Gynecol
1997;89:113–117
53. Timor-Tritsch IE, Haratz-Rubinstein N,
Murphy K, Monteagudo A. Transvaginal
ultrasound in the detection of ureteral jets.
Contemporary Reviews in Obstetrics and
Gynecology 1997;143–148
54. Timor-Tritsch IE, Lerner JP, Monteagudo
A, Murphy KE, Heller DS. Sonographic
markers of inflammatory tubal disease.
Ultrasound Obstet Gynecol 1998;12:56–66
55. Timor-Tritsch IE, Monteagudo A, Rebarber
A et al. Transrectal scanning: an alternative
when transvaginal scanning is not feasible.
Ultrasound Obstet Gynecol 2003;21:
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56. Timor-Tritsch IE, Monteagudo A.
Transvaginal fetal neurosonography:
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used by anatomic landmarks. Ultrasound
Obstet Gynecol 1996;8:42–47
57. Timor-Tritsch IE, Rottem S (eds)
Transvaginal sonography, 2nd edn. Elsevier,
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58. Timor-Tritsch IE. Standardization of
ultrasonographic images: let's all talk the
same language! Ultrasound Obstet Gynecol
1992;2:311–312
59. Ueland FR, DePriest PD, Pavlik EJ,
Kryscio RJ, van Nagell JR Jr. Preoperative
differentiation of malignant from benign
ovarian tumors: the efficacy of morphology
indexing and Doppler flow sonography.
Gynecol Oncol 2003;91:46–50
60. Whitlow BJ, Chatzipapas IK, Lazanakis
ML, Kadir RA, Economides DL. The
value of sonography in early pregnancy
for the detection of fetal abnormalities
in an unselected population. Br J Obstet
Gynaecol 1999;106:929–936
61. Zimmer EZ, Timor-Tritsch IE, Rottem S.
The technique of transvaginal sonography.
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Transvaginal sonography, 2nd edn. Elsevier,
New York, 1991
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Investigation of early pregnancy
Harm-Gerd K Blaas José M Carrera
ABSTRACT
The preferred approach for the first-trimester examination is transvaginal
sonography (TVS) although transabdominal sonography (TAS) could be and
sometimes should be used to get a better overview. The presentation of images
made by TVS and TAS should be standardized.
In early pregnancy, use established measurement methods and measure several
parameters: the crown–rump length (CRL), the head width, the heart rate, the
diameter of the amniotic cavity and the diameter of the yolk sac; if possible, describe
the anatomy. Looking at the heart activity alone is an incomplete examination.
A detailed description of the embryonic development starting at week 4 and
ending at week 10 is presented.
KEYWORDS
Early pregnancy loss, ectopic pregnancy, first trimester ultrasound, miscarriage,
sonoembryology.
INTRODUCTION
Approximately 12–15% of all pregnancies end in recognizable miscarriages.1 The
most common indication for emergency referral in early pregnancy is vaginal
bleeding. However, there are many other reasons for a pregnant woman to visit
her doctor, such as abdominal pain, poor obstetric history, recurrent miscarriages,
previous pregnancy with anomalous embryonic/fetal development, check-up following assisted fertilization, possible teratogenic exposure, uncertain gestational
age or general anxiety. Today an ultrasound assessment of the pregnancy is a natural part of a first-trimester clinical examination.
57
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An ultrasound examination in the first trimester is expected to provide answers
to important questions. Is the embryo/young fetus alive? Is the pregnancy properly located in the cavity of the uterus? Is it a single or multiple pregnancy, and
in cases of multiple pregnancy, what is the chorionicity and amnionicity? What is
the age of the conceptus? The examiner must recognize the signs of early pregnancy failure such as embryonic demise, spontaneous abortion, ectopic pregnancy,
hydatidiform mole, and be able to identify normal anatomy and/or anomalies in
very early viable pregnancies.
2
The characteristics of the early conceptus are its small size, its constantly changing
anatomical appearance, and its uniform development and constant growth. Therefore,
the prerequisite for any early scan, in addition to adequate ultrasound equipment,
is a thorough knowledge of the normal sonographic appearance of the developing
embryo and its associated structures.2 The transvaginal approach is preferred.
In this chapter, fetal age is always given in completed weeks and completed
days based on the last menstrual period, i.e. the standard in obstetrics.
Ultrasound in obstetrics and gynaecology
DESCRIPTION OF THE SONOANATOMIC DEVELOPMENT
During the last two decades, systematic ultrasound studies have provided important and extensive knowledge about the development of the living embryo up to
10 weeks and the young fetus from 10 weeks on with detailed anatomic descriptions of embryonic organs and extraembryonic structures.
3–9
58
4.5 weeks
After approximately 4.5 weeks (LMP-based), a tiny gestational sac (diameter
2 mm) becomes visible within the decidua surrounded by the echogenic trophoblastic ring.
5 weeks 0–6 days, CRL ª0–3 mm
At 5 weeks the thin-walled yolk sac usually appears (Fig. 4.1). After ≈5.5 weeks
the yolk sac is always visible, which indicates that the pregnancy is properly
located in the uterine cavity, even if the embryo is not yet identified. The embryonic pole appears adjacent to the yolk sac. Since the connecting stalk is short, the
embryonic pole is located near the wall. The heart rate is about 80–100 beats per
minute (bpm) at the end of this week.
6 weeks 0–6 days, CRL ª4–8 mm
The embryonic pole, yolk sac and the heart activity are always present. The heart
rate increases to 130 bpm (Fig. 4.2).
7 weeks 0–6 days, CRL ª9–14 mm
In sagittal section, the embryonic body appears as a triangle. The sides consist of
the back and the roof of the rhombencephalon, and the frontal part includes the
head, the basis of the umbilical cord, and the embryonic tail (Fig. 4.3). The embry-
onic body is slender in the coronal plane. The limbs appear as short hypoechogenic
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Chor cavity
Yolk
sac
Embryo
Heart
Fig. 4.1 5 weeks 1 day old pregnancy: retroverted uterus, trophoblastic ring in fundus;
(arrow) small secondary yolk sac.
Investigation of early pregnancy
Fig. 4.2 6 weeks 1 day old pregnancy: CRL 5.2 mm. The embryo and the yolk sac lie close to
the wall (future placenta). The beating heart can easily be identified by real-time ultrasound.
outgrowths. The hypoechogenic brain cavities can be seen. The shallow rhombencephalic cavity is also visible from 7 weeks on. It has a well-defined rhombic shape
in the cranial pole of the embryo. The heart can easily be recognized by real-time
ultrasound as a relatively large beating structure below the embryonic head. It is
large and echogenic, the frequency has increased from 130 to 160 bpm. The thin
amniotic membrane surrounding the embryo becomes visible. The mean diameter
of the amniotic cavity is approximately identical with the CRL.
59
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Rhombencephalon
Mesencephalon
Diencephalon
A
B
Ultrasound in obstetrics and gynaecology
Fig. 4.3 7 weeks, CRL 13 mm. (A) Sagittal section through body; dotted line = section
of B. (B) Horizontal section through the head showing measurement of head width and
OFD (occipitofrontal diameter).
8 weeks 0–6 days, CRL ª15–22 mm
The brain cavities are easily seen as large ‘holes’ in the embryonic head (Fig. 4.4).
Choroid plexuses become visible as echogenic areas in the enlarged lateral ventricles and in the roof of the fourth ventricle. The third ventricle is still rather wide,
as is the mesencephalic cavity. The mesencephalon is on top of the head. The
spine is seen as two echogenic parallel lines. It is possible to recognize the fluidfilled stomach as a small hypoechogenic area on the left side of the upper abdomen below the heart. The physiological herniation of the gut can be identified as
an echogenic area in the umbilical cord at the abdominal insertion. Within a few
days, this echogenic structure becomes more distinct. At the end of the week, the
fingers may be distinguishable.
9 weeks 0–6 days, CRL ª23–31 mm (Fig. 4.5)
At week 9 it is possible to obtain acceptable images of the embryonic profile. The lateral ventricles are always visible. They are best seen in the parasagittal plane, where the C-shape becomes apparent. The bright choroid plexuses
of the lateral ventricles are regularly detectable at 9 weeks. The width of the
60
diencephalic cavity narrows gradually while the mesencephalon remains wide.
✩✩✩✩✩✩✩✩✩✩✩ ✩
Chorionic
cavity
Amn
cavity
Rhomb
Mes
Umb
Lower
limb
3. ventr
Amn
cavity
Mes
Lat
ventr
Lower
limb
3. ventr
Lower
limb
Investigation of early pregnancy
Fig. 4.4 8/1 weeks, CRL 15 mm, sagittal section through embryo lying in amniotic cavity; the
dotted line indicates section of image on the right side, horizontal section through the head.
Mes, mesencephalic cavity; Rhomb, rhombencephalic cavity.
The choroid plexuses of the fourth ventricle are echogenic landmarks which
divide the fourth ventricle into a rostral and a caudal compartment. The cerebellar hemispheres are easily detectable. The spine is still characterized by two
echogenic parallel lines. During week 9 the heart rate reaches a maximum of
mean 175 bpm. The midgut herniation is now a large hyperechogenic mass in the
umbilical cord (Fig. 4.6).
10 weeks 0–6 days, CRL ª32–42 mm, and 11 weeks 0–6 days,
CRL ª43–54 mm
The fetus has developed a human appearance. The head is relatively large with a
marked chin, a prominent forehead and a flat occiput. Ossification starts at about
11 weeks with the occipital bone,10 then the ossification of the spine becomes
apparent. The lateral ventricles fill the anterior part of the head and conceal the
diencephalic cavity. The cerebellar hemispheres seem to meet in the midline during weeks 11 and 12. The heart rate slows down to 165 bpm at the end of week
11. Anatomical details of the heart become obvious. The midgut herniation has
its maximal extension at the beginning of week 10; it returns into the abdominal
cavity during weeks 10–11. Fetuses that are older than 12 weeks do not demonstrate any sign of the midgut herniation. The stomach is always visible at 11
weeks. During weeks 9–11 the shape of the yolk sac alters and its wall becomes
thinner. The yolk sac enlarges in some cases, while in other cases it shrinks.
9
61
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Echogenic midgut
herniation in
umbilical cord
A
B
Echogenic midgut
herniation in
umbilical cord
Cord cyst (normal
phenomenon in
early first trimester)
Body
Chorionic cavity
Amniotic cavity
Choroid plexus
of 4th ventricle
Mesencephalic
cavity
3rd ventricle
Spine
Ultrasound in obstetrics and gynaecology
Fig. 4.5 Approximately 9-week-old embryo, CRL 22 mm, sagittal section through the embryo
in the amniotic cavity.
62
Fig. 4.6 Sagittal (A) and horizontal (B) section through an embryo (CRL 28 mm) at the end
of week 9. The midgut herniation of the bowel is identified as an echogenic area in the
umbilical cord. In (B) horizontal section through the embryonic abdomen; the arrows point
at the abdominal insertion of the umbilical cord, containing echogenic bowel.