"2nd half pregnancy"This issue of eMedRef provides information to clinicians on the pathophysiology, diagnosis, and therapeutics of intrauterine growth restriction

Bacak, Brian S.

Wachtl, Zach

University of Missouri: MOspace

2nd Half Pregnancy  Intrauterine Growth Restriction: Diagnostics Background 1. Definition  o Intrauterine growth restriction (IUGR)   Fetus w/ estimated wt <10th percentile for gestational age o Small for gestation age (SGA)   Infant w/ birth wt <10th percentile o Constitutionally small   Healthy infants on low-end of growth curve 2. General info  o 10% of all pregnancies will meet criteria for IUGR based on percentage cut-off   Many will be nml, constitutionally small  Must differentiate nml from pathologic  Lower cut-off may be more accurate in finding pathologic processes (5th or 3rd percentile) o IUGR diagnosis controversial   Guidelines for diagnosis and mgmt vary by country   This summary follows ACOG guidelines 3. Normal fetal growth patterns  o Cellular hyperplasia (1st 16 wks) o Hyperplasia and hypertrophy (16-32 wks) o Cellular hypertrophy (32-term) o Head circumference (HC) / abdominal circumference (AC) ratios:   Decr linearly through pregnancy 4. Abnormal fetal growth patterns  o Symmetric:   20-30% of IUGR   All fetal organs decr proportionally, impairment of early fetal cellular hyperplasia (genetic abnl) o Asymmetric:   70-80% of IUGR  Greater decr in AC (liver, SQ fat) compared w/HC, fetal adaptation to hostile environment (redistribution of blood flow to vital organs at expense of nonvital organs) 5. Abbreviations  o AC: abdominal circumference o AFV: amniotic fluid volume o AGA: appropriate for gestational age o EFW: estimated fetal weight o EGA: estimated gestational age o FH: fundal height o FL: femur length o GA: gestational age o HC: head circumference o SGA: small for gestational age o S/D ratio: systolic / diastolic ratio Pathophysiology 1. Pathology  o Variable, dependant on etiology o Uteroplacental insufficiency   Decr supply of nutrients/oxygen to developing fetus o See risk factors 2. Incidence  o By defn 10% of all pregnancies will meet criteria o Incidence of pathologic IUGR <10% 3. Risk factors  o Maternal medical conditions   HTN, preeclampsia  Chronic renal dz  Hypoxia   Cyanotic heart dz  Lung dz  High altitude  Diabetes  SLE/antiphospholipid syndrome  Collagen vascular dz  Hemoglobinopathies o Maternal behavioral conditions  Smoking  Alcohol use  Substance abuse, including   Methadone  Cocaine  Heroin  Poor wt gain, malnutrition  Hx of prior SGA infant  Maternal age extremes (<16 yo or >35)  Low socioeconomic status o Placental  Small placental size  Abruption  Previa  Infarcts  Confined placental mosaicism  Chorioangioma o Fetal   Genetic abnormalities   Aneuploidy  Trisomy  Ring chromosomes  Congenital malformations   Anencephaly  Multiple gestation  Infections   Rubella  CMV  Varicella  Toxoplasmosis  Syphilis  Teratogen exposure   Warfarin  Phenytoin  Methotrexate 4. Morbidity /mortality  o Sig incr risk for oligohydramnios and stillbirth   Depends on GA, etiology, deg of IUGR/SGA o Higher rates of cesarean delivery due to incr incidence of abnormal heart tones and oligohydramnios o Neonatal polycythemia, hyperbilirubinemia, hypoglycemia, hypothermia, apnea o Low APGARs Diagnostics 1. History  o Assess for presence of risk factors  2. Physical exam  o Screen all pregnancies with serial FH measurements   FH: upper edge pubic symphysis to top of fundus   Approximates GA after 20 wks gestation  Serial measurements starting at 20 wks gestation  Difference of 3 cm from EGA: abnormal   Esp at 32-34 wks GA  Accuracy varies widely   Improved if same provider examines every time  3. Initial evaluation  o Accurate GA is crucial o Screen for risk factors  o Fetal anatomic survey   Identify major congenital anomalies o Fetal karyotyping   Structural abnl, early or severe IUGR, polyhydramnios  10-20% of structural abnormalities have abnl karyotype o Infectious dz evaluation   Maternal serum studies   Suspicion of infection  Check for evidence of seroconversion (CMV, rubella, VZV)  Amniotic fluid testing for viral DNA as indicated o Thrombophilic disorder   Especially if recurrent, early or severe  ATIII, protein C&S, Factor V Leiden, prothrombin gene mutation (PCR), APLAb, homocysteine  4. Periodic evaluation  o Optimal method and frequency not established   Test to determine benefit of preterm delivery  Start at point of viability o Serial EFW (U/S): every 2-4 wks o Biophysical Profile (BPP)  1-2/wk  Every day if >1 significant abnl  Severe IUGR (<3rd percentile), severe oligohydramnios, absent or reversed flow on Doppler, borderline BPP scores   Insufficient evidence to evaluate BPP as test of fetal well-being in high risk pregnancies o Amniotic fluid: part of BPP o Doppler velocimetry: 1/wk   Abnl umbilical vein or ductus venosus highest risk of imminent demise o Fetal blood sampling   Assess fetal acid base status to assist timing of delivery  9-14% procedure-related loss so repeat use limited due to high loss rate 5. Diagnostic tests  o U/S should be done for high-risk pregnancies or those with discordant fundal heights   EFW  Fetal biometrics  Anatomic survey  Amniotic fluid volume o Biophysical profile   Not indicated for initial Dx of IUGR o Doppler U/S   Not indicated for initial Dx of IUGR Therapeutics 1. Acute Tx  o Appropriately timed delivery   Only intervention that improves morbidity/mortality of IUGR infant  2. Further mgmt (24 hrs)  o Antenatal surveillance   Indicated once Dx of IUGR confirmed and fetus is viable   Goal to assess fetal growth rate, fetal well being, and amniotic fluid volumes to minimize complications  Methods of antenatal surveillance   Serial Doppler U/S for absence or reversal of flow in the umbilical cord   Serial BPPs, modified BPPs, or non-stress tests 1-2x per week  Serial U/S for growth rate (q2-4 wk)  Interventions   If antenatal surveillance reassuring, continue  If antenatal surveillance nonreassuring, consider prompt delivery  Term and late preterm infants should be delivered  Preterm infants <34 wks GA with IUGR are more complicated; require perinatal input as to their timing  Evaluation of fetal lung maturity may help in decision to deliver o Other studies   Karyotyping indicated in extreme IUGR or if anatomic abnormalities present Follow-Up 1. Return to office  o Timeframe for return visit   Weekly for antenatal testing  2. Refer to specialist  o Consider referral to high-risk OB once Dx confirmed  3. Admit to hospital  o For induction/delivery if antenatal testing nonreassuring  Prognosis 1. Prognosis depends on etiology  o Guarded prognosis   Intrinsic fetal factors (aneuploidy, congenital malformations, infection) o Better prognosis   Inadequate substrates for fetus and decreased O2 (dependent upon eval, monitoring and timing of delivery) 2. Recurrence risk  o SGA risk in 2nd pregnancy 29% (vs 9% if 1st pregnancy AGA) o SGA risk in 3rd pregnancy after 2 SGA births 44% 3. Long-term outcomes of infants  o Normal catch-up of growth by age 2 in most cases o 2x incr risk of neurological sequalae o More prone to HTN and CVD as adults Prevention 1. No evidence that the following treat IUGR  o Nutrient/mineral supplementation  o Volume expansion  o Maternal oxygen therapy  o Antihypertensive therapy  o Heparin  o ASA  2. Avoid smoking during pregnancy  Patient Education 1. Handout from American Academy of Family Physicians  o http://familydoctor.org/online/famdocen/home/women/pregnancy/fetal/313.html  References 1. Restriction. ACOG Practice Bulletin Number 12. January 2000. 2. Chauhan SP, Gupta LM, Hendrix NW, et al. Intrauterine growth restriction: comparison of American College of Obstetricians and Gynecologists practice bulletein with other national guidelines. Am J Obstet Gynecol 2009;200:409.e1-409.e6. 3. American College of Radiology. Growth disturbances - risk of intrauterine growth restriction. ACR Appropriateness Criteria. 1996, reviewed 2007.   Contributors Authors  1. Zach Wachtl 2. Brian Bacak Editor: Brett White  

Intrauterine growth restrictions: diagnostics

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University of Missouri: MOspace