CLINICAL APPLICATION OF DOPPLER IN OBSTETRICS

1. CLINICAL APPLICATION OF
DOPPLER IN OBSTETRICS
BY DR.SYEDA AYESHA IFFAT

2. UMBILICAL ARTERY
• Umbilical arterial (UA) Doppler assessment is used
in surveillance of fetal well-being in the 3RD trimester
of pregnancy. Abnormal umbilical artery Doppler is a
marker of placental insufficiency and
consequent intrauterine growth restriction (IUGR) or
suspected pre-eclampsia.
• It has been shown to reduce perinatal mortality and
morbidity in high-risk obstetric situations 5.
• As a general rule, a degree of caution should be
exercised with the routine use of Doppler in
pregnancy, due to the concerns related
to heating/thermal effects from the high intensities

3. PARAMETERS
• The commonly used parameters are:
• umbilical arterial S/D ratio (SDR): systolic velocity / diastolic velocity
• pulsatility index (PI) (Gosling index): (PSV - EDV) / TAV
• resistive index (RI) (Pourcelot index): (PSV - EDV) / PSV
• PSV: peak systolic velocity
• EDV: end-diastolic velocity
• TAV: time-averaged velocity
• The Doppler indices have been found to decline gradually with gestational age
(i.e. there is more diastolic flow as the fetus matures):
• S/D ratio mean value decreases with fetal age 8
– at 20 weeks, the 50th percentile for the S/D ratio is 4
– at 30 weeks, the 50th percentile is 2.83
– at 40 weeks, the 50th percentile is 2.18
• RI mean value decreases from 0.756 to 0.609
• PI mean value decreases from 1.270 to 0.967
• Classification of severity
• In growth-restricted fetuses and fetuses developing intrauterine distress, the
umbilical artery blood velocity waveform usually changes in a progressive manner
as below
• reduction in end-diastolic flow: increasing RI values, PI values, and S/D ratio
• absent end-diastolic flow (AEDF): RI = 1

4. RADIOGRAPHIC FEATURES
• Waveform
• The umbilical arterial waveform usually has a
"sawtooth" pattern with flow always in the forward
direction, that is towards the placenta. An abnormal
waveform shows absent or reversed diastolic flow.
Before the 15th week, the absence of diastolic flow may
be a normal finding 6.
• The 95% confidence interval limit slowly decreases for
both the resistive index (RI) and pulsatility index
(PI) through the course of gestation due to progressive
maturation of the placenta and increase in the number
of tertiary stem villi.

5. INDICATIONS
• Umbilical Doppler assessment is indicated in scenarios where there is a
risk of fetal growth restriction or poor perinatal outcome. It is also used to
stage twin-twin transfusion 7.
• Doppler ultrasound evaluation of the fetoplacental circulation is not
indicated in low-risk pregnancies 7.
• Maternal conditions
• diabetes mellitus
• chronic kidney disease
• hypertension
• prothrombotic states
• Pregnancy-related conditions
• suspected IUGR
• previous pregnancy with IUGR or fetal death in utero
• decreased fetal movement
• oligohydramnios
• polyhydramnios
• multifetal pregnancy
• . Cochrane trial[compares use of doppler with no doppler][29%
REDUCTION IN PERINATAL DEATHS

6. SINGLE UMBILICAL ARTERY
• Single umbilical artery (SUA) results when there is a congenital absence
of either the right or left umbilical artery. In the usual situation, there are
paired umbilical arteries.the absence of the left umbilical artery is much
more common (~70%).
• Epidemiology
• prevalence is ~0.4-1% of pregnancies 5,6,10.There may be an increased
incidence of twin pregnancies and maternal diabetes.
• Pathology
• The occurrence of a single umbilical artery is thought to be due to
secondary atresia or atrophy rather than primary agenesis of the
artery.The remaining single artery is often quite large and approaches
the size of the umbilical vein (which is usually larger than the artery).
• In ~65% (range 57-75%) of cases, a single umbilical artery is present in
isolation 1
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7. ASSOCIATIONS
• When found in isolation, it is usually not of clinical significance but there is
an increased incidence of intrauterine growth restriction (IUGR) 6 (~15%).
• Recognized associations are thought to be present in ~35% (range 25-
43%) of cases:
• lesser number of coils in the umbilical cord
• umbilical arterial aneurysm
• twin reversed arterial perfusion sequence
• increased incidence of intrauterine growth restriction (IUGR)
• When found with other fetal anomalies, it can be also be associated with:
• chromosomal anomalies
– trisomy 21 (12.8% had an SUA), trisomy 18 (50% had an SUA), trisomy
13 (25% had an SUA) 11
• persistent right umbilical vein
• congenital renal anomalies
– renal agenesis: occurs usually on the side where the artery is absent 10
• sirenomelia
• velamentous insertion of the cord
• Some suggest that complex congenital and chromosomal abnormalities
are found almost exclusively when the left umbilical artery is absent

8. RADIOLOGIC FEATURES
• This is the imaging investigation of choice and an SUA is often detected
incidentally on ultrasound. High-resolution ultrasound has a sensitivity
and specificity approaching 100% 1. Sonographic features include:
• two vessels within the umbilical cord (one artery and one vein) instead of
the usual three (best seen in cross-section)
• the single artery is often larger in caliber than normal and approaches the
diameter of the accompanying vein
• examination of the fetal pelvis will demonstrate only one umbilical artery
lateral to the bladder in its course toward the umbilical cord
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10. ABSENT END DIASTOLIC FLOW
• in an umbilical artery Doppler assessment is a useful feature which
indicates underlying fetal vascular stress if detected in mid or late
pregnancy. It is often classified as Class II in severity in abnormal umbilical
arterial Dopplers 9.
• Pathology
• The presence of absent end-diastolic flow (AEDF) can be normal in early
pregnancy (up to 16 weeks). In mid to late pregnancy it usually occurs as
a result of placental insufficiency 7,8. Flow in the umbilical artery should be
in the forward direction in normal circumstances. If placental resistance
increases, the diastolic flow may reduce, later becoming absent and
finally reverses.
• Associations
• intra-uterine growth restriction (IUGR)
• increased risk of neonatal thrombocytopenia 6
• increased risk of necrotizing enterocolitis1

11. REVERSAL OF END DIASTOLIC FLOW
REDF velocity is often an ominous finding if detected after 16 weeks. It is
classified as Class III in severity in abnormal umbilical arterial Dopplers 6.
• Epidemiology
• The estimated incidence is at ~0.5% of all pregnancies with a much higher
rate in intrauterine growth-restricted (IUGR) fetuses.
• Pathology
• The feature is seen as a result of a significant increase in resistance to
blood flow within the placenta and often represents a "tip of the iceberg"
where there is a much larger underlying pathology.
• In a normal situation, umbilical arterial flow should always be in the
forward direction in both systole and diastole.
• However, during the first 16 weeks, a reversal in end diastolic flow can be
a normal finding due to the low resistance arcuate arteries and
intervillous spaces not yet being formed.
• Flow reversal can also be detected in the fetal aorta.

16. MCA DOPPLER
• Fetal middle cerebral arterial (MCA) Doppler assessment is an important part of
assessing fetal cardiovascular distress, fetal anemia or fetal hypoxia. In the
appropriate situation it is a very useful adjunct to umbilical artery Doppler
assessment. It is also used in the additional work up of:
• intra-uterine growth restriction (IUGR)
• twin to twin transfusion syndrome (TTTS) 5
• twin anemia polycythemia sequence (TAPS)
• Parameters used include:
• fetal MCA pulsatility index (PI)
• fetal MCA peak systolic velocity (PSV): the highest velocity should be recorded
• fetal MCA systolic/diastolic (S/D) ratio: a normal fetal MCA S/D ratio should
always be higher than the umbilical arterial S/D ratio
• cerebroplacental ratio (CPR): ratio of pulsatility index of MCA and umbilical artery
• Interpretation
• in the normal situation the fetal MCA has a high resistance flow which means
there is minimal antegrade flow in fetal diastole
• in pathological states this can turn into a low resistance flow mainly as a result of
the fetal head sparing theory
• paradoxically in some situations such as with severe cerebral edema, the flow can
revert back to a high resistance pattern when the pathology has not yet resolved -

17. FETAL MCA PSV
• The fetal middle cerebral arterial (MCA) peak
systolic velocity (PSV) is an important
parameter in fetal MCA Doppler assessment.
• Interpretation
• reliable between 18-35 weeks
• increased PSV can indicate moderate-to-severe
anemia in non-hydrops fetuses
•
•

18. MCA S/D RATIO
• Fetal MCA systolic/diastolic (S/D) ratio is an important
parameter in fetal middle cerebral arterial Doppler
assessment. It is a useful predictor of fetal
distress and intrauterine growth restriction (IUGR).
• Interpretation
• Normal
• During pregnancy the middle cerebral (and other intracranial)
arteries demonstrate high resistance waveforms, i.e. high
systolic velocity and low/absent diastolic velocity.
• A normal fetal MCA S/D ratio should always be higher than
the umbilical arterial S/D ratio.The fetal MCA S/D ratio value
will decrease as the pregnancy progresses.
• Abnormal
• A reduced S/D ratio is abnormal and implies an increased
diastolic flow in MCA. Loss of high resistance waveform is

19. MCA DOPPLER IN FETAL ANEMIA
• Uncommon but life threatening
• MC- red cell alloimm,parvo virus inf,feto maternal hemorrhage.
• MCA PSV –prim technique to detect foetal anemia
• Can be detected on basis of increase in peak velocity of systolic
blood blow in MCA
• As the hb decreases,MCA-PSV increases—can be used to
determine hb
• 100% Sensitivity,false positive rate-12%
• Doppler assessment of MCA-PSV represent an alternative to
cordocentesis for timing the need of intrauterine transfusion
• MCA-PSV>1.5 MoM represent the optimum time to perform
cordocentesis and IUT

24. FETAL DUCTUS VENOSUS DOPPLER
• It is used number of situations in fetal ultrasound:
• first-trimester screening for aneuploidic anomalies
• second and third-trimester scanning when there are concerns regarding
– intrauterine growth restriction (IUGR)
– fetal cardiac compromise
• Of all the pre-cardiac veins, the ductus venosus allows the most accurate
interpretation of fetal cardiac function as well as myocardial
hemodynamics 9.
• n Doppler ultrasound, the flow in the ductus venosus has a
characteristic triphasic waveform where in a normal physiological
situation flow should always be in the forward direction 7 (i.e. towards the
fetal heart).
• This triphasic waveform comprises of:
• S wave: corresponds to fetal ventricular systolic contraction and is the
highest peak
• D wave: corresponds to fetal early ventricular diastole and is the second
highest peak
• A wave: corresponds to fetal atrial contraction and is the lowest point in
the wave form albeit still being in the forward direction
– as above, reversal of the A wave (i.e. crossing the baseline) is always

26. UMBILICAL VEIN
• Umbilical venous flow in the physiological situation comprises of a
monophasic non-pulsatile flow pattern in the umbilical vein with a mean
velocity of 10-15 cm/s. Since a normal umbilical vein supplies a continuous
forward flow of oxygenated blood to the fetal heart, the presence of
pulsatility implies a pathological state unless in the following situations:
• early in pregnancy: up to ~13 weeks gestation
– the presence of pulsatility may be higher in chromosomally abnormal
fetuses even in early pregnancy 5
• when confounded by other movement variables such as
– fetal breathing movement
– fetal hiccups 1
• Pulsations of the umbilical venous system, especially double pulsations
have been associated with increase in the perinatal mortality when
associated with the absent and reversed end-diastolic flow velocity in the
umbilical artery.

29. UTERINE ARTERY
• Uterine artery flow notching refers to a phenomenon observed in uterine arterial Doppler
ultrasound assessment.
• Pathology
• Associations
• The presence of notching after 22 weeks is associated with several other conditions
including adverse pregnancy outcomes.These include
• pregnancy induced hypertension (PIH)
• pre-eclampsia
• placental abruption
• intrauterine growth restriction (IUGR)
• increased maternal serum alpha fetoprotein (MSAFP)
• Radiographic features
• Doppler ultrasound
• While notching can be either systolic or diastolic, it is typically seen as a trough-like notch
between the systolic and diastolic phases.
• Significance
• The presence of notching in late pregnancy is an indicator of increased uterine vascular
resistance and impaired uterine circulation 2.
• Bilateral notching is more concerning. Unilateral notching of the uterine artery on the
ipsilateral side of the placenta, if the placenta is along one lateral wall (right or left) carries
the same significance as bilateral notching. The presence of an early diastolic notch can
however be a normal finding in a non-pregnant uterus and even in a gravid uterus, at least
up to 16 weeks, but notching typically begins to disappear in the gravid uterus by 13 weeks
with clearly established diastolic flow by 20 weeks 7.

30. UTEROPLACENTAL BLOOD FLOW
ASSESSMENT
• IT is an important part of fetal well-being assessment .
• Pathology
• In a non-gravid state and at the very start of pregnancy the flow in the
uterine artery is of high pulsatility with a high systolic flow and low
diastolic flow.A physiological early diastolic notch may be present.
• Resistance to blood flow gradually drops during gestation as a greater
trophoblastic invasion of the myometrium takes place.An abnormally
high resistance can persist in pre-eclampsia and IUGR. If resistance is low,
it has an excellent negative predictive value with a less than 1% chance of
developing either pre-eclampsia or having IUGR . A high resistance often
equates to a 70% chance of pre-eclampsia and 30% chance of IUGR.
•
•

31. PARAMETERS USED
• The parameters used in the assessment of uteroplacental blood flow include:
• RI = resistive index
• PI = pulsatility index
• presence of persistent diastolic notching
• Resistive index (RI)
• This is calculated by the following equation:
• RI = (PSV-EDV) / PSV = (peak systolic velocity - end-diastolic velocity) / peak
systolic velocity
• normal (low resistance) RI <0.55
• high resistance
– bilateral notches RI >0.55
– unilateral notches RI >0.65
• Pulsatility index (PI)
• This is calculated by the following equation:
• PI = (PSV - EDV) /TAV = (peak systolic velocity - end-diastolic velocity) / time-
averaged velocity

32. ABNORMAL PATTERNS
• persistence of a high resistance flow
throughout pregnancy
• persistence of notching throughout
pregnancy
• reversal of diastolic flow throughout
pregnancy: severe state

35. DOPPLER IN HYPERTENSIVE
DISEASES
• INCREASED PIWITH NOTCHING IN 2ND TRIMESTER
• INCREASED PI ALONE OR IN COMBINATIONWITH
NOTCHING-IUGR IN LOW RISK PTS
• INCREASED RIWITH/WITHOUT NOTCHING-HIGH
RISKWOMEN
• AN EARLY DIASTOLIC NOTCH IN UTERINE ARTERIES
BTW 12-14WK-DELAYEDTROPHOBLASTIC
INVASION IN HIGH RISK PT
• PERSISTENCE OF BILATERAL NOTCHINGAFTER 24TH
WK-INADEQUATETROPHOBLASTIC INVASION
• MEAN PI>95th centile-high risk for pre
eclampsia.gest.HTN,foetal growth restriction

36. • Early identification is essential for timely
commencement of preventive treatment with
low dose aspirin for pre eclampsia,foetal growth
restriction
• Acc to ASPRE[combined multimarker screening
&randomized patient treatment with aspirin for
evidence based preeclampsia prevention] study
combined screening using MAP,UtArtery
PI,PIGF,PAPP-A has detected 76.6% ofearly
preeclampsia & 38% of late preeclampsia

38. VASA PREVIA
• is a rare but potentially catastrophic cause of antepartum hemorrhage.
• Pathology
• Vasa previa can be of two types:Vasa previa refers to a situation where there are
aberrant fetal vessels crossing over or in close proximity to the internal cervical os,
ahead of the fetal presenting part.These vessels are within the amniotic
membranes, without the support of the placenta. Vasa previa
• type I (present in ~ 90% of cases with vasa previa 3): abnormal fetal vessels
connect a velamentous cord insertion with the main body of the placenta
• type II
– abnormal vessels connect portions of a bilobed placenta
– placenta with a succenturiate lobe: due to this association, vasa previa needs
to be excluded in patients with variant placental morphology
• These vessels are unsupported by Wharton jelly or placental tissue and are at risk
of rupture during labor.
• Epidemiology
• Vasa previa occurs in 0.6 per 1000 pregnancies11
•
•

39. • Risk factors include:
• multiple gestations
• low lying placenta
• succenturiate lobe or bilobed placenta
• IVF pregnancy
• Clinical presentation
• Prior to rupture of the amniotic membrane during labor,
compression of the vulnerable fetal blood vessels by the
presenting part may lead to fetal heart decelerations and
bradycardia.
• However once ruptured, vasa previa will result in brisk
vaginal bleeding with rapid fetal exsanguination.

40. • DOPPLER ultrasound
• Sonographic features are considered generally specific (~90%) 2.
• The diagnosis is often made with transabdominal color Doppler sonography
demonstrating flow within vessels which are seen overlying the internal cervical
os. Non-Doppler (greyscale) images may suggest the diagnosis if there are
echogenic parallel or circular lines within the placenta near the cervix.
• Occasionally a transvaginal scan is required to better visualize aberrant vessels.
Transvaginal ultrasound has a reported sensitivity of 100% and specificity of 99-
99.8% when performed with color Doppler 12.
• Treatment and prognosis
• If recognized antenatally, vasa previa usually requires an elective cesarean section
to avoid the risk of complications during vaginal delivery.
• If recognized intrapartum, an emergency cesarean section is usually performed
•

42. MONOCHORIONIC MONOAMNIOTIC
TWIN PREGNANCY
• It is a subtype of monozygotic twin pregnancy. These fetuses share a single chorionic sac, a
single amniotic sac, and, in general, a single yolk sac.
• Epidemiology
• It accounts for the minority (~5%) of monozygotic twin pregnancies and ~1-2% of all twin
pregnancies. The incidence is ~1 in 10000 of all pregnancies 2.
• Pathology
• It results from a separation of a single ovum at ~ 8-13 days following formation . By this time
a trophoblast has already formed, yielding a single placenta. These fetuses share a
single chorionic sac, a single amniotic sac, and most often a single yolk sac.The twins are
identical (and of course of the same gender).
• Radiographic features
• Ultrasound
• First trimester
• shows a twin pregnancy with a single gestational sac and a most often a single yolk sac
(which helps to differentiate from a DCDA and MCDA pregnancy)
• there is no inter-twin membrane: this differentiates from a DCDA and MCDA pregnanancy
• Second trimester
• Features noted on a second-trimester scan includes:
• specific to an MCMA pregnancy
– cord entanglement
– cord fusion
– absent inter-twin membrane
• common to both MCMA and MCDA pregnancies

43. COMPLICATIONS
• An MCMA pregnancy carries the highest level of potential complications out of all
twin pregnancies (with reported rates of overall perinatal mortality up to 70-
80% 1).These include:
• problems related to abnormal placental vascular anastomoses
– twin to twin transfusion syndrome: his particular complication only occurs in ~10-15% of
MCMA pregnancies and therefore less common than MCDA pregnancies 7
– twin embolization syndrome
– twin reversed arterial perfusion sequence
• demise of one twin: often associated with some adverse outcome to the other
twin
• placental insertion related problems
– increased incidence of velamentous cord insertion (c.f singleton pregnancy)
– increased incidence of marginal cord insertion (c.f singleton pregnancy)
• umbilical cord related complications
– umbilical cord knots
– umbilical cord thrombosis
•

46. MONOCHORIONIC DIAMNIOTIC
PREGNANCY
• It is a subtype of monozygotic twin pregnancy.These fetuses share a single chorionic sac but have
two amniotic sacs and two yolk sacs.
• Epidemiology
• It accounts for the vast majority (70-75%) of monozygotic twin pregnancies although only ~30% of all
twin pregnancies.The estimated incidence is at ~1:400 pregnancies 11.
• Pathology
• An MCDA pregnancy results from a separation of a single zygote at ~4-8 days (blastocyst) following
formation.These fetuses share a single chorionic sac but two yolk sacs and two amniotic sacs. By this
time a trophoblast has already formed yielding a single placenta.
• The layman term is that the twins are "identical" - in reality, they are phenotypically similar, and of course
of the same gender.
• Radiographic features
• Ultrasound
• First trimester
• shows a twin pregnancy with a single gestational sac, and almost always two separate yolk sacs 9-
10 (differentiating from an MCMA pregnancy)
• at 14-18 weeks, often a single placenta is seen: differentiating from a DCDA pregnancy
• a thin inter-twin membrane may be seen
– due to amnions abutting the placenta
– present: differentiating from an MCMA pregnancy
– but appears very thin without intervening chorion (often taken as <2 mm): differentiating from
a DCDA pregnancy
– T-sign of the intertwin membrane
• Second and third trimesters
• Findings:
• the number of placental masses, thickness of the membrane, and the presence/absence of the twin-peak
sign are still viable options for determining chorionicity

47. COMPLICATIONS
• problems related to abnormal placental vascular
anastomoses
– twin to twin transfusion syndrome: can occur in ~15 1 -
30 4 % of MCDA pregnancies
– twin embolization syndrome
– twin reversed arterial perfusion sequence:
• demise of one twin: often associated with some adverse
outcome to the other twin
• placental insertion related problems
– increased incidence of velamentous cord insertion
– increased incidence of marginal cord insertion
•
•

48. TTTS
• itis a potential complication that can occur in
a monochorionic (either MCDA or MCMA) twin pregnancy.
• This complication can occur in ~10% (range 15-25%) of monochorionic
pregnancies giving an estimated prevalence of ~1:2000 of all pregnancies.
• Marked abdominal distension has been described as a clinical feature.
• Pathology
• TTTS results from unbalanced vascular (arteriovenous and
arterioarterial) anastomoses in the placenta - that is, placental circulation is
directed predominantly towards one twin and away from the other.
• The resultant hypovolemia and hypoperfusion in one twin and hypervolemia and
hypertension in the other create a cascade of hormonal changes including the
renin-angiotensin system.This in turn leads to chronic tubulopathy and oliguria in
the hypovolemic (donor) twin with consequent oligohydramnios, and polyuria and
consequent polyhydramnios in the hypervolemic (recipient) twin.
• Staging
• The extent of the syndrome can be staged according to severity. One method
proposed by Quintero et al. is as 3:
• stage I: oligohydramnios/polyhydramnios
• stage II: bladder not visible in donor twin
• stage III: abnormal Dopplers in either twin
• stage IV: hydrops fetalis in either twin*
• stageV: in-utero demise of either twin

49. DOPPLER
• absent or reversed diastolic flow in the umbilical artery is an indication of
worsening twin-to-twin transfusion syndrome
• abnormal ductus venosus waveform pattern suggests the possibility of cardiac
diastolic dysfunction
• Treatment and prognosis
• Serial sonographic monitoring is common practice. In an uncomplicated
monochorionic twin pregnancy,TTTS screening should start from 16 weeks
gestation with assessment fetal growth, DVPs and umbilical arterial pulsatility
index (UA-PI) performed every two weeks. Detailed morphology ultrasound is
routine at 20 weeks. Additional fetal middle cerebral arterial-peak systolic
velocity (MCA-PSV) is recommended from 22 weeks.
• Untreated,TTTS generally carries a poor prognosis, with up to 90% perinatal
mortality 8. Laser coagulation of the chorionic plate is the treatment of choice and
significantly improves the prognosis for both twins - although both morbidity and
mortality remain considerably higher than in non-TTTS monochorionic
pregnancies.
• Other management options include:
• conservative management with surveillance for Quintero stage 1TTT
• serial amnioreduction, where laser treatment is not available

52. TAPS
• It is considered a variant of the twin to twin transfusion syndrome (TTTS).
• Epidemiology
• TAPS may occur spontaneously in up to 5% of monochorionic twins and may also develop after
incomplete laser treatment in twin-to-twin transfusion syndrome cases 2.
• Pathology
• As with twin-to-twin transfusion syndrome, the underlying mechanism is thought to be abnormal
placental vascular anastomoses, however, inTAPS the rate of transfusion is slow and therefore
results in a gradual discordance of fetal hemoglobin, without the hormonal disbalance and
subsequent liquor discordance seen inTTTS. One twin develops anemia and the other
polycythemia.
• Radiographic features
• Doppler ultrasound
• One of the features suggesting the diagnosis is a discordance in fetal middle cerebral artery peak
systolic velocity (MCA-PSV) measurements 4. In contrast to the classic twin-to-twin transfusion
syndrome, there is no amniotic fluid discordance (i.e. no-twin oligo-polyhydramnios sequence
(TOPS)) 5.
•

54. TWIN EMBOLISATION SYNDROME
• It is a rare complication of a monozygotic twin pregnancy following an in utero demise of the co-twin.
• Pathology
• It was traditionally thought to result from the passage of thromboplastic material into the circulation of the surviving twin
which causes ischemic structural defects in various organs (particularly the highly vascularized organs such as the central
nervous system, gastrointestinal tract, and genitourinary system). An acute hemodynamic shift from live to dead fetus
resulting in hypoperfusion is more recently thought to play a role 3.
• Associations
• There is usually an underlying twin-twin transfusion syndrome as a causative association.
• Radiographic features
• Antenatal ultrasound
• The presence of a dead twin associated with a surviving twin with various anomalies may suggest the diagnosis. Such
anomalies include :
• CNS anomalies
• fetal ventriculomegaly
• porencephaly
• fetal cerebral atrophy
• cystic encephalomalacia 4
• microcephaly
• Non-CNS anomalies
• small bowel atresia
• fetal hydrothorax
• gastroschisis
• fetal renal cortical necrosis
• Treatment and prognosis
• While it carries a poor outcome, prenatal sonographic diagnosis may influence the antenatal neonatal management of the
surviving monozygous twin

55. TRAP
• Twin reversed arterial perfusion (TRAP) sequence is a rare complication of monochorionic
pregnancies. It develops when the following conditions are present:
• 1. lack of a well-formed heart in one of the twins (so-called acardiac twin), and
• 2. a superficial artery to artery placental anastomosis providing perfusion of the acardiac
twin by the donor (pump) twin. This can be shown on Doppler ultrasound by reversal of the
acardiac twin umbilical arterial blood (i.e. flow towards the fetus).
• Epidemiology
• It is thought to occur in ~0.5% (range 0.3-1 % 1,4)of monozygotic pregnancies with an
estimated incidence of 1:35,000 births overall 1,10.
• It can rarely occur with higher-order multifetal pregnancies 3.
• Pathology
• TRAP is considered to primarily result from an abnormal placental arterial-to-arterial
anastomosis. Venovenous anastomoses may also be present 11.
• Classically this results in one normal and one abnormal twin:
• viable twin (pump twin)
– usually normal, but 9% risk of abnormal karyotype
• non-viable twin (recipient/acardiac twin)
– this twin can have four morphological types
• acardius acephalus
• acardius anceps

56. DOPPLER FINDINGS
• REVERSAL OF FLOW ON SPECTRAL
WAVEFORM CONFIRMED BY PULSED
DOPPLER OFTHE UMBILICAL ARTERY OF
RECIPIENTTWIN

61. COMPLICATIONS
• TRAP sequence pump twin is at risk of:
• cardiac failure
• cerebral ischemic sequelae
• preterm birth
• fetal demise in utero
• The risk of adverse outcomes in the pump twin is closely related to its size ratio to
the acardiac twin.
• Treatment and prognosis
• As the acardiac twin is non-viable, the majority of efforts in management are
focused or maintaining the viability of the other donor (pump) twin.The perinatal
mortality for the pump twin can be as high as 50% 10.
• Treatment is around the surgical destruction of the inter-twin anastomosis and
includes:
• endoscopic laser coagulation/radio-frequency ablation 5
• surgical (fetoscopic) ligation of acardiac twin umbilical cord
• selective delivery of acardiac twin 7

62. IUGR
• IUGR is defined as an estimated fetal weight (EFW) /
abdominal circumference (AC) at one point in time
during pregnancy being below 3rd percentile or
EFW/AC below the 10th percentile for gestational age
with deranged Doppler parameters 14.
• An IUGR can be broadly divided into two main types:
• type I: symmetrical intrauterine growth restriction
• type II: asymmetrical intrauterine growth restriction

63. DOPPLER FEATURES
– umbilical artery Doppler assessment
• increased PI above 95th percentile
• absent/reversed diastolic flow
– umbilical venous Doppler assessment
• presence of pulsatility
– uterine arterial Doppler assessment
• increased mean uterine artery PI above 95th percentile
• presence of notching in mid to late pregnancy
• CP ratio: reduced below 5th percentile

64. • FETUSWITH GROWTH RESTRICTION
• WEEKLY DOPPLER USG OF UMBILICAL ARTERY
•
• NORMAL DELIVERY AT 38-39WKS
• ABNORMAL[ DBF]–PERFORMEDWEEKLY-
DELIVERY AT 36WKS
• ABSENT/REVERSED EDBF2-3TIMES
/WK+STEROIDTHERAPYTERMINATIONAT
34WKS[ABSENT EDBF],32WKS[REVERSED
EDBF]