INTRAUTERINE GROWTH RESTRICTION Max Brinsmead MB BS PhD August 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 1 st 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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