Ultrasonography and Doppler 3rd Year Lecture 2012
Transcript of Ultrasonography and Doppler 3rd Year Lecture 2012
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ULTRASONOGRAPHY AND DOPPLER
Far Eastern UniversityDr. Nicanor Reyes Medical Foundation
Department of Obstetrics and Gynecology
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ULTRASONOGRAPHY
INOBSTETRICS
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Technology
picture displayed is produced by SOUND WAVESreflected back from the imaged structure
a transducer containing piezoelectric crystals
converts electrical energy to high-frequency
sound waves
water-soluble gel- as a coupling agent
Dense tissue (bone) produces high-velocity
reflected waves- WHITE
Fluid- generates few reflected waves- BLACK
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Technology
Images are generated quickly (> 40
frames/sec) picture appear real-time.
Higher-frequency transducers- better image
resolution
Lower- frequencies penetrate tissue more
effectively but resolution is poor
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Safety
only for valid medical indication
no confirmed damaging biological effects inmammalian tissue
no fetal harm has been demonstrated in morethan 30 years of use
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Clinical Applications
ACCURATE ASSESSMENT OF:
GESTATIONAL AGEFETAL GROWTH
FETAL AND PLACENTAL ANOMALIES
AOG based on ultrasound
- more accurate than the LMP
reduction in the number of labor inductions forpostterm pregnancy AND avoidance of deliveringa premature baby
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Table 162. Components of Standard Ultrasound Examination by Trimester
FIRST TRIMESTER SECOND AND THIRD TRIMESTER
Gestational sac location Fetal number
Embryo or yolk sac identification Presentation
Crown-rump length Fetal heart motion
Cardiac activity Placental location
Fetal number, including number of
amnions and chorions of multiples
when possible
Amnionic fluid volume
Gestational age assessment
Fetal weight estimation
Uterus, adnexal, and cul-de-sac
evaluation
Evaluation for maternal pelvic
masses
Fetal anatomic survey
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Some Indications for First-Trimester
Ultrasound Examination
Confirm intrauterine pregnancy
Evaluate suspected ectopic pregnancy
Estimate gestational age (most accurate)
Diagnose or evaluate multiple gestations
Confirm cardiac activity Assist to chorionic villus sampling, embryo transfer, and
localization and removal of intrauterine device
Evaluate suspected gestational trophoblastic disease
Define cause of vaginal bleeding Evaluate pelvic pain
Evaluate maternal pelvic masses or uterine abnormalities
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First Trimester
Transabdominal Scan
Gestational sac 6 weeks
Fetal echoes & cardiac activity
7 weeks
Transvaginal Scan
Gestational sac
5 weeks Fetal echoes & cardiac activity 6 weeks
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First Trimester Diagnosis ofpregnancy viability
TVS: cardiac motion usually is observed when theembryo is 5 mm in length (CRL)
valuable in diagnosing abnormalities such asembryonic demise as well as anembryonic gestation
Multifetal gestation can be identified- OPTIMAL TIMEto determine chorionicity
BEST TIME to evaluate the uterus, adnexal structures,and cul-de-sac
Between 11-14 weeks- fetal nuchal translucencycan beaccurately- often in conjunction with maternal serummarkers, in the detection ofaneuploidy
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Table 163. Some Indications for Second- or Third-Trimester Ultrasound
Examination
Estimation of gestational ageEvaluation of fetal growth
Vaginal bleeding
Abdominal or pelvic pain
Incompetent cervixDetermination of fetal presentation
Suspected multiple gestation
Adjunct to amniocentesis
Significant uterine size or clinical dates discrepancy
Pelvic mass
Suspected molar pregnancy
Adjunct to cervical cerclage
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Table 163. Some Indications for Second- or Third-Trimester Ultrasound
Examination
Suspected ectopic pregnancy
Suspected fetal death
Suspected uterine abnormality
Evaluation of fetal well-being
Suspected hydramnios or oligohydramnios
Suspected abruptio placentaeAdjunct to external cephalic version
Preterm prematurely ruptured membranes or preterm labor
Abnormal biochemical markers
Follow-up observation of identified fetal anomalyFollow-up evaluation of placental location for suspected placenta previa
History of previous congenital anomaly
Serial evaluation of fetal growth in multifetal gestation
Evaluation of fetal condition in late registrants for prenatal care
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Table 164. Essential Elements of a Standard Examination of Fetal Anatomy
Head and Neck
Cerebellum
Choroid plexus
Cisterna magna
Lateral cerebral ventricles
Midline falx
Cavum septi pellucid
Chest
Four-chamber view of heart
Evaluation of both outflow tracts if technically feasible
Abdomen
Stomachpresence, size, and location
Kidneys
Bladder
Umbilical cord insertion into fetal abdomen
Umbilical cord vessel number
Spine
Cervical, thoracic, lumbar, and sacral spine
Extremities
Legs and armspresence or absence
Gender
Indicated in low-risk pregnancies only for evaluation of multiple gestations
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Fetal Biometry
formulas and nomograms allow accurate assessment of
gestational age
describe normal growth of fetal structures
provides an estimated gestational age from the crown-rump
length measurement in the first trimester
estimates both gestational age and fetal weight in the second
and third trimester using measurements of the biparietal
diameter, head circumference, abdominal circumference, and
femur length.
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Fetal Measurements
Gestational sac (GS) - 4
6 weeks
Crown-Rump Length(CRL) - most accurate at 6-10 weeks
CRL- obtained in a sagittal plane and include neither the yolksac nor a limb bud; variation of only 3 to 5 days
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Fetal Measurements
Biparietal Diameter (BPD) - at 14- 26 weeks, is usually themost accurate parameter, with a variation of 7 to 10 days
BPD- outer edge of the proximal skull to the inner edge of the
distal skull, at the level of the thalami and cavum septumpellucidum
Head circumference (HC) - If the head shape is flattened
(dolichocephaly) or rounded (brachycephaly), thismeasurement is more reliable than the BPD
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Transthalamic view showing thalami (TH) and cavum septi pellucidi (CSP).
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Transventricular view of the atrium, which is marked by calipers and
contains the echogenic choroid plexus (CH).
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Transcerebellar view of the posterior fossa, demonstrating
measurement of the cerebellum (C) and cisterna magna (CM).
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Fetal Measurements
Femur length (FL) - correlates
well with both BPD and
gestational age, has a variation of7 to 11 days in the second
trimester
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Femur Length
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Fetal Measurements
Abdominal circumference (AC) - parameterwith the widest variation of 2 to 3 weeks,involves soft tissue rather than bone and is alsothe parameter most affected by fetal growth
AC- skin line in a transverse view of the fetus atthe level of the fetal stomach and umbilical vein
variability of gestational age estimationincreases as pregnancy advances
third trimester- all individual measurementsbecome less accurate
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Fetal Measurements
variability of gestational age
estimation increases as
pregnancy advances
third trimester- all individual
measurements become lessaccurate
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Amnionic Fluid
amount of amnionic fluid
Oligohydramnios - seen as obvious crowding of
the fetus and absence of any significant pockets of
fluid
Polyhydramnios - an apparent excess of fluid
Most widely used is the amnionic fluid index (AFI)
AFI- NV: 8 and 24 cm ( > 24 weeks )
Largest vertical pocket- NV: 2 to 8 cm (< 24 weeks)
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used to measure amniotic fluid
calculated by adding the verticaldepths of the largest pocket in each of
four equal quadrants
Amniotic Fluid Index
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Central Nervous System
Neural-Tube Defects-
second most common class of congenital anomalies
Defects result from incomplete closure of the neural
tube by the sixth week, or the embryonic age of 26 to28 days.
Anencephaly
Cephalocele Spina bifida
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Anencephaly
A lethal defect characterized by the absenceof the brain and cranium above the base of
the skull and orbits
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Anencephaly
can be diagnosed as early as the first trimester
Inability to obtain a view of the biparietal
diameter should raise suspicion
Polyhydramnios from impaired fetal
swallowing is common in the third trimester.
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Anencephaly
the diagnosiscan be made
as early as
12 -13 weeks
Ultrasonography
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Anencephaly (Pregnancy Management)
Prognosis:
* invariably lethal* 50% - stillborn
* 50% - neonatal
death
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Anencephaly (Pregnancy Management)
Monitoring:
* usual prenatalcare
- emotional support for the family
- assess for polyhydramnios
- tocolysis is NOT indicated
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Anencephaly (Pregnancy Management)
Delivery:
Vaginal
Special Issues:
Termination
Induction oflabor
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Anencephaly (Neonatology)
Resuscitation:
never indicated
Nursery management:
warmth, hygiene
facilitation of parentalgrief
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Cephalocele
herniation of meninges and brain tissue
through a defect in the cranium, typically an
occipital midline defect
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Spina Bifida
- a neural tubedefect of the
spine in whichthe dorsal
vertebral
arches fail tofuse together
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Spina Bifida
meningocoele
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Spina Bifida
meningomyelocoele
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Spina Bifida
the diagnosiscan be made
as early as
16 -18 weeks
Ultrasonography
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Sagittal (LEFT) and transverse (RIGHT) views of the spine in a fetus with
a large lumbosacral meningomyelocele
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Spina Bifida
Ultrasonography
Transverse
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Frontal scalloping or lemon sign in a fetus with a spinal meningomyelocele
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The banana sign, seen in this fetus with a meningomyelocele, develops when the
cerebellum is bowed and inferiorly displaced, causing effacement of the cisterna
magna
V i l l
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Ventriculomegaly
Enlargement of the cerebral ventricles
The lateral ventricle is commonly measured at its atrium,
which is the confluence of the temporal and occipital horn.
the measurement is relatively constant at 7 mm, with
standard deviation of 1 mm, from 15 weeks onward
Mild ventriculomegaly is diagnosed when the atrial width
measures 10 to 15 mm, and overt ventriculomegaly when it
exceeds 15 mm
A dangling choroid plexuscharacteristically is found in severe
cases
prognosis is determined by both etiology and rate of
progression
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Transventricular view of the atrium, which is marked by calipers and
contains the echogenic choroid plexus (CH).
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The atria appear unusually prominent in this fetus with mild ventriculomegaly
(caliper measurement 12 mm).
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Cystic Hygroma
congenital malformation of the lymphatic
system in which large, often multiseptated,
fluid-filled sacs extend from the posterior neck
usually develop as part of lymphaticobstruction sequence, in which lymph from
the head fails to drain into the jugular vein
and collects instead in jugular lymphatic sacs. Prognosis depends on the karyotype
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Large, septated cystic hygromas in a 17-week fetus with Turner syndrome
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Thorax
four-chamber view of the heart filling
approximately two thirds of the area
lungs are best visualized after 20 to 25 weeks
appear as homogeneous structures
surrounding the heart
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Diaphragmatic Hernia
left-sided and posterior
displacement of the heart to the middle or
right side of the thorax by the stomach and
bowel
absence of the stomach bubble within the
abdomen, small abdominal circumference
bowel peristalsis seen in the fetal chest
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Heart
cardiac malformations are the most common congenitalanomalies
Almost 90 percent of cardiac defects are multifactorial
As many as 30 to 40 percent of cardiac defects diagnosed
prenatally are associated with chromosomal abnormalities
recognition of a cardiac malformation should prompt fetal
karyotyping.
The most frequently encountered aneuploidies are trisomies
21, 18, and 13, and 45, X (Turner syndrome).
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Four-chamber view of the fetal heart, showing the location of the left and right
atria (LA, RA), left and right ventricles (LV, RV), foramen ovale (FO), and
descending thoracic aorta (A).
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Gastrointestinal Tract
stomach is visibleafter 14 weeks
the liver, spleen, gallbladder, and bowel can be
identified in many second- and third-trimester
fetuses
Non-visualization of the stomach within the
abdomen is associated with a number of
abnormalities, such as: diaphragmatic hernia,abdominal wall defects and esophageal atresia
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Transverse sonogram of a second-trimester fetus with an intact anterior
abdominal wall and normal cord insertion.
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Normal Abdominal Wall Development
Physiologic gut herniation:
6th 10th week AOG
Complete closure of the
abdominal wall:
10th 12th week AOG
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Abdominal Wall Defects
Omphalocoele Gastroschisis
Abdominal Wall Defects
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Abdominal Wall Defects
Gastroschisis full-thickness defect in the abdominal wall
Typically it is located to the right of the umbilical cord insertion
bowel herniates into the amnionic cavity
survival rate of at least 90 percent
result from an early vascular occlusion that leads to localizedabdominal wall ischemia.
Omphalocele
abdominal contents covered only by a two-layered sac of amnionand peritoneum.
The umbilical cord inserts into the apex of the sac may occur as part of a genetic syndrome, such as Beckwith
Wiedemann orpentalogy of Cantrell
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In this fetus with gastroschisis, extruded bowel loops are floating in the
amnionic fluid to the right of the normal umbilical cord insertion site (arrow).
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Abdominal Wall Defects
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Abdominal Wall Defects
Gastroschisis full-thickness defect in the abdominal wall
Typically it is located to the right of the umbilical cord insertion
bowel herniates into the amnionic cavity
survival rate of at least 90 percent
result from an early vascular occlusion that leads to localizedabdominal wall ischemia.
Omphalocele
abdominal contents covered only by a two-layered sac of amnionand peritoneum.
The umbilical cord inserts into the apex of the sac may occur as part of a genetic syndrome, such as Beckwith
Wiedemann orpentalogy of Cantrell
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Transverse view of the abdomen showing an omphalocele as a large
abdominal wall defect with exteriorized liver covered by a thin membrane.
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G i i l A i
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Gastrointestinal Atresia
Most atresias are characterized by obstructionwith proximal bowel dilatation
the more proximal the obstruction, the more
likely it is to be associated with hydramnios.
Esophageal atresia may be suspected when
the stomach cannot be visualized and
hydramnios is present.
E h l At i
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Esophageal Atresia
D d l i
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Duodenal atresia
so-called double-bubble sign, whichrepresents distention of the stomach and the
first part of the duodenum
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Double-bubble sign of duodenal atresia is seen on this axial abdominal
image of the fetus.
Kid d U i T t
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Kidneys and Urinary Tract
paraspinous masses frequently as early as 14 weeks, and routinely by
18 weeks
The placenta and membranes produce amniotic
fluid early in pregnancy,. but after 18 weeks, mostof the fluid is produced by the fetal kidneys
Fetal urine production increases from 5 mL/hr at20 weeks to about 50 mL/hr at term
Unexplained oligohydramnios suggests a urinarytract abnormality
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Longitudinal sonogram of fetal kidney depicting the hypoechoic medullary
pyramids (M).
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R l A i
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Renal Agenesis
No kidneys are seen ultrasonographically at any point during
gestation.
The adrenal glands typically enlarge and occupy the renal
fossae
Without kidneys, no urine is produced, and the resulting
severe oligohydramnios leads to pulmonary hypoplasia, limb
contractures, a distinctive compressed face, and death from
cord compression or pulmonary hypoplasia.
When this combination of abnormalities results from renal
agenesis, it is called Potter syndrome
When these abnormalities result from scant amnionic fluid of
some other etiology, it is called Potter sequence.
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Urinary Bladder
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Urinary Bladder
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Secondary hydronephrosis from
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bladder outlet obstruction
Three Dimensional Ultrasonography
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Three-Dimensional Ultrasonography
superior views of fetal surface anatomy improved visualization of selected structures such
as the face, ear, and extremities.
to adequately image a fetal structure in three
dimensions, the part must be surrounded byamnionic fluid because crowding by adjacentstructures obscures the captured image.
even under ideal circumstances, image
processing may take considerably more time thanis typically devoted to two-dimensional (2-D)scanning.
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used to determine the volume and rate of blood flowthrough maternal and fetal vessels
Clinical Applications:
systolic
diastolic ratio (S/D ratio) - comparesmaximum (peak) systolic flow with end-diastolic flow,
thereby evaluating downstream impedance to flow
DOPPLER VELOCIMETRY
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Doppler waveforms from normal pregnancy. Shown clockwise are normal waveforms
from the maternal arcuate, uterine, and external iliac arteries, and from the fetal
umbilical artery and descending aorta. Reversed end-diastolic flow velocity is
apparent in the external iliac artery, whereas continuous diastolic flow characterizes
the uterine and arcuate vessels. Finally, note the greatly diminished end-diastolic flow
in the fetal descending aorta.
Umbilical Artery
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Umbilical Artery
This vessel normally has forward flow throughout the cardiaccycle, and the amount of flow during diastole increases as
gestation advances.
Thus the S/D ratio decreases, from about 4.0 at 20 weeks to
2.0 at term. The S/D ratio is generally less than 3.0 after 30 weeks
Umbilical artery Doppler may be a useful adjunct in the
management of pregnancies complicated by fetal growth
restriction. Not recommended for screening of low-risk pregnancies or for
complications other than growth restriction
Umbilical Artery
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Umbilical Artery
ABNORMAL:
ifthe S/D ratio is above the 95th percentile for gestational
age.
In extreme cases of growth restriction, end-diastolic flow
may become absent or even reversed
These are ominous findings and should prompt a
complete fetal evaluationalmost half of cases are due to
fetal aneuploidy or a major anomaly
In the absence of a reversible maternal complication or afetal anomaly, reversed end-diastolic flow suggests severe
fetal circulatory compromise and usually prompts
immediate delivery
Umbilical artery
D l f
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Doppler waveforms:
A. Normal diastolic flow.
B. Absence of end-diastolic
flow.
C. Reversed end-diastolic
flow.
DOPPLER VELOCIMETRY
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DOPPLER VELOCIMETRY
Diminished blood flow may be reflected such asthe ff:
1. Diastolic notch
2. Increased SD ratio (Stuart Index)
3. Pulsatility index; Resistance index
4. Absence or reversed end diastolic (ARED)
blood flow
Ductus Arteriosus
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Ductus Arteriosus
used primarily to monitor fetuses exposed toindomethacin and other nonsteroidal anti-inflammatory agents.
Indomethacin, which is used for tocolysis, causes
constriction of the ductus in sheep and human fetuses The resulting increased pulmonary flow may cause
reactive hypertrophy of the pulmonary arterioles, andeventually pulmonary hypertension develops
this complication is largely reversible if medication isdiscontinued before 32 weeks
Middle Cerebral Artery
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Middle Cerebral Artery
Peak systolic velocity in the middle cerebralartery is increased with fetal anemia because
of increased cardiac output and decreased
blood viscosity The cerebroplacental ratio has been
introduced as an indicator of brain sparing in
fetuses with growth restriction
Uterine Artery
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Uterine Artery
Uterine blood flow increases from 50 mL/minearly in gestation to 500 to 750 mL/min by term
Increased resistance to flow and development of
a diastolicnotch have been associated withpregnancy-induced hypertension
increased impedance of uterine artery
velocimetry at 16 to 20 weeks was predictive of
superimposed preeclampsia developing in
women with chronic hypertension.
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Normal uterine artery waveform with high-velocity diastolic flow.
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