Size and Date Discrepancies Flashcards
Define small for gestational age (SGA)
≤10th percentile
Define very small for gestational age (VSGA)
<3rd percentile
- associated w/ increased risk of poor outcome
- often associated w/ IUGR
IUGR vs SGA
IUGR = growth restriction
VS
SGA = constitutionally small
- if otherwise normal, no intervention required
- no antenatal surveillance required
What is the best method to identify SGA vs IUGR?
customized growth potential: assesses individual growth potential for each baby in each pregnancy based on:
- fetal sex
- maternal height
- weight
- parity
- ethnic origin
Define IUGR/FGR
fetus that fails to reach potential growth
OR
failure of fetus to achieve genetic growth potential in utero
What are the 4 underlying etiologies of IUGR?
1) aneuploidy
2) viral infection
3) nonaneuploid syndromes
4) placental insufficiency
What are maternal prepregnancy conditions that are associated w/ IUGR?
- HTN
- pre-GDM
- renal disease
- autoimmune disease
- thrombophilias
- severe anemia, malabsorptive disease, malnutrition
- 20>BMI>/=30
- high altitutude
- tobacco/substance abuse
What are pregnancy conditions that are associated w/ IUGR?
- multiple gestation
- inadequate weight gain (esp low protein intake)
- placental abnormalities (e.g. previa, abruption, mosaicism)
- relative hypoglycemia (i.e. “flat response” on 3h GTT)
How does symmetric IUGR occur?
early alteration in process of cell division –> smaller number and size of cells
- occurs during hyperplasia
- fetal cell number decreased
When/How can symmetric IUGR be seen?
at early 2nd tri U/S
- uniform diminishment of fetal organs, length, body weight
- body and head growth usually similarly affected
What causes symmetric IUGR?
genetic, infectious, or teratogenic insults
1) chromosomal or congenital anomalies
2) infections (e.g. CMV, rubella)
3) teratogens (e.g. smoking, alcohol, cocaine, narcotics, valproate)
What are antenatal interventions for symmetric IUGR?
there aren’t any!
not usually improved w/ antenatal interventions
How does asymmetric IUGR occur?
- occurs during hypertrophy
- fetal cell number normal
- cell size is small
What does asymmetric IUGR look like?
- abdomen and lower body experience delay
- head growth spared
What maternal conditions are risk factors to assymetric IUGR?
- uteroplacental insufficiency
- maternal HTN (preeclampsia)
- malnutrition (esp protein/glucose restriction)
- diabetes
- renal disease
- placental abnormalities
- multiple gestation
- autoimmune disorders
- hemoglobinopathies
What are antenatal interventions for asymmetric IUGR?
- nutrition
- hydration
- improvement of uteroplacental blood flow
- optimize timing of delivery
What are fetal risk factors for IUGR?
1) chromosomal or congenital anomalies
2) teratogen exposure
3) fetal infection
4) genetic disorders
5) structural abnormalities
What are neonatal risks associated w/ IUGR?
1) increased risk respiratory distress, NEC, intraventricular hemorrhage, clotting disorders, multiorgan failure
2) increased mortality
3) meconium aspiration
4) hypoglycemia
5) electrolyte abnormalities
6) hypocalcemia
7) impaired renal function
8) polycythemia, anemia, thrombocytopenia, hyperbili
9) hypothermia
What is prognosis of IUGR?
- expected to have normal growth curves and height as adults, esp if IUGR only close to delivery
- earlier onset/prolonged IUGR may be related to growth lag
- head circumference <10th percentile –> 2-3x more serious neuro sequelae
Define oligohydramnios
AFI≤5cm or DVP≤2cm
What are possible causes of early onset oligo?
1) renal agenesis
2) renal dysplasia
3) renal obstructive disorders
–> lack of urine production OR inability to pass urine produced
4) HTN
5) IUGR
What are possible causes of 3rd tri oligo?
1) uteroplacental insufficiency
2) prolonged pregnancy (>42wks –> fluid volume decrease)
3) idiopathic - resolves w/ time or w/ hydration
What are risks associated w/ oligo at 42wks?
1) meconium stained amniotic fluid
2) fetal intolerance of labor
3) NICU admission
4) increased perinatal morbidity and mortality
What is the clinical hallmark of IUGR?
fundal height < 3cm from sure dates
How should S
- evaluate for PPROM
- order U/S (anatomy, AFV)
How should IUGR be managed?
- serial Doppler blood flow studies
- serial growth scans q3-4wks (include BPD, HC/AC ratio, EFW, AFV)
- ongoing fetal surveillance (NST, mBPP)
Define large for gestational age (LGA)
> /= 90th percentile
Define macrosomia
nondiabetic gestational carrier: 4500g
diabetic gestational carrier: 4000g
Define polyhydramnios
AFV>2100ml or AFI >/= 25cm or DVP>8cm
What are risk factors for macrosomia?
1) DM
2) abnormal 1h GTT w/ normal 3h GTT
3) hx of infant>4000g
4) maternal prepregnant obesity
5) excessive prenatal weight gain
6) prolonged pregnancy
7) fetal male sex
8) high paternal birth weight
What are fetal causes of poly?
1) congenital anomalies
2) GI disorders
3) CNS disorders (e.g. anencephaly, NTDs)
4) cystic hygromas
5) nonimmune hydrops
6) genetic syndromes
7) congenital infections
8) placental abnormalities
9) twin gestation
10) twin-to-twin transfusion
What are maternal causes of poly?
1) idiopathic
2) poorly controlled DM
3) maternal-fetal hemorrhage
What are risks associated w/ poly?
1) macrosomia
2) cardiac anomalies
3) aneuploidy
4) PTB
5) fetal intolerance of labor
6) meconium stained amniotic fluid
7) emergency c/s
8) cord pH<7
9) low 5min APGAR
10) increased NICU admission
11) placental abruption
12) PP hemorrhage
What is management for macrosomia?
1) anatomy U/S to detect fetal anomalies as cause
2) serial growth q3-4wks (include BPD, HC/AC ratio, EFW, AFV) - AC>35cm identifies 90% macrosomia
Describe MOA of indomethacin
prostaglandin synthetase inhibitor
- decreases production of fetal urine
- increases fluid reabsorption by fetal lungs
- increases amt of intermembranous fluid movement from fetus to gestational carrier
What is the outcome of indomethacin?
reduces AFV w/in 24h
How can indomethacin be used safely?
- 72h = safe time course
- avoid after 31-32wks –> premature closure of ductus arteriosus and renal abnormalities
Describe amnioreduction
removal of 1-5L fluid
- usually only done in setting of maternal cardiopulmonary decompensation d/t poly
- repeated amnioreduction may prolong pregnancy
