Imaging in pregnancy Flashcards
What four things during pregnancy are you imaging for?
Imaging the pregnant woman – health concerns
Imaging the pregnant uterus/cervix
Imaging the placenta
Imaging the embryo/foetus/baby
What is the main concern of an ultrasound?
Main concern is false positive
For example finding ovarian cysts of unknown significance – leading to unnecessary intervention and anxiety.
How do you image the pregnant uterus?
The lower segment of the uterus develops from the upper part of the cervix are usually from about 25 weeks or sooner if there is premature labour In labour the service gradually dilates
By the timer full dilation is achieved, all of the cervix has disappeared and turned into the pregnant uterus? The lowest segment of the uterus develops from the upper part of the cervix are usually from about 25 weeks or sooner if there is premature labour
In labour the cervix gradually dilates
By the time full dilation is achieved, all of the cervix has disappeared and turned into lower segment.
During labour how much of the cervix turns into the lower segment?
In labour upon full dilation all the cervix has turned into the lower segment.
What are you looking for when you are imaging the uterus?
uterine anomalies – bicornuate uterus
Uterine tumours – fibroids bracket (fibromyomata)
Cervix – length is the predictor for onset of labour.
– Especially important if very premature/late to miscarriage
– Uterine artery blood supply forward – a predictor for pre-eclampsia
What are you looking for when you are imaging the placenta?
Location of placenta – major and minor placenta praevia
Location of cord vessels – Vasa praevia
Abnormal placentation (accrete/percreta)
Define placenta praevia?
When the placenta inserts into the lower uterine segment
Define placenta praevia major and minor.
Covers the internal cervical os = major
Doesn’t cover the internal cervical OS = minor – normal birth can sometimes occur
Major PP in earlier pregnancy can become minor PP in later pregnancy as the lower segment develops
Define vasa praevia
The vessels joining the placenta to the umbilical cord run through the membrane and pass through the lower segment across the internal cervical OS.
What happens during vasa praevia?
The baby to comes through its own blood supply during labour.
- Uncommon*
- Difficult to spot*
Define placenta accrete/percreta
Which types of births is this more common in?
Is it dangerous? If so to who?
Placental trophoblast invade through the endometrium (called decidua in pregnancy and into or through the myometrium)
Repeat Caesarean section
Can be life-threatening
To mother and baby
What are the consequences of placenta accrete/percreta?
Results in hysterectomy at the time of CS – can result in major haemorrhage
Usually uncommon – one of the major reasons to avoid Caesarean section unless necessary
Difficult to spot reliably
Why do we do an ultrasound image on the baby during pregnancy?
To check for a foetal heart
up to 7 weeks no certainty
Even at full term, especially with maternal obesity or twins, could still be difficult.
What are the five main things you look at in early pregnancy up to 13 weeks?
Foetus- alive or not
Location – inter uterine/ectopic
Number of foetuses – type of foetus is multiple
Size of foetus –gestation
Basic anatomical structures
What are you looking for during early pregnancy?
Conception at ovulation – approximately two weeks after last period
Pregnancy test – urine sample – will detect HCG at 10iu/l (within few days of conception)
Ultrasound – detect gestation sack 2 to 3 weeks after conception 1HCG levels or at least 1000iu/l
