Fetal Growth and Abnormal Lie Flashcards
What are causes of perinatal mortality?
Preterm delivery IUGR Congenital abnormalities Intra-partum (hypoxia) Placental abruption
What is cerebral palsy associated with?
Prematurity IUGR Infection Pre-eclampsia Congenital abnormalities Intra-partum fetal distress
What is the definition of small for dates?
Weight of fetus is less than tenth centile
What is the definition of intrauterine growth restriction?
Failure to meet growth potential
What is the definition of fetal distress?
Acute situation which may result in fetal damage or death
Mainly used in labour
What is the definition of fetal compromise?
Chronic situation when conditions for normal growth and neurological development are not optimal
Poor nutrient transfer through placenta
IUGR
What are pre-pregnancy risk factors?
Mother’s age
Previous medical and obstetric history
Not a specific or sensitive screening test
What are the benefits and limitations of serial growth scans?
Safe and shows consistent growth in high-risk and multiple pregnancies
Inaccurate measurements common, misleading and potentially harmful
What are the benefits and limitations of Doppler umbilical artery waveforms
High resistance circulation (reduced flow in fetal diastole compared to systole) suggests placental dysfunction
Identifies which small fetuses are IUGR
Less effective identifying normal weight, compromised fetus
What are the benefits and limitations of Doppler waveforms of the fetal circulation?
Esp middle cerebral arteries (reduced resistance) and ductus venosus
Used in high risk pregnancy and with suspected anaemia
What are causes of IUGR?
Pre-existing maternal disease Maternal pregnancy complications Multiple pregnancy Smoking Drug usage Infection Extreme malnutrition
What is a prolonged pregnancy?
More than 42 weeks are completed
More common in nulliparous women
What are risks of a prolonged pregnancy?
Stillbirth
Encephalopathy
Meconium passage
How is prolonged pregnancy managed?
Induce labour between 41 to 42 weeks
Sweep cervix
What are causes of an abnormal lie?
Polyhydramnios
High parity
Fetal/uterine abnormalities
Twin pregnancies
What are complications of an unstable lie?
Umbilical cord may prolapse when membranes rupture
May cause uterine rupture
How are unstable or transverse lie managed?
After 37 weeks, admit to hospital in case membranes rupture
USS to exclude known causes - polyhydramnios, placenta praevia
ECV unjustified as it turns back
What are types of breech presentation?
Extended - 70% both legs extended at knee
Flexed breech - 15% both legs flexed at knee
Footling breech - 15% one or both feet are below the buttocks
What are complications of a breech presentation?
Cord prolapse
Head may get trapped
What is ECV?
Done from 37 weeks
Success rate of 50%
3% will turn back
Done without anaesthetic but tocolytic given to relax uterus
CTG done afterwards with anti-D if needed
What are contraindications to ECV?
Compromised fetus If vaginal delivery would be contraindicated Twins ROM Recent APH
How common are twins and triplets?
1 in 80 are twins
1 in 1000 are triplets
What are dizygotic twins?
Fertilisation of different ooxytes by different sperm
May be different sex and as genetically similar as siblings
What are monozygotic twins?
Mitotic division of single zygote into identical twins
Whether they share the same amnion and placenta depends on when in division they split
What are the different types of monozygotic twins?
Division before day 3 (30%) - separate placentas and amnions (dichorionic diamniotic DCDA)
Division between days 4 and 8 (70%) - shared placenta but separate amnions (monochorionic diamnioric MCDA)
Later division very rare and causes twins with shared placenta and amnion (monochorionic monoamniotic MCMA)
How are multiple pregnancies diagnosed?
Vomiting
Larger uterus than expected for dates
What are maternal complications of multiple pregnancy?
Gestational diabetes
Pre-eclampsia
Anaemia - greater increase in blood volume
What are fetal complications of multiple pregnancies?
Greater mortality and long term handicap Preterm delivery IUGR TTTS Miscarriage - one twin can vanish with a first trimester death
What are complications of monochorionicity?
Twin-twin transfusion syndrome
IUGR
Co-twin death - if one twin dies, the drop in BP allows acute transfusion of blood from the alive twin -> hypovolaemia -> death or neuro damage
Monoamniotic twins - cords are tangled -> death
What is twin-twin transfusion syndrome?
Only occurs in MCDA twins
Unequal blood distribution through anastamoses of shared placenta
Donor twin is volume depleted and becomes anaemic, IUGR and oligohydramnios
Recipient twin is volume overloaded and develops polycythaemia, cardiac failure and polyhydramnios
What are intrapartum complications of twins?
Malpresention of first twin (20%) - indication for c-section
Fetal distress - second twin may die of hypoxia, cord prolapse, tetanic uterine contraction or placental abruption
PPH
How are multiple pregnancies managed antepartum?
Consultant led care
Iron and folic acid supplements
Normal screen for abnormalities
At 12 weeks, selective reduction offered to triplets
TV ultrasound to identify short cervix = risk of preterm
Serial USS at 28, 32 and 36 weeks to identify IUGR
What extra antepartum management is done for monochorionic twins?
USS from 12 weeks - watch out for TTTS (tricuspid regurg and polyhydramnios)
Laser photocoagulation of placental anastomoses in fetal medicine centre
How are fetal abnormalities managed in twins?
Before 14 weeks - KCl, or can be done after 32 weeks so if delivery happens, remaining twin will survive
In MCDA twins, cord must be occluded using bipolar diathermy as circulation is shared
How are twins delivered?
C-section - esp if first fetus is breech or transverse lie
34-38 weeks
CTG
Epidural helpful
Contractions diminish after first twin, usually return quickly - check lie of baby and do ECV if needed
Normally deliver 2nd twin within 20 mins
Can have vaginal delivery if first twin is cephalic
