Placenta Previa (Low-lying placenta) is one of the complications of pregnancy which presents with bleeding vaginally. 
In placenta Previa, the placenta (which is the unit that interfaces between the mum and the growing unborn baby) is attached to the lower part of the womb/ or near the cervix. 

Low-lying placenta (LLP) could usually be picked up on a routine 20 week ultrasound scan visit. 
***Point to note : most of Low-lying placenta picked up on the 20 week scan would ‘move’ later in the pregnancy and very few of these cases would remain low. 
***However, once a LLP is picked on a 20 week scan, it is ideal to pay attention for any vaginally bleeding in the pregnancy. 
***Also, if a LLP was found at 20 week , then it would be be ideal to do a scan at 34 weeks (if the pregnancy remained uncomplicated (i.e. No bleeding) to reconfirm the placenta location. Any bleeding during pregnancy should prompt you to see your doctor for a review.
Types of placenta praevia:

* A low-lying placenta is near the cervical opening but not covering it. It will often move upward in the womb as your due date approaches.

* A partial placenta praevia covers part of the cervical opening.

* A total placenta praevia covers and blocks the cervical opening.
With low-lying placenta, most especially the total placenta Previa as described above means it is more likely that a cs would the option for safe delivery, and your doctor should recommend this. 
What causes a placenta praevia?

Like in medical practice, the commonest cause of placenta praevia is usually unknown. 
Studies and research in to LLP has also shown that it occurs more pregnant women who:
have had a caesarean section or other surgery on the womb ( including myomectomy : removal of fibroids) or have scars inside the womb from other reasons.  
have had children before 
***NB: Women with placenta praevia – specifically if they have a placenta praevia after having delivered a previous baby by caesarean section – are at increased risk of placenta accreta, placenta increta or placenta percreta.

*Placenta accreta: the placenta is firmly attached to the uterus. In placenta increta, the placenta has grown into the uterus; 
*Placenta percreta, here the placenta has grown through the uterus. This condition is often first suspected because the woman has both a praevia and a prior caesarean section. It can be confirmed by ultrasound, CT scan or via MRI, (though those tests are not completely reliable). 
Women with one of these conditions usually require a hysterectomy or (treatment with methotrexate) after delivery of the baby, because the placenta does not separate from the uterus.
What are the symptoms of placenta praevia?

The main symptom of placenta praevia, and the greatest risk to you and your baby, is vaginal bleeding. 
Depending on the severity of the blood loss other symptoms include: 

anaemia, rapid and weak pulse, shortness of breath, low Blood pressure 
Usually Vaginal bleeding (heavy or light ) as a result of placenta praevia may occur at the end of the 2nd trimester or at the beginning of the 3rd trimester. 

The bleeding from LLP is usually painless, and it may happen without labour or during labour. 
Mothers with a placenta praevia are also at increased risk of delivering prematurely, before 37 weeks of pregnancy.
How do I know if I have placenta praevia?
Most women with placenta praevia have no bleeding and are usually diagnosed by a routine ultrasound scan early in pregnancy. 
If you start bleeding, your doctor will probably not (except absolutely necessary ) perform a cervical examination if placenta praevia is suspected, because this can further disturb the placenta and promote dangerous bleeding.
What are the treatments for placenta praevia?
You may be advised to abstain from sex. 
Your doctor will usually repeat ultrasounds later in pregnancy to verify the position of the placenta. 
Also, monitoring the unborn baby is essential. ( hence a facility to look preterm babies is essential if delivery happens sooner than expected). 
Medications ( like antenatal steroids could be given to preterm pregnancies to mature the lungs of the unborn child) , especially if delivery is sooner than expected). 
Women with placenta praevia as their due date approaches nearly always give birth by caesarean delivery. 
If bleeding is severe, an emergency caesarean section may be performed.
Edited by Dr B A Alalade


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