Large for Dates Pregnancy (Macrosomia, Polyhydramnios and Multiple Pregnancy) Flashcards
How is a foetus diagnosed as being large for dates?
Symphysial fundal height > 2cm greater than what would be expected for gestation / a foetus which is > 90th centile for symphysial fundal height/estimated foetal weight
What are the 5 main aetiologies of a large for dates baby?
Wrong estimated gestation date, foetal macrosomia, polyhydramnios, multiple pregnancy, diabetes
Why do wrong estimated gestational dates most commonly occur?
Due to late bookers, because they forget when they really had their last period
What are some causes of being a late booker?
Concealed pregnancy, vulnerable woman, transfer of care
What does foetal macrosomia mean?
It is the medical term for being a big baby - an US shows an estimated foetal weight > 90th centile on both generalised and personalised growth charts
What are some risks associated with foetal macrosomia?
Labour dystocia, shoulder dystocia, PPH
What is labour dystocia?
The uterus is contracting normally but the baby does not exit the pelvis because it is physically blocked
What is shoulder dystocia?
The baby’s head has been delivered but one of its shoulders is stuck behind the pubic bone
Shoulder dystocia is more common in mothers with what?
Diabetes
If a baby has foetal macrosomia, what must be excluded?
Maternal diabetes
What are some management options for foetal macrosomia?
Conservative, IOL, C-section delivery (decreases risk of shoulder dystocia)
What is the definition of polyhydramnios?
Excess amniotic fluid
The volume of amniotic fluid is controlled by what? How does this cause polyhydramnios?
Swallowing and urination - any imbalance in this intake and output can cause polyhydramnios
How is polyhydramnios diagnosed?
Ultrasound scan showing deepest pool > 8cm / amniotic fluid index > 25cm
What is the maternal aetiology of polyhydramnios?
Diabetes
What are some foetal aetiologies of polyhydramnios?
Structural anomalies, monochorionic twin pregnancy, viral infections, hydrops foetalis
What is hydrops foetalis (a cause of polyhydramnios)? What are some things that can cause it?
Accumulation of fluid in at least 2 foetal compartments, is usually caused by anaemia but also be Rh disease
Can polyhydramnios occcur idiopathically?
Yes
TORCH viral infections in the foetus can predispose to polyhydramnios. What are these?
Toxoplasmosis, other (VZV, syphilis, parvovirus), rubella, cytomegalovirus, herpes
What are some symptoms of polyhydramnios?
Abdominal discomfort and shortness of breath
What are some complications that may arise as a result of polyhydramnios?
P-PROM, preterm labour, cord prolapse, malpresentation, PPH
What are 4 clinical signs of polyhydramnios?
Symphysial-fundal height > expected, malpresentation, tense shiny abdomen, inability to feel foetal parts
What are some investigations you could do to investigate an underlying cause of polyhydramnios?
Oral glucose tolerance test, serology for viruses, antibody screen and Hb, US for foetal anomaly
If a woman has polyhydramnios and a chromosomal abnormality is suspected as the cause, what investigation should be performed?
Amniocentesis
How should polyhydramnios be managed?
Patient information and discuss possible labour complications, serial US scans to monitor growth and presentation, induction of labour by 40 weeks
How common is a spontaneous a) twin and b) triplet pregnancy?
a) 1/80 b) 1/10,000
There is an increased risk of multiple pregnancy with what?
Assisted conception treatment
Aside from assisted conception, what are some factors that increase the risk of a multiple pregnancy?
Increased maternal age, height and parity, African ethnicity, family history
Explain what is meant by a monozygous twin pregnancy? How common is this?
Twin pregnancy formed by the splitting of a single fertilised egg. Accounts for 30% of all twin pregnancies.
Explain what is meant by a dizygous twin pregnancy? How common is this?
Twin pregnancy formed by 2 eggs being fertilised by 2 sperm. Accounts for 70% of all twin pregnancies.
Chorionicity refers to the presence of one or two what in a twin pregnancy?
Placentas
Dizygous twin pregnancies are always what type? Describe what this means?
Dichorionic diamniotic (2 placentas and 2 amniotic sacs)
The chorionicity of a monozygous twin pregnancy depends on what?
The time of splitting of the single egg after fertilisation
A DCDA monozygous pregnancy occurs when there is splitting of the ova at what stage after fertilisation?
0-3 days after, at the morula stage
A MCDA monozygous pregnancy occurs when there is splitting of the ova at what stage after fertilisation?
4-7 days after, at the blastocyst stage
A MCMA monozygous pregnancy occurs when there is splitting of the ova at what stage after fertilisation?
8-14 days after, at the implanted blastocyst stage
A conjoined monozygous pregnancy occurs when there is splitting of the ova at what stage after fertilisation?
15+ days after, at the formed embryonic disc stage
How is the chorionicity of a twin pregnancy determined? When is this best observed?
The shape and thickness of the membrane on an ultrasound scan, ideally between 11-14 weeks gestation
Each of the following are signs which may be seen on ultrasound to help determine chorionicity. Which type of chorionicity do each of the following suggest: a) Lambda sign? b) T sign?
a) DCDA b) MCDA
Why is it so important to determine a specific subtype of twin pregnancy?
Because monozygous, and especially monochorionic twin pregnancies are at increased risk of complications
What is the main symptom which may be suggestive of a multiple pregnancy? What is the differential to this?
Excessive vomiting (hyperemesis gravidarum) / hyperthyroidism
What are some signs which may be suggestive of a multiple pregnancy?
Increased AFP, large for dates uterus, multiple foetal poles
A multiple pregnancy can be confirmed on ultrasound at what gestation?
12 weeks
What are some foetal complications of a multiple pregnancy?
Higher perinatal mortality, preterm birth, growth restriction (both/discordant), cerebral palsy
What are some maternal complications of a multiple pregnancy?
Anaemia, pre-eclampsia, antepartum haemorrhage, preterm labour, C-section
What are some complications specific to a monochorionic twin pregnancy?
Single foetal death, selective growth restriction, twin to twin transfusion syndrome
If in a multiple pregnancy, one of the foetuses dies, what is the risk to the other?
15% risk of IUD, 26% risk of neurological abnormality
What investigation should be performed on the surviving foetus after there has been single foetal death in a twin pregnancy?
MRI foetal brain 4 weeks after the death of the twin
Serial ultrasound scans are used to assess growth in a multiple pregnancy. How can you tell if there has been selective growth restriction?
Calculate the weight discordance: (larger EFW - smaller EFW) / Larger EFW x 100 - if this is larger than 20% there are increased perinatal risks
If selective growth restriction is early in onset in a multiple pregnancy, what investigation should you do? If these are abnormal, what is a management option?
Doppler scans / selective reduction
Describe what happens in twin-twin transfusion syndrome?
Only occurs when twins share a placenta. Connections between blood vessels in the placenta will result in one receiving too much blood and developing heart failure, while one will receive too little blood resulting in growth restriction
Oligohydramnios-polyhydramnios is seen in which condition?
Twin-twin transfusion syndrome
Twin-twin transfusion syndrome is rare after when?
26 weeks
How should twin-twin transfusion syndrome be treated a) before 26 week? b) after 26 weeks?
a) Foetoscopic laser ablation b) amnioreduction/septostomy
When should a twin pregnancy with twin-twin transfusion syndrome be delivered?
34-36 weeks
When can twin anaemia-polycythaemia sequence occur?
Following foetoscopic laser ablation for twin twin transfusion syndrome
What is the biggest risk associated with birth of MCMA twins? When and how should they be delivered?
Cord entanglement - deliver at 32-34 weeks by C-section
How often should mothers of a) monochorionic and b) dichorionic twins attend clinic appointments and have ultrasound scans?
a) every 2 weeks (from week 16 onwards) b) every 4 weeks
What medications should always be used in a multiple pregnancy?
Folic acid, low dose aspirin and iron supplements
For monochorionic twins, what other investigations should be done when they attend for an ultrasound scan?
Measure vertical pool, perform bladder and umbilical artery Doppler and estimate foetal weight
When should a) DCDA and b) MCDA twins be delivered?
a) 37-38 weeks b) 36 weeks with steroids
With regards to multiple pregnancies, in which scenarios should a C-section always be performed?
Triplets or more, MCMA, if first twin is transverse or breech
When can you do a vaginal delivery for twins?
If one is cephalic in presentation
What medication should be given after the delivery of twin 1?
Syntocinon
What monitoring should be used during a twin delivery?
US and FSE
During a twin delivery, you should aim for an intertwin delivery time of what?
< 30 mins
When is the risk of PPH highest in a multiple birth?
In the active 3rd stage
