obs - fetal growth Flashcards
define small for getational age (sga) aka small for dates (sfd)
the weight of the fetus is less than the tenth centile for its gestation (so compared to sll other fetes of that gestation)
Other cut-off points (e.g. third centile) can also be used.
define growth restriiction
fetuses that have failed to reach their own
‘growth potential’
they can either be normal weight or small for dates
what is the difference between fetal distress and compromise?
distress :
an acute situation, such as hypoxia, that
may result in fetal damage or death if it is not reversed
compromise:
chronic situation - when conditions for the normal growth and development are not optimal - placental dysfunction
what are the negatives of fetal surveillance?
False positives - things over interpreted
Can identify but dont solve problems
Expensive
Can medicalise a normal pregnancy
list some pre-pregnancy factors associated with a high risk pregnancy?
(and thus those who may likely need fetal surveillance)
o Poor PObsHx or very small baby
o Maternal disease
o Assisted conception
o Extremes of reproductive age
o Heavy smoking and/or drug abuse
list some intra-pregnancy factors associated with a high risk pregnancy?
(and thus those who may likely need fetal surveillance)
o HTN / Proteinuria
o Vaginal bleeding
o SFD - small for dates
o Prolonged pregnancy
o Multiple pregnancy
what is classifiied as an abnormal Uterine artery Doppler result? what does this mean?
Abnormal result; if resistance is NOT low
this means there is INCREASED resistance (in the circulation) =>
It identifies pregnancy at risk of adverse neonatal outcomes in the early third trimester:
Increased RISK of IUGR, Pre-eclampsia, Abruption
when would a Uterine artery Doppler usually be done?
23 weeks
which hormone is used to help determine IUGR risk? what do the results mean?
PAPP-A
Low level = high risk IUGR, placental abruption and still birth
also - Down syndrome (1st trimester test)
list some methods of fetal surveillance?
- Routine pregnancy care - more important in low risk pregnancies as the wont access the below:
- US assessment of fetal growth
- Doppler umbilical artery waveform
- Fetal circualtion dopplers;
- MCA, Ductus venosus - US assessment of amniotic fluid volume and
movements - - CTG, non stress test: low risk too
- Kick chart: no. of kicks felt. low risk
in low risks pregnancies (they dont get access to more specialist fetal surveillance), what is the cornerstone of the identification of the small or compromised fetus ?
serial measurement of the
symphysis fundal height
and other aspects of antenatal visits.
what does US assessment of fetal growth measure?
head, abdominal circumference
femur length
how does one tell the difference between small and growth restricted babies on US?
- Rate of growth:
consistent (small), slowing (iugr) - Pattern of smallness:
thin/asymmetrical (iugr - blood diverted to brain)
list the maternal and fetal arteries in which dopplers could be done?
Uterine artery - maternal
Umbilical artery - fetal
MCA - fetal
Ductus venosus* - fetal
*shunt for oxygenated blood
say, you cant tell the difference bewteen small a nd growth restricted fetus on US. what next?
Umbilical doppler - can actually tell the difference
Reduced flow in fetal diastole compared to systole shows high resistance circulation and placental dysfunction
in dopplers of fetal circulation, what changes are usaully seen with fetal compromise ?
With fetal compromise, the MCA often develops a low resistance pattern in comparison to the
thoracic aorta or renal vessels
increased EDV end diastolic volume
anaemia - increased FV flow velocity seen
what are indications of dopplers of fetal venous circulation?
ductus venosus waveform is a measure
of a cardiac function,
is used to assess extremely
preterm fetuses (<28 weeks) as an alternative to CTG
monitoring, and is better <26 weeks.
list some causes of IUGR (sfd and growth restricted fetuses) ?
Maternal factors;
o Drug use- cocaine
o Some medications
o extremes of age: <16, 35>
o Extreme malnutrition o Maternal obesity o Smoking o Pre-existing maternal disease; Renal, Autoimmune o Maternal pregnancy complications - Pre eclampsia
Placental factors:
Abnromal size, Abruption,
Placental infarction
Chorioangioma, Umbiilical cord abnormality
Fetal factors:
o Congenital abnormalities - hence amniocentesis done to ivx
o Infection - CMV
o Multiple pregnancy
complications of IUGR?
Mother:
Preterm delivery
Maternal risks increase
Increased Caesarean section
Fetal preiod:
Stillbirth
Acidaemia
Neonatal period: Cerebral palsy Polycythaemia Hypoglycaemia Apneoa
Adult life:
Diabetes, cardiovascular disease
how is would you SCREEN for possible iugr/sfd baby ?
Examination
o Serial measurement of SFH
o Reduced or slowing
o BP and urine checked -> PET associated with IUGR
Investigations:
1. 3+ Minor risk factors (identified at booking)
- reassess at 20 weeks
- UTERINE artery doppler at 20-24 weeks
- 3rd trimester: normal -> assess fetal size and umbilical
doppler
- 1+ Major SGA risk factor
- reassess at 20 weeks
- assess fetal size and UMBILICAL doppler at 26-28 wks - Unsuitable for monitoring via SFH (large fibroids, BMI>35)
- assess fetal size and umbilical doppler at 26-28 wks
briefly how would one manage sfd ?
SFDates only
o Growth rechecked with US at 2 week intervals
o No need for intervention is consistently growing with normal UA Doppler
what are the risks of a prolonged pregnancy?
Still birth
Meconium passage into amniotic fluid -> meconium aspiration syndrome
Fetal distress
Neonatal illness and encephalopathy
how is a prolonged pregnancy managed?
Induction before 41 weeks is inappropriate
unless complications are present
From 41 weeks :
Examine the patient vaginally and
OFFER induction
- failed induction -> C-Section
If doesnt want induction:
Sweep cervix and arrange daily (CTG)
If CTG abnormal Deliver whatever the condition of
the cervix, by caesarean
if a woman develops sever gestational or other hypertension, pre-eclampsia, Antepartum haemorrhage (praaevia, abruption etc), in the 3rd trimester how should they be monitored?
serial assessments of:
- fetal size - US
- umbilical artery doppler
list some factors identified that would make a woman unsuitable for monitoring by SFH?
large fibroids
BMI > 35
how would you manage SFD/IUGR?
if conditions are found, move on to next investigation
- SFH < 10th centile or showing iugr
or hx + biochemistry or Uterine artery doppler:
-Identify high risk - US Fetal biometry/Growth scan:
abdominal circumference! head circum (biparietal),
femur length
or EFWeight < 10th - Uterine artery doppler
- management and delivery date depends on findings especially the end diastolic volume.
with SFD/IUGR, what are the options following umbilical artery doppler results?
Normal UA doppler:
- delivery by 37 weeks WITH senior clinician input
- steoroids if c-section
- can do by 34 wks, if static growth
UA doppler - Increased Resistance, PI, RI >2 but end-daiastolic volume normal:
- deliver by 37 weeks (give steroids if by section)
- can do by 34 wks, if static growth
o Absent OR Reversed end-diastolic flow -> admit, and daily CTG and UA and D Venosus dopplers!
- give steroids & deliver befrore 32 weeks
o Severe IUGR -> ELCS
list some causes of small for dates pregnancy
Slow fetal growth (intrauterine growth restriction)
Too little amniotic fluid (oligohydramnios)
list some causes of large for dates pregnancy
A multiple pregnancy
A significantly larger than average baby (fetal macrosomia)
Too much amniotic fluid (polyhydramnios)
what are some causes of oligohydramnios?
Spontaneous rupture of membranes SROM
Renal agenesis
Placental insufficiency - pre-eclampsia
what are some causes of polyhydramnios?
Diabetes
Oesophogeal atresia
list some indications for US use on the labour ward?
- Most common: unable to hear fetal HR (with doppler sonicaid)
- Before instrumental birth
- Placenta praevia: determine location before c-section (especially in anterior previa)
- Determine fetal lie and presentation
- To help site an epidural
what are the 2 types of IUGR and epidemiology?
- Symmetric 20%
- can be small for dates - Assymetric: 80%
- head bigger than abdomen ‘head sparing’
- restricted
define large for dates?
baby with weight above the 90th percentile
4.5kg
classify the following weights;
Low birth weight,
Very low birht weight,
Extremely low birthweight
Low birth weight: 2500g
Very low birht weight: 1500g
Extremely low birth weight: 1000g
the term IUGR covers which terms?
Fetal growth restriction
Small for GA
define constitutional smallness.
causes?
baby is small because paretns are small
o Low maternal height and weight
o Asian ethnic group
o Female fetal gender
maternal, fetal and placental factors cause which types of growth restriction?
Maternal, placental - Assymetric
fetal - symmetric
List 3 tests that can be doneto confirm IUGR - though not the preferred initial tests?
Amniocentesis
CVS
Percutaneous umbilical blood sampling
what is the role of the ductus venosus?
carries OXYGENATED blood from placenta to heart
Poor flow in the ductus venosus doppler indcates?
poor prognosis
deliver by 32 weeks + steroids.
what finding on the pulsatility index is associated with the ‘head sparing’ effect?
increased diastoloic flow on pulsatility index (PI)
What is the end diastolic flow supposed to be in the different trimesters?
what is the meaning of a reversed EDF?
Doppler flow velocity waveforms of the umbilical artery in uncomplicated early pregnancies show ABSENT end-diastolic flow (AEDF) up to the 11th week of gestation.
Between the 11th and 14th weeks, positive diastolic flow emerges and remains detectable from then onwards.
So a reversed EDF is abnormal
In babies with potential heart failure and twin–twin transfusion syndrome, which doppler might be most useful to do?
Ductus venosus - doppler of venous circulation.
