Foetus and monitoring Flashcards
Monozygotic twin means?
Identical twins from a single zygote
Dizygotic twin means?
Non-identical twins from two different zygotes
Monoamniotic means?
Single amniotic sac
Diamniotic means?
Two separate amniotic sacs
Monochorionic means?
Share single placenta
Dichorionic means?
Two separate placentas
Best outcomes for twins are with ______, ______ pregnancies as each fetus has their own nutrient supply.
Diamniotic
Dichorionic
Dichoronic, diamniotic twins are differentiated how using USS?
Dichoronic, diamniotic twins have membrane between them.
Lambda sign/ twin peak sign
What is the lambda sign/twin peak sign?
Occurs in USS with dichorionic, diamniotic twins.
Triangular appearance where membrane between the twins meets the chorion (as the chorion blends partially in the membrane).
Monochoronic, diamniotic twins are differentiated how using USS?
Monochoronic, diamniotic twins have a membrane between them.
T sign
What is the T sign?
Occurs in USS with monochoronic, diamniotic twins.
Membrane between the twins abruptly meets the chorion, giving a T appearance.
What are maternal risks associated with multiple pregnancies?
Anaemia Polyhydramnios HTN Malpresentation Spontaneous preterm birth Instrument/C-section delivery PPH
What are foetal/neonatal risks associated with multiple pregnancies?
Miscarriage Stillbirth Fetal growth restriction Prematurity Twin-twin transfusion syndrome Twin anaemia polycythaemia seqeuence Congenital abnormalities
What is twin-twin tranfusion syndrome?
Occurs when foetuses share a placenta.
One twin gets more of the blood (recipient) than the other (donor).
Recipient - fluid overloaded, heart failure, polyhydramnios
Donar - FGR, anaemia, oligohydramnios
Size difference between the fetuses!
How is twin-twin transfusion syndrome managed?
Referral to tertiary specialist fetal medicine centre
(If severe) - laser treatment to destroy connection between the 2 blood supplies
What is twin anaemia polycythaemia sequence?
Similar to twin-twin transfusion syndrome, happens with twins sharing 1 placenta.
Difference is it’s less acute.
One twin becomes anaemia while other gets polycythaemia.
When women with multiple pregnancies are monitored for anaemia, their FBC is taken at which 3 time points?
Booking clinic
20 weeks
28 weeks
USS is used in multiple pregnancy women to monitor for which 3 issues?
FGR
Unequal growth
Twin-twin transfusion syndrome
USS scans of multiple pregnancy women are done at which time periods?
2 weekly scans from 16 weeks + for monochorionic twins
4 weekly scans from 20 weeks for dichorionic twins
Why is planned birth offered to women with multiple pregnancies?
Decrease risk of fetal death.
Allows timing of birth to reduce complications.
Allow corticosteroids to be administered before delivery to help lungs mature.
Monoamniotic twins require what form of delivery between 32 - 34 weeks?
Elective C-section
Diamniotic twins can be delivered how?
Vaginal delivery (if cephalic)
C-section (for 2nd baby after 1st successfully born)
Elective caesarean when presenting twin is not cephalic
Prematurity is defined as birth before __ weeks gestation
37 weeks
Babies are considered non-viable below __ weeks gestation.
23 weeks
Prematurity is classed as:
Extreme preterm -> 1.
Very preterm -> 2
Moderate to late preterm -> 3
- Under 28 weeks
- 28-32 weeks
- 32-37 weeks
What 2 methods can be used as prophylaxis against preterm labour?
Vaginal progesterone
Cervical cerclage
Progesterone is given as a vaginal pessary/gel why?
How does it work?
Prophylaxis against preterm labour.
Maintains pregnancy, prevents labour by decreasing myometrium activity and prevents cervix remodelling in preparation for delivery.
What is the criteria for offering vaginal progesterone to women?
Risk of preterm labour
Cervical length less than 25mm on vaginal USS between 16-24 weeks gestation
What is cervical cerclage and why is it used?
Put stitch in cervix to add support and keep it closed.
Stitch removed when woman goes into labour or reaches term.
Used prophylactically against preterm labour
When is “rescue” cervical cerclage used?
Between 16 and 27+6 weeks when there is cervical dilatation without rupture of membranes
To prevent progression and premature delivery
What is PPROM?
Amniotic sac ruptures, releasing amniotic fluid before onset of labour and in a preterm pregnancy (under 37 weeks gestation)
How is PPROM diagnosed?
Speculum examination revealing pooling of amniotic fluid in the vagina
If there is doubt:
- IGFBP-1 protein test (high in amniotic fluid) - test vaginal fluid for this
- PAMG-1 protein test is an alternative
How is PPROM managed?
Prophylactic antibiotics to prevent chorioamnionitis (erythromycin)
Induction of labour (from 34 weeks)
What is preterm labour with intact membranes?
Regular painful contractions and cervical dilatation without rupture of amniotic sac
How is cervical length measured?
Transvaginal USS
What is the relevance of cervical length <15mm in 30+ weeks gestation?
Preterm labour more likely
Fetal ______ is alternative test to vaginal USS. It is the glue between chorion and uterus and is found in vagina during labour.
Can be used to determine preterm labour
Fibronectin
How can preterm labour be managed?
Fetal monitoring (CTG)
Tocolysis with nifedipine
Maternal corticosteroids
IV magnesium sulphate
Delayed cord clamping/milking
What is tocolysis?
What medication is used 1st line for this?
Medicines used to stop uterine contractions. SHORT TERM MEASURE - buys time for further fetal development.
Nifedipine (or Atosiban as an alternative)
During which gestational age can tocolysis be used?
24 and 33+6 weeks gestation in preterm labour
Giving mother ______ helps develop fetal lungs and reduce ______ syndrome
Corticosteroids
Respiratory distress
______ helps protect fetal brain during premature delivery
It reduces the risk of cerebral palsy
IV magnesium sulfate
Why must magnesium sulphate be monitored post-administration?
Magnesium toxicity
Check obs, tendon reflexes (patella).
Signs:
Reduced RR
Reduced BP
Absent reflexes
How is intermittent foetal monitoring performed?
Pinard stethoscope
Handheld doppler
Using either of these, listen to foetal heartbeat
How is continuous foetal monitoring performed?
CTG +/- Foetal scalp electrode (more accurate)
Which 2 measurements are used to assess fetal size on USS?
Estimated fetal weight (EFW)
Fetal abdominal circumference (AC)
Which 4 factors are taken into account on customised growth charts used to assess the size of a foetus?
Ethnicity
Weight
Height
Parity
Severe SGA is when the fetus is below the ___ centile for gestational age
3rd
Low birth weight is defined as a birth weight of _______
<2500g
What are the 2 main categories of causes of SGA?
Constituionally small (match mother and others in family, growing appropriately on growth chart)
Foetal growth restriction (FGr) - when small fetus due to pathology reducing amount of nutrients anx oxygen being delivered to foetus via placenta
What are the 2 categories of causes of Foetal growth restriction (FGR)?
Placenta-mediated growth restriction (conditions affecting nutrient transfer via placenta)
Non-placenta mediated growth restriction (pathology of foetus itself)
What are causes of placenta mediated growth restriction?
Idiopathic Pre-eclampsia Maternal smoking/alcohol Anaemia Malnutrition Infection Maternal health conditions
What are causes of non-placenta mediated growth restriction?
Genetic abnormalities
Structural abnormalities
Fetal infection
Errors of metabolism
Other than being SGA, what other signs would indicated foetal growth restriction?
Oligohydramnios
Abnormal Doppler studies
Reduced foetal movements
Abnormal CTG
What are short-term complications of foetal growth restriction?
Foetal death/stillbirth
Birth asphyxia
Neonatal hypothermia
Neonatal hypoglycaemia
What are long-term complications of foetal growth restriction?
Cardiovascular disease (HTN)
T2DM
Obesity
Mood/behaviour problems
What are risk factors for SGA?
List 5
Previous SGA baby Obesity Smoking Diabetes Existing HTN Pre-eclampsia Older mother (35 yo+) Multiple pregnancy Low PAPPA protein Antepartum haemorrhage Antiphospholipid syndrome
What measurement is taken routinely to identify SGA in low-risk women?
SFH (symphysial-fundal height)
Done at every antenatal appointment from 24 weeks+
If symphysis fundal height is less than 10th centile, woman are booked for what investigation for SGA?
Serial growth scans with umbilical artery Doppler
What issues can make measuring the symphysis fundal height harder?
Large fibroids
BMI >35
____ , ____ and ____measurements determine growth velocity in serial USS
Estimated foetal weight (EFW)
Abdominal circumference (AC)
Amniotic fluid volume
What are the important management steps for SGA?
Identify those at risk
Aspirin -> risk of pre-eclampsia
Treating modifiable risk factors (stop smoking)
Serial growth scans (monitor growth)
Early delivery if growth static (or other concerns)
If a fetus is identified as SGA, what investigations are carried out to find the underlying cause?
BP/urine dip for pre-eclampsia
Uterine artery Doppler scanning
Detailed foetal anatomy scan
Karyotyping for chromosomal abnormalities
Testing for infections (TORCH, malaria, syphillis)
Why is early delivery performed if growth becomes static on growth charts?
Reduces risk of stillbirth
Corticosteroids given when delivery planned early
Allows pediatricians to be present at birth to help with neonatal resuscitation/management if required.
What are 2 important things to remember about macrosomia?
Hint: 1. pathology that could cause it
2. complication during birth
- gestational diabetes can cause macrosomia
2. shoulder dystocia can occur during birth
LGA (macrosomia) is defined as when the weight of the newborn being ____ kg at birth
During pregnancy, an estimated fetal weight (EFW) above ____ centile is considered LGA.
> 4.5kg
90th centile
What are possible causes of LGA/macrosomia?
Constitutional (normal for mother/family) GDM Previous macrosomia Maternal obesity/rapid weight gain Overdue Male baby
What are risks to the mother having LGA/macrosomic baby?
Failure to progress Perineal tears Delivery - instrument/C-section PPH Uterine rupture (rare)
What are the risks to the baby of LGA/macrosomia?
Shoulder dystocia
Birth injury (Erb’s palsy, clavicular fracture, fetal distress, hypoxia)
Neonatal hypoglycaemia
Obesity in childhood/later life
T2DM in adulthood
What investigations are carried out for LGA fetuses?
USS (exclude polyhydramnios + estimate fetal weight)
OGTT (test for GDM)
Most women with LGA pregnancy will have a successful vaginal delivery. True or False?
True.
NICE guidelines advise against labour induction only on grounds of macrosomia
How can the risk of shoulder dystocia in LGA babies be reduced?
Delivery on consultant-lead unit
Delivery by experienced midwife/obstetrician
Access to obstetrician/theatre if required
Active management of thrid stage (delivery of placenta)
Early decision for C-section if required
Pediatrician attending the birth
What is fetal hydrops?
When extra fluid accumulates in 2+ areas in the fetus.
E.g. pleural effusion, skin oedema, pericardial effusions, ascites
What are causes of “immune” fetal hydrops?
Anaemia
Haemolysis (result of Rhesus disease)
What are causes of “non-immune” fetal hydrops
Chromosome abnormalities (Trisomy-21)
Structural abnormalities (pleural effusions)
Cardiac abnormalities/arrhythmias
Anaemia causing cardiac failure (infection, fetomaternal haemorrhage, thalassemia)
Twin-twin transfusion syndrome in severe cases.
What are investigations for fetal hydrops?
USS
Echo
Assessment of middle cerebral artery
Bloods: Kleihauer, viral PCR
FBS if anaemia suspected
Amniocentesis for karyotyping
What is the treatment for fetal hydrops?
Depends on cause
Anaemia - transfusion
Pleural effusions - vesicoamniotic shunting of fetus
Twin-twin transfusion syndrome - laser ablation
Where are rhesus antigens found?
On surface of RBCs
Not always (i.e. when Rhesus negative)
Women who are rhesus-D ______ve do not need any additional treatment during pregnancy.
Positive
When does sensitisation to foetal Rhesus-D become a problem?
Why?
During 2nd + subsequent pregnancies
During subsequent pregnancies, the anti-D antibodies can cross placenta into foetus. Attach themselves to RBCs of foetus and causes auto-immune response from mother to attach foetal RBCs, causing haemolytic disease of the newborn.
How is Rhesus disease managed?
How does this intervention work?
Preventing senitisation by giving IM anti-D injections to Rhesus negative women.
Anti-D medication works by attaching to the rhesus-D antigens on the fetal RBCs in the mother’s circulation, causing them to be destroyed. This prevents mother’s own immune system recognising the antigen and creating its own antibodies. “Kill the foetal RBCs in maternal blood before they get recognised and antibodies start being made!”
When are anti-D injections given ROUTINELY?
28 weeks gestation
Birth (if baby blood group is Rh +ve)
Aside from routine, when might anti-D injections be given against Rhesus disease?
Antepartum hemorrhage (APH) Amniocentesis procedures Abdominal trauma
This is because these procedures may involve maternal blood mixing with foetal blood.
At which gestational age can the Kleihauer test be used onwards from?
Any sensitising event from 20 weeks gestation onwards
What is the purpose of the Kleihauer test in Rhesus disease?
Determine amount of foetal blood mixing with maternal blood to determine dose of anti-D required for prophylaxis.
What does the Kleihauer test involve in terms of method?
Acid added to mother’s blood sample.
Foetal Hb is naturally more resistant to acid.
Foetal Hb persists in response to added acid, mother’s Hb destroyed.
Number of cells still containing Hb (aka remaining foetal cells) can then be calculated.
