Prenatal diagnosis and assessment of fetal state in pregnancy Flashcards
Methods used in screening tests
maternal history
maternal biochemistry
maternal virology
ultrasound
Triple test(biochemistry)
B-hcg
alpha - FP
estriol
Which two conditions are hcg elevated in
Down’s syndrome
Trophoblastic diseases
which two conditions are alpha - fp elevated
Neural tube defects
Omphalocele and gastrochisis
which condition is alpha - fp low in
Down’s syndrome
other trisomies
Time to do fetal anomaly scan
18-20 weeks
when are they done
- Amniocentesis
- Chorionic villus sampling
- Cordocentesis
- Amniocentesis 15 weeks or before
- Chorionic villus sampling 10 weeks or after
- Cordocentesis 20 weeks or after
Which invasive test is associated with higher rate of miscarriage, neonatal talipes and respiratory difficulties
Amnioncentesis
Which invasive test is associated with cleft lip, palate and digital amputation
CVS
sfh state the correspondences in gestational age Symphysis pubis Umbilicus Below xiphisternum
12 weeks
22 weeks
36 weeks
Differentials for SFH higher than gestational age
Wrong dates Polyhydramnios Multiple gestations Intrauterine mass Bibe baby due to maternal diabetes or constitutionally big baby Wrong technique
Differentials for SFH lower than gestational age
Wrong dates Oligohydramnios INtrauterine growth restriction IUD Constitutionally small baby Abnormal lie Wrong technique
Which fetal biometry is a better measurement of gestational age before 12 weeks
CRL
Which fetal biometry is a better measurement of gestational age from 12 - 20 weeks
BPD
HC
FL
For maximum vertical pool, which suggests oligohydramnios and polyhydramnios
Oligo - <2cm
Poly - >7cm
For AFI
oligo
poly
oligo - <5cm
poly - >25cm
Define baseline fetal heart rate and normal value
This is the average fetal heart rate in between accelerations and decelerations; it is best
determined over 5-10mins.
normal value - 110 - 160 bpm
Define baseline variability
This is the variation in the baseline rate over one minute excluding accelerations and decelerations.
Normal value is 10-25bpm
What is baseline variability is a reflection of
Normal baseline variability reflects a normal autonomic nervous system and cardiac conducting system
Define fetal heart rate accelerations
What defines a reactive trace
These are increases in the baseline fetal heart rate of at least 15bpm, lasting for at least 15secs.
The presence of 2 or more accelerations in 20-30-min CTG defines a reactive trace.
Define a normal antepartum fetal CTG
is defined as a baseline of 120-150bpm, with
baseline variability exceeding 10bpm, and with 2 or more accelerations seen in a 20- 30-min tracing, with no decelerations.
What is a reactive non-stress test
It is one with fetal heart rate acceleration of at least 2 in 20-30 minutes associated with fetal movement
What is a positive stress test
Dilute oxytocin infusion or repetitive nipple stimulation is done to induce uterine contractions
A positive test is fetal cardiac decelerations in response to uterine contractions, and
this is interpreted as abnormal
It has the highest specificity for detecting the compromised
fetus
5 components of BPP
amniotic fluid index
fetal tone
fetal activity (gross body movement)
fetal breathing movements
normal BPP results
8-10
Modified BPP
NST
AFI
Normal fetal kick count
A healthy fetus usually moves or kicks about 10 times within 2
hours
