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.
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 405.
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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.
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 404.
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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..
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 404.
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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)
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 405.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 407.
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Maternal Complications of Placenta PreviaSepticemia – opened blood vessels near cervical
os and can become infected easilyProlonged hospital stayThrombophlebitisCesarean SectionAbruptionFetal Malpresentation
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 406-7.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 408.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 407.
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)
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 407.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 407-8.
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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.
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 392.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 393.
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Grades of Abruptio Placenta
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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Grades of Abruptio Placenta
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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 392.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 392.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 397.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 395.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 392.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 392.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 392.
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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)
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 392.
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 392.
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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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Diagnosis of Abruptio Placenta
U/S for placental localization - accurate
50 % of the timePalpation of abdomen, measure fundal
heightConfirm after delivery – inspect the
placenta
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Diagnosis of Abruptio Placenta
Serum markers are being studied
- MSAFP associated with a 10X increase
in abruption
- hCG
- Inhibin A
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Diagnosis of Abruptio Placenta
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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 392.
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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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Velamentous Insertion of the Cord
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Velamentous Insertion of the Cord
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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 414.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 415.
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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.
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 414.
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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.
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 415.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 415.
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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
Gilbert, E.S. (2007). High risk pregnancy & delivery(4th ed.). St. Louis, MI : Mosby Elsevier, p. 413.
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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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Amniotic Band Syndrome
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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Amniotic Band Syndrome
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)