Intrauterine Growth Restriction

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

3. 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

4. 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

5. When is small, too small? Defining IUGR

6. 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

7. IUGR: PNM and EFW

8. Background Information

9. Normal Versus Abnormal

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

11. IUGR: Etiology Fetal / Placental Maternal Chromosomal / Genetic History of IUGR Twins Hypertension Congenital malformation Diabetes Infectious disease MSAFP increase CMV APS Toxoplasmosis Chronic illness Rubella Weight < 90% IBW Placental pathology Hemoglobinopathy Previa Substance abuse Abruption Anemia/Hypoxia Mosaiacism Infarction

12. 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

13. 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

14. 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

15. IUGR: Fetal Growth Patterns When did you last watch a fetus grow?

16. Strategy

17. Strategy • Normal versus abnormal • Symmetric versus asymmetric • Fetal causes • Anomalies, arrhythmias, infection • Placental problems • Amniotic fluid • Dopplers • Fetal surveillance

18. HC/AC Ratios Weeks Ratio <32 > 1.0 32-34 ~ 1.0 >34 < 1.0 Asymmetric HC preserved, ratio > 1.0 Symmetric HC, AC both small, ratio ~ 1.0

19. IUGR: HC/AC Ratios Asymmetric Symmetric HC HC HC/AC HC/AC AC AC

20. Asymmetric vs. Symmetric Asymmetric Utereo-placental Symmetric Constitutional Aneuploidy Infection

21. Fetal Causes • Aneuploidy • Anomalies • Arrhythmias • Infection

22. Aneuploidy

23. Anomalies

24. Arrhythmias

25. Infection

26. Placental Causes

29. Amniotic Fluid Volume

31. 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