placenta previa 2010

8/7/2019 placenta previa 2010

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Placenta previa (PP)I. Placenta previa (PP) is defined asthe presence of placental tissue over ornear the internal cervical os.PP can be classified into

four types based onthe location of the placenta relative tothe cervical os:

to the internal os.


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complete or total previa,the placenta covers the entirecervical os;partial previa,the margin of the placenta covers

part but not all of the internal os;marginal previa,the edge of the placenta liesadjacent to the internal os;

low-lying placenta,placenta is located near (2 to 3 cm)

but not directly adjacent


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A . Epidemiology1. the incidence of PP is 1 in 200 to 1 in 390

pregnancies over 20 weeks' gestational age).varies with parity,For nulliparous, the incidence is 0.2%,

in grand multiparous, it may be as high as 5%2. The most important risk factor for PP is a

previous cesarean section.PP occurs in 1% of pregnancies after a

cesarean section.The incidence after four or more cs increases

to 10%


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3. Other risk factorsincreasing maternal age after age 40),multiple gestation, and previousuterine curettage4. the placenta covers the cervical os

in 5% of pregnancies when examinedat midpregnancy.The majority resolve as the uterus

grows with gestational age.The upper third of the cervix developsinto the lower uterine segment, andthe placenta "migrates " away from theinternal os.


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B . Etiology. unknown.

a. Endometrial scarring.b. A reduction inuteroplacental oxygen

promotes need foran increase in the placental

surface area

that favors previa formation.


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2. B leeding occur in association withthe development of the lower uterinesegment in the third trimester.

Placental attachment is disrupted

because this area gradually thins inpreparation for labor.


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the thinned lower uterine segment is

unable to contract adequately toprevent blood flow from the open

vessels. shearing action3. Vaginal examination orintercourse may also cause separation

of the placenta from the uterine wall.


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C . C linical Manifestations1. 80% of affected patients present

with painless vaginal bleedingMost commonly,the first episode is around 34 weeks of

gestation;one-third of patients develop bleedingbefore 30 weeks


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2. 30% patients develop bleeding after36 weeks,

10% go to term without any bleedingThe fluid is usually bright red,and the bleeding is acute in onset.

3. The number of bleeding episodes isunrelated to the degree of placenta

previa or

the prognosis for fetal survival.


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4. pp is associated with a doubling of the rate of congenital malformations.a. CNS , GI tract, cardiovascularsystem, and respiratory systemb. Pp is also associated with

fetal malpresentation,preterm premature rupture of membranes, and

intrauterine growth restriction.


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c. A bnormal growth of the placentainto the uterus can result in one of the

following 3 complications:i. Placenta Previa A ccreta.The placenta adheres to the uterine

wall without the usual interveningdecidua basalis.The incidence in patients with previawho have not had previous uterinesurgery is 4%.The risk is increased 25%in patients who have had a previous

cs or uterine surgery


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ii. Placenta Previa Increta.

placenta invades myometrium.iii. Placenta Previa Percreta.

The placenta penetrates theentire uterine wall

growing into bladder or bowel.


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D . D iagnosis1. History.PP presents with acute onset of painless vaginal bleeding.A thorough history should be obtained

from the patient, including obstetricand surgical history as well asdocumentation of previous ultrasoundexaminations.Other causes of vaginal bleeding must

also be ruled out, such as placentalabruption.


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2. Vaginal sonography is the goldstandard for diagnosis of previa

Placental tissue has to be overlying orwithin 2 cm of the internal cervical os tomake the diagnosis.

The diagnosis may be missed bytransabdominal scan,if the placenta lies in the posterior

portionempty bladder may help in identifying

anterior previas, andTrendelenburg positioning may be

useful in diagnosing posterior previas.


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C omplete placenta previa. S agittal mid-line view of the loweruterus performed tau the placenta (PL) completely covering the cx


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Marginal/partial placenta previa in 3RD trimester patient w ith

b leeding. T vu sho w s inferior edge of posterior pl (P) located at

internal CX os


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3. Examination. IfPP is present, digitalexamination is contraindicated.

a. A speculum examination can be usedto evaluate the presence and quantity

of vaginal bleeding;, the amount of vaginal bleeding can be

assessed without placing a speculumand potentially causing more bleeding.

b. Maternal vital signs,abdominal exam, uterine tone, and

fetal heart rate monitoring should beevaluated.


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4. Laboratory S tudies. The followinglaboratory studies should be done for a

patient with PP with vaginal bleeding:a. C omplete blood cell countb. Type and cross-match

c. Prothrombin time and activatedthromboplastin timed. Kleihauer test to assess forfetomaternal hemorrhage


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E. Management1. S tandard Management

a. In the third trimester in a patient whois not bleeding,recommendations includeultrasound confirmation

pelvic rest (nothing in the vagina,including intercourse or pelvic exams),explanation of warning signs and when to

seek immediate medical attention,

avoidance of exercise and strenuousactivity,and fetal growth ultrasounds every 3 to 4

weeks.Fetal testing semiweekly


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b. S tandard management of symptomatic patients with PP

hos-pitalization with hemodynamicstabilization andcontinuous maternal and fetalmonitoring.Laboratory studies should be orderedS teroids should be given to promotelung maturity for gestations between

24 and 34 weeks.Rho( D ) immunoglobulin should beadministered to Rh-neg-ativemothers.


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c. Management of PP is then based ongestational age,severity of the bleeding, andfetal condition and presentation.

d. Management of complications, such

asplacenta accreta or one of its variants


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In patients with PP and a previoushistory of cesarean section, cesarean

hysterectomy-may be required.in cases where uterine preservation is

highly desired and no bladder invasionhas occurred,

bleeding has been successfullycontrolled with selective arterialembolization or

packing of the lower uterine segment,with subsequent removal of the packthrough the vagina in 24 hours.


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2. Term Gestation, Maternal andFetal Hemodynamic S tability.A t this point, management depends

on placental location.a. C omplete Previa.Patients with complete previa at

term require cesarean section.


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b. Partial, Marginal Previa.These patients may deliver vaginally;a double setup in the operating room isrecommended.The patient should be prepared and

draped for cesarean section.A n anesthesiologist and the operating

room team should be present.

If at any point maternal or fetalstability is compromised, urgentcesarean section is indicated.


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3. Term Gestation,Maternal and Fetal

Hemodynamic Instability.The first priority is to stabilize

the mother withfluid resuscitation andadministration of blood products,

if necessary.


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a. D elivery is indicated withevidence of nonreassuring fetal heart

rate tracing,life-threatening maternal hemorrhage,or any bleeding after 34 weeks with

known fetal lung maturity.b. D elivery should then occur via cs.If the mother is hemody-namically

stable and fetal loss has occurred orthe fetus is less than 24 weeks,then vaginal delivery can beconsidered.


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4. Preterm Gestation, Maternal andFetal Hemodynamic S tability

a. Labor A bsent.Patients at 24 to 37 weeks' gestation

with PP who are hemo-dynamically

stable can bemanaged expectantly until fetal lung

maturity has occurred.

Hospitalization until stabilizedB ed rest withperiodic assessment of maternal

hematocrit


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B lood transfusions to keep hematocritabove 30% in patients with a

low-grade continuous bleedsteroids for fetal lung maturityFetal testing, and serial ultrasoundsTocolysis is used forthe administration of antenatal

steroids in an otherwise stablepatient.


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A fter initial hospital

management,care as an outpatientif the bleeding has stoppedfor more than 1 week,no other complications exist,

and the following criteria aremet:


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once a patient has been

hospitalizedfor three separate episodes of

bleeding,she remains in the hospital until

delivery


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b. Labor Present.Twenty percent of patients with

PP show evidence of uterinecontractions.If the patient and fetus arestable,tocolysis may be considered

with magnesium sulfate.


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Preterm Gestation,Maternal and Fetal Hemodynamic

Instability.maternal stabilization withresuscitative measures is the

priority.Once stable,

the patient should be delivered byurgent cesarean section.


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RUPTURE V ASA PR A EVI A

This is a very rare condition in which

the umbilical vessels in themembranes are passing oppo - site theinternal cervical in case of velamentous insertion of the cord.

Rupture of these vessels will lead to

bleeding of fetal origin which is verydangerous


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It should be suspected when

fetal distress is marked with mildvaginal bleeding and good generalcondition of the mother. Examination of the blood will showfetal R BC s.Treatment is by immediatecaesarean section


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KEY POI N TS I N A PH1. In cases ofPP the patient presents

with painless, causeless, and recurrentbleeding.

If bleeding is severe the patient willbe in state of hypovolaemic shock.


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2. In concealed accidentalhaemorrhage the patient usually

presents with acute ab-dominal painwhich is sudden, severe, andprogressive.

S hock if present may behypovolaemic or neurogenic.


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3.In concealed accidental hagethe patient's general conditionmay be poor, and deteriorating,in-spite of absent, or minimal,revealed vaginal bleeding.S uch cases are also at high risk

for development of D I C , and

C ouvelaire's uterus


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4. The fetus is more affected

in cases of placental abruptionthan in PP

5. Ultrasonographyis the gold standard in

diagnosing the cause of A PH.


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6. In cases of mild A PH, with

non recurrent bleeding,conservative management isallowed only

until reasonable fetalmaturity is achieved.


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7. In cases of severe A PH,irrespective of the cause,

immediate anti-shock measures andpregnancy termination are indicated. C aesarian section is the most

appropri-ate choice inthe majority of cases.


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8. A nti- D immunoglobulin is to begiven to non sensitized RH negativemothers (those without previouslydetected antibodies)if they experience a moderate

bleed-ing episode in the thirdtrimesterwhile conservative management has

been de-cided.

placenta previa 2010

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