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Fetal Growth Restriction.pptx

This document discusses fetal growth restriction (FGR), also known as intrauterine growth restriction (IUGR). It defines FGR as failure of a fetus to reach its genetic growth potential in utero, putting it at risk for perinatal mortality and morbidity. The document covers causes, diagnosis, surveillance, and management of FGR, with a focus on the role of Doppler ultrasound in assessing the fetus and timing of delivery. Key points include using umbilical, uterine, middle cerebral artery and ductus venosus Doppler to evaluate the fetus's circulation and response to placental insufficiency. Abnormal Doppler findings help determine the need for interventions like corticosteroids or timing of preterm delivery.

Education◦
FETAL GROWTH RESTRICTION
Short for Gestational Age • A fetus that has been unable to achieve a specific biometric or estimated weight threshold by a specific gestational age is called a short for gestational age (SGA) fetus. • Using the WHO cut-off, the term SGA is used when the newborn baby’s weight is below the 10th percentile for its gestational age (ACOG). – Constitutionally small and healthy fetuses (50-70% of SGA) – Fetuses with growth restriction • Early Onset FGR <32 weeks • Late Onset FGR >32 weeks • Incidence: About 3-10% infants are growth restricted; 12-40 % in twin gestation.
Definition FGR is a pathological condition defined as failure of a fetus to reach its genetic growth potential in utero putting it at risk of perinatal mortality and morbidity. Smallness is defined as estimated fetal weight (EFW) or abdominal circumference (AC) less than the 10th centile and severe SGA as EFW or AC less than 3rd centile.
Symmetry & Asymmetry The concept of symmetry means that all fetal segments (head, abdomen, long bones) are small and the centiles of their measurements are comparable. Asymmetry is related to the more accentuated reduction of the abdomen, compared to other fetal segments.
Classification
Early Onset IUGR- Increased Perinatal Risk Late Onset IUGR- Lesser Perinatal Risk
Etiology • Fetal Factors – Chromosomal abnormality – Genomic Imprinting – Congenital Malformations – Congenital Infections – Multiple Gestation • Maternal Factors – Pre eclampsia, chronic/essential HTN – Renal Disease – Diabetes with vasculopathy – APLA,SLE – Thrombophilia – Severe or Cyanotic Heart Disease – Asthma – Hemoglobinopathy – Smoking, alcoholism, substance abuse – Therapeutic agents like anticancer drugs – Malnutrition • Placental factors – Confined Placental Mosaicism – Placenta previa – Abruption – Infarction – Placenta accreta – Hemangioma – Circumvallate placenta – Abdominal Pregnancy
Pathophysiology- Sequence of Events in Growth Restricted Fetus Increased impedence to flow in umbilical artery Arterial Redistribution in fetal circulation Failure of compensatory mechanisms Abnormal Venous Flow Abnormal Fetal Heart Rate Pattern
Pathophysiology In the early stages of hypoxia, the fetus uses adaptive techniques such as – growth reduction, – Decreased fetal movements, – And vascular redistribution to reduce its oxygen requirement, in an attempt to prevent hypoxic injury. There is stimulation of erythropoiesis with an increase in hematocrit.
Pathophysiology Fetal hypoxia or acidosis Aortic Body Chemoreceptor Stimulation Reflex Redistribution of Fetal cardiac output
Pathophysiology- Arterial Redistribution Kidney; Lung; Muscle; Liver; Skin Brain; Heart; Adrenals Brain Sparing Effect Vasodilatation Vasoconstriction Decrease in urine output and hence Oligohydramnios; Decrease subcutaneous Fat and glycogen storage
Timeline for Fetal Hypoxemia Abnormal Fetal Growth Abnormal Arterial Doppler Abnormal Venous Doppler Abnormal CTG/BPP Doppler is Earliest
Risk Factors MAJOR • Previous SGA • Previous Stillbirth • Chronic HTN/ Pre eclampsia • Renal Impairment • APLA • Threatened abortion with heavy bleeding • Unexplained APH • Low Maternal weight gain • Paternal SGA • Maternal age >= 40 years • Smoker > 11 cigarettes per day • Fetal Echogenic Bowel on USG • PAPP-A < 0.4 MOM • Daily vigorous Exercise MINOR • Age >= 35 years • BMI <20 or >25 • Nulliparity • IVF Singleton Pregnancy • Low fruit intake Prepregnancy • Caffeine >300mg per day • Interpregnancy Interval <6 months or >60 months • Placental abruption
Complications Early Neonatal Complications Metabolic Hypothermia Hypoglycemia Hypocalcemia Polycythemia Hyperviscosity Syndrome Complications Due to Asphyxia HIE Persistent Fetal Circulation MAS NEC Pulmonary Hemorrhage Electrolyte Imbalance Metabolic Acidosis Late Neonatal Complications 1. Symmetrically growth restricted babies tend to grow slowly after birth. The Asymmetrical growth restricted babies tend to catch up growth in early infancy. 2. Increased chances of retarded neurological, intellectual, cognitive and behavioural development and cerebral palsy in infancy esp. in symmetrical GR. 3. Increased risk of cardiovascular disease, Type 2 diabetes and hyperlipidemia in adulthood (Barker Hypothesis 1992) Fetal Complications: 1. Risk of Stillbirth 2. Non reassuring fetal status due to hypoxia, acidosis and meconium aspiration.
Prediction and Screening 1. History • Maternal Characteristics like age, parity, Ethnicity, Nulliparity, social deprivation, unmaried status, low pre pregnancy weight, intense daily exercise, • Maternal Medical History like Diabetes with vascular disease, Chronic HTN, renal impairment esp associated with HTN, APLA • Paternal medical history like Paternal SGA • Past Obstetric History like previous SGA, previous stillbirth, previous pre eclampsia, interpregnancy interval, – Previous SGA is associated with 6 fold increase risk for SGA • Trimester History: heavy vaginal bleeding during first trimester similar to menses • Substance abuse, smoking, caffeine intake
Risk factors related to Current Pregnancy
Prediction and Screening 2. Examination • Weight • SFH • Fundal height by palpation • Girth of the abdomen 3. Maternal Serum Screening AFP, uE3, hPL, HCG PAPP-A <0.4 MOM in the first trimester is also used as a predictor for FGR later on.
Prediction and Screening 4. Ultrasound Markers- Fetal echogenic bowel and abnormal uterine artery doppler velocimetry in second trimester. The combination of unexplained elevated AFP with abnormal uterine artery doppler velocimetry or echogenic bowel is a better predictor of adverse perinatal outcome.
Screening For SGA due to Placental Insufficiency RCOG Green Top Guideline No. 31
Prediction and Screening Uterine artery (UtA) doppler directly reflects the involvement of trophoblastic invasion and can be used as a screening tool for all high risk pregnancy for the prediction of pregnancy outcome. UtA doppler assessment at 20-24 weeks gestation may be offered in women who have one major or three or more minor risk factors for SGA.
Diagnosis- Clinical Examination • If the height of the uterus is less than 4 weeks or more than the estimated gestation, FGR should be suspected. • SFH The uterine height in cm coincide with the weeks of gestation between 18 and 30 weeks. • Static or falling maternal weight after 20 weeks may indicate FGR • Static or falling abdominal girth measured at umbilicus may indicate FGR
Diagnosis- Ultrasound Biometry An AC within normal range for gestational age rules out FGR while an AC of <5th percentile is highly suggestive of FGR (ACOG 2000) The RCOG green top guideline suggests fetal AC or EFW <10th percentile of GA as recommended cut off for SGA. AC is the most sensitive parameter to diagnose FGR.
Diagnosis Biophysical tests such as amniotic fluid volume, cardiotocography and Biophysical profile scoring have been shown to be poor diagnostic tests for FGR.
Fetal Surveillance 1. Fetal Biometry Serial assessment of fetal biometry can identify worsening of growth velocity in fetuses diagnosed as SGA. Fetal USG biometry is performed every 2-3 weeks. Patient can be followed up on OPD basis. 2. Doppler Assessment Two weekly (weekly in severe SGA) doppler of UA is recommended as the primary modalily of FWB. This is increased to twice a week in a compromised UA doppler with present diastolic flow and daily with absent diastolic flow.
Fetal Surveillance 3. Amniotic Fluid Volume Single deepest vertical pocket <2cm should be used for diagnosing oligohydramnios. Decreased AF volume may signify placental insufficiency or fetal anomalies. Antepartum AFI <= 5 is associated with increased risk of caesarean section for fetal Distress and an APGAR <7 at 5 minutes. A low or marginal AFI should be followed by more frequent surveillance. AFI <=5 should prompt consideration for delivery.
Fetal Surveillance 4. Biophysical Profile Score includes four acute fetal variables, each score 2 a) Breathing movements b) Gross body movements c) Cardiotocoraphy d) Amniotic fluid volume Score <=4 are considered abnormal Recent studies on preterm SGA suggest BPP as poor predictor of fetal acidemia, hence should not be used for fetal surveillance in preterm SGA.
Fetal Surveillance 5. Cardiotocography CTG should not be used as the only surveillance tool Computerised CTG should be preferred to conventional CTG Interpretation should be based on short term fetal heart rate variability.
Interventions in Preterm SGA Women with POG 24 to 35+6 weeks gestation, where delivery is being considered, should receive a single course of antenatal corticosteroids to accelerate fetal lung maturity and reduce neonatal death and morbidity Maternal administration of Magnesium Sulphate have been shown to have neuroprotective effect and to reduce the incidence of cerebral palsy among preterm infants <30 weeks.
Prevention of SGA • Aspirin started at <16 weeks POG in women at risk of developing pre eclampsia • Smoking cessation
Timing of Delivery The timing of delivery remains a critical issue. The risk of prolonging pregnancy(i.e stillbirth) has to be weighed against the risk of prematurity. Gestational age is critical in decision making. The other critical issue in decision making is the interpretation of surveillance tests that are used to predict perinatal outcome.
The Role of Doppler
Fetal Circulation
Doppler Indices Peak Systolic Velocity Peak Diastolic Velocity Systolic to Diastolic Ratio:- Systolic peak velocity/Diastolic peak velocity Pulsatility Index:- Systolic-End diastolic peak velociy Mean Velocity Resistence Index Systolic-End Diastolic peak velocity Systolic peak velocity Cerebroplacental Ratio MCA PI/UA PI
Uterine Artery Doppler • Uterine artery doppler reflects trophoblastic invasion and placental development. • Uterine artery doppler between 20 and 24 weeks has a moderate predictive value in the predicition of FGR. • Women with abnormal UtA doppler >p95 or early diastolic notching should be followed up with serial fetal growth and well being scan from 26 weeks to 28 weeks. • UtA doppler resistence profile that is high, with PI >95th centile or persistently notched, or both, indentifies women who are at risk for pre eclampsia and FGR. It has a sensitivity of 85% when done between 22 and 23 weeks. • Low dose aspirin initiated this late in pregnancy does not improve placental function. • A marked reduction in early onset pre eclampsia and FGR is seen in high risk women identified on the basis of high risk factors like maternal history, mean arterial ptressure, UtA doppler at 11-13 weeks, PAPP-A and treated with 100-150 mg aspirin in the evening started at less than 16 weeks till 36 weeks.
Umbilical Artery Doppler
Umbilical Artery Doppler Umbilical artery doppler reflects placental function and indicates the degree of placental insufficiency In the normal fetus, Doppler of UA shows presence of diastolic flow by 15 weeks. As the placental resistence decreases with advancing gestation due to trophoblastic invasion, diastolic flow increases. This is manifested as decrease in SD ratio or PI. Thus the UA shows a waveform with continuous flow during systole and diastole. In a growth restricted fetus with decreased placental perfusion and increasing resistence to flow, the SD ratio, PI and RI show and increasing trend. Gradually the diastolic flow ends (AEDV) and then reverses (REDV). High UA PI (above p95) indicates placental insufficiency Positive EDF >=50% Absent EDF >=70% Reverse EDF >=90% AEDV and REDV are associated with increased perinatal morbidity and mortality and if identified, urgent intervention with steroid administration for fetal lung maturity, increased surveillance and delivery is required even in preterm fetus.
Umbilical Artery Doppler
Umbilical Artery Doppler
Middle Cerebral Artery
Middle Cerebral Artery MCA Doppler shows how the fetus is coping. In the normal fetus, MCA is characterized by higher impedance to flow as compared to UA and hence it exhibits low amplitude of diastolic flow in the normal circumstances. The flow increases in a hypoxic fetus due to cerebral vasaodilatation which occurs as an adaptive mechanism known as the brain sparing effect, resulting in a decreased PI value. Therefore, reduced MCA PI and CPR are early predictors of fetal hypoxemia in SGA fetus. The MCA PI <5th centile or CP ratio <5th centile is a moderate predictor of acidosis at birth in a term SGA and should be used to time delivery even in a normal UA doppler In a preterm fetus less than 32 weeks MCA doppler has limited value and should not be used to predict outcome.
Middle Cerebral Artery • The brain sparing effect may develop in 2 scenarios – In Early onset SGA, where UA are already abnormal for the worsening of placental circulation. – In late onset SGA, where UA is typically normal because fetal metabolic needs are greater than placental capacity even in the absence of placental insufficiency. • Predictive ability for adverse perinatal outcome is greater in the latter scenario. • According to these findings, the development of brain sparing effect should be considered for the time to deliver in late onset SGA (32-34 weeks POG), where UA is normal.
Ductus Venosus • Venous Doppler changes usually occur late in fetuses with growth restriction when there is fetal acidosis and cardiac function compromise. • Atrial pressure volume changes with increased preload manifests as: – Pulsations in umbilical vein – Absence or reversal of flow during atrial contraction (a wave) in the DV • DV doppler should be used in – Preterm SGA fetuses with abnormal UA doppler – Decision for time to delivery in early onset SGA