Small for Dates Flashcards
What are the two main reasons for small for dates?
Pre term delivery
Small for gestational age
Define preterm delivery and the three subtypes
Delivery before 37 weeks gestation
- extreme (24-27+6weeks)
- very (28-31+6weeks)
- moderate (32-36+6 weeks)
What is the survival rate of preterm babies?
23 weeks 19%
26 weeks 77%
>32 weeks >95%
State the causes of preterm delivery
Infection Over distension Vascular Intercurrent illness Cervical incompetence Idiopathic
What are the risk factors for preterm delivery?
Previous PTL, multiple, uterine anomalies, teenagers, parity =0 or >5, ethnicity, low SE status, smoking, drugs, low BMI
What is meant by small for gestational age?
Estimated fetal weight or abdominal circumference below 10th centile
Describe the difference between fetal growth restriction and low birth weight
FGR - failure to achieve growth potential
LBW - birth weight <2.5kg regardless of gestation
Name the two types of IUGR
Symmetrical - small head and body
Asymmetrical - normal head and small body
What are the reasons for each of the types of IUGR?
Symmetrical - chromosomal abnormality, infection, congenital, environment
Asymmetrical - placental reasons, smoking, PET
State the major risk factors for small for gestational age
Mum >40 Smoker >11/day Paternal/maternal SGA Cocaine Vigorous exercise Previous stillbirth/SGA Hypertension Diabetes APLS Renal diseases Low PAPP-A BMI >35 Large fibroids Echogenic bowel
State the minor risk factors for small for gestational age
IVF Mum>35 Nullparity BMI<20 or 25-34.9 smoker previous PET low fruit intake pre-pregnancy Pregnancy interval <6months or >60 months
When are serial growth scans carried out?
26-28weeks, 28,32,36 weeks
How many minor factors equate to a major?
3 + abnormal doppler at 20 weeks
How is small for gestational age screened?
Symphysial fundal height from 24 weeks
Growth scan if <10th centile or slow/static growth
How is small for gestational age diagnosed?
Fetal abdominal circumference and head circumference and femur length - estimated fetal weight
Additional AFI, doppler, liquor volume
What can cause small babies?
Maternal - lifestyle, height/weight, age, diseases
Placental - infarcts, abruption, hypertension
Fetal - infection, congenital anomalies, chromosomal anomalies
Describe an umbilical artery doppler
20 weeks, umbilical arteries should be low resistance in second trimester. Resistance indicates risk of SGA and hypertension usually due to placental abnormality or failure or spiral artery invasion
State the consequences of SGA
Antenatal/labour - hypoxia/death
Post-natal - hypoglycaemia, hypothermia, polycythaemia, abnormal neurodevelopment, hyperbilirubinaemia, effects of asphyxia
How will women with SGA present?
Predisposing factor, reduced fundal height, reduced liquor, reduced fetal movement
How is SGA managed?
- Assess foetus
- Umbilical artery doppler
- MCA/ductus venous doppler
- Plan delivery
How is a foetus with SGA assessed?
Growth scans, doppler, CTG
Biophysical profile - USS and CTG to calculate movement, tone, fetal breathing, liquor volume (score out of 10
Describe the scoring of biophysical profile
Out of 10
8+ satisfactory
4-6 repeat
0-2 deliver
What is used to determine delivery instead of biophysical profile?
Umbilical arterial doppler
What may be seen on umbilical arterial doppler?
Reduced
Absent
Reversed end diastolic flow
At what age should SGA babies be delivered
37 weeks
What are the indications for early delivery by c-section
Static growth
Abnormal umbilical artery doppler
Abnormal MCA 32-37 weeks
Abnormal ductus venous 24-32 weeks
