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Intrauterine Growth Restriction Eric H. Dellinger, MD Greenville Hospital System IUGR: Introduction • IUGR 2nd leading contributor to PNM rate • PNM rate increased 6-10 fold • PNM rate 8/1000 background: – 120/1000 for all IUGR – 60-80/1000 when anomalies excluded IUGR: Introduction • 40% of stillbirths have IUGR – 53% of preterm stillbirths – 26% of term stillbirths • Intrapartum asphyxia reported in up to 50% of IUGR fetuses • > 60% of IUGR fetuses with FHR tracing abnormalities have hypoxia/acidosis • Pardi, NEJM 328:692, 1993 When is small, too small? Defining IUGR IUGR: Definition • Birth weight < 10th percentile used to define growth restriction at birth • Definition carried over to fetuses using ultrasound measurements (+/- 15%) • Using 10th percentile, 70% will be constitutionally small (no increase risk) • Two SD = less than 3rd percentile • AC < 2.5th percentile has 95% sensitivity Perinatal Mortality / 1000 LB IUGR: PNM and EFW 200 180 160 140 120 100 80 60 40 20 0 > 10 10 9 8 7 6 5 4 Birth Weight (percentile) 3 2 1 0.5 Background Information Normal Versus Abnormal Normal Versus Abnormal < 10th Percentile 70% Normal (Constitutional IUGR) 30% Abnormal (Pathological IUGR) IUGR: Etiology Fetal / Placental Chromosomal / Genetic Twins Congenital malformation Infectious disease CMV Toxoplasmosis Rubella Placental pathology Previa Abruption Mosaiacism Infarction Maternal History of IUGR Hypertension Diabetes MSAFP increase APS Chronic illness Weight < 90% IBW Hemoglobinopathy Substance abuse Anemia/Hypoxia Past History of IUGR • Prior history #1 risk factor for subsequent IUGR • 1 prior episode: 25% recurrence • 2 episodes: Fourfold increase • 1/3 population “at risk”: 2/3 IUGR babies • 2/3 population “low risk”: 1/3 of the IUGR babies, but most are constitutional IUGR: Diagnosis • The Fundal Height Myth: – best from 20-32 weeks: lightening – lag of 4 cm suspicious – Sensitivity of 27%, PPV of 18% • Fundal height of limited value – risk factors more predictive IUGR: Fetal Measurements • Have you weighed a fetus lately? – EFW derived indirectly • “Normal” growth curves difficult to establish • PTL strongly associated with IUGR – BW derived charts inaccurate • U/S growth curves more accurate over preterm age ranges IUGR: Fetal Growth Patterns When did you last watch a fetus grow? Strategy Strategy • Normal versus abnormal • Symmetric versus asymmetric • Fetal causes – Anomalies, arrhythmias, infection • • • • Placental problems Amniotic fluid Dopplers Fetal surveillance HC/AC Ratios Weeks Ratio <32 > 1.0 32-34 ~ 1.0 >34 < 1.0 Asymmetric Symmetric HC preserved, ratio > 1.0 HC, AC both small, ratio ~ 1.0 IUGR: HC/AC Ratios Asymmetric Symmetric HC HC HC/AC AC HC/AC AC Asymmetric vs. Symmetric Asymmetric Symmetric Utereo-placental Constitutional Aneuploidy Infection Fetal Causes • • • • Aneuploidy Anomalies Arrhythmias Infection Aneuploidy Anomalies Arrhythmias Infection Placental Causes Amniotic Fluid Volume IUGR: Oligohydramnios • Initial harbinger of doom – IUGR, preeclampsia – may precede abnormal HC/AC • Fluid pocket of BPP: – – – – >2 cm 6% IUGR 1-2 cm 20% IUGR <1 cm 39% IUGR also predicts intrapartum distress