Abnormalities of Fetal Growth Flashcards
Assessment of Gestational Age
Clinical assessment:
- Embryonic age (embryologists)
*gestation lasts 38wks (266 days) from conception
- Menstrual age (obstetricians)
*gestation lasts 40wks (280 days) from the first day of the last menstrual cycle (FDLMP) [assumes idealized 28 day menstrual cycle, and conception occurs on cycle day #14]
Naegle’s rule
- The EDC is calculated by subtracting 3 months from the FDLMP, and adding 7 days
Techniques for assessing baby’s size
- Fundal height
- Leopold’s maneuvers
- Ultrasound
Fundal height measurement
- Measure the internal abdomen w/ a tape measure from tip of the pubic bone to the top of the fundus of the uterus in centimeters
- B/w 20-35wks the number of centimeters correlates w/ the # of wks pregnant
Leopold’s Maneuvers
- Placing hands on mother abdomen to determine orientation of baby in utero as well as size
Most accurate US parameter to establish gestational age?
- Crown Rump Length
Most predictive US parameter of gestational age b/w 14-22 weeks?
- Head circumference
Best single measurement of gestational age based upon fetal biometry in the 3rd trimester?
- Femur length
Fetal Macrosomia Diagnosis
Large Fetus
- 4000 grams (ACOG-morbidity sharply increases >4500 grams
- Estimated fetal weight (EFW) >90th percentile for gestational age
- Prevalence of birth weights >4000 gms is 9%
- Prevalence of birth weights >5000 gms is 0.1%
Fetal Macrosomia Risk Factors
Large Fetus
- Diabetes
*excess sugar can cross the placenta and the babys body will secrete insulin which can act as a growth hormone
- Prior history of fetal macrosomia
- Maternal pre-pregnancy weight
- Weight gain during pregnancy
- Multiparity
- Male fetus
Fetal Macrosomia Maternal Risk Factors
- Protracted/arrested labor
- Operative vaginal delivery
- Cesarean delivery
- Genital tract lacerations
- Postpartum hemorrhage
- Uterine rupture
Fetal Macrosomia Fetal Risks
- Neonatal hypoglycemia
- Development of impaired glucose tolerance and obesity
- Development of metabolic syndrome
Perinatal mortality vs. birth weight trend
- Mortality for neonate increases as birth weight decreases
*10th percentile is usually used as a marker, but the rate of problems only significantly increase at the 5th percentile point
*80% of the time <10th percentil for weight is normal (genetics) 20% then is pathologic (75% of which is placental problems and 25% is chromosomal, infections, or anomalies)
Middle cerebral artery fetal ultrasound imaging
- Blood flow through fetuses middle cerebral artery is used to asses for anemia (faster the blood flow the more likely of anemia being present); anemia is likely at >1.5 MoMs which reflects risk for moderate to severe fetal anemia (meaning 1.5 MCA velocity; upper limit of normal)
First appearance of Gestational Sac on TVUS
- 4.5-5wks
