Placenta previa occurs in about 1 in 200 pregnancies
at term. The condition is one where the placenta
attaches itself to the lower part of the uterus
wall covering the cervical opening to some extent.
It is more common in the early months of pregnancy.
Placenta previa poses a risk to the mother and her
unborn child because of the potential danger associated
with excessive bleeding should it occur during pregnancy
or delivery. Another variation to placental abnormality
is the low-lying placenta, where the placenta is
very close to the cervical opening but doesn't quite
reach it.
Placenta previa is uncommon
in a first pregnancy but the tendency increases
with additional gestations. The three placenta
previa types are total placenta previa, partial
placenta previa and marginal placenta previa,
with marginal being the most common of the three.
A routine ultrasound performed in weeks 18-20
allows the diagnosis of previa. In other instances
diagnosis is made when the pregnant mother experiences
2nd trimester bleeding. A reevaluation through
ultrasound will be typically performed between
weeks 30-36. In a large number of cases the placenta
will move out of the way before week 30 when the
pregnancy progresses and the uterus would have
expanded and stretched.
What Causes Placenta
Previa
Once again the cause is not known but the risk
increases in the following situations:
• Placenta previa in an earlier pregnancy
• If you had previous c-section(s)
• In multiple pregnancy
• In older women
• In women who smoke
• If uterine surgeries were performed e.g. D&C
or fibroids removal
Any bleeding
in the second half of pregnancy warrants medical
attention. Painless vaginal bleeding which is sudden
near the end of the 2nd trimester or the beginning
of the 3rd is indicative of placenta previa. Ultrasounds
are effective in detecting this problem. Vaginal
probe is never performed as it may cause a disruption
and result in severe bleeding.
• Bleeding in late pregnancy suggests pre-labor
contractions are dislodging the roots of the placenta.
This threatens baby's nourishment and oxygen supply
if labor were allowed to proceed. The added stress
is that the placenta will hinder baby's way out
through the birth canal. Cesarean becomes necessary
to save the baby.
• Cesarean becomes inevitable in cases with
total previa. With marginal or partial previa vaginal
birth is still possible. A vaginal or cesarean delivery
will depend on how much the cervix is covered.
• A woman with any kind of previa should not
put anything into her vagina including douches or
medications. Sexual intercourse should be avoided.
Bed rest is advised to decrease pressure at the
placental site. All kinds of strenuous activities
should be avoided and that includes heavy jobs and
carrying heavy articles.
• If after week 36 the placenta is found to
be lying low but not covering the cervix and there
is no bleeding, the mother has the option of staying
at home but extra visits to the doctor is necessary.
Most doctors would prefer the 'wait and see approach'
so that baby matures up while still in the utero.
Others would prefer to induce labor early. Either
way you have to take things easy.
