Obs Flashcards
(29 cards)
What is placenta praevia?
The placenta lying wholly or partly over the internal os
What percentage of patients will have low-lying placenta when scanned at 16-20 weeks?
5%
What is the incidence of placenta praevia at delivery?
0.5%
What are the risk factors for placenta praevia?
- Previous uterine scars (C-sections, more c-sections higher risk)
- Advanced maternal age (>35)
- Multiparity
- Multigravity
- Assisted reproductive technology
- Maternal smoking
- Previous placental praevia
Why are c-sections a risk factor for placenta praevia?
Because embryos are more likely to implant on a lower segment scar from a previous c-section
When are the highest rates of complications for placental praevia observed?
When they are diagnosed at delivery
What is the difference between low lying placenta and placenta praevia?
- Low lying = less than 20mm from the internal os
- Praevia = covering the os
What are the clinical features of placenta praevia?
- Shock
- No pain
- No uterine tenderness
- Normal fetal heart sound
- Coagulation problems are rare
- Small bleeds during 2nd half of pregnancy, prior to larger bleeds
When are patients screened for placenta praevia?
During the mid-pregnancy (fetal anomaly) scan at between 18-21 weeks of pregnancy
What is recommended if placenta praevia is suspected after mid-pregnancy scan?
A follow-up TV ultrasound at 32 weeks of gestation
What is recommended if placenta praevia is confirmed at 32 week TV ultrasound?
An additional TV ultrasound at 36 weeks of gestation to inform discussions about mode of delivery
If grade 1/2, scan every 2 weeks
How does cervical length help facilitate the management of placenta praevia?
A short cervical length on TVS before 34 weeks gestation increases the risk of preterm emergency delivery and massive haemorrhage at c-section
What is the classical grading of placenta praevia?
- 1- placenta reaches lower segment but not the internal os
- 2- placenta reaches internal os but doesn’t cover it
- 3- placenta covers the internal os before dilation but not when dilated
- 4- placenta completely covers the internal os
What is the mode of delivery for placenta praevia grade 3/4?
Elective caesarean between 37-38 weeks
What is the mode of delivery for placenta praevia grade 1 at 36-37 weeks?
Trail of vaginal delivery
What is the management if a placenta praevia patient goes into labour prior to elective c-section?
Emergency c-section, due to risk of post-partum haemorrhage
What’s the management of placenta praevia with bleeding?
- Admit
- A-E approach to stabilise
- If unable to stabilise, emergency c-section
- If in labour or term reached, emergency c-section
What is the major cause of death in women with placenta praevia?
Post partum haemorrhage
When is antenatal corticosteroid therapy recommended in placenta praevia?
Between 34+0 and 35+6 weeks of gestation and is appropriate prior to 34+0 weeks in women at higher risk of preterm birth
What investigation should never be performed in suspected placenta praevia?
Bimanual/ digital vaginal examination, due to this risk of haemorrhage
What investigations should be ordered for someone presenting to a&e with suspected placenta praevia?
- Urgent TV ultrasound (if PP suspected, referral for colour flow doppler ultrasound to screen for placenta accreta)
- FBC (anaemia)
- Cross-match and group and save
- CTG (fetal heartbeat)
How would known placental praevia with active bleeding be managed?
- A-E assessment
- Administration of tranexamic acid
- Transfusion of RBCs, FFP and platelets
- Continuous CTG
- Immediate c-section if bleeding doesn’t subside or evidence of fetal compromise
What are tocolytics?
Drugs used to relax the uterine smooth muscle and delay labour
- Prolong pregnancy and allow administration of cortiosteroids
- Time to transfer to a secondary or tertiary centre
What colour is the blood in placental praevia?
Bright red
