Placenta Previa Flashcards
The number of cases of placenta previa and its complications are increasing due to
The rising incidence of cesarean sections, and increasing maternal age
What is vasa previa?
It describes a fetal vessels coursing through the membranes between the internal os, and the fetal presenting part. Unprotected by placental tissue or the umbilical cord.
Type one vasa previa
A velamentous cord inserted in a single, or bilobed placenta
What is the type 2 vasa preview?
Fetal vessels running between lobes of a placenta with accessory lobes
What is the incidence of vasa previa?
1/2000 to 1/6000 pregnancies
Mortality rate of vasa previa
60%
Presentation of vasa previa
- Fresh vaginal bleeding at the time of membrane rupture
- Fetal heart rate abnormalities like decelerations, bradycardia, Sinusoidal trace, or fetal demise
Fetal blood volume
80-100 ml/kg
Risk factors of vasa previa
- Placental anomalies such as bilobed placenta or succenturiate lobes
- History of low lying placenta in the second trimester
- Multiple pregnancy
- IVF. As high, as 1/300.
Definition and grades of PLACENTA PREVIA
lacenta develops within the lower uterine segment and graded according to the distance between the lower placenta edge and internal os
Grade 1: minor lower edge
Grade 2: marginal lower edge reaches the internal ps
Grade 3: partial previa ….partially cover os
Grade 4: complete previa
AIUM grading of placenta previa
Placenta praevia - Placenta directly over the os
Low-lying - when lower edge is <20 mm from the os
Normal - lower edge 20 mm or more from the os
This is for pregnancies more than 16 weeks
Incidence of PP ?
1/200 pregnancies
Risk factors of placenta previa
- Pvs CS:
1. 1%
2. 2%
3. 3%
4. 44% - pvs PP (10 folds)
- last CS with 1 y
- multiple pregnancy
- ART
- advanced maternal age
- smoking
when to do screening for placenta previa
TAS 20W routine fetal anomaly,
if low lying/ PP TAS or TVS at 32w
and again TVS at 36 W
when to use the term low-lying placenta
if >16w, when placental edge is less than 20 mm from internal os
if lowlying or previa at routine fetal anomaly scan (18-22w), when to follow up
follow-up u/s including tvs at 32 w
TVS in diagnosing placenta previa
safe and superior over TAS or Transperineal
how cervical lenght importnant in management of Placenta previa
A short cervical length on TVS before 34 weeks of gestation increases the risk of preterm emergency delivery and massive haemorrhage at caesarean section.
when women should be attend to hospital in 3rd trimester
if she experienced any bleeding (spotting, contractions or pain)
including vague suprapubic period-like aches
do women with placenta previa need to get course of corticosteroids
yes at 34 to 35+6 W
- give it before 34 w if high risk of premature labour
Do we give tocolytics to women with symptomatic pp
yes for 48 hours to facilitate adminstration of corticosteroids
If delivery is indicated based on maternal or fetal concerns, tocolysis should not be used in an attempt to prolong gestation.
Suspicion should be raised for placenta previa if
- vaginal bleeding after 20 weeks of gestation
- high presenting part
- abnormal lie
- painless of provoked bleeding irrespective of previous imaging results
Placental migration from lower segment during 2nd or 3rd trimester is less likely to occur if
- placenta is posterior
- placenta covering the internal os
- there is a previous cs
Any home based care for PP requires
- Close proximity to the hospital
- Ready access to hospital
- Constant presence of companion
- Full informed consent by the women
When to admit women with pp
If major pp who have previously bled should be admitted from 34 weeks
At what gestation should planned delivery occur?
Late preterm (34+0 to 36+6 weeks of gestation) delivery should be considered for women presenting with:
- placenta praevia or a low-lying placenta
- a history of vaginal bleeding or other associated risk factors for preterm delivery.
Delivery for uncomplicated pp should be when?
Between 36 to 37 weeks
In what situations is vaginal delivery appropriate for women with a low-lying placenta?
In women with a
- third trimester
- asymptomatic low-lying placenta
the mode of delivery should be based on the clinical background, the woman’s preferences, and supplemented by ultrasound findings, including the distance between the placental edge and the fetal head position relative to the leading edge of the placenta on TVS.
Most serious complications of PP at delivery
massive obstetric hmge
need of blood transfusion or hysterectomy
What anaesthetic procedure is most appropriate for women having a caesarean section for placenta praevia?
Regional anaesthesia is considered safe and is associated with lower risks of haemorrhage than general anaesthesia
What to do if the placenta is transected during the uterine incision?
immediately clamp the umbilical cord after fetal delivery to avoid excessive fetal blood loss
What to do if pharmacological measures fail to control haemorrhage after pp cs
initiate intrauterine tamponade and/or surgical haemostatic techniques sooner rather than later.
if both medical and surgical intervention fail to control hmge after PP Cs
Early recourse to hysterectomy is recommended
What is cell salvage
A method of collecting blood that you may lose during operation
May cell salvage considered in cs of PP patient
Yes it may be considered in patient with high risk of massive hmge or who refuse donor blood
Increased risk of obstetric hmge in labour of pp
12 times more than elective cs
During CS, if place ta failed to separate by usual measures
Leavit in place and close, start conservative management or hysterectomy
Management of placental retention
- prophylactic antibiotics to reduce risk of infection and bleeding
- neither Methotrexate of arterial embolization is of a benefit
- follow up with us and bhcg to check if it falls continuously
What is more common PA and PP
PA is 2.2%
PP: 0.5%
Time of delivery in case of PP
PP BLEEDING: 34- 37 w
PP NOT BLEEDING: 36-37
PP ACCRETA: 35-37
VP: 34-36
Do we do cerclage in women with low lying or PP
Not supported
Placental mugration isnt done if
Placenta is posterior
Previous CS
Mode of delivery in PP AND LL
PP: CS
LL: vaginal or CS if:
- placental edge is thicker >10 mm
- contains a sponge or marginal sinus
