"We are the centre with highest IUI pregnancy rates and have more than 8000 IUI pregnancies at our credit."

IUGR

Doppler in IUGR

IUGR is suggested if gestational weeks determined by computer
programs repeatedly show delay in the growth parameters from the weeks determined by CRL or correct LMP.(Picture1)

That means the intrinsic growth potential, intrinsic capacity of the fetus to grow is restricted, either due to the factors related to mother, fetus or the connecting link, the uteroplacental circulation.

Causes of IUGR

Maternal

  • PIH
  • Chronic hypertension
  • Severe Diabetes mellitus
  • Collagen vascular disease
  • Cardiac or renal disease
  • Smoking and poor nutrition
  • P/H IUGR baby

Uteroplacental

  • Uteroplacental dysfn
  • Placental infarct
  • Chronic abruption
  • Twin to twin transfusion
  • Confined placental mosaicism

Normal uterine artery flow

Persistent protodiastolic notch in uterine artery upto 25 –26 weeks.
(Picture 2,3)

Diagnosis of IUGR

  • Fundal height below 5th percentile – chronic distress is likely
  • Biometric findings – depend on the scan in the first trimester
    - If only in 2nd trimester, depend on least variable parameters
    e.g. cerebellar diameter
  • Doppler findings – depend on the first scan at 22 – 24 weeks

Physiology of Umbilical artery circulation (Picture 4)

Increase in umbilical artery flow velocities and decreased resistance are due to
-Continuous maturation of placental villi
-Widening of placental vessels
-Continuous rise in fetal cardiac out-put
-Continuous changes in vessel compliance
-Continuous rise in fetal blood pressure

Natural protective mechanism

Organs of preference for oxygenated • blood • Heart • Brain • Adrenals
Organs of secondary preference
• Lungs • Skin • Skeleton
• Digestive system

Reduced umbilical artery flow Pathophysiology(Picture 5)

56% of IUGR fetuses – altered umbilical artery FVW, but only 52% had altered heamodynamic pattern, because as long as the two primary compensatory mechanisms are sufficient, no change occurs. Increase in umbilical artery resistance is therefore the first sign of hypoxemia induced by altered villous microcirculation but when the cause is not the uteroplacental circulation but it is the maternal hypoxia, the umbilical artery flows may remain normal and still the MCA and CCA flows will be altered.

Centralization of blood flow ‑ Pathophysiology (Picture 6)

  • Reduced villous circulation upto 75%
  • Rise in umbilical artery resistance
  • Decreased PO2 in umbilical vein 16 – 17 mm of Hg, with increasing umb. Artery resistance, pH 7.2
  • Fall in CCA and MCA resistance

Advanced phase (Picture 7)

  • 80% reduced villous circulation
  • Fetus is already suffering from a degree of hypoxemia and acidosis.
  • Hypoxemia in 70-80% of fetuses and acidosis in 40-60% of fetuses
  • Loss of fetal reactivity
  • Mortality rate is 1 in 4

 

oppler-iugr
1. Doppler in IUGR
normal-uterine-artery
2. Normal Uterine artery flow
uterine-artery-notch
3. Uterine Artery Notch
umbilical-artery-circulation
4. Umbilical Artery circulation
umbilical-artery-flow
5. Umbilical artery flow

Centralization-blood-flow
6. Centralization of blood flow

advanced-phase
7. Advanced phase

1. IUGR with normal heamodynamic profile

  • No immediate decision
  • Doppler and biophysical profile repeated every 1-2 weeks

2.IUGR with heamodynamic redistribution > 34weeks

DO NOT PROLONG THE PREGNANCY.

IUGR with heamodynamic redistribution 32 – 34weeks

  • Decelerative TNS pattern,< 5beats / mt variability
  • Late advanced stage of centralization

    -Absent end diastolic flow in umbilical artery
    -Altered venous flow patterns
  • Termination of pregnancy
  • Earlier stage of centralization Doppler and BPP weekly monitoring

IUGR with heamodyanamic redistribution — 28-32 weeks

  • Decelerative/ silent TNS pattern
  • Reverse diastolic flow in umbilical artery
  • Altered venous flows
  • Terminate pregnancy
  • Initial phase of centralization – expectant management with doppler and BPP follow up every 4-5 days

IUGR with heamodyanamic redistribution < 28 weeks

Late advanced stage of centralization – termination
Earlier stage – expectant treatment – continue pregnancy as far as possible, at least upto 30 weeks.

Summary

  • Uterine artery notch at 25 – 26 weeks : higher risk of IUGR
  • Rising umbilical artery resistance after 28 weeks – an alerting signal
  • Falling MCA resistance – alarming signal
  • Reverse flows in umbilical arteries, normalizing of MCA flow and altered venous signals – a firebrigading signal.