**Chapter 37 - Obstetric Ultrasound (CHERI NOTES) Flashcards Preview

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Flashcards in **Chapter 37 - Obstetric Ultrasound (CHERI NOTES) Deck (115):
1

Standards for the performance of obstetric UTZ exams: First trimester includes (6)? (P.910)

1. Gestational sac (location and appearance)
2. Yolk sac and embryo (present or absent)
3. If embryo is present, CRL and fetal cardiac activity are documented
4. Fetal number
5. Uterus and Adnexa (thoroughly examined)
6. If possible , fetal neck region and nuchal translucency are examined and measured, respectively.

2

Standards for the performance of obstetric UTZ exams: Second and third trimesters includes (9) ? (P.910)

1.  Fetal presentation
2. Amniotic fluid volume
3. Cardiac activity
4. Placental position
5. Fetal measurements (biometry)
6. Fetal number
7. Fetal anatomic survey
8. Maternal cervix
9. Adnexa

3

STANDARD FETAL ANATOMIC SURVEY includes (19)? (P.910)

1. Head, 2. Face , 3. neck, 4. upper lip, 5. cerebellum,
6. choroid plexus, 7. cisterna magna,
8. lateral cerebral ventricles, 9. midline falx,
10. cavum septum pellucidi, 11. four-chamber heart,
12. outflow tracts, 13. stomach , 14. kidneys, 15. bladder, 16. umbilical cord insertion site,
17. umbilical cord vessel number, 18. the entire spine,
19. and presence or absence of the arms or legs

4

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

LIMITED EXAMINATION

5

When a fetal anomaly is suspected, a _____ is performed. (P.910) - may include fetal echocardiography, biophysical profile, fetal Doppler sonography

SPECIALIZED EXAMINATION

6

_____ and _____ are most significant in the FIRST TRIMESTER (Doppler UTZ) when embryologic tissues are tiny and loosely tethered. (P.910)

Potential cavitation; tissue disruptive effects

7

______ are more significant in the 2nd and 3rd trimesters (Doppler UTZ) when bone is present increasing sound absorption and heating. (P.910)

THERMAL EFFECTS

8

When imaging the normal embryo in the first trimester , all forms of Doppler should be _____.(p.910)

AVOIDED

- M-mode UTZ or recording of real-time UTZ by cine loop provide the same documentation at much lower energies

9

Covers the period from conception to the end of the 13th menstrual week (p.910)

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

The ___ and the _____ have the greatest risk of maldevelopment , injury and death during the first trimester...(p.911)

Embryo ; fetus

11

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)

Serum b-hCG

12

The EARLY GESTATIONAL SAC can be seen by TVS at _______ as a tiny cystic structure implanted within the echogenic decidua (p.911)

3.5 to 4.5 menstrual weeks

13

Tiny cystic structure within the echogenic decidua (early gestational sac); (p.911)

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

A normal gestational sac is visualized by the transabdominal approach by _______ (p.911)

5 menstrual weeks

15

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)

GESTATIONAL SAC

*normal gestational sac has an echogenic border GREATER THAN 2MM THICK, which represents the choriodecidual reaction

16

Sign produced by visualization of three layers of decidua early in pregnancy (p.911) - evident in about 85% of normal pregnancies

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

Refers to the endometrium of the pregnant uterus

DECIDUA

18

Lines the endometrial cavity

DECIDUA VERA

19

Covers the gestational sac

DECIDUA CAPSULARIS

20

Contributes to the formation of the placenta at the site of implantation (p.911)

DECIDUA BASALIS

21

The free margin of the gestational sac consists of _____ (2) and is normally at least ____ thick. (P.912)

Chorion and Decidua capsularis ; 2mm

22

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)

DOUBLE SAC ; ABSENT Double sac sign

23

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)

YOLK SAC

24

A remnant of the connection of the Vitelline duct (also called the omphalomesenteric duct) to the distal ileum. (P.912)

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.

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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.]

 

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DOUBLE DECIDUAL SAC SIGN

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.

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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.]

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VITELLINE DUCT

67

IDENTIFY THIS SIGN.
[FIGURE 37.4.]

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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.]

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CORPUS LUTEUM

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.]

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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]

 

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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? 

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.]

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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.]

 

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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.]

 

 

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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.

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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.

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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.]

 

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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.

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THECA LUTEIN CYSTS

78

The ___ is measured from the top of the head to the bottom of the torso (between cursors, + ). [FIGURE 37.15] 

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CROWN-RUMP LENGTH (CRL)

79

IDENTIFY THIS FETAL MEASUREMENT. [FIGURE 37.17] 

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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).

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TRANSTHALAMIC (BIPARIETAL DIAMETER/HEAD
CIRCUMFERENCE [BPD/HC]) PLANE.
1.  BPD

2. HEAD CIRCUMFERENCE

81

 IDENTIFY THIS FETAL MEASUREMENT. [FIGURE 37.18]

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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 ?

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FIGURE A: NORMAL
FIGURE B: ABNORMAL 

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.

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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.

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NORMAL PLACENTA

RETROPLACENTAL COMPLEX OF VEINS

85

DIAGNOSIS? [FIGURE 37.23] 

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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]

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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]

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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]

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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]

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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]
 

 

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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]

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 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] 

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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]  

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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).

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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

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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]

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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.

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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.

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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.

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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.

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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]

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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

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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]

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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.

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CYSTIC ADENOMATOID MALFORMATION
 

The appearance is characteristic of
type III, cystic adenomatoid malformation.

105

IDENTIFY THIS ULTRASOUND VIEW. [FIGURE 37.42]

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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]

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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]

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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] 

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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.

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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]

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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]

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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.]

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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, +)

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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