2018 27a Placenta Praevia & Placenta Accreta

Question 1

What are the risk factors for placenta praevia?

Answer 1

1. Previous CS, increasing with number
2. Assisted reproductive technology
3. Maternal smoking

Question 2

How do we screen for placenta praevia?

Answer 2

Mid pregnancy routine anomaly scan

Question 3

** What placenta praevia terminology is used? **

Answer 3

1. Placenta praevia when placenta directly over internal os
2. Low-lying placenta when 16+/40 & placental edge <20mm from os

Question 4

** What is the placenta praevia follow-up? **

Answer 4

1. 32/40 TVUS
   (NB short cervical length <34/40 ⬆️ risk PTB & MOH)
2. 36/40 TVUS if persistent & asymptomatic, to inform MoD

Question 5

** When are antenatal steroids offered in placenta praevia? **

Answer 5

1. Single course 34+0 to 35+6
2. Prior to 34/40 if high risk PTB

Question 6

** When are tocolytics used & not used in placenta praevia?**

Answer 6

1. Used for 48 hours to enable steroids & transfer
2. Not used to prolong gestation if maternal or fetal concerns

Question 7

** At what gestations should planned delivery occur in placenta praevia? **

Answer 7

1. 36+0 to 37+0 if uncomplicated
2. 34+0 to 36+6 if hx PVB or other risk factors for PTB

Question 8

** How should delivery be optimised in placenta praevia? **

Answer 8

1. Prepare for blood transfusion +/- hysterectomy
2. Involve haematologist & blood bank if atypical antibodies
3. Prevent & treat anaemia

Question 9

** What surgical approach should be used in placenta praevia? **

Answer 9

1. Consider vertical incisions with transverse lie, particularly <28/40
2. Consider pre/intraop US for placental location
3. If placenta transected, immediately clamp cord after fetal delivery
4. Early use of intrauterine tamponade &/or surgical haemostasis &/or IR
5. Early recourse to hysterectomy

Question 10

** What are the risk factors for placenta accreta spectrum? **

Answer 10

1. Hx of accreta
2. Previous Caesarean, increasing with number
3. Previous uterine surgery including repeat curettage

Question 11

** How is PAS diagnosed & referred? **

Answer 11

1. Routine anomaly scan
2. Specific screening if LLP with hx CS
3. Refer to specialist unit if suspected
4. MRI for depth of invasion & lateral extension

Question 12

** When should delivery be planned for PAS? **

Answer 12

35+0 to 36+6 if no RFs for PTB

Question 13

** What additional things should be consented for in CS for PAS? **

Answer 13

1. MOH
2. ⬆️ risk of urinary tract damage
3. Blood transfusion
4. Hysterectomy
5. Cell salvage
6. IR if available

Question 14

** What surgical approach should be used for PAS? **

Answer 14

1. CS hysterectomy with placenta left in situ
2. Consider uterus-preserving surgery eg partial myometrial resection if limited extent, accessible & visualised
3. Stents if bladder invaded

Question 15

What is the incidence of placenta praevia?

Answer 15

1:200 pregnancies

Question 16

What is the prevalence of placenta accreta?

Answer 16

1:300 to 1:2000!!

Question 17

How many cases of LLP resolve by term?

Answer 17

90%

Question 18

How often should G&D be sent in placenta praevia?

Answer 18

Weekly

Question 19

What are the greyscale US signs of PAS?

Answer 19

1. Loss of the “clear zone”
2. Bladder wall interruption
3. Myometrial thinning
4. Placental bulge
5. Focal exophytic mass

Question 20

What are the greyscale US signs of PAS?

Answer 20

1. Loss of the “clear zone”
2. Bladder wall interruption
3. Myometrial thinning
4. Placental bulge
5. Focal exophytic mass

Question 21

What are the Doppler US signs of PAS?

Answer 21

1. Uterovesical hypervascularity
2. Subplacental hypervascularity
3. Bridging vessels
4. Placental lacunae feeder vessels

Question 22

What are the 6 elements of good care for PAS?

Answer 22

1. Consultant obstetrician
2. Consultant anaesthetist
3. Blood & blood products available
4. MDT involvement in pre-op planning
5. Discussion & consent of interventions
6. Local availability critical care level 2