Large for Gestational Age Flashcards
What is characterised by ‘LGA’?
fundal height greater than 2cm of the normal for that gestation
How does fundal height tend to relate to gestational age?
match it e.g. 24 weeks gestation should have a fundal height of 24cm
What is foetal macrosomnia?
This is basically a ‘big baby’ and can be caused by many things.
Defined as an USS estimated foetal weight (EFW) as > 90th centile on population and personalised growth charts
What is a customised growth chart?
this take into account the mothers ethnicity, BMI and parity to allow for adjustment
What are the risks of delivering a macrosomic baby?
labour or shoulder dystocia (obstruted labour)
PPH
What should be excluded if a baby is macrosomic?
Diabetes
What is the management of a macrosomic baby?
Reassurance and think about induction of labour (early) or C-section
What is polyhydramnios?
Excess of amniotic fluid
How is amniotic fluid measured and what boundaries are considered polyhydramnios?
Amniotic fluid index (AFI) >25
Deepest pool >8cm
(along with a sujective impression)
What causes polyhydramnios?
Maternal - diabetes
Foetal - anomaly (GI atresia, cardiac etc), foetalis hydrops, monochorionic twin pregnancy, viral infection (erythrovirus B19, CMV and toxoplasmosis)
What is foetalis hydrops?
This is the abnormal collection of fluid in at least 2 places e.g. under skin, abdominal cavity, pleural effusion, pericardial effusion
What is monochorionic twin pregnancy?
monozygotic twins that share the same placenta
What can cause hydrops foetalis?
This can be caused by immune process (anti-RhD attacking RBC causing haemolysis in the foetal spleen and collection of excess fluid) or non-immune process (relating to failure of interstitial fluid to enter the venous system)
What are the symptoms of polyhydramnios?
Abdominal discomfort
premature rupture of membranes
cord prolapse
pre-term labour
What are the signs of polyhydramnios?
large for dates
tense shiny abdomen
inability to feel foetal parts
malpresentation
What investigations should be carried out for polyhyrdramnios causes?
OGTT - maternal diabetes
Serology - CMV, toxoplasmosis, erythrovirus B19
Antibody screen
USS - for foetal survey
What can increase risk of multiple pregnancy?
Age (older) Parity (more) Height (taller) Ethnicity (african) Assisted conception Family history
What are monozygotic twins?
When 2 foetuses are derived from the same egg (e.g. egg splits) - 30%
What are dizygotic twins?
When there are 2 eggs fertilised
What is chorionicity?
This is the number of placentas:
mono - one
di - 2 (always di-amniotic)
If there is splitting of the morula (days 1-3) into monozygotic twins what will the amniotic sac and placenta be?
Diamniotic dichorionic
If there is splitting on the blastocyst (days 4-7) into monozygotic twins what will the amniotic sac and placenta be?
Diamniotic monochorionic
If there is splitting of the implanted blastocyst (days 8-14) into monozygotic twins what will the amniotic sac and placenta be?
Monoamniotic monochorionic
If there is splitting of the blastocyst once the embryonic disc has formed (after day 15) what will happen?
Conjoined twins
What will lambda sign on USS show?
Dichorionicity in a twin pregnancy - although absence cannot exclude two placentas present
Seen at around 11-14 week scan
(and diamniocity)
What will a T sign show on USS?
Monochorionicity in a twin pregnancy (with diamniocity)
Is monochorionic twin pregnancy worse or better?
at risk of more complications during pregnancy
What are the symptoms of multiple pregnancy?
exagerrated symptoms of pregnancy e.g. hyperemesis gravidarum
What are the signs of multiple pregnancy?
High AFP
Large for dates
Multiple foetal poles (thickened margin of the yolk sac that is the first sign of an embryo - seen on scan around 6-9weeks)
What is the length of foetal pole when a heartbeat should be detected?
> 7mm
What complications can affect a multiple pregnancy?
They are at a 6x higher risk of perinatal death:
- congenital anomalies
- growth restriction
- IUD
- preterm
- cerebral palsy
- twin to twin transfusion
What can occur in the mother in terms of complications in multiple pregnancy?
- anaemia
- hyperemesis gravidarum
- pre-eclampsia
- antepartum haemorrhage (placental abruption/praevia)
- pre-term labour/c-section
Describe the antenatal management of a multiple pregnancy
Consultant led
If monochorionic then clinic appointments every 2 weeks (and USS every 2 weeks from 16 weeks onwards)
if dichorionic then clinic appointments every 4 weeks (with USS)
Anomaly scan at 18 weeks
What medications can be given to support a multiple pregnancy?
Iron supplements
low dose aspirin
folate supplements
What are monochorionic twins at risk of?
single foetal death - with a 15% risk of survivor passing too. need to mri survivor brain 4 weeks after IUD.
Selective growth restriction - disproportionate nutrition resulting in growth restriction of one
Twin anaemia-polycythaemis sequence
Twin-twin transfusion
absent/reversed EDV
What is twin anaemia-polycythaemia sequence (TAPS)
There is unequal sharing of blood between the twins resulting in one having anaemia and the other having polycythaemia (type of twin-twin transfusion)
What is twin-twin transfusion syndrome (TTTS)?
this is where there are normal blood vessel connections between the foetuses resulting in one becoming a ‘donor’ and the other becoming the ‘recipient’ - R has high BP and produces a lot of urine resulting in overfilling of the amniotic sac.
How are monochorionic monoamniotic twins delivered and why?
C-section between 32-34 weeks due to the high risk of cord enlangement and foetal death
What is gestational diabetes?
carbohydrate intolerance resulting in hyperglycaemia that starts with pregnancy
What can uncontrolled pre-existing diabetes cause in pregnancy?
Intra-uterine death
anomalies (if HbA1C is high at first booking)
Miscarriage
What are complications shared by pre-existing and gestational diabetes?
Pre-clampsia polyhydramnios macrosomnia shoulder dystocia neonatal hypoglycaemia
What is the guidelines for pre-pregnancy counselling in patients with pre-existing diabetes?
avoid pregnancy is >86mmol/mol (10%) - aim for 48mmol/mol
Stop ACEi and statins
calculate macro and microvascular risks
High dose folate 3 months prior to conception
Why does gestational diabetes occur?
pregnancy hormones are diabetogenic and placental hormones cause relative insulin deficiency - this all results in overgrowth of insulin sensitive tissue and a hypoxaemic state in utero
What are the risks to the child if gestational diabetes?
Obesity, diabetes (due to foetal metabolic reprogramming in utero)
How do you screen for gestational diabetes?
Identify risk factors at booking (previous hx, FHx, BMI>30, ethnicity, previous large baby etc)
If previous then OGTT in 1st trimester and repeat in 24-28 weeks
What are the diagnostic values for gestational diabetes?
fasting >5.1mmol/mol
2hr OGTT > 8.5mmol/mol
What are the glycaemic targets for gestational diabetes?
fasting = 3.5-5.5
1 hr post meal = <7.8
What medications can be given in gestational diabetes?
Insulin (doesn't cross the placenta but risk of hypo) Oral tablet (no risk of hypo or weight gain)
Why do you check bloods after birth in gestational diabetes?
check 6 weeks post-natal to determine if long term T2DM will be present
