INTRAUTERINE GROWTH RESTRICTION AND ROLE OF OBSTETRIC DOPPLER - PowerPoint Presentation

Slide1

INTRAUTERINE GROWTH RESTRICTION AND ROLE OF OBSTETRIC DOPPLER

Dr.

KAVITA MAKASARE

JR III

Slide2

DEFINITION

CAUSES

PATHOPHYSIOLOGYTYPESINVESTIGATION: BIOMETRY DOPPLERMANAGEMENT

IUGR

Slide3

a fetus

is growth-retarded if its weight is

below the 10th percentile for its gestational age with underachiving of growth potential IUGR fetus a)Birth weight <10th percentileb)Inadequate interval growth in sequential screening

DEFINITION

Slide4

MATERNAL CAUSES

FETAL CAUSESGeneticNutritionalFetal infections Chromosomal anomaliesHypoxicSevere lung diseasesCyanotic heart diseasesCongenital malformations VascularChronic hypertension Pre-

eclampsia

Collagen

vascular diseases

Diabetes mellitusPlacental factorsAbnormal trophoblastic invasionPlacenta previaRenalGlomerulonephritisAntiphospho-lipid antibodyMultiple gestationsPoor obstetric historyPrevious stillbirthPrevious preterm birthsdrug or alcohol abuse

CAUSES

OF IUGR

Slide5

Effect of IUGR

Common cause

is placental insufficiency which results intoReduced supply of oxygenNutrients reductionFetal response to this by, Primary adaptive response

Decrease

fetal

growth

(IUGR)Secondary adaptive response Decreased fetal movement which is assessed by Biophysical profile scorePatho

-physiology

Slide6

Slide7

Asymmetric growth restriction is the

differential reduction in growth velocity of the fetal head to abdominal circumferenceMost common – 90%Also called Decreased cell size IUGR or Late-onset IUGR or Late-flattening IUGR.

Due to fetal

malnutrition.

Due

to Utero-placental insufficiency :The development of a good utero-placental circulation is essential for the achievement of a normal pregnancy. AC is the single most effective fetal parameter.

High HC/AC and FL/AC

ratios

&

oligohydramnios

without

ruptured membranes

Asymmetric IUGR

Slide8

Symmetric

IUGR

Symmetric growth restriction is the equivalent reduction in growth velocity of both the fetal head circumference and abdominal circumferenceLess

common (10

%)

Also

called Decreased cell number IUGR or Early insult IUGR or Low-profile IUGR.Due to diminished cell growth. Due to insult during the process of Embryogenesis

Proportionate

decrease in HC & AC, but HC/AC ratio is maintained. Anomalies seen.

Amniotic

fluid volume is normal.

Slide9

Asymmetric (90%)

Symmetric (10%)

Occurs in late pregnancy.

Occurs in early pregnancy.

Due to

Uteroplacental

insufficiency.

Due to insult during the process of Embryogenesis.

Disproportionate decrease in HC and AC, HC/AC affected.

Proportionate decrease in HC and AC, HC/AC not affected.

Fetal anomalies not common.

Fetal anomalies common.

Oligohydramnios

noted.

Amniotic fluid may be normal.

Slide10

1. Constitutionally small

fetuses

The growth velocities in these pregnancies continue along the same centile There is an absence of ultrasound features of uteroplacental insufficiency or

fetal

abnormality.

Uterine

, umbilical and fetal Doppler values remain in the normal range.2. Pathologically small fetuses

The

growth velocity in these pregnancies continues to fall and progressively cross lower centiles

The majority of these pregnancies have severe early-onset

uteroplacental

insufficiency or

fetal

abnormality

typically

triploidy

Slide11

Investigations

Ultrasonography

: Modality of choiceFetal biometric measurement Biophysical profileDoppler study

.

Slide12

Steps involved in usg

prediction of IUGR

Fetal gestational age determinationAssess fetal weightCalculate weight percentile

Slide13

1.

Fetal

gestational age determinationGestational age should be calculated at the time of the first sonogram during the pregnancy First trimester scans are better predictor of fetal ageAccuracy of age assignment at the initial sonographic

examination becomes

progressively worse as pregnancy proceeds,

First trimester : crown

rump length (CRL)Second trimester : Head circumference (HC) and corrected BPD

Third trimester

:

Head

circumference

and

Biparietal diameter,

femur length

Variation

in USG determination of age,

+/- 0.5 wk in first trimester

+/- 2-2.5 wk in third trimester

+/- 3.5

wk

in third trimester.

Slide14

2. Assess

fetal

weight Accuracy of fetal weight prediction improves with increasing numbers of body parts up to three. No further improvement in accuracy by

adding a fourth or fifth body part to the weight formula

Optimal weight

prediction

formulas use sonographic measurements of the fetal head, abdomen, and femurFetal weight can be estimated from one of many published formulas that use measurements of a variety of fetal body parts

Fetal

growth is continuous rather than sporadic.

Recommended interval between ultrasound evaluation is 3 weeks because shorter intervals leads to false positive results.

3. Calculate

weight percentile

Charts and graphs are available for to calculate percentile of

fetal

weight for a given gestational age

Slide15

Slide16

Slide17

When patient came for a scan in third trimester for first time ,

fetal

weight falls bellow 10th percentile for a period of amenorrhoea then we are not sure about IUGR or wrong LMP.In this situation other parameters are useful to suspect iugr Additional USG features for iugr are elevated

HC/AC

ratio : High negative predictive value

elevated ratio of femur length to abdominal

circumferencepresence of oligohydramnios without ruptured membranespresence of advanced placental grade

Slide18

0

2

Fetal gross body movement AbsentpresentFetal tonePoor GoodRespiratory movementAbsent Present

Amniotic fluid volume

single pocket < 2cm

Single pocket > 2cm

Normal score 8/8Biophysical profile

Slide19

Modified BPP

Slide20

Role of Doppler

Help in evaluation of

uteroplacentral insufficienciesInformation about the resistance to the blood flow.

For diagnosis of

IUGR

Diagnosis of

fetal anemiaFetal hypoxia Doppler

Slide21

Analyses of the Doppler waveforms

Measuring the peak systolic(S) and end

diastolic (D) velocities.Three angle independent indices are considered related to the vascular resistance

:

S/D ratio : systolic / diastolic velocity ratio

Resistivity index (RI) :

RI = systolic velocity- diastolic velocity/ systolic velocity3. Pulsatility index (PI) : systolic velocity- diastolic velocity/ mean velocity

PI

most widely used as it can evaluate absent diastolic flow

Slide22

ARTERIES

: Indirect assessment of placental resistance Uterine arteriesUmbilical arteryMiddle cerebral arteryAortic isthmusDescending aorta

Structures examined

VEINS :

Assessment of

fetal cardiac functionDuctus venosus

Umbilical vein

IVC, Hepatic veins

FETAL HEART

E/A ratio

Regurgitation

Slide23

Uterine arteries.

Branch of internal iliac artery.

Cross external iliac artery-reach cervico-isthmal junction.Divides –Ascending and descending branches. Ascending-arcuate

, radial, spiral

arteries.

Spiral arteries forms the endometrial vascular bedUterine Artery Doppler correlates well with hemodynamic changes in the placental circulation.

Slide24

As

the gestational age advances the impedance in the uterine artery decreases due to trophoblastic

invasion of spiral arteries.Diastolic component in the uterine artery waveform appears during the early second trimester at 14 weeks of gestation and progressively increases upto 20 to 24weeks

1st & early 2nd trimester – High resistance flow with

prediastolic

notch24 weeks onwards–Disappearance of the diastolic notch

It is better indicator of pre-

eclampsia

than IUGR

Slide25

Normal flow

Low resistance

with good diastolic flowAs the pregnancy advances diastolic component increases.No prediastolic notch

Abnormal flow

Prediastolic

notch

Intra systolic notch s/o extremely high resistance

Slide26

UMBILICAL ARTERY

Umbilical artery is the signature vessel in the Doppler study of the

fetus It is a direct reflection of the flow within the placenta. It is usually the first vessel to be studied when suspecting an IUGR

Three sites

The placental origin,

Fetal

abdominal insertion site In the mid free floating loop : Best site for examination. Resistances at the abdominal cord insertion tend to be higher and those at the placental insertion tend to be lowerPlacental site is last place to shows changes in case of abnormal waveform

Slide27

NORMAL

FLOW

Low resistance, continuous forward flow – saw tooth appearance In the normal fetus, the pulsatility index decreases with advancing gestation. This reflects a decrease of the placental vascular resistanceABNORMAL FLOW

IUGR there is an increase of the

pulsatility

index secondary to the decrease, absence or reversal of end-diastolic flow

Slide28

Middle cerebral artery

Middle cerebral artery is the vessel of choice to assess the fetal cerebral circulation because it is easy to identify and has a high reproducibilityDuring normal pregnancy, the MCA shows high resistance and low diastolic flow pattern with continuous forward flow

MCA

RI : 0.7-0.9

PI : before term is 1.4

At term 1

Slide29

REDISTRIBUTION / BRAIN SPARING Adaptive mechanism in hypoxia,

to

increase blood flow to vital organs and decrease blood flow to the periphery.NormalAbnormal

Slide30

CEREBROPLACENTAL RATIO ( CPR ) = MCA PI / UA PI

CPR > 1.1

normal CPR < 1.1 s/o hypoxia and redistribution.PARADOXICAL NORMALITYIn severe IUGR there can be disappearance of the brain sparing effect, resulting in normal MCA PI values as a consequence of brain edema

s/o critical

for

fetus.IUGR AND MCA PSVIncrease in MCA PSV better predictor of perinatal mortality than MCA PI

Slide31

Ductus

venosus connects the umbilical vein to IVC Sample DV at inlet, keeping the gate minimum.NORMAL FLOW - Biphasic waveformS systoleD diastole

A

atrial

contraction, always away from baseline.a wave near baseline ( high PIV > 0.8).Absent a wave.Reversed a wave.DUCTUS VENOSUS

Slide32

In cardiac failure umbilical vein shows pulsatile flow which signifies severe

cardiac

decompensationIn cases when ductus venosis is difficult to image the umbilical vein pulsatility can be useUsed for prediction of fetal

acidemia

.

Umbilical vein

.Normal umbilical vein shows smooth uniform continuous flow.

Slide33

AORTIC ISTHMUS

Isthmus is the region between origin of the left

subclavian artery and the aortic end of the ductus arteriosus.Indicates the state of efficiency of adaptive mechanismsIn hypoxemia, cerebral oxygenation is preserved as long as the net flow in the isthmus is ante-grade.Reversal of net blood flow in aortic isthmus is a sign of failure of the adaptive mechanisms against hypoxemia, and s/o cerebral hypoxia.

Slide34

STAGE

Features

ManagementSTAGE IAbnormal UA PIAbnormal MCA PIMild IUGRManaged on OPD basis

STAGE II

UA AEDF/ RDF

MCA PSV

Abnormal /absent flow DVUmbilical vein pulsationsNeed hospitalization for observation

STAGE III

DV reversed flow

Umbilical vein reversed flow

Tricuspid valve E/A

> 1

Hospitalization - high risk for

fetal

demise

DOPPLER US STAGING GUIDELINES FOR IUGR

Slide35

Management