Q: I am a 29 years old woman and LMP 8 months back. A single live foetus is seen in cephalic presentation in the ultrasound report. Foetal Maturity - L 32 weeks 3 days +/- 1 week, Approx Weight: 1770 gm +/- 258 gm, cardiac activity and foetal movements are normal. Foetal heart rate is 132 bmp, liquor amnii is adequate. AVI is 11.9, placenta is posterior and in upper segment grade I mature. NST is reactive. Bio-physical score is 10/10. Colour Doppler showed umbilical artery: PI=1.19, RI=0.69, S/D=3.2 (increased impedance), middle cerebral artery: PI=1.32, RI=0.70 S/D=3.3. The doctor says that S/D is high, and there is less blood flowing to the baby from umbilical cord. What could be the reason for this? What should we do for a full term delivery and a healthy baby?

A:The Doppler ultrasound umbilical artery peak systolic and diastolic blood flow velocity ratio (umbilical S/D) is used in the monitoring of foetal safety. Many studies have come to the conclusion that increase of umbilical artery S/D ratio was associated with increased incidence of cord around the neck, moderate and severe hypertensive disorder of pregnancy, mode of delivery, foetal distress and IUGR. Doppler blood flow spectrum can be measured using 3 indices of umbilical artery flow S/D ratio may reflect resistance of the placenta and placenta microcirculation. Umbilical artery resistance can be studied by: 1) Pusatility Index (PI) (S – D /mean) - Peak systolic velocity – diastolic velocity ÷ time average max velocity (mean) 2) R.I. resistance index (S – D / S) (Peak systolic velocity – diastolic velocity – peak systolic velocity 3) S/D ratio – (peak systolic velocity / diastolic velocity) These three indices provide a semi quantitative method to assess the resistance of blood vessels to be monitored. Increased S/D ratio is associated with:- - Hypertensive disorders of pregnancy - Intra-uterine growth retardation (IUGR) - Cord around the neck - Fetal malformation - Abnormal amniotic fluid - Anaemia in the mother - Placental abruption - Placental previa Studies have reported foetuses with S/D ratio greater than 3.0 after 30 gestational weeks, to be at an increased risk of low birth weight. Management Early onset IUGR (before 32 weeks) - Classify IUGR by aetiology - Determine IUGR type - Treat maternal condition – improve nutrition, reduce stress - Evaluate growth scans and umbilical Doppler velocity every 3 weeks unless 36 weeks or severe oligohydramnios develops, consider hospitalization if AFI < 2.5 percentile with normal umbilical artery Doppler - Absent umbilical artery diastolic flow or reversed umbilical end diastolic flow (AEDF /REDF) - Determine IUGR type – symmetric vs. asymmetric Consider delivery of - Anhydramnios (no pockets of fluid that are clear of cord loop at 30 weeks gestation or beyond - Repetitive fetal heart decelerations - Lack of growth over 3 weeks period and mature lung studies - Abnormal UAD (AEDF or REDF) on umbilical artery Doppler Late onset IUGR (32 weeks or greater) - Classify IUGR - Determine IUGR type - Treat maternal condition, reduce stress - Encourage maternal rest in lateral positions - Growth scans and UAD every 3 weeks - Weekly BPP and NST Decision depends upon:- - Gestational age - Underlying aetiology - Probability of intact extra uterine survival - Level of expertise - Available technology Maternal Nutrition Weight gain in women with normal pre-pregnancy BMI – 11.29 kg to prevent growth restriction Energy needs: - 36 k cal / kg - Increase 10-15% over pre- pregnancy state - Protein additional 10-12 grams - Mineral calcium 1000grams - Iron – 30 mg - Vitamin folic acid – 30 mg, vitamin C-70mg, Vitamin A – 6000 IU Bed rest Results in decreased blood flow to periphery and increased blood flow to utero- placental circulation that improves foetal growth Maternal hyoperoxygenation therapy Aspirin ANP/IGF (atrial natriuretic peptides) / (insulin-like growth factors) Fetal Therapy i) Foetal nutritional supplementation ii) Mechanical therapy iii) Status of induction of pulmonary maturity