Intrauterine Growth Restriction Eric H Dellinger MD Greenville

Intrauterine Growth Restriction Eric H. Dellinger, MD Greenville Hospital System

IUGR: Introduction • IUGR 2 nd 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 < 10 th percentile used to define growth restriction at birth • Definition carried over to fetuses using ultrasound measurements (+/- 15%) • Using 10 th percentile, 70% will be constitutionally small (no increase risk) • Two SD = less than 3 rd percentile • AC < 2. 5 th percentile has 95% sensitivity

IUGR: PNM and EFW

Background Information

Normal Versus Abnormal

Normal Versus Abnormal < 10 th Percentile 70% Normal (Constitutional IUGR) 30% Abnormal (Pathological IUGR)

IUGR: Etiology Fetal / Placental Chromosomal / Genetic Twins Congenital malformation Infectious disease CMV Toxoplasmosis illness Rubella Placental pathology Previa Abruption Mosaiacism Infarction Maternal History of IUGR Hypertension Diabetes MSAFP increase APS Chronic 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

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