INTRAUTERINE GROWTH RESTRICTION

1. INTRAUTERINE GROWTH RESTRICTION Max Brinsmead PhD FRANZCOG August 2014

2. 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

3. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. Umbilical Artery Doppler changes with Gestation

15. 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

16. 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

17. 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 DuctusVenosus • 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

18. Uterine Artery Doppler

19. 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