SGA Flashcards
Define SGA?
Small for Gestation Age
Defined as… EFW <10%ile for given
gestational age
2/3 will be normal small and 1/3 will have FGR = fetal growth restriction = a fetus that has failed to achieve its growth potential. AKA IUGR.
- IUGR: <5%ile
Low Birth Weight < 2500g or very low birth weight < 1500g
What are the underlying causes of SGA?
Physiological Growth:
- Constitutional
- Missdating
- small parental size
- past hx of SGA
Pathological growth:
1. Maternal
Infections (CMV, rubella), smoking, drug abuse, hypertension, chronic illness
- Fetal
MG, chr abnormality,
fetal malformation - Placental
placental insufficiency
What are the risks of SGA?
- Intrauterine: Fetal hypoxia
Intrauterine fetal demise - Neonatal:
Hyperbilirubinaemia
Hypoglycaemia
Meconium aspiration
Polycythaemia
Temperature dysregulation
6-Fold increased perinatal mortality - Infant
Physically small
Delayed neurological development - Adult
Increased risk of cardiovascular disease and diabetes later in adulthood
What might you find on abdo exam in SGA?
Symphyseal pubic height >2cm too
small
What might you find in TAUS in SGA?
- Fetal biometry (HC, AC, BPD, FL)
- Serial measurements for growth
trajectory - 20w anomaly scan for congenital
abnormalities assoc. with
chromosomal disorders - Uterine Artery doppler
o A/REDF: severe hypox
Other testing for SGA?
NIFT/amniocentesis – Karyotype for chr
abnormalities
What findings might suggest the SGA is abnormally so?
- Asymmetric: large head compared
to the body (associated with
hypoxia) - Symmetric: proportionally small
head and body measurement
(associated with infection or chr
abnormalities)
What to do if SGA noted on US?
- May monitor as an outpatient with US
scans every 2weeks - In the case of deterioration of the fetus
o CTG
o Umbilical artery doppler
If anomaly scan and UAD or normal likely
constitutionally small and aim to deliver at 37w
If abnormal doppler
→ admit for daily CTG and biophysical profile
→ any deterioration of CTG or BPP: admin
steroids and delivery
How do you diagnose SGA?
Abdominal palpation and symphyseal-fundal height measurement has a limited accuracy in predicting SGA, detects only 30% SGA fetuses
Ultrasound measurement of:
Abdominal circumference(AC),
Head circumference(HC)
Femur length (FL)
Biparietal diameter (BPD), then use these 4 to calculate:
Estimated fetal weight (EFW)
Serial ultrasound measurements 2 weeks apart of AC, HC,BPD and FL allow EFW calculation and give an indication of fetal growth
What are the types of fetal growth restriction
asymmetric
-utero placental insufficiency = ratio of head to abdo circumference is high because abdo growth is restricted to preserve growth of the head = Brain sparing effect. fetal CO is redistributed towards the brain. AF is often reduced towards the end.
symmetric
- both the head and abdo circumference are less than the 10th %
- amniotic fluid volume is normal
- often have chromosomal abnormalities or are infected with virus in utero
- often pathologic insult occurring early in pregnancy
What is the management of FGR?
- Assess for chromosomal defects (amniocentesis to determine fetal karyotype if indicated)
- surveillance/ fetal wellbeing
Monitor as an outpatient with ultrasound for growth every 2 weeks
CTG helps identify deterioration in FGR immediately (hours/days)
Umbilical artery Doppler (UAD) helps identify deterioration in FGR over longer time (weeks)
If anomaly scan and umbilical artery Doppler are normal, it is likely that the fetus is a “normal” small
Aim to deliver at 37 weeks or if fetal testing deteriorates
If AEDF or REDF admit with close monitoring, daily CTG and biophysical profile, dopple twice weekly, steroids if under 37, if abnormal CTG or biophysical profile delivery is indicated usually by CS
- Delivery in a unit with optimal neonatal facilities
When are antenatal corticosteroids indicated?
Indicated between 24 0/7 – 36 6/7 weeks’ gestation, if delivery about to occur
(either spontaneous or indicated preterm birth)
Indications - Antepartum haemorrhage (APH)
- PPROM
- Threatened preterm labour (PTL)
- FGR with abnormal Doppler
- Other conditions where preterm delivery likely (e.g. preeclampsia)
What are the neonatal benefits of antenatal corticosteroids?
- Increased production of surfactant from type 2 pneumocytes, thereby reducing respiratory distress syndrome and, ultimately, chronic lung disease
- Reduced incidence of necrotising enterocolitis
- Reduced incidence of intraventricular haemorrhage
What are the maternal risks of antenatal corticosteroids?
Poor sleep
Elevated blood sugars requiring admission in diabetic mothers (for 48 hours following 2nd dose)
Points to note in IUGR Hx?
smoking/drinking
previous sga
gestation at booking and dating scan
accuracy of dates
first trimester screening/ NIPT
gestation at anatomy scan, presence of abnormalities?
gestation when IUGR diagnosed?
TORCH screen?
amniocentesis?
most recent scan findings?
antenatal corticosteroids?
fetal movements?
CTG?
management plan?
patients are usually in hospital for daily CTGs because of abnormal umbilical artery dopplers or for planned delivery
