INTRAUTERINE GROWTH RESTRICTION

Max Brinsmead MB BS PhDAugust 2014

The fetus is unique because... He or she cannot signal his or health by way

of any history And we can only examine through his or her

mother We can only...

Document size and growth Evaluate his or her movements Listen to his or her heart Evaluate the fluid around him or her Assess his or her reaction to stimuli

When the uterus is SFD you first need to know…

What is normal SFH = Weeks of gestation is valid only

between 20 and 32 weeks Thereafter the mean runs off to 37 cm at

40 weeks This should be validated in each population And the 95% confidence limits are not less

than +/- 3 cm

When the uterus is SFD you also need to know DATES accurately…

Ultrasound is unreliable when… It is done by a non expert or with poor

equipment It is done late in pregnancy There is something wrong with the fetus e.g.

microcephaly

If the uterus is SFD think of…

Wrong dates Oligohydramnios

Premature rupture of membranes Abnormality of the fetal renal tract Intrauterine growth retardation (IUGR)

Intra uterine growth retardation There are two major categories Symmetrical = head, trunk and body reduced

proportionaely Asymmetrical = head-sparing growth restriction

Causes of Symmetrical IUGR

Constitutional smallness Consider maternal size Ethnic origin Paternal influence less important

Fetal Infections TORCH = Toxoplasmosis, Other, Rubella,

Cytomegalovirus and Herpes Remember Syphilis, HIV and Malaria

Fetal Abnormalities Especially chromosomal abnormalities such as

Trisomy 21, 13&16

Asymmetrical Growth Restriction

Occurs because the hypoxic baby will redistribute its cardiac output

From glycogen storage (liver size) From the kidneys (oligohydramnios) From the trunk and limbs From the bowel (meconium) And it does this to maintain blood

flow to the head, brain and heart

Causes of Asymmetrical IUGR

Anything that reduces Maternal-Uterine-Placental to Fetus transfer of oxygen and nutrients

Maternal smoking and malnutrition Severe maternal anaemia Chronic maternal disease Maternal hypertension especially pre eclampsia Uterine malformations Some placental diseases Maternal thrombophilias congenital or acquired Recurrent antepartum haemorrhage An idiopathic group

Diagnosis of IUGR

Only 30 – 50% will be detected by measuring SFH

Serial measures more valuable than a single one

We need to have a high index of suspicion in a fetus at risk

Hypertensive disorders Recurrent APH Poor obstetric history Multiple pregnancy

And use ultrasound selectively to confirm or exclude the diagnosis

A SFD uterus is more serious when…

The mother was underweight to begin with

She has not gained weight appropriately There is a past history of IUGR or

pregnancy loss A condition known to be associated with

IUGR is also diagnosed Pre eclampsia Recurrent APH Chronic maternal disease or anaemia

Management of the SFD baby

Accurate diagnosis Is the baby salvageable? Mother at risk?

Steps that improve M-U-P-Fetal transfer of oxygen and nutrients

Stop maternal smoking Bed rest Correct anaemia Improve nutrition

Monitor fetal growth and well being There is little point in ultrasound at less than 2w

intervals Timely delivery

Must weigh up the risks of induced delivery against the risk of remaining in utero

Umbilical Artery Doppler Study

Upper panel represents peak (systolic) and trough (diastolic) flow often expressed as S/D ratio

Lower panel is constant flow through a uterine vein

UA Doppler reflects downstream placental resistance

Is the 1st change to occur with placental disease

Umbilical Artery Doppler changes with Gestation

Abnormal UA Doppler Flows When flow ceases

in the diastolic phase (AEDF) the S/D ratio is very high (∞)

Flow may even reverse in the diastolic phase (RDF) as shown opposite

Uterine Artery Dopplers…

Are of limited use when…▪ The fetus is very premature (<30 weeks)▪ Pregnancy is prolonged (>40 weeks)▪ It is a low risk pregnancy

▪ 5% will be high but normal▪ Are useful in High Risk Pregnancies▪ May be used to prolong pregnancy with

immature fetus and apparent IUGR▪ Have a high negative predictive value for fetal

death▪ Will change 4 – 7 days before other

changes in fetal wellbeing e.g. Biophysical Profile

Other Pregnancy Doppler Studies

Fetal Middle Cerebral Artery Resistance falls as brain-sparing IUGR begins Strong correlation with fetal HB Of particular use in monitoring intrauterine

haemolysis

Fetal Ductus Venosus Resistance rises as the placenta deteriorates

Maternal Uterine Arteries Increased resistance with bilateral notching at

12 – 24w predicts early (but not late) onset pre eclampsia with ≈ 60% sensitivity

Uterine Artery Doppler

Fetal Biophysical Profile Ultrasound for…

Fetal Breathing Fetal Movements Fetal Tone Amniotic Fluid Volume

Non Stress CTG Looking at fetal heart short term variability and

accelerations Assigns a score of 0,1,2 to each of

these five measures as with the Apgar Score

Scores ≤ 6 are abnormal

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