32. Placenta previa. Flashcards
what is placenta praaevia ?
placenta attaches to the lower part of the uterus
partially or completely block the internal os
what are the risk factors for placenta praaevia ?
older maternal age >35
smoking
previous c section or lower uterine scars from curettage or myometcomy
multiparty
what are the symptoms for placenta praaevia ?
Symptoms include vaginal bleeding in the second half of pregnancy which is sudden onset, painless, apparently causeless and recurrent
there may not be any bleeding in major complete placenta previa until labor starts
the bleeding is unrelated to activity and often occurs during sleep
what us the cause of bleeding in placenta previa?
placental growth
slows down in later months and the lower segment
progressively dilates, the inelastic placenta is sheared off
the wall of the lower segment
separation of the placenta may
be provoked by trauma including vaginal examination,
coital act, external versio
placenta praaevia is classified into what ?
Praevia is divided into four grades depending on the relationship and distance to the internal cervical os:
grade I: low-lying placenta: placenta lies in the lower uterine segment but its lower edge does not abut the internal cervical os (i.e lower edge 0.5-2.0 cm from internal os).
grade II: marginal praevia: placental tissue reaches the margin of the internal cervical os, but does not cover it
grade III: partial praevia: placenta partially covers the internal cervical os
grade IV: complete praevia: placenta completely covers the internal cervical os
majorly the placenta lies where in placenta previa?
posterior wall (more common) anterior wall
in placenta previa the blood is almost all from whom?
almost always maternal
what is diagnosis of placenta praevia ?
inspection of the vulva to note the presence of any active bleeding
head is floating, malpresentation
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Fetal heart sound - Slowing of the fetal heart rate when pressing head down into the pelvis which recovers promptly as the pressure is released =suggestive of low lying placenta especially of posterior type Stallworthy’s sign = not reliable
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Vaginal examination must not be done!
TAS US
False positives of TAS common be due to :
Overfilled bladder compressing lower uterine segment
Myometrial contraction simulating placental tissue in abnormally low location
also
poor imaging
in a posteriorly situated placenta are—due to
acoustic shadow from the fetal presenting part
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TVS - without touching cervix and more accurate
to note Complete placenta previa diagnosed in the second trimester will persist into the third trimester in 25% of cases, whereas marginal placenta previa with persist in only 2.5%
that’s why Antenatal diagnosis of low lying placenta at 20 weeks needs routine repeat of
ultrasound examination at 34 weeks to confirm the diagnosis.
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Transperineal (TPS)
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Three-dimensional (3-D) Power Doppler is the best. Hypervascularity at the uterine serosa – bladder junction is diagnosti
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MRI - to see if placenta previa or accreta
and posterioir placenta previa
what is a dangerous placenta previa?
marginal posterior placenta previa
major thickness of the placenta overlies the sacral promontory, thereby diminishing the anteroposterior diameter of the inlet and prevents engagement of the presenting part
hinders effective compression of the separated placenta to stop bleeding.
(2) Placenta is more likely to be compressed, if vaginal delivery is allowed.
(3) More chance of cord compression or cord prolapse.
management of placenta praaevia ?
All cases of APH should be admitted
infusion of normal saline is started and compatible cross matched blood transfusion should be arranged.
fresh frozen plasma
less than 36 weeks pregnant with only a small amount of bleeding recommendations may include bed rest and avoiding sexual intercourse.
Steroid therapy if less than 34 wks
Use of tocolysis (magnesium sulfate) can be done if vaginal bleeding is associated with uterine contractions
carried till 37 wks
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For those after 36 weeks of pregnancy or with a significant amount of bleeding,
cesarean section is generally recommended.
especially indicated if it is posterior
Vaginal delivery may be considered where placenta edge is > 2–3 cm away from the internal
cervical os
complication of placenta praaevia ?
antepartum haemorrhage with varying degrees of shock
antepartum anemic state - leding to post partum shock shock
malpresentation
preterm labour
prom
cord prolapse - intrauterine death
slw dilation of cervix due to plaenta attacmnet
post partum hemorrhage -
due to uterine atony of anemic state
or imperfect contraction of the lower uterine segmnet
IUGR
placenta accreta
what are the placenta previa complication in puerperium?
Sepsis is increased due to: (b) placental site near to the vagina and anemia a
Subinvolution
Embolis
what may complicate a case of placenta previa
preeclampsia
bleeding occurs before 38 weeks
what is placenta accreta?
chorionic villi attach to the myometrium, rather than being restricted within the decidua basalis.
Important risk factors for placenta accreta are
placenta previa and prior cesarean deliver
