|
Placenta Praevia
During pregnancy, the placenta provides the growing baby with
oxygen and nutrients from the mother's bloodstream. When the baby is
ready to be born, the cervix (neck of the womb) dilates to allow the
baby passage out of the uterus and into the vagina. Placenta praevia
means the placenta has implanted at the bottom of the uterus, over the
cervix or close by, which means the baby can't be born vaginally.
'Partial placenta praevia' means the cervix is partly blocked, while
'complete placenta praevia' means the entire cervix is obstructed. Some
of the causes include scarring of the uterine lining (endometrium) and
abnormalities of the placenta. Around one in every 200 pregnancies is
affected by placenta praevia. The baby survival rate is around 80 to 85
per cent. Prematurity is the main cause of death.
Symptoms
In some cases, placenta praevia has no symptoms and is only picked up
during the routine ultrasound scan in the second trimester. The
placenta may reposition itself as the pregnancy progresses, and no
symptoms or complications may occur. In other cases, placenta praevia
causes symptoms and complications. The main symptoms include:
- Bleeding after sexual intercourse
- Light bleeding during the first and second trimesters
- Heavy, painless bleeding of bright red blood during the
third trimester.
Ruptured blood vessels
During the later stages of pregnancy, the bottom part of the uterus
thins and spreads to accommodate the growing baby. If the placenta is
anchored to the bottom of the uterus (placenta praevia), this thinning
and spreading tears the placenta and ruptures its blood vessels. Sexual
intercourse can injure the placenta because of the pressure of the
penis against the cervix. During labour, the cervix thins and dilates,
which would normally allow the baby to exit into the vagina. In
placenta praevia, the dilation of the cervix further tears the placenta
and causes bleeding. Sometimes, this can cause the baby to lose blood
too.
Possible complications
Some of the complications of placenta praevia include:
- Infection
- Major haemorrhage for the mother
- Major haemorrhage for the baby
- Shock from loss of blood
- Foetal distress from lack of oxygen
- Embolism (blood clot lodging in a blood vessel)
- Premature labour or delivery
- Health risks to the baby, if born prematurely
- Emergency caesarean delivery
- Hysterectomy, if the placenta fails to come away from the
uterine lining
- Death.
Causes and risk factors
Some of the possible causes and risk factors of placenta praevia
include:
- Abnormalities of the uterine lining, such as fibroids.
- Scarring of the uterine lining (endometrium).
- Abnormalities of the placenta.
- Multiple babies, such as twins.
- The risk increases with each pregnancy - a woman who has
already had six or more deliveries has a risk of one in 20.
- Prior caesarean delivery, especially if the scar is low on
the abdomen.
- Advancing maternal age (35 years and over).
Diagnosis methods
- A pregnant woman who experiences vaginal bleeding should be
hospitalised and tested. Some of the tests used to diagnose placenta
praevia include:
- Ultrasound scan.
- Feeling the mother's belly to establish the baby's position
(the baby is sideways or presenting bottom-first in around one in three
cases of placenta praevia).
- Blood tests, including blood cell counts.
Vaginal examinations should be strictly avoided
It is sometimes difficult to distinguish placenta praevia from placenta
abruptio, a condition characterised by the separation of the placenta
from the uterine wall. Both conditions are flagged by heavy bleeding of
bright red blood. A vaginal examination is often used to help diagnose
placenta abruptio, but could trigger heavier bleeding in the case of
placenta praevia. An ultrasound scan should always be taken first, and
vaginal examinations strictly avoided in the case of placenta praevia.
Once the diagnosis is made, the pregnancy needs to be very carefully
monitored. Placenta praevia is a potentially life threatening condition
for the both the mother and her baby.
Treatment options vary
Treatment depends on a number of factors, including:
- Whether the placenta praevia is complete or partial
- The exact location of the placenta
- The amount of blood lost
- The gestational age of the baby
- The position of the baby
- The health of the baby
- The health of the mother
- The prior number of deliveries for the mother.
Treatment during early pregnancy
A baby can safely be born (or induced) at around 36 weeks. Prior to
that point, medical treatment aims to ease the symptoms and prolong the
pregnancy. Options may include:
- Avoiding any activity that triggers uterine contractions or
irritates the cervix, such as sexual intercourse or orgasms.
- Bed rest.
- Hospitalisation.
- Close monitoring, such as using a foetal monitor and
regularly checking the mother's vital signs (for example, blood
pressure).
- Blood transfusion for the mother.
- Medications to prevent premature labour.
Treatment during late pregnancy
Once the baby is old enough to be delivered, a caesarean section is
usually performed. The baby will need to be monitored in intensive care
to make sure all is well. The mother will undergo a range of tests,
including tests to check her blood cell counts and the clotting ability
of her blood.
Where to get help
- Your doctor
- Obstetrician
- Emergency department of your nearest hospital
- Always call an ambulance in an emergency Tel. 000
- Family Planning Victoria Tel. (03) 9257 0100
Things to remember
- During pregnancy, the placenta provides the growing baby
with oxygen and nutrients from the mother's bloodstream.
- Placenta praevia means the placenta has implanted at the
bottom of the uterus, over the cervix or close by, which means the baby
can't be born vaginally.
- Risk factors include scarring of the uterine lining,
multiple foetuses, prior caesarean section and fibroids.
- Treatment aims to ease the symptoms and prolong the
pregnancy until at least 36 weeks.
Copied from:
http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Placenta_praevia?open
|