Size/Dates Flashcards Preview

AP Exam 4 (UPenn) > Size/Dates > Flashcards

Flashcards in Size/Dates Deck (24):

"small for dates" uterine size

SGA: wt for gestational age below a given threshold; commonly defined <= 10th percentile.
Fundal height measurement of size less than dates >3cm in women with certain pregnancy dating

- 70% of SGA neonates are normally developed, constitutionally small

VSGA: < 3rd percentile ~ commonly assoc w/ IUGR


SGA etiologies

Consider fetal sex and maternal characteristics of height, weight, parity, and ethnic origin

- if true SGA by customized growth potential, then assoc w/: abnormal doppler studies, fetal intolerance in labor, need for c/s, NICU admission, stillbirth, neonatal death

other causes: aneuploidy, nonaneuploid syndromes, viral infection, placental disease


IUGR/FGR definition

IUGR/FGR: fetus that fails to reach potential growth. Growth less than or equal to 10th percentile.
- growth pattern slows


IUGR/FGR Multifactorial Causes

1. Maternal prepregnancy conditions
[vascular /heme/BMI issues]
-Hypertension, cyanotic cardiac disease
-Renal disease
-Collagen vascular disease
-Autoimmune disorders (lupus)
-Some hemoglobinopathies (sickle cell)
-Severe anemia
-Prepregnancy BMI <20 or >/= 30

2. Present pregnancy conditions
-Multiple gestation
-Inadequate weight gain
-Placental abnormalities (circumvallate placenta, placenta accreta, single umbilical artery, partial placental infarction, hemangioma, placental abruption, placenta previa)
-relative hypoglycemia on a 3hr OGTT
-Unexplained abnormal biochemical markers on genetic screening
-abnormal 2nd tri UA Doppler velocimetry

3. Prior maternity and family hx
-prior IUGR infant
-family or personal hx of infant w/ chromosomal abnormalities, congenital malformations, or genetic syndromes

4. Teratogens
-Substance use
-Environmental exposures

5. Maternal exposure to infection
-HErpes SV


Symmetric IUGR

-Appears as uniform diminishment of fetal organs, length and weight -- overall proportionally smaller newborn
-Associated w/ 25% of IUGR
-not usually improved w/ antenatal interventions

1. genetic-- chromosomal, congenital anomalies
2. infectious--CMV, rubella
3. teratogens--smoking, alcohol, cocaine, narcotics, drugs i.e. phenytoin, valproate

Management: weigh risk of prematurity vs risk of adverse in utero environment


Asymmetric IUGR

-Head sparing, abdomen and lower body experience delay in growth
-Associated w/ 75% of IUGR

-Uteroplacental insufficiency -- causes chronic fetal hypoxemia and malnutrition in utero
-Renal disease
-Abnormal placentation (circumvallate placenta, placenta previa)
-Multiple gestation
-Autoimmune disorders- lupus
-Hemoglobinopathies - sickle cell anemia

-Improvement of uteroplacental blood flow


Risks associated with LBW

-Increased perinatal and neonatal mortality
-Neonatal mortality
-Delayed effects of CP and adult onset of diseases



Less than normal amniotic fluid volume
AFI <=5
DVP <= 2
AFV <= 200-500


Oligo etiology

- renal agenesis
- urinary tract obstruction
- Abnormal placentation
- Elevation of maternal serum AFP
- Pregnancy at or past 42 weeks' gestation
- Severe FGR

- dehydration
- HTN disorders
- uteroplacental insufficiency
- antiphospholipid syndrome
- unknown etiology


Oligo risks

- Oligo in 2T considered early onset, has a high mortality rate d/t etiologies associated with it
- Oligo that develops in the 3T is more commonly associated with either uteroplacental insufficiency, prolonged pregnancy, or idiopathic
- Idiopathic resolves spontaneously in -4 days or in response to maternal hydration


Oligo Dx

-Accurate pregnancy dating and serial assessments of fundal height
-US if not previously performed for dating
-If EDD confirmed, targeted US to obtain anatomy scan and AFV
-If PPROM suspected -- sterile spec exam for pooling, nitrazine (pH) test, fern test


Oligo management

Fetal surveillance
-Serial doppler blood flow studies
-Fetal kick counts
-BPP/modified BPP

Induction of labor at or after 41 wks GA


"large for dates" uterine size

LGA: newborn weight greater than or equal to 90th percentile for GA


LGA associated etiologies

-Abnormal 1hr OGTT with normal 3hr
-Prev birth of infant >4000g
-Maternal prepregnant obesity
-Excessive prenatal weight gain
-Prolonged pregnancy
-Fetal male gender
-High paternal birth weight


Polyhydramnios defined

AFV >2100 mL
AFI >=25cm
LVP >8cm


Poly etiologies

-GI disorders
-CNS abnormalities
-Cystic hygromas
-Nonimmune hydrops
-Genetic syndromes--beckwith-wiedemann syndrome
-Congenital infections -- toxoplasmosis, rubella, CMV, HSV, parvovirus B19
-Placental abnormalities
-Twin gestation

-Poorly controlled DM
-Maternal-fetal hemorrhage


Macrosomia defined

>4000g (8lb 13oz) in a diabetic mother
>4500g in non-diabetic mother


Macrosomia etiologies

[Same as LGA]

-Abnormal 1hr OGTT with normal 3hr
-Prev birth of infant >4000g
-Maternal prepregnant obesity
-Excessive prenatal weight gain
-Prolonged pregnancy
-Fetal male gender
-High paternal birth weight


Poly diagnosis

-Serial fundal heights
-AFI >=25
-LVP >8
-Medical and family hx for presence of diabetes and results of GDM should be reviewed


Poly management

-Serial dopplers
-Fetal kick counts
-BPP/modified BPPs

-indomethacin: to dec production of fetal urine, inc fluid reabsorption by fetal lungs, and inc intermembranous fluid movement from fetus to mother *but contraindicated after 32 wks
-serial amniocentesis reduction (for severe poly). Must be repeated since amniotic fluid is regenerated every 48-72hrs. Risks include ROM, PTL, placental abruption if fluid decompressed too quickly.


Macrosomia dx

- >4,000g diabetic, >4,500 non-diabetic
- Confirm EDD
- Fundal height >3cm for GA, possible macrosomia
- EFW and anatomy scan to r/o anomalies
- Measurements of BPD, HC/AC ratio, fetal weight, and AFV
*Fetal AC of >35cm identifies more than 90% of macrosomic infants


Macrosomia management

- Serial growth US at 3-4 wk intervals to assess fetal growth curve
-Leopolds and fundal heights
-Include EFW, leopolds, sonographic findings, and woman's own perception of fetal size when discussing mode of delivery
-waiting to induce >41 weeks GA associated w/ lower c/s even in presence of macrosomia


IUGR: primary underlying etiologies

- aneuploidy
- viral infection
- nonaneuploid syndromes
- placental insufficiency
- US findings: small AC, normal anatomy, low or normal AFV, abnormal UA Doppler


Absolute contraindications to ECV

antepartum hemorrhage within last 7 days, abnormal cardiotocography (FHTs), major uterine anomalies, ROM, multiple pregnancy (except delivery of 2nd twin), severe fetal growth restriction, known fetal compromise