Placenta Praevia Flashcards
Define
A placenta directly covers/ lies on the cervical os
It may be:
- Complete- placenta covers entire internal cervical os
- Partial- placenta covers portion of the internal cervical os
- Low-lying- edge of placenta lies < 2cm internal cervical os (term used at 16 weeks)
NOTE: Vasa praevia: where the foetal vessels lie over the cervical os
Aetiology
- The blastocyst implants in the lower uterine segment near the cervical os- most cases are accidental and as a result of the normal variation in placentation.
- Presence of a uterine scar in the lower segment (most commonly from prior C-section) may interfere with the process of placentation as it may be associated with an abnormally adherent placenta (where the placenta attaches to the myometrial layer of the uterus).
- NOTE: cannot call it placenta praevia < 20 weeks as the lower segment is not fully formed
- Low lying placenta= 16 - < 20 weeks
- Placenta praevia= ≥ 20 weeks
- Most move by 28-32 weeks
- IMPORTANT: this is MORE dangerous for the MOTHER than for the foetus.
Risk factors
- Multiple pregnancy
- Increased maternal age
- Previous uterine surgery (i.e. CS)
- Previous praevia history
- Smoking
- IVF (6x increased risk)
Symptoms
Presenting Symptoms
- Intermittent PAINLESS PV bleeding – spontaneous or provoked
- May be spotting or more severe bleeds and it may increase over the subsequent weeks
- Can be provoked by sex or trauma
- Irregular abdominal pain associated with uterine contractions- bleeding may trigger preterm labour
- Post - can get back pain
- Maternal collapse
- Feeling cold
- Light headedness
- Restlessness
- Distress and panic
NOTE: placenta < 2cm from the internal os is likely to be praevia at term
Signs O/E
- Low BP and tachycardia- due to haemorrhage
- Breech presentation and transverse lie is common
- Low-lying placenta at 20-week anomaly scan
- High presenting part
- Uterus is NOT tender
Investigation
Vaginal bimanual exam is NEVER performed in a woman who is bleeding unless placenta praevia is excluded- can provoke bleed
Speculum examination
Basic observations
Bloods
- FBC – Hb will be low
- G&S and Crossmatch – preparation for transfusion in pregnancy
- INR/ PTT, fibrinogen and fibrinogen degradation products- if DIC present, elevated INR/ PTT + fibrinogen degradation products, decreased fibrinogen
CTG
TVUSS - DIAGNOSTIC
- Abdo USS usually check for
Kleihauer test (if the mother is Rh -ve) – determine whether any or how much foetal blood has leaked into the maternal circulation as Anti-D will need to be given
DDx
- Placental abruption (painful)
- Vasa praevia (foetal CTG may show abnormalities)
- Uterine rupture
- Local genital causes:
- Benign or malignant lesions – e.g. polyps, carcinoma. cervical ectropion (common).
- Infections – e.g. candida, bacterial vaginosis and chlamydia.
- Trauma (check for sex/ strenuous exercise)
1st line diagnosis: TVUSS
o Bloods – FBC, clotting studies, G&S, U&E, LFT
o Kleihauer test / Rhesus status
- If mother if RhD -ve à Kleihauer test (check level of foetal blood in maternal circulation)
- Administer anti-D
o CTG Do NOT perform a bimanual (speculum ok to assess bleeding)
Management
General advice:
- Advise NOT to have sex if low-lying placenta or placenta praevia
- Delivery will be by caesarean section
Minimal bleeding and the cause is clearly local vaginal bleeding -> symptomatic management (with reasonable certainty that cervical carcinoma is excluded by smear history and direct visualisation of the cervix)
- If bleeding settles, they should be admitted for 48 hours for observation
Low-Lying Placenta at 20-Week Scan:
- Only 10% go on to have a low-lying placenta later in pregnancy
- Rescan at 32 weeks -
> if still present and grade I/II, rescan at 36 weeks -> if still low, recommend CS
- > if still present and grade III/IV, admit at 34 weeks -> CS at 37 weeks
- USS at 36 weeks à method of delivery:
o CS (grade III/IV at 37 weeks)
o Vaginal delivery (grade I)
- Consider assessing cervical length to determine risk of preterm labour
- If high presenting part or abnormal lie at 37 weeks à C-section
Antenatal corticosteroids from 34-36 weeks (can be earlier if at risk of preterm delivery)
- Tocolysis (facilitate antenatal corticosteroids)
Placenta Praevia with Bleeding:
ABC -> IV access and fluids
Bloods: FBC, G&S, consider crossmatch, Kleihauer test (if negative)
· Anti-D if Rh-D -ve and Kleihauer test
· Steroids (between 24-34(+6) weeks)
Scans:
· CTG if >27 weeks Umbilical artery dopplers (every 2 weeks)
· Growth scan
Induction of labour if early foetal compromise
Admit at least until bleeding has stopped (and keep them in for 48 hours to observe)
Complications
Maternal mortality is 1 in 300
o Maternal – haemorrhage – antepartum haemorrhage and postpartum haemorrhage, DIC, hysterectomy
o Foetal – IUGR, death
PACES
Risk Factors: previous praevia, multiple pregnancy, previous CS, smoking and drug use, advanced maternal age
Diagnosis:
The cause of the vaginal bleeding you have been experiencing is something called ‘Placenta Praevia’
Have you heard of this before?
Briefly explain what Placenta Praevia is:
As you may already know, inside your womb, there is something called the placenta which delivers baby with blood containing oxygen and nutrients needed to grow properly.
Normally, the placenta is attached to the womb lining at the top of your womb.
However, in your situation, the placenta has attached itself too low in the womb. The placenta is in fact covering the neck of the womb which is the cause of your vaginal bleeding.
The problem is that it can be potentially harmful for yourself and baby- as you can imagine, the placenta is blocking the birth canal and can cause problems for delivery. Additionally there is a risk of further bleeding which is very serious.
Explain to the patient what the next steps are:
In order to ensure that you and baby are safe, we have to admit you into hospital for at least 48 hours to observe yourself and baby
Basic ob sand CTG
We will give you fluids via a tube that sits in your vein called a cannula and take some blood samples from you
We also have to give you an injection called ‘anti-d’ which is the same as the one you had at 28 weeks
If bleeding settles and observations are stable, we can discharge you after 48 hours
CONFIRM WHERE THEY LIVE AND ENSURE THEY HAVE EASY ACCESS TO HOSPITAL IN CASE THEY EXPERIENCE BLEEDING AGAIN
However, if there are complications such as profuse bleeding, baby being in distress, or problems with baby’s growth, then we will move forward to delivery as soon as possible
Mention giving corticosteroids for lung maturation in this case
Discuss the mode of delivery and timing of delivery with patient:
Ask patient what their initial plan for delivery was
With regards to delivery, we will deliver baby via a C section as this is a grade 3 Praevia
Explain C Section procedure- will be given spinal anaesthetic and taken into theatre where the doctors will make an incision into your womb to bring baby out. The doctors will explain the procedure in more detail when they brief you prior to the procedure.
Explain risks of C section – bleeding, perforation to other organs, infection, soreness post procedure, headaches due to the epidural
With regards to the timing, we aim to deliver baby between 36 and 37 weeks as long as there are no complications from now until then
To monitor this we will be assessing the growth and taking scans (umbilical artery doppler) every 2 weeks until then
Risks and safety net
Keep an eye out for the following and come back into see us immediately if they occur:
Normal vaginal bleeding
Reduced kicking from baby
Gushing of fluid or abnormal discharge from your vagina
Please avoid any penetrative sexual intercourse from now until delivery
