BACKGROUND 10% for all pregnancies 3-5% for healthy mothers 25% or higher for some high-risk groups Increased risk of perinatal mortality and morbidity Most fetuses with IUGR are constitutionally small Timely diagnosis and management of IUGR iscrucial Ultrasound biometry is the gold standard forassessment of fetal size and the amount ofamniotic fluid
DEFINITION fetus whose estimated weight is below the 10thpercentile for its gestational age Has a NPV of 99%, a sensitivity of 89%, and aspecificity of 88% for the detection of IUGR, Fetal growth is dependent on genetic, placental andmaternal factors The cutoff birth weight for IUGR is 2,500 g at term, 70% of fetuses with a birth weight below the 10thpercentile for gestational age are constitutionallysmall Only in 30%, the cause of IUGR is pathologic.
FETAL WEIGHT PERCENTILES THROUGHOUTGESTATION
IMPORTANCE OF ACCURATE DATING Essential for making the diagnosis of IUGR LMP Ultrasound examination performed before 20thgestational week( the margin of error is seven to 10 days) More accurate estimation of gestational age isbased on early ultrasound examination, ideally ateight to 13 weeks of gestation Third-trimester ultrasonogram is only accurate toabout three weeks Ultrasound assessment is used later in pregnancyto estimate fetal weight
SYMMETRIC AND ASYMMETRIC IUGR Low growth potential – symmetrical Loss of growth support - asymmetrical HC/AC ratio is normal in the fetus with symmetricgrowth restriction and elevated in the infant withasymmetric growth restriction
IUGR - LOW GROWTH POTENTIAL Symmetrical growth restriction Measurements reduced from mid-pregnancy Short & light with all measurements Mother may be biologically small (< 45kg) May be pathological cause Chromosomal abnormality Viral infection
IUGR - LOSS OF GROWTH SUPPORT Usually found after 30 weeks Due to Restriction of oxygen & nutrients Vascular disease affecting uteroplacental circulation egpre-eclampsia Foetus : long, light, reduced abdominal girth Asymmetrical growth restriction Starvation - Glycogen stores in liver are depleted AC is reduced
DIAGNOSIS Ultrasound is the gold standard for assessing fetalgrowth biparietal diameter, head circumference, abdominalcircumference and femur length Accurate dating of the pregnancy is essential in theuse of any parameter In the absence of reliable dating, serial scans attwo- or three-week intervals must be performed toidentify IUGR Do not forget error potential for each parameters Transcerebellar diameter is an unbiased measureof gestational age up to 22 wks
BPD & HC
FETAL WEIGHT PERCENTILES THROUGHOUTGESTATION
HC/AC RATIO ratio of the head circumference to the abdominalcircumference (HC/AC) Between 20 - 36 wks, the HC/AC ratio normallydrops almost linearly from 1.2 to 1.0 An elevated HC-to-AC ratio has a negativepredictive value of 98%, a sensitivity of 82%, and aspecificity of 94% for the detection of IUGR.
AMNIOTIC FLUID INDEX Less than 5cm= oligohydramniosisPercentiles for amniotic fluid index based on gestational age
TRIPLEX MODE Is used for the evaluation of the umbilical vesselsblood flow Includes color Doppler sonography of the umbilicalvessels, pulsed Doppler velocimetry, and real-timesonography to measure the diameter of theumbilical vessels Use of Doppler in IUGR is associated with areduction in perinatal death and induction of laborand less emergency cesarean sections(Cochrane).
UMBILICAL ARTERY DOPPLERDoppler waveform assessmentIndicates flow resistanceProgressive vessel obliteration in the placentaAbsent/ reversed end-diastolic flow Progressive deterioration of Placenta
DOPPLER WAVEFORM OF UMBILICAL ARTERY ININTRAUTERINE GROWTH RETARDATION (IUGR)DEMONSTRATES LOSS OF DIASTOLIC FLOWNormal loss of diastolic flow
STAGING OF IUGR (STUDY) 1. abnormal UA or MCA index; 2. abnormal MCA peak systolic velocity, UAabsent/reversed diastolic flow, UV pulsation & anabnormal ductus venosus pulsatility index; 3. Reversed flow at the ductus venosus or reversedflow at the UV, an abnormal tricuspid E wave (earlyventricular filling)/A wave (late ventricular filling)ratio, and tricuspid regurgitation. Each stage was divided into A (amniotic fluid index[AFI] <5 cm) and B (AFI >5 cm)
SUMMARY The key parameters for diagnosing IUGR are thefollowing: Estimated fetal weight according to gestational age Volume of amniotic fluid Mothers blood pressure status Triplex mode is best for detection of severity andprogression of IUGR