Wiki.placental abnormalities1

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Placental Abnormalities

Christina Rust, MSN, RNC-OB

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Bleeding In Pregnancy

5% of all women experience some kind of vaginal bleeding during the 3rd trimester

Two major causes:

- Placenta Previa

- Abruption

Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 404.

Gilbert, E.S. (2007). Manual of high risk pregnancy & delivery (4th ed.). St. Louis, MI.: Mosby Elsevier, p.392.

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Placenta Previa - Definition

Abnormally implanted placenta placed totallly or partially in the lower segment of the uterus, rather than in the fundus.

When the cervix begins to dilate and efface, the placenta separates, allowing bleeding from the open vessels.


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Three Categories of Placenta Previa

Total/Complete – The placenta completely covers the internal cervical os in the third trimester.(20-43%)

Partial – The placenta implants near and partially covers the internal os.(23-49%)

Marginal – The edge of the placenta is within 2-3 cm of the internal os. (31%)

* Low Lying – The exact relationship of the placenta to the internal os is unknown.Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 404.

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Placenta Previa

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Etiology of Placenta Previa

Unknown cause – When the embryo is ready to implant and the decidua in the fundus is deficient, it will choose another spot lower in the uterine segment

Placentas are larger on the maternal side, cord often has marginal or vellamentous insertion. Suggests that the placenta was growing toward more favorable decidua.


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Chorionic Villi

Two types of chorionic villi

- Opens up into intervillous spaces that support exchange of oxygen and nutrients between fetal and maternal circulation

- Anchors the placenta to the wall of the uterusChorionic villi growth normally stays within the

endometrium because of the fibrinoid layer of Nitabuch. It separates the decidua from the myometrium and stops villi growth..


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Theories of Placenta Previa

Damage to endometrium or myometrium from surgery or infection

Any process that prevents migrationImpeded endometrial vascularization due to poor

blood supply from hypertension, diabetes, cigarette smoking, AMA

Early or late ovulationLarge placental mass (multiples)


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Do Placentas Move?

90% of placentas that implant low migrate ↑If > 2 cm cervical overlap migration is rareMigration - uterine growth from .5 cm to 5 cm

causes movement of the placenta away from the cervical os

Chorionic villi have the ability to grow in one area and be dormant in another area

Lower uterine segment elongates while uterine fundus hypertrophies during 3rd trimester

Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 405-6.

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Placenta Previa

Painless bright red vaginal bleeding – usually first bleeding episode not before 30 wks.

Suspected with oblique or transverse lie (placenta prevents descent into pelvis)

Diagnosed by U/S80-90% bleeding occurs without warningUterus non-tender – no rise in fundal heightAccompanied by contractions 20% of the timeGilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 406.

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Placenta Previa

Often occurs when sleepingFirst episode of bleeding usually scant, then

each episode more Hemorrhagic or hypovolemic shockDeliver by C/S if placenta covers cervix

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Risk Factors for Placenta Previa

Endometriosis after previous pregnancyUterine scars – abortions, C/S, molar

pregnancyTumors altering the contour of the uterusClose pregnancy spacingMultiparityLarge placenta

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Risk Factors for Placenta Previa

Hypertension, diabetesAdvanced maternal ageAfrican Americans or AsiansCigarette smoking

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Incidence of Placenta PreviaDepends on which trimester of pregnancy

- 2nd trimester – 45% of placentas in lower uterine segment.

- 3rd trimester - .5 -1% in lower uterine segment1 in 200 pregnanciesOccurs more often in grand multiparas – 2%History of previa – 4-8%Previous C/S - 2nd C/S – no increase in risk,

3rd C/S– 2.2%, 4th or more C/S - 10%

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Maternal Complications of Placenta Previa

Antepartum, intrapartum, postpartum hemorrhage and hypovolemic shock

- Lower uterine segment not as muscular, less able to contract

Accreta, increta, percretaAnemiaDICVasa PreviaRenal failure


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Maternal Complications of Placenta PreviaSepticemia – opened blood vessels near cervical

os and can become infected easilyProlonged hospital stayThrombophlebitisCesarean SectionAbruptionFetal Malpresentation


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Medical Management

Medical management depends on gestational age and severity of bleeding:

- Bedrest with BRP - IV - 16 g angio (Hep lock if no active bleeding) - CBC, Type & Screen, platelet count, fibrinogen, bleeding time - Observe closely for s/s of bleeding - Steroids for lung maturity - Rhogam if indicated


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Transvaginal ultrasound is modality of choice Transabdominal ultrasound lacks some precision in

identifying placenta previaSerial U/S should be performed to check for

placental placement, fluid level, and fetal growth


Medical Management

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Medical Management

No pelvic exams – Sterile speculum exam to rule out other causes of bright red bleeding - Polyps - Cervicitis - Cervical carcinoma - Sexual abuse

Controversy regarding tocolysis for contractions - bleeding causes uterine irritability (Magnesium sulfate not Brethine)


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Medical Management

No douching or intercourseNST daily, bi-weekly BPP Measure and mark fundal heightDaily iron and vitamin supplement If HCT < 30% - transfuseO2 at 10 liters per non-rebreathing face maskAmniocentesis at 34-36 wks. C/S for large blood loss


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Medical Management at Home

May be D/C home after 72 hrs. without bleeding in 2nd trimester

Requires strict instructions for bedrest w/BRP, kick counts, and when to return to the hospital

Long term hospital stay for bleeding in 3rd trimester

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Maternal Outcomes

Mortality less than 1%, morbidity 20%Most will have at least one significant

hemorrhage – 25 % will go into shockVaginal and cervical lacerations occur more

often with vaginal deliveriesPoor endometrium may contribute to placenta

accreta – 15 %Vasa previa more common with placenta

previaGilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 407.

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Fetal Outcome

Fetal mortality – 20 %

- Prematurity

- Hypoxia

- Severe anemia

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Fetal Outcome

Fetal morbidity

- Preterm birth

- IUGR

- Fetal anemia

- Malpresentation

- Developmental disorders

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Abruptio Placenta - Definition

Separation of the placenta from its uterine site of implantation after 20 weeks gestation, but before delivery of the fetus.


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Grades of Abruptio Placenta

Grade 1(Mild) (48%)

- Dark red vaginal bleeding mild/moderate

(< 500 ml)

- No uterine tenderness

- Mild tetany

- Reactive FHR strip

- < 1/6 of placenta separates


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Grade 2 (Moderate)- (27%)

- Dark red vaginal bleeding (1000-1500 ml

blood loss) but may be concealed

- Gradual or abrupt onset of abdominal pain

- Tetanic contractions possible

- Maternal tachycardia, tachypnea, BP okay

- Nonreassuring FHR tracing

- S/S DIC, fibrinogen 150-300 mg/dl

- 1/6 to 1/2 of placenta separatesGilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 393.

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Grade 3 (Severe) - (24%)

- Mod. to severe dark red bleeding(> 1500 ml)

- > 1/2 of placenta separates

- Tetanic contractions/ boardlike abdomen

- Usually abrupt knife-like abdominal pain

- Profound maternal hypovolemia and shock

- Significant fetal compromise including death,

- DIC, fibrinogen < 150 mg/dl Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 393.

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Classifications of Maternal Bleeding

Marginal or apparent - Separation near edge of placenta and blood can escape

Central or concealed - Separation in center of placenta and blood is trapped

Mixed or combined - Part of separation is at the edge and part in the center of placenta


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Incidence of Abruptio Placenta

Incidence 1:150 History of abruption - 5-17%10X greater risk in subsequent pregnancies Smoking - 90% increase in risk (Ananath 1999) Occurs in approximately 1% of primips, 2.5%

of multips


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Incidence of Abruptio Placenta

Mortality rate

- Maternal - 1% (14 in 1,000)

- Fetal - 25 to 30 %One of the leading causes of fetal and neonatal

mortality rates80% of all abruptions occur before the onset of

labor


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Etiology of Abruptio Placenta

Exact cause unknownPossibly begins with degenerative changes in

the spiral arteries that supply the intervillous spaces, resulting in thrombosis, degeneration of the decidua, necrosis, and finally rupture of the vessel.

Bleeding occurs because uterus is distended and can’t contract down on blood vessels


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Etiology of Abruptio Placenta

Hematomas form along with retroperitoneal clot, compressing adjacent placenta causing local destruction.

Further bleeding causes increased pressure behind the placenta which causes further separation.

Retroplacental hematoma (concealed bleed) releases large amounts of thromboplastin leading to DIC


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Conditions Associated with Abruptio PlacentaChronic hypertension/Preeclampsia - 5X higherShort umbilical cordTrauma - 5% risk with minor trauma - 50% risk

with major trauma - car accident, abuse, fallsHydramniosIV cocaine/crack use -10%Uterine AnomaliesGilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 392.

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OB Conditions Associated with Abruptio Placenta

History of abortionsPremature laborAntepartum hemorrhageStillbirth or neonatal

death6X greater with parity > 7Folic acid deficiencyMultiple gestationPROM -5% riskGilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI :

Mosby Elsevier, p. 393.

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OB Conditions Associated with Abruptio PlacentaCircumvallate placentaHx of Abruption - recurrence rate 10% with 1

abruption, 25% with 2 abruptionsDiabetesUterine fibroidsExtremes of maternal age Sudden uterine decompression Cigarette smoking - decidual necrosis


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Signs and Symptoms

Depends on type of abruption, location

and amount:

- Abdominal or low back pain - 50%

- Uterine hypertonus - 17%

- Uterine contractions - 17%

- Uterine tenderness

- Severe knife-like pain with boardlike

abdomen


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Signs and Symptoms

Uterus could be tender at point of separation or may be generalized over entire abdomen Increases uterine distention – elevated fundal height Bleeding - minimal or diffuse - Dark red, vaginal bleeding – 80% - (dark because it has had time to begin clotting)



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Signs and Symptoms

If some of the trapped blood is forced through fetal membranes into amniotic cavity, amniotic fluid become bloody

Shock is severeFetal distress or deathCoagulopathy / DICHypovolemia

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Diagnosis of Abruptio Placenta

Based on hx., physical exam, lab valuesNo analgesia / anesthesia until dx. confirmedVaginal bleeding with or without pain /shockIncreased uterine tone, tenderness, sustained

tetanic contractionsFetal distress

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U/S for placental localization - accurate

50 % of the timePalpation of abdomen, measure fundal

heightConfirm after delivery – inspect the

placenta

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Serum markers are being studied

- MSAFP associated with a 10X increase

in abruption

- hCG

- Inhibin A

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Couvelaire Uterus – Abruption that is concealed – Builds up enough pressure under the placenta that it forces the blood into the myometrial muscle fibers – also known as a “Blue Uterus”

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Maternal Outcomes

Renal failure from hypovolemiaBlood transfusionDIC – 30%Amniotic fluid embolisUterine rupturePostpartum endometritisPostpartum hemorrhageProlonged hospitalizationCesarean section / hysterectomy

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Fetal Outcomes

Cause of 12% of stillborns

PrematurityHypoxiaAnemia IUGRNeurologic deficts


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Medical Management

R/O placenta previaBedrest w/ BRPUltrasoundIV with large bore catheterType & Crossmatch, CBC, platelet count,

fibrinogen, bleeding time, PT/PTTRestore blood loss, correct coagulation defectFrequent vital signsStrict I & OGilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 399-400.

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Medical Management

No tocolytics until diagnosis confirmed -Magnesium sulfate may be used to prolong pregnancy for 48 hrs. to give time for steroids to work. DO NOT use Brethine - It will mask signs of shock.

Assess for signs of shock - cold, clammy skin, pale, anxious, thirsty

Assess FHR and uterine activityMeasure and mark fundal heightObserve for signs of vaginal bleedingGilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 399-400.

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Medical Management

C/S for fetal distress, maternal blood loss or compromise, coagulopathy, poor labor progress

Amniotomy to assess blood in fluidO2 per maskAvoid episiotomyBe aware of postpartum hemorrhageProvide emotional supportPatient teachingRhogam if indicated

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Velamentous Insertion of the Cord

Cord is implanted at the edge of the placentaVessels of the cord separate at a distance away

from the margin of the placenta surrounded only by a fold of amnion

Minimal to no Wharton’s Jelly to protect the vessels

Fetus may become hypovolemic and die quickly if vessels rupture

If bleeding is seen, mother should be tested for fetal cells (Kleihauer-Betke)

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Increased incidence of structural defects:

- Congenital hip dislocation

- Asymmetrical head shapeIncreased risk for IUGR and preterm birthOccurs in 1% singleton births (1:1275 to 1:8333)

Mattson, S. & Smith, J.E. (2004).Core curriculum for maternal-newborn nursing (3rd ed.). St. Louis, MO.: Elsevier Saunders, p.64.

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Vasa Previa

Rare circumstance that may occur with velamentous insertion of the cord where umbilical vessels cross the internal os presenting ahead of the fetus. Requires a C/S.

Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MO.: Mosby Elsevier, p.414.

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Vasa Previa

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Vasa Previa

Because fetal blood volume is only 80 to 100 ml., tearing of fetal vessels will cause hemorrhage and rapid fetal death

No problem to the motherWhen the fetal membranes rupture

75-90 % of the time the velamentous vessels will rupture


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Vasa Previa

Risk Factors - Succenturiate or low lying placenta - Multiple gestations - No Wharton’s jelly - cord compression- fetal hypoxia - fetal death 75% of time


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Vasa Previa

Treatment - U/S - Observe for vaginal bleeding - especially after vaginal exam - Hospitalize at 30 - 32 wks. - Steroid management - C/S at 35-36 wks.


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Circumvelate Placenta

The fetal surface of the placenta is exposed through a ring of chorion and amnion opening around the umbilical cord

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Circumvelate Placenta

Abnormally thickened placenta with smaller surface area over the uterine wall because membranes do not insert at the edge of the placenta.

Villi are left uncovered by the membranes resulting in bleeding and increased possibility of abruption.

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Succenturiate Placenta

One or more accessory lobes of the villi have developed

Vessels from the major to the minor lobes are only supported by membrane.

Increase the likelihood that the minor lobe(s) may be retained during the third stage of labor.

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Succenturiate Placenta

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Battledore Placenta

Cord is inserted at or near the placental margin rather than in the center

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Battledore Placenta

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Placenta Accreta

A rare condition in which all or part of the placenta is unusually adherent to the myometrium.

The normal spongy layer of the decidua is absent or defective allowing the placental villi to grow down through the endometrium into the myometrium.


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Types of Accretas

Accreta – Chorionic villi adhere to the myometrium

Increta – Villi invade into the myometriumPercreta – Villi invade into through myometrium

and beyond the serosa layer, often into the bladder or rectum


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Placenta Accreta

Predisposing Factors - Implantation over a previous C/S scar or other surgical scar in the uterine cavity - 2nd C/S - 10-25% risk , 3rd or more C/S – 40-50% risk - Previous curetagge - Prior hx. of endometritis or other endometrial trauma - High parity - Placenta previa – 5-10%Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 415.

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Placenta Accreta

May involve one cotyledon, a few

cotyledons, or all of the cotyledons Rate has increased over last 20 yrs.,

most likely due to the increase in C/S rate1:2500

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Signs and Symptoms

None until deliveryDepends on depth, site of penetration, number

of cotyledons involvedIf accreta is partial some cotyledons may

separate from uterine wall leaving open, bleeding vessels. Uterus unable to contract because of adherent placenta still within uterine cavity. Profuse hemorrhage occurs.

If total accreta, tearing occurs when doctor tries to deliver placenta.Uterine inversion may occur.

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Diagnosis

Sometimes can be diagnosed by U/S or MRI – but not 100% effective

Usually when attempt is made to remove the placenta and it will not come out


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Outcome of Placenta Accreta

Hemorrhage – Average blood loss 3000ml to 5000 ml

ShockHysterectomyUterine inversionInfectionMaternal death

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Treatment of Placenta Accreta

Large bore IV catheterIV fluids, replace blood lossUltrasoundType & Screen, CBC, platelet count, fibrinogen,

Pt, PTT, bleeding timeAccurate I & OAssess vital signsD & C / HysterectomyDO NOT pull too hard on the umbilical cord

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Other Causes of Bleeding in Pregnancy

Vascular changes in cervix due to pregnancy

IntercourseSTIs’ – Chlamydia, Bacterial Vaginosis,

TrichimoniasisCervical change with preterm laborUterine dehisenceCervical cancer

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Cervical CancerOne in 34 women diagnosed with cervical

cancer is pregnantRare complication – 0.2% to 0.9%Remains the most common type of gynecologic

malignancy Mean age of diagnosis is 31.8 years

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Amniotic Band Syndrome

Arise from rupture of amnion, usually at cord insertion site usually between 28 days after conception and 18 weeks of gestation

Etiology unknown but results in floating strands and cords of the amnion

Sticky floating bands that can adhere to fetus

Amniotic Band Syndrome retrieved on May 31, 2009 from http://www.fetalcarecenter.org

Mattson, S. & Smith, J.E. (2004). Core curriculum for maternal-newborn nursing (3rd ed.). St. Louis, MO.: Elsevier Saunders,. p. 61-62.

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Incidence – 1:1,200 to 1;15,000Possible causes:

- Premature rupture of membranes

- Inflammation and trauma

- After amniocentesis - Oligohydramnios may be present

Amniotic Band Syndrome retrieved on May 31, 2009 from http://www.fetalcarecenter.org

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Restricts embryonic development or causes structural abnormalities later in gestation - Anenecepahly

- Cleft lip and palate

- Choanal atresia

- Limb reduction/amputations/syndactaly

- Omphaloceles and gastrochesis

- Ear deformities - Club feet Mattson, S. &

Smith, J.E. (2004). Core curriculum for maternal-newborn nursing (3rd ed.). St. Louis, MO.: Elsevier Saunders,. p. 61-62.

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Amniotic Band Syndrome (ABS)

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