*Chapter 37 - Obstetric Ultrasound (CHERI NOTES) Flashcards
(115 cards)
1
Q
Standards for the performance of obstetric UTZ exams: First trimester includes (6)? (P.910)
A
- Gestational sac (location and appearance)
- Yolk sac and embryo (present or absent)
- If embryo is present, CRL and fetal cardiac activity are documented
- Fetal number
- Uterus and Adnexa (thoroughly examined)
- If possible , fetal neck region and nuchal translucency are examined and measured, respectively.
2
Q
Standards for the performance of obstetric UTZ exams: Second and third trimesters includes (9) ? (P.910)
A
- Fetal presentation
- Amniotic fluid volume
- Cardiac activity
- Placental position
- Fetal measurements (biometry)
- Fetal number
- Fetal anatomic survey
- Maternal cervix
- Adnexa
3
Q
STANDARD FETAL ANATOMIC SURVEY includes (19)? (P.910)
A
- Head, 2. Face , 3. neck, 4. upper lip, 5. cerebellum,
- choroid plexus, 7. cisterna magna,
- lateral cerebral ventricles, 9. midline falx,
- cavum septum pellucidi, 11. four-chamber heart,
- outflow tracts, 13. stomach , 14. kidneys, 15. bladder, 16. umbilical cord insertion site,
- umbilical cord vessel number, 18. the entire spine,
- and presence or absence of the arms or legs
4
Q
A ____ is performed to answer a specific question such as to verify fetal position or to confirm fetal cardiac activity. (P.910) - performed generally only when a prior complete examination is on record
A
LIMITED EXAMINATION
5
Q
When a fetal anomaly is suspected, a _____ is performed. (P.910) - may include fetal echocardiography, biophysical profile, fetal Doppler sonography
A
SPECIALIZED EXAMINATION
6
Q
_____ and _____ are most significant in the FIRST TRIMESTER (Doppler UTZ) when embryologic tissues are tiny and loosely tethered. (P.910)
A
Potential cavitation; tissue disruptive effects
7
Q
______ are more significant in the 2nd and 3rd trimesters (Doppler UTZ) when bone is present increasing sound absorption and heating. (P.910)
A
THERMAL EFFECTS
8
Q
When imaging the normal embryo in the first trimester , all forms of Doppler should be _____.(p.910)
A
AVOIDED
- M-mode UTZ or recording of real-time UTZ by cine loop provide the same documentation at much lower energies
9
Q
Covers the period from conception to the end of the 13th menstrual week (p.910)
A
FIRST TRIMESTER
- includes the entire EMBRYONIC PERIOD (0-10 weeks) and is a time for dynamic growth and the differentiation and development of most organ systems
10
Q
The ___ and the _____ have the greatest risk of maldevelopment , injury and death during the first trimester…(p.911)
A
Embryo ; fetus
11
Q
Radioimmunoassay for ____ allows pregnancy to be detected within 2 weeks of conception (as early as 23 menstrual days) before a gestational sac can be detected by either transabdominal or transvaginal UTZ. (P.911)
A
Serum b-hCG
12
Q
The EARLY GESTATIONAL SAC can be seen by TVS at _______ as a tiny cystic structure implanted within the echogenic decidua (p.911)
A
3.5 to 4.5 menstrual weeks
13
Q
Tiny cystic structure within the echogenic decidua (early gestational sac); (p.911)
A
INTRADECIDUAL SIGN
*not specific for early intrauterine pregnancy and may be mimicked by INTRAUTERINE FLUID COLLECTION or DECIDUAL CYSTS in the presence of ectopic pregnancy
14
Q
A normal gestational sac is visualized by the transabdominal approach by _______ (p.911)
A
5 menstrual weeks
15
Q
The normal ______ appears on UTZ as a smoothly contoured, round, or oval, fluid-containing structure positioned within the endometrium near the fundus of the uterus (p.911)
A
GESTATIONAL SAC
*normal gestational sac has an echogenic border GREATER THAN 2MM THICK, which represents the choriodecidual reaction
16
Q
Sign produced by visualization of three layers of decidua early in pregnancy (p.911) - evident in about 85% of normal pregnancies
A
DOUBLE DECIDUAL SAC SIGN
*a small amount of fluid in the endometrial cavity separates the Decidua Vera from the Decidua capsularis, enabling the visualization of this sign
17
Q
Refers to the endometrium of the pregnant uterus
A
DECIDUA
18
Q
Lines the endometrial cavity
A
DECIDUA VERA
19
Q
Covers the gestational sac
A
DECIDUA CAPSULARIS
20
Q
Contributes to the formation of the placenta at the site of implantation (p.911)
A
DECIDUA BASALIS
21
Q
The free margin of the gestational sac consists of _____ (2) and is normally at least ____ thick. (P.912)
A
Chorion and Decidua capsularis ; 2mm
22
Q
A well-visualized _____ is excellent evidence of intrauterine pregnancy.(p.912) An ______ is evidence of an ABNORMAL intrauterine pregnancy or an ECTOPIC pregnancy.(p.912)
A
DOUBLE SAC ; ABSENT Double sac sign
23
Q
A 2 to 6 mm diameter, spherical, cystic structure that is connected to the midgut of the embryo by a thin stalk, the vitteline duct. (P.912)
A
YOLK SAC
24
Q
A remnant of the connection of the Vitelline duct (also called the omphalomesenteric duct) to the distal ileum. (P.912)
A
MECKEL DIVERTICULUM
25
The earliest site of blood cell formation in the embryo (p.912)
**YOLK SAC**
\*EARLIEST STRUCTURE VISUALIZED WITHIN THE GESTATIONAL SAC
\* serves as definitive evidence of early pregnancy
26
The yolk sac should always be visualized in normal pregnancy in gestational sacs of: (p.912) A. _____ mm mean sac diameter (MSD) by Transabdominal UTZ B. _____ mm MSD by transvaginal UTZ
**A. 20 mm; B. 8 mm**
27
The yolk sac is generally seen between _____ weeks gestational age. (P.912)
**5 and 12 weeks**
28
The earliest demonstration of the embryo is \_\_\_\_\_. (P.912) - produced by the amniotic sac and the yolk sac with the embryonic disc between them
**DOUBLE BLEB SIGN**
29
Immediately following ovulation, the ____ appears as an area of focal hemorrhage on the ovary. (P.912)
**CORPUS LUTEUM**
30
REMEMBER that most ECTOPIC PREGNANCIES occur \_\_\_\_\_, while the CORPUS LUTEUM is \_\_\_\_\_\_\_. (P.912)
**In the tube; an ovarian structure**
31
Between 6 and 8 weeks GA, the hindbrain (rhombencephalon) forms a prominent cystic structure that becomes the normal \_\_\_\_\_. (P.912)
**FOURTH VENTRICLE**
32
Between 9 and 11 weeks GA, the midgut herniates into the base of the umbilicus forming a physiologic _______ seen as a protruding midline anterior abdominal wall mass 6 to 9 mm in size. (P.913)
**OMPHALOCELE**
33
The termination of pregnancy before 20 weeks GA. (P.913)
**ABORTION**
34
The termination of pregnancy by NATURAL CAUSES. (P.913)
**SPONTANEOUS ABORTION**
35
Refers to the occurrence of VAGINAL BLEEDING AND UTERINE CRAMPING with a CLOSED cervical os in early pregnancy. (P.913)
**THREATENED ABORTION**
36
Presents with CERVICAL DILATION and FETAL OR PLACENTAL TISSUES within the cervical os. (P.914)
**INEVITABLE ABORTION**
37
All uterine contents have been expelled (abortion type); (P.914)
**COMPLETE ABORTION**
38
Refers to the presence of residual products of conception within the uterus. (P.914)
**INCOMPLETE ABORTION**
39
In a ____ (abortion type) , the fetus has died but remains within the fetus. (P.914)
**MISSED ABORTION**
40
Defined as three or more successive spontaneous abortions. (P.914)
**HABITUAL ABORTION**
41
A pregnancy in which the embryo has died and is no longer visible or never developed. (P.914)
**Anembryonic pregnancy OR Blighted ovum**
42
\_\_\_\_ may be a very early intrauterine pregnancy or a nonviable intrauterine pregnancy (anembryonic pregnancy); (p.914)
**"Empty" gestational sac**
\* must be differentiated from a pseudogestational sac associated with ectopic pregnancy
43
A gestational sac is considered to be ABNORMAL if it demonstrates the following features (6): (P.914)
1. Large size without an embryo or yolk sac (MAJOR)
2. Distorted shape (MAJOR)
3. Irregular contour (minor)
4. Thin or weak choriodecidual reaction (minor)
5. Absence of a double decidual sac (minor)
6. Abnormal position (minor)
\*any ONE of the MAJOR criteria or THREE of the MINOR criteria are considered diagnostic of a FAILED PREGNANCY.
44
\_\_\_ and ____ have a reported 100% specificity and positive predictive value for identification of NONVIABLE PREGNANCY. (P.914)
**Large sac w/o visualized yolk sac or embryo;
Distorted sac contour**
45
Strong evidence of abnormal sac development. (P.914)
**Growth of the gestational sac of less than 1 mm/d MSD**
46
Diagnosed by UTZ confirmation of the absence of cardiac activity. (P.914)
**Embryonic or Fetal demise**
\*absence of cardiac activity in a fetus or an embryo large enough to be visualized by transabdominal UTZ is DEFINITIVE EVIDENCE OF DEATH.
47
All cases of suspected demise of small embryos should be confirmed by \_\_\_\_, which may demonstrate cardiac activity even in embryos as small as 1.5 mm CRL. (P.914)
**Transvaginal UTZ**
48
Absence of cardiac activity in embryos larger than ____ on TVS is considered DIAGNOSTIC OF EMBRYOLOGIC DEMISE (missed abortion); (p.915)
**5 mm**
49
\_\_\_\_\_ UTZ is used to document visualized cardiac activity. (P.915)
**M-mode**
50
A normal intrauterine pregnancy demonstrates serum b-hCG levels that double every ___ hours
| (serial measurements); (P.915)
**48**
\*a failure of doubling indicates an abnormal pregnancy
51
\_\_\_\_\_ remains one of the most common areas of medical malpractice litigation. (P.915)
**MISDIAGNOSIS OF ECTOPIC PREGNANCY**
52
Patients at risk for ectopic pregnancy include (6): (P.915)
1. History of PID
2. Tubal surgery
3. Endometriosis
4. Ovulation induction
5. Previous ectopic pregnancy
6. Use of IUD for contraception
53
95% of ectopic pregnancies occur in the \_\_\_\_, most commonly in the \_\_\_\_\_. (P.915)
**Fallopian tube ; isthmic portion**
54
All patients with a positive pregnancy test, vaginal bleeding, pelvic pain or adnexal mass must be considered at risk for \_\_\_\_\_. (P.915)
**ECTOPIC PREGNANCY**
55
A completely confident diagnosis of ectopic pregnancy can be made sonographically only when a living embryo or a gestational sac containing a yolk sac is positively demonstrated to be in a \_\_\_\_\_. (P.915)
**Position outside of the uterus**
| (18% to 26% of ectopic pregnancies)
56
Term for concurrent intrauterine and extrauterine pregnancies (P.915)
**HETEROTROPIC pregnancy**
57
UTZ demonstration of an extrauterine gestational sac appearing as a fluid-containing structure with an echogenic ring. (p.915)
**TUBAL RING SIGN**
| (40% to 68 % of ectopic pregnancies)
58
Ectopic pregnancy vs Corpus luteal cyst (UTZ); (P.915)
A. **ECTOPIC PREGNANCY** - mostly occur in the _fallopian_ _tube_; rarely seen in the ovary
B. **CORPUS LUTEAL CYST** - ALWAYS arises from the _ovary_
59
\_\_\_\_\_\_ may appear (in UTZ) as an amorphous solid or complex adnexal mass (a hematoma) LACKING AN EMBRYO OR SAC. (P.915)
**Hematosalpinx or ruptured ectopic pregnancy**
60
Moderate or large volumes of echogenic fluid or blood clots in the ____ are highly predictive of ectopic pregnancy. (P.915)
**Cul-de-sac**
\*a small volume of anechoic fluid in the cul-de-sac is a common and NORMAL finding
61
Term used for blood in the uterine cavity producing a cystic appearing mass (p.915)
**Pseudogestational sac**
\*in 10% to 20% of ectopic pregnancies
62
TRUE gestational sac vs "pseudosac" (p.915)
- Presence of a yolk sac or embryo (seen in true gestational sac)
- _pseudosacs_ are located CENTRALLY within the uterine canal; demonstrates ABSENT OR MINIMAL PERITROPHOBLASTIC FLOW in Doppler studies.
- _normal true gestational sac_ is ECCENTRICALLY implanted within the Decidua; demonstrates HIGH VELOCITY, LOW IMPEDANCE FLOW in doppler studies
63
IDENTIFY THIS SIGN.
Transvaginal US image of the uterus in a transverse plane demonstrates a tiny gestational sac (arrow) implanted within the thickened decidual (between arrowheads).
[FIGURE 37.1.]
The _size of the sac_ corresponds to a pregnancy of approximately _4 weeks menstrual age._
**INTRADECIDUAL SIGN**
64
IDENTIFY THIS SIGN.
A magnified longitudinal endovaginal US image of the uterus demonstrates an intrauterine gestational sac (GS) and the normal layers of decidua. [FIGURE 37.2.]
**DOUBLE DECIDUAL SAC SIGN**
## Footnote
```
_decidua capsularis_ (long thin arrow )
- covers the gestational sac
```
```
_decidual vera_ ( short fat arrow )
- lines the uterine cavity.
```
These two decidual surfaces are separated by a dark
line representing the uterine cavity. The uterine cavity continues into the lower uterine segment (curved arrow), which is lined by the thickened
echogenic decidua vera.
The site of implantation (arrowhead) on the anterior wall of the uterine cavity shows only one layer of _decidua basalis_, which is joining with the _chorionic villi_ of the gestational sac to produce an _anterior placenta_.
65
The ____ (arrow) is shown within the gestational sac by transvaginal US. [FIGURE 37.3.]
\*The normal ______ is _less than 6 mm_
in diameter, spherical, and fluid filled with a thin wall.
**YOLK SAC**
The yolk sac is in the _chorionic fluid space_ (C) between the thin membrane of the _amnion_ (white arrowhead) and the chorion that defines the limit of fluid within the gestational sac.
The embryo develops within the _amniotic space_ ( A ).
66
```
Image of an 11-week embryo shows the ______________ (long thin arrow) extending from the umbilicus to the yolk sac (short arrow).
The fingers (curved arrow) of the developing infant are also well shown. [FIGURE 37.3.]
```
**VITELLINE DUCT**
67
IDENTIFY THIS SIGN.
[FIGURE 37.4.]
**DOUBLE BLEB SIGN**
The **double bleb** is formed by the _yolk sac_ (white arrowhead) and the _amniotic sac_ (black arrowhead)
suspended in the fluid of the early chorionic sac.
The _embryo_ is seen as a tiny disc-like structure (arrow) within the amniotic sac.
Early cardiac activity can frequently be observed in the tiny embryo.
68
IDENTIFY.
[FIGURE 37.5.]
**CORPUS LUTEUM**
## Footnote
A. Transvaginal color Doppler image of the ovary reveals a 3-cm cyst surrounded by an intense ring of vascularity (“_ring of fire_”) characteristic of the corpus Luteum. The corpus luteum secretes hormones essential for the development of the pregnancy.
B. Transvaginal image of the ovary shows the collapsed cyst appearance of the corpus luteum (between arrowheads ) that occurs just after ovulation.
Note the follicles (arrow) that confirm location of the structure on the ovary.
C. Being highly vascular, the corpus luteum is _prone to internal hemorrhage_ creating a hemorrhagic ovarian cyst (between arrowheads). Note the echogenic fluid and clot (arrow) within the cyst.
D. A **hemorrhagic corpus luteal cyst** (between arrowheads) may enlarge to become a prominent pelvic structure and be a source of adnexal pain in early pregnancy. This corpus luteal cyst measures 5 cm in diameter. _Blood clots (arrow) within the cyst may simulate an ectopic pregnancy containing
an embryo._
69
IDENTIFY.
A 7-week embryo has a prominent cystic structure
(arrow) within the cranium. [FIGURE 37.6.]
**NORMAL CYSTIC RHOMBENCEPHALON**
This is the normal cystic phase of development of the rhombencephalon that is seen _between 6 and 8 weeks gestational age._
Development of the rhombencephalon _results in normal structures in the posterior fossa_
70
IDENTIFY.
A 10-week embryo shows a prominent bulge (arrow) at the level of the umbilicus. [FIGURE 37.7]
**NORMAL MIDGUT HERNIATION**
This is caused by the normal herniation of the midgut into the base of the umbilical cord that _occurs between 9 and 11 weeks gestation_. This normal structure _should not exceed 1 cm in size._
71
DIAGNOSIS?
## Footnote
An empty gestational sac measuring 27 mm in mean sac diameter (MSD) is demonstrated within the uterus by transvaginal US.
The margin of the sac is irregular in contour, and the decidual reaction is poorly defined and only weakly echogenic.
Color Doppler shows blood flow only in the myometrium. [FIGURE 37.8.]
**ANEMBRYONIC PREGNANCY**
In a normal intrauterine pregnancy, a _yolk sac should always be demonstrable by transvaginal US_ when the MSD exceeds 8 mm and an _embryo should be seen_ when the MSD exceeds 16 mm.
_Doppler US should be used with caution_, especially in the first trimester, and only when the pregnancy is believed to be abnormal.
72
IDENTIFY. [FIGURE 37.10.]
**PSEUDOGESTATIONAL SAC**
Fluid within the endometrial
cavity in a patient with an ectopic pregnancy mimics an intrauterine gestational sac.
The _intrauterine fluid_ (arrow) is echogenic and particulate indicative of blood.
The _decidual reaction_ (arrowhead) will be
present whether the pregnancy is intrauterine or ectopic.
73
DIAGNOSIS? [FIGURE 37.11.]
**SUBCHORIONIC HEMORRHAGE**
Hemorrhage (black arrowhead) is seen in the uterine cavity between the decidua capsularis
and the decidua vera. Some of the blood is clotted and appears more echogenic (white arrowhead) than the liquid blood.
A live embryo (arrow) was present within its amniotic sac.
74
DIAGNOSIS? [FIGURE 37.9.]
A. Transvaginal US in a longitudinal
plane demonstrates an empty uterus
(between calipers, + , x) in a pregnant patient.
Echogenic blood (arrow) distends the cul-de-sac.
**ECTOPIC PREGNANCY**
B. Transverse transvaginal image reveals a _tubal ring sign_ (arrow) in the right adnexa highly indicative of ectopic pregnancy. U, uterus (between
calipers, + ).
C. Color Doppler image of a tubal ectopic pregnancy shows a tubal ring sign with a “_ring of fire_” made up of prominent blood vessels.
_Note_ the similarity in appearance to the corpus luteal cyst in Figure 37.5A . Differential is made by real-time US determination of the location of the mass as arising from the ovary or as being separate from the
ovary. _This differentiation is not always possible._
75
IDENTIFY. [FIGURE 37.12]
A. Transverse image of the uterus in a woman with continuing bleeding following a spontaneous
abortion.
B. Transverse color Doppler image of the uterus in the same patient.
**RETAINED PRODUCTS OF CONCEPTION**
A. Transverse image of the uterus in a woman with continuing bleeding following a spontaneous
abortion reveals echogenic material (arrow) representing _retained placenta_ and echolucent material (arrowhead) representing _blood and clots_
within the uterine cavity.
B. Transverse color Doppler image of the uterus in the same patient documents continuing blood flow to the retained placenta.
76
DIAGNOSIS? [FIGURE 37.13.]
**HYDATIDIFORM MOLE**
A. Transvaginal US shows the _“snowstorm”_ appearance of a molar pregnancy (between arrowheads) filling the uterine cavity in the first trimester.
B. In another patient examined early in the second trimester, more discrete cysts are seen within the molar tissue (arrowheads). m, myometrium.
77
DIAGNOSIS? [FIGURE 37.14]
```
Transabdominal image demonstrates
the ovary (between calipers, +) to be greatly enlarged by
numerous cysts in this patient with a twin pregnancy following infertility therapy.
```
The β -hCG level was greatly elevated.
This ovary measured 16 × 12 × 8 cm in size.
**THECA LUTEIN CYSTS**
78
The ___ is measured from the top of the head to the bottom of the torso (between cursors, + ). [FIGURE 37.15]
**CROWN-RUMP LENGTH (CRL)**
79
IDENTIFY THIS FETAL MEASUREMENT. [FIGURE 37.17]
**ABDOMINAL CIRCUMFERENCE**
The correct plane of measurement of the abdominal circumference is an _axial plane showing
a round abdomen at the level of the umbilical vein
(arrowhead) junction with the left portal vein._
80
[FIGURE 37.16] Axial image of the fetal cranium
demonstrates the paired thalami (arrowhead) on either side of the midline third ventricle (long arrow).
The _____ is measured in this plane from the outer surface of the near cranium to the inner surface of the far cranium (+ , cursors).
The _________ is measured as an outer perimeter measurement of the cranium in the same plane
(elliptical dashed line, x cursors).
TRANSTHALAMIC (BIPARIETAL DIAMETER/HEAD
CIRCUMFERENCE [BPD/HC]) PLANE.
1. **BPD**
2. **HEAD CIRCUMFERENCE**
81
IDENTIFY THIS FETAL MEASUREMENT. [FIGURE 37.18]
**FEMUR LENGTH (FL)**
The FL is the measurement of
the ossified portion of the femoral diaphysis
(between calipers, + ).
82
This is an Umbilical Artery Doppler tracing.
[FIGURE 37.19]
FIGURE A: NORMAL OR ABNORMAL ?
FIGURE B: NORMAL OR ABNORMAL ?
**FIGURE A: NORMAL
FIGURE B: ABNORMAL**
## Footnote
**A.** Spectral Doppler tracing from an umbilical artery shows a _normal pattern_ with forward flow maintained throughout diastole and a low vascular resistance
with RI = 0.58.
**B.** Spectral Doppler in a severely growth retarded
fetus shows a high vascular resistance pattern with fl ow toward the placenta during systole and reversal of blood fl ow direction in diastole (arrowhead). This finding is highly indicative of _severe fetal distress_.
This fetus died 4 days after this examination.
83
DIAGNOSIS ? [FIGURE 37.20]
The cervix is best evaluated
with a _______ view with the bladder (B) empty. The transducer is aimed down the long axis of the vagina (V). The cervix, measured between the internal os and the external os (arrowheads), is shortened
to 9 mm in this patient with a _history of multiple spontaneous abortions in the second trimester_.
The cervix is also dilated allowing amniotic
fluid ( asterisk ) to enter the endocervical canal.
The fetal head ( H ) is presenting at the internal cervical os.
**CERVICAL INCOMPETENCE;
TRANSLABIAL view**
84
[FIGURE 37.21]
```
A transabdominal scan demonstrates
a ________ (P) and the insertion site of the cord onto the placenta (arrowhead).
```
The _\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\__
(arrows) appears as a network of tubular lucencies beneath the placenta. A, amniotic cavity.
**NORMAL PLACENTA**
**RETROPLACENTAL COMPLEX OF VEINS**
85
DIAGNOSIS? [FIGURE 37.23]
**PLACENTAL ABRUPTION**
The placenta (P) is displaced away from the wall of the uterus (U) by an echogenic hematoma (H).
Note the absence of visualization of the retroplacental complex of veins. A, amniotic cavity.
86
DIAGNOSIS? [FIGURE 37.22]
**PLACENTA PREVIA**
Transabdominal US shows a normal cervix (between cursors, +) measuring 34 mm. The _placenta (P) covers
the internal os_. A, amniotic cavity; B, bladder; V, vagina.
87
IDENTIFY THIS NORMAL STRUCTURE.
[FIGURE 37.24]
**NORMAL UMBILICAL CORD**
A. Color Doppler image shows the normal spiral (“_barber pole_”) appearance of the three-vessel
umbilical cord as it extends from the placenta.
B. Transverse color Doppler image through the fetal pelvis shows the bladder (B encompassed by
the two umbilical arteries (arrowheads) as they course to join the fetal internal iliac arteries. _This view provides a handy way to confirm the presence of a three-vessel cord with two umbilical arteries._
88
DIAGNOSIS ? [FIGURE 37.25]
**AMNIOTIC BAND SYNDROME**
```
The forearm (arrowhead) of a fetus at 15 weeks gestational age is _entangled within fibrous bands_
(arrows) that extend across the chorionic cavity (C).
```
89
IDENTIFY. [FIGURE 37.26]
**AMNIOTIC SHEET**
A. A fibrous band covered by chorioamniotic membranes (arrow) extends across the amniotic cavity. The uterine synechia forms a shelf-like structure that partially compartmentalizes the uterine cavity. The fetus has free access to both compartments.
B. The characteristic free edge ( arrow ) of the amniotic sheet is demonstrated.
90
DIAGNOSIS ? [FIGURE 37.27]
**NUCHAL SKIN THICKENING**
Transcerebellar view of the fetal cranium shows thickening of the nuchal fold (between cursors, +)
to 8 mm. The _measurement is made between the fetal skull and the skin surface._
The _normal measurement should not exceed 6 mm_ in the _second trimester_.
This fetus proved to have Down syndrome.
91
What are the landmarks in the transcerebellar
plane (in cranial ultrasound) ? [FIGURE 37.29]
**thalami** (t), **third ventricle** (arrow),
and **cerebellar hemispheres** (c).
The cisterna magna (between arrowheads) is _measured
from the vermis to the occiput._ The _normal cisterna magna measures 2 to 11 mm throughout pregnancy_.
92
WHAT IS THE IMAGING PLANE IN THIS PICTURE?
DIAGNOSIS?
[FIGURE 37.28]
**TRANSVENTRICULAR PLANE**
**EARLY VENTRICULOMEGALY**
The choroid plexus (skinny arrow) hangs dependently in the atrium of the downside lateral ventricle. The ventricular atrium is measured from its medial wall to its lateral wall (between cursors, +).
The _normal ventricular atrium does not exceed 10 mm in width at any time during pregnancy._
The diameter of the atrium in this case measures
12 mm indicating ventriculomegaly.
This fetus has a spina bifida defect with associated Arnold–Chiari II malformation as the cause of ventriculomegaly.
Note the bossing of the frontal bones (thick arrow)
giving the outline of the cranium an appearance similar in shape to a lemon (lemon head).
93
DIAGNOSIS ? [FIGURE 37.30]
**VENTRICULOMEGALY**
An axial image of the fetal brain, an infant with aqueduct stenosis, demonstrates marked enlargement
of the lateral ventricles (V).
```
The _falx_ (arrowhead) is seen as an echogenic stripe in the midline. A _rind of cortex_ (arrow) is present. _These
latter two findings differentiate ventriculomegaly from hydranencephaly and holoprosencephaly._
```
94
DIAGNOSIS ? [FIGURE 37.31]
A sagittal image through the head of a fetus.
The mouth and the lips are evident (arrowhead).
**ANENCEPHALY**
A sagittal image through the head of a
fetus demonstrates absence of the cranial vault (thick arrow) above the level of the eye (skinny arrow).
The volume of amniotic fluid (A) is increased.
_Polyhydramnios is common in the presence of anencephaly_. Arm, fetalarm.
95
DIAGNOSIS ? [FIGURE 37.32]
Axial US image through the fetal skull
**ENCEPHALOCOELE**
Axial US image through the fetal skull demonstrates herniation of brain tissue (B) through a large defect
(long arrows) in the skull, forming an occipital encephalocele (between arrowheads). The intracranial contents are reduced, and the biparietal diameter (between cursors, +) is less than expected for
gestational age because of the encephalocele.
96
FIGURE A.: NORMAL SPINE OR SPINA BIFIDA ?
FIGURE B.: NORMAL SPINE OR SPINA BIFIDA ?
[FIGURE 37.33]
**Figure A. NORMAL SPINE**
**Figure B. SPINA BIFIDA**
**A. Normal spine.** Posterior transverse image through a normal fetal spine at the L4 to L5 level demonstrates normal converging orientation of the ossified portions of the lamina (arrows). The skin overlying the posterior aspect of the vertebra is intact (arrowhead).
**B. Spina bifida.** Posterior transverse image through a spina bifida defect demonstrates abnormal divergence of ossified portions of the lamina (arrows) posteriorly. The skin surface ends abruptly (arrowheads) at the open defect. IC, iliac crest.
97
DIAGNOSIS ? [FIGURE 37.34]
Image through the cranium of a fetus.
**ALOBAR PROSENCEPHALY**
Image through the cranium of a fetus reveals _a single large midline ventricle_ (V) and _fused thalami_ (arrow).
A _thin rim of cortex_ (arrowhead) is present.
These findings are characteristic of alobar holoprosencephaly.
The fetal face should be examined for associated defects such as midline cleft and proboscis.
98
DIAGNOSIS ? [FIGURE 37.35]
Axial sonogram through the brain of a near-term fetus.
**HYDRANENCEPHALY**
Axial sonogram through the brain of a near-term fetus demonstrates two massive ventricles (V), a well defined midline falx (arrowhead) and total absence of detectable cortical tissue (arrow).
These findings are characteristic of hydranencephaly.
99
DIAGNOSIS ? [FIGURE 37.36]
Coronal plane image.
**DANDY WALKER MALFORMATION**
Coronal plane image demonstrates _cystic enlargement of the posterior fossa_ (arrow). The _lateral ventricles (V) are enlarged_ indicating associated hydrocephalus.
100
DIAGNOSIS ? [FIGURE 37.38]
A multiseptated cystic mass (C) extends over the occipital region of the fetal skull.
**CYSTIC HYGROMA**
Cystic hygroma is _differentiated from occipital cephalocele by demonstration of the midline
septum_ (arrow) due to the nuchal ligament and by absence of a bony defect in the skull.
101
Figure A: Normal Face View or Cleft Lip ?
Figure B: Normal Face View or Cleft Lip ?
[FIGURE 37.37]
**Figure A: Normal Face View
Figure B: Cleft Lip
A. Normal face view.** Coronal view of a normal fetal face (“up your nose”view) shows both nares (arrow), an open mouth (arrowhead) and the muscles of the upper (L) and the lower (LL) lips.
**B. Cleft lip.** Matching coronal view of another fetus reveals a cleft (thick arrow) in the left upper lip extending into the left nares (skinny arrow). The mouth is slightly open. The lower lip (LL) is apparent. An arm (A) extends across the face.
102
DIAGNOSIS ? [FIGURE 37.39]
A. A transverse image through the fetal thorax at the level of a four-chamber view of the heart.
B. Transverse US of the fetal abdomen
**FETAL HYDROPS**
A. A transverse image through the fetal thorax at the level of a four-chamber view of the heart (arrow) demonstrates _large bilateral pleural effusions_ (e). The skin surrounding the thorax is markedly thickened (T).
B. Transverse US of the fetal abdomen also
shows marked skin thickening (T).
103
DIAGNOSIS ? [FIGURE 37.40]
**CONGENITAL DIAPHRAGMATIC HERNIA**
Axial plane image of the fetal thorax stomach (St) and small bowel (between arrows) herniated into the left thorax. The heart (H) is shifted markedly
into the right thorax and is abnormally rotated.
Only a small volume of compressed right lung (L) is present.
Severe pulmonary hypoplasia is likely and the prognosis for this fetus is grim. The spine (S) is seen posteriorly.
104
DIAGNOSIS ? [FIGURE 37.41]
An echogenic solid-appearing mass (between arrows) is seen in the right thorax displacing and compressing the heart (H). A small portion of the compressed left lung (L) is evident.
**CYSTIC ADENOMATOID MALFORMATION**
The appearance is characteristic of
type III, cystic adenomatoid malformation.
105
IDENTIFY THIS ULTRASOUND VIEW. [FIGURE 37.42]
**NORMAL FOUR-CHAMBER HEART VIEW**
Axial sonogram through the fetal chest demonstrates the normal heart and fluid-filled lungs in an 18-week fetus. The right ventricle (rv) and the left ventricle
(lv) are approximately equal in size, as are the right atrium (ra) and the left atrium (la).
The _heart normally occupies about one-third of
the cross-sectional area of the thorax_.
The developing lungs are echogenic.
The spine (S) is seen posteriorly. rl, right lung; ll, left lung.
106
IDENTIFY THIS SIGN. [FIGURE 37.43]
**DOUBLE BUBBLE**
Fluid distension of the stomach dilated (St) and the duodenal bulb (D) is caused by obstruction at the level of the descending duodenum.
107
DIAGNOSIS ? [FIGURE 37.45]
**HYDRONEPHROSIS**
Coronal plane image through the fetal abdomen reveals bilateral hydronephrosis (skinny arrows) resulting
from posterior urethral valves.
_Calyces and the renal pelvis are dilated._ Both kidneys (between short arrows) are normal in size.
108
DIAGNOSIS ? [FIGURE 37.44]
**SMALL BOWEL OBSTRUCTION**
Ileal atresia was the cause of markedly dilated loops of small bowel seen throughout the abdomen.
109
DIAGNOSIS ? [FIGURE 37.46]
Coronal plane image in a 22-week fetus.
**AUTOSOMAL RECESSIVE POLYCYSTIC
KIDNEY DISEASE**
Coronal plane image in a 22-week fetus shows _two markedly enlarged, highly echogenic kidneys_
(between cursors,+,x) filling and distending
the abdomen. Each kidney exceeded 5 cm in length. _Severe oligohydramnios_ was present. This appearance is characteristic of the _infantile form of autosomal recessive polycystic disease._
110
IDENTIFY THIS NORMAL STRUCTURE.
[FIGURE 37.47]
**NORMAL UMBILICAL CORD INSERTION SITE**
A. Normal. Axial image through the fetal abdomen at
the level of the umbilicus shows the normal cord insertion site (arrowhead).
111
DIAGNOSIS ? [FIGURE 37.4]
**GASTROSCHISIS**
Axial image through the abdomen of another fetus shows loops of bowel (short fat arrow) extending through a defect in the anterior abdominal wall (long skinny arrow) just to the right of the insertion site of the umbilical cord (arrowhead).
112
DIAGNOSIS ? [FIGURE 37.47.]
**OMPHALOCELE**
Axial image of another fetus at the level of the umbilicus shows liver herniating through a defect (between arrowheads ) in the anterior abdominal wall. The defect involves the umbilical cord (skinny arrow).
A covering membrane (short fat arrow) is easily seen because it is outlined by ascites (a) within the omphalocele and the amniotic fluid.
113
DIAGNOSIS ? [FIGURE 37.48]
A longitudinal image of the femur (between cursors, +)
**MICROMELIC DWARF**
A longitudinal image of the femur (between cursors, +) demonstrates poor mineralization, central bowing (arrowhead), and length that is markedly short for gestational age.
114
Definitive therapy for Ectopic Pregnancy ?
| (p. 916)
**SURGICAL RESECTION OF THE**
**INVOLVED FALLOPIAN TUBE**
115
