Antepartum haemorrhage Flashcards
What are the common and rarer causes of antepartum haemorrhage?
Common:
Undetermined origin
Placental abruption
Placenta praevia
Rare:
Vasa praevia
Uterine rupture
Incidental genital tract pathology - cervical carcinoma in overdue smear.
What is placenta praevia?
When the placenta is implanted in the lower segment of the uterus.
Why are only 1 in 10 low lying placentas actually praevia at term?
Because the placenta implants in the myometrium and this moves away from the internal cervical os. The low lying placentas therefore look like they move upwards as pregnancy continues .
What are marginal and major placenta praevia?
Marginal = placenta in lower segment, not over os. Major = placenta completely or partially covering os.
In which situations is placenta praevia more common?
In twins
Advancing maternal age
Advancing parity
Uterine scarring
What are the major complications of placenta praevia?
Abnormal lie and lack of head engagement in major placenta praevia –> caesarian section is required.
Can cause severe haemorrhage postpartum as the lower uterus is not able to contract as well to constrict the maternal blood vessels.
If the placenta also implants in a previous c-section scar, it may develop so deep that it prevents placental separation (placenta accreta) - this may provoke massive haemorrhage and often requires hysterectomy.
What is suggested by NICE about vaginal examination on a pregnant woman with vaginal bleeding?
Never perform a vaginal examination on a woman with vaginal bleeding unless placenta praevia has been excluded.
What are the presentations of placenta praevia?
Found on ultrasound Vaginal bleeding (mild) before delivery Abnormal lie/breech presentation (seen in major subtype)
What investigation is used to make the diagnosis of placenta praevia?
Ultrasound
After discovery of placenta praevia, what is done?
Ultrasound is repeated at 32 weeks. This is done vaginally if the placenta is posterior.
How close to the internal os does a low-lying placenta need to be to make it likely to be placenta praevia at term?
<2cm.
If the placenta is anterior and the mother has had a previous caesarian section, what is done?
3D power ultrasound is performed to determine if there is a placenta accreta and how severe it is. MRI is also useful.
When presentation of placenta praevia is with bleeding, what needs to be done to assess wellbeing of mother and foetus?
Cardiotocography (TCG)
FBC
Clotting studies
Cross match
When is delivery for a pregnancy with a placenta praevia which is asymptomatic? What about symptomatic?
Asymptomatic: 39 weeks by caesarian section
Symptomatic: delivery. Blood is kept available, steroids administered if gestation < 34 weeks, anti-D to Rhesus negative women.
What is a common consequence after delivery of a baby with placenta praevia?
Intraoperative and postpartum haemorrhage. Common because the lower segment of the uterus doesn’t contract well after delivery, or because the placenta is accreta.