INTRAUTRINE GROWTH RESTRICTION

Dr. H. Nuswil Bernolian, SpOG(K)

Diagnosis of symptomFetal growth failing (arising from maternal, placental, or fetal origins)Birth weight lower than expected in the suitable gestational week (may be the variable described as below the 3rd, 5th, or 10th percentile)A perinatological definition of fetal IUGR

Dynamic phenomenon defined the bestA a delay of the growth of the fetus estimated as a decrease of 25 centiles in the measure of the abdominal circumference, according to the standard curve at the gestational age, and in subsequent echograhic evaluations performed at least every 2 weeks.

ClassificationAsymmetrical (late onset around 30 weeks of pregnancy) affects abdominal growth more that the head circumference.Symmetrical (early from the beginning of the second trimester) proportional lagging of the head circumference, abdominal circumference, and long bone growth.

Natural HistoryThe first 16 weeks of pregnancy cellular hyperplasiaFrom 16 to 32 weeks of pregnancy, both cellular hyperplasia and cellular hypertrophy occur.The last weeks, cellular hypertrophy predominates

Risk factors fetal :Chromosomal abnormalities (triploidy, trisomy 13 and 18)Structural malformations (especially cardiac malformations)Fetal infections (TORCH, parvovirus B19, syphilis, listeriosis)

Risk factors placental : Abnormalities of the placentation (reduction of number of thin-walled, distended uteroplacental vessels)Acute atherosisObliteration of small muscular arteries of the tertiary villiConfined placental mosaicismChorioangioma

Risk factors maternal :Low socioeconomic statusChronic maternal under nutritionMalnutrition (anorexia nervosa, bulimia)Cardiovascular diseases (cardiac failures, hypertension, pre-eclampsia)Gastroenteric diseases (chronic enteritis, malabsorption diseases)

Risk factors maternal :Pulmonary diseases (CF, asthma, respiratory failure)Renal diseasesAnemiaAlcohol and drug abuse, smokingUterine abnormalities (fibroids, uterine malformations)

Clinical features : Clinical examination (symphyseal fundal distance)Diagnostic ultrasound (BPD, FL, AC, EFW) serial measurementsAFI amniotic fluid indexMaturity of the placenta stages according to Grannum

Doppler examinationUterine arteries approximately 25% of women with unilateral persistant notch and 50% of those with bilateral notch at 24 weeks of pgregnancy will have an IUGR fetus, develop pre-eclampsia, or experience both (sensitivity 82% and specificity of 38%)Umbilical arteries affected fetuses show a reduced blood flow pattern during diastole

Fetal compromiseGradually increasing resistance to blood flow in umbilical arteriesEnd diastolic component may disappear or may reverseRedistribution of blood flow occursBrain, heart and adrenal glands are preferentially perfusedMCA blood flow increases

Brain Sparing PhenomenonCerebroplacental ratio is below 2 SDPrior to abnormal CTG recordings about a couple days to 2 weeksAssociated with fetal hypoxiaWhen resistance in MCA begins to rise cerebral edema occurs

Utero-placental insufficiency during pregnancyDiagnosis and management

During pregnancy, fetus depends on the placenta and umbilical vessels for transport of oxygen and nutrients from maternal blood, and for excretion of carbon dioxide and products of metabolism

During pregnancy and labor, fetus may be at risk of damage or death from acute or chronic utero-placental insufficiency.

Acute placental failure may result from placental separation by hemorrhage (abruptio placentae) or it may come at the end of a phase of gradually declining placental efficiency.

Chronic restriction of maternal blood flow through the placenta can have a serious effect upon fetal growth and development.

Medical History :Pregnancy induced hypertensionMaternal diseases (DM; severe anemia; renal, intestinal, cardiac and lung failures; malnutrition)Infections in pregnancyMultiple pregnanciesSome drugsAddictions (smoking, alcohol, drug abuse)Placental pathology (placental infarction, fetal stem artery thrombosis, antepartum, hemorrhage)

Tests of placental function :Maternal weightUterine growth fundal heightFetal body movementsFetal growth obtained by ultrasoundFetal activity biophysical profile, non-stress test (CTG)Color doppler studiesPlacental biochemical tests

Maternal weightShould normally increase by about 0.5 kg weekly after the first trimester (provided that the patient is not dieting or vomiting and has no other disorder causing malnutrition)Components of this weight gain include: the fetus, plcenta, liquid, uterus, breasts and fat store. Additionally there is the increase in blood volume and ECF.These changes depend directly on placental function, or indirectly by the hormone production

Uterine growthSimple measurements of the height of the fundus of uterus in relation to the symphysis pubis and umbilicus (eg. in 16th week of gestation midpoint between pubic symphysis and the umbilicus; at 24th week umbilical level)Fundal height should increase by about 1 cm weekly from the 16th week of pregnancy, and with an average sized fetus, should equal the number of weeks of gestation plus or minus 2cm

Fetal body movementsThe most important indication of placental function is the well being of the fetusThe oldest and simplest method of evaluation of the fetal well being is kick countMother is asked to note how frequently the fetus moves in a gives period of time, perhaps in 30 minutesAlternatively, she can be asked to note how long it takes for the fetus to move 10 times

Fetal growthDating a pregnancySerial measurements obtained with ultrasoundBPD, AC, HC/AC, FL, EFWCenters of ossification in long bones to confirm fetal maturityDetecting congenital abnormality

Fetal activityContinuous record of FHR over a period of 30 minutes or more so called NST (non stress test). It includes recording of changes in FHR variability (from beat to beat) in association with fetal movements and uterine contractions cardiotocography (CTG)Biophysical profile a score based on real time ultrasound observation of fetal breathing, gross body movements, tone and amniotic fluid volume

Stress testIn a case of doubtful or suspicious results of non stress testContraction stress test CSTOxitocin challenge test OCTFetal acoustic stimulation test FAST

Color Doppler examinationReflection of ultrasound waves from the wave produced by the pulse of blood moving along a blood vessel is detected and compared with the energy output of the sourceThis provides a measure of the speed of passage of the pulse wave and appears as a typical shape of blood waveformSeems to be the most useful tool in prediction of chronic fetal hypoxia

Biochemical markers of placental functionEvaluation of functional activity of the placenta by measuring one or more of its hormone or enzymes products in maternal blood or urineExcretion of estriol in the maternal urine during 24 hour period gives an indication of placental function, isolated observations are of little value, but related observations may show an obvious trendOther tests: serum levels of placental lactogen and of heat stable alkaline phosphatase