IMAGES Chapter 37 - Obstetric Ultrasound Flashcards
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.
IDENTIFY.
[FIGURE 37.5.]
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.
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
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.
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.]
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.
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.
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.
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.
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.
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.
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
The ___ is measured from the top of the head to the bottom of the torso (between cursors, + ). [FIGURE 37.15]
CROWN-RUMP LENGTH (CRL)
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.
[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
- HEAD CIRCUMFERENCE
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, + ).
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
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.
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**
[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