6 Prevalence of Placenta Previa Occurs in 1/200 pregnancies that reach 3rd trimesterLow-lying placenta seen in 50% of ultrasound scans at weeks90% will have normal implantation when scan >30 weeksNo proven benefit to routine screening ultrasound for this diagnosis.
7 Risk factors for previa Previous Cesarean SectionsPrevious Uterine InstrumentationHigh ParityAdvancing Maternal AgeWomen over 40 have a RR of 9.0SmokingMultiple GestationBleeding More Likely than those with an unscarred uterusIncidence increases with increasing number of cesareansFebrile Post-op Period3.9% in women with previous C-sectionsIncreased inEndometritisShort Inter-pregnancy interval
8 Morbidity with Placenta Previa Maternal HemorrhageOperative Delivery ComplicationsTransfusionPlacenta accreta, increta or percretaPrematurityDigital exam can cause exanguinating hemorrhageTransfusion may be necessaryPlacenta accreta et al more common in women with a previous c-section as depicted in the previous slideComplications of premarturity, and management should be influenced by the gestational age and balanced against the maternal condition
9 Placenta MigrationMigration means the dynamic relationship between the placenta and the internal osTrophotropism vs elongating lower uterine segment!
10 Previous C-sections and Previas 10% risk of an accreta with a previous cesarean and a previa.In any patient with a previous cesarean and a previa, a transvaginal sono of the LUS should be done to determine in vaginal or cesarean delivery is donePrevious Cesarean Sections - preference to ant. Wall- 66%,Bleeding more likely than in those with an intact uterus 44%-28.5%Incidence increases with increasing number of cesareans (Anath). Metanalysis of studies published betweenAnath ObGyn 1996
11 Patient History - Placenta Previa Painless Bleeding*2nd or 3rd trimester, or at termOften following intercourseMay have preterm contractions*Sentinel BleedFrom large central previa@ weeks gestationBleeding after intercourse is often reported yet is nonspecificPain that persists btwn contractions is suggestive of abruptionSentinal Bleed is that which is not so excessive as to require delivery, but is a warning. With slowing of bleeding, clinician must decide wjether to care for locally od transfer.
12 Physical Exam-Placenta Previa Vital SignsAssess Fundal HeightFetal LieEstimated Fetal Weight (Leopold)Presence of fetal heart tonesGentle Speculum ExamNo digital exam unless placental location knownPrevia should be considered in patients with an abnormal lie. May influence the type of uterine incision - transverse lie with spine up - consider low trans, spine down - vertical incisionGentle speculum exam permissible and useful. The endocervical canal and the vagina are at right angles.
13 Speculum exam revealing an anterior placenta previa
14 Laboratory - Placenta Previa Hematocrit or complete blood countBlood Type and RhCoagulation tests(While waiting - serum clot tube taped to the wall)
15 Ultrasound - Placenta Previa Can confirm diagnosisFull bladder can create false appearance of anterior previaPresenting part may overshadow posterior previaTransvaginal scan can locate placental edge and internal os
16 The Placenta’s Ultrasound Appearance Echodense placental tissueEcholucent myometrialArea rich in blood supply
17 Vagina and Cervix meet at 90 degrees )Transvaginal Ultrasound Scanning is safe in the bleeding patientVagina and the cervix meet at a 90 degree angle, careful insertion of the vaginal probe midway into the vagina will image theCareful insertion of the vaginal probe midway into the vagina will image the LUS and the cervical os
20 False Previa Full bladder No Previa c Lower placental border Normal cervical canal. Longitudinal scans demonstrate a normal canal(arrows)Which is in a nearly vertical orientation because of an empty urinary bladder(test?)With a full urinary bladder the cervical canal(arrow) is in a more horizontal orientation.Also note that the cervical canal and lower uterine segment are artificially lengthened from compression by a distended bladderLower placental borderFull bladderNo Previa
21 False Previa - Overdistended Bladder Cervical canalA false positive diagnosis of placenta previa in this case owing to an overly distended placenta previa in this case owing to an overly distended urinary bladder which resulted in the elongation of the cervix to 7 cmArrows point to the the artificially elongated endocervical canalc
22 Placental Edge by U/S and Route of Delivery >2 cm os - placenta edge = safe for vaginal delivery<1cm os - placenta edge - Cesarean delivery1-2 cm = may be able to deliver vaginalDawson et al Jultrasound Medicine 1996
23 Ultrasound’s RolePrevia = usually definitive except in very low lying posterior placentas in the obese patientAbruption - definitive diagnosis is not possibleTransvaginal Scanning is safe in the bleeding patient
25 Initial management 1) ABC’s 2) Fetal Well Being 3) No Vaginal Exams Amount of bleeding noted is unreliable2) Fetal Well Being3) No Vaginal ExamsUntil you know where the placenta is!4) Ultrasound
26 Fetal/Neonatal Considerations Gestational Age of Fetus dictates local of careSGA/Prematurity are major problemsCommunication with consultants is key!Fetal/Neonatal ConsiderationsGA of fetus may dictate where patients are observed/delivered as well as considerations for obstetrical co-morbiditySGA, Prematurity and asphyxia were major problems associated with placental abruptions in a Scandinavian study of 9592 cases of placental abruption in 1.4 million births over a 24 year period.Communication between primary physician and consultant is key!
27 Cesarean Sections and Previas Category CPre-op ScanPatients with Previas undergoing C-SectionBleed MoreRequire More Blood TransfusionRequire More C-HysterectomiesPlacenta accreta may accompany 10%Bladder invasion may be associated withDIC and massive hemorrhageConsiderations for those performing C-sections on patients. Since risk of a previa increases with each cesarean, this entity is something every patient should be screened for in the prenatal period to alert clinician of this condition (Deutchman). Ultrasonography can be also utilized to screen and detect placenta perorate wit bladder invasion. (Chung)In one study, the patients who had previas undergoing sections were compared with control patients undergoing cesarean section. Patients with previas bled more (1154 vs 632cc’s), required more blood transfusions (15% vs. 4.5%) and underwent Cesarean Hysterectomy 4.5% vs 0%. In one study the incidence of placenta accreta among women with placenta previa was nearly 10%(Craig). If bladder invasion occurs, other potential complications can result, including massive hemorrhage and the development of DIC(Silver) at the time of surgery. This underscores the importance of having the intra-operative involvement of a surgeon capable of performing a cesarean hysterectomy at the time of surgery.
28 Treatment Placenta Previa With no active bleedingExpectant managementNo intercourse, digital examRescan after 30 weeksWith late pregnancy bleedingAssess overall status, circulatory stabilityFull dose Rhogam if Rh -Consider maternal transfer if prematureMay need corticosteroids, tocolysis, amniocentesisCategory BInpatient vs Output management depends on the gestational age, number and severity of bleeding episodes, pt reliability and distance from homeHospital care may provide no benefit (Cat C)Cerclage placement may reduce the risk of delivery prior to 34 weeks.(Cat C)No contraindications to tocolytic in a 3ry care center. No rtc data- Cat B
29 Expectant ManagementMay discharge home if stable after 72 hours of inpatient observation.Reduces stay in hospital by average of 14 days.No increase inHemorrhageNeed for transfusionPoor maternal or neonatal outcomes
30 Tocolytics in Placenta Previa Greatest morbidity and mortlity related to prematurity.Tocolytics can add an additional 11 days to pregnancy.Allows for administration of corticosteroidsNo increase in maternal or fetal complicationsIncrease birth weights average of 320 grams
31 Double Set-up Exam: digital exam in OR with ability to do immediate CD Appropriate only in marginal (anterior) previa with vertex presentationPalpation of placental edge and fetal head with set up for immediate surgeryCesarean delivery under regional anesthesia ifComplete previaFetal head not engagedNon-Reassuring tracingBrisk or Persistant bleedingMature fetusA posterior low lying or a posterior a posterior marginal previa may obstruct the descent of the fetal head.Marginal Ant previa test ? If vaginal delivery is felt to be permissible, then labor is allowed to proceed, with close monitoring and ready availability of operative personnel.General anesthesia is associated with increased blood loss and need for a blood transfusion. Regional anesthesia is a safe alternativeCategory D
32 Placental Abruption Premature separation of placenta from uterine wall Partial or Complete“Marginal sinus separation” or “marginal sinus rupture”Bleeding, but abnormal implantation or abruption never establishedIN marginal sinus rupture - fetal compromise not present. Vaginal bleeding resolves without explanation, uterine tenderness are absent and prognosis is good.
33 Epidemiology of Abruption* Occurs in 1-2% of all pregnanciesRisk FactorsHypertensive diseases of pregnancySmoking or substance abuse*Trauma*Overdistension of the Uterus*History of Previous Abruption*Unexplained elevation of MSAFPPlacental insufficiencyMaternal Thrombophilia/Metabolic abnormalitiesSubstance abuse-particularly alcohol and cocaine
34 Abruptions and Trauma Category C Can occur with blunt abdominal trauma and rapid deceleration without direct traumaComplications include prematurity, growth restriction and stillbirthFetal evaluation after traumaIncreased use of FHR monitoring may decrease mortalitySeparation of the placenta and retroplacental hemorrhage can occur with traumaShearing forces or shock in deceleration without traumaIn pregnant women at Level 1/II trauma centers - 84% experienced blunt trauma, 16% had penetrating injuriesPlacental abruptions was the most common, 3.5% of injured pregnant women, >50% demise. Only 61% received cardiotoco monitoring.Category C
35 Bleeding from Abruption Externalized hemorrhageBloody amniotic fluidRetroplacental clot20% occult“uteroplacental apoplexy or Couvelaire uterusLook for consumptive coagulopathy20% of abruptions are occult.Bleeding into the myometrium results in “uteroplacental apoplexy or a Couvelaire uterus which may or not contract effectively and result in postpartum hemorrhageCoagulaopathy results from a consumption of clotting factors in extravacular coagulopathies. Separation of the placenta is also associated with a release of thrombi plastic substances that may set off clotting cascade.
37 Cigarette Smoking as Risk factor Nova Scotia Registry of 87, 184 pregnancies33% smoked2.05 Relative Risk of Abruption1.75 Relative Risk of PreviaNo dose effect notedAnath AmJ of Epidemiology 1996
38 Cocaine/Metamphetamine Associated withchorionic villous hemorrhageVillous edemaEven in the absence of clinical abruption placenta
39 Patient History: Abruption Pain = hallmark symptom*Varies from mild cramping to severe painBack Pain - think posterior abruptionBleedingMay not reflect amount of blood loss*Differentiate from exuberant bloody showTraumaOther risk factors (e/g hypertension/drugs)Membrane ruptureActive laboring women should not complain of abd pain or tenderness(test?) between contractionsIf bleeding occurs at time of SROM-vasaprevia should be suspectedQuestions re: trauma, presence of pain, contractions, srom and risk factors
40 Physical Exam- Abruption Signs of circulatory instabilityMild tachycardia normalSigns and symptoms of shock represent > 30% blood lossMaternal abdomenFundal heightLeopold’s:estimated fetal weight, fetal lieLocation of tendernessTetanic contractionsExamine patient quickly for:Are there orthostatic changesIf patient has previous hypertensive disease - consider her BP in comparisonNeuro exam or complete physical may be neededTetanic contractions - high resting tone with superimposed small frequent contractions. The presence of the finding is significant as it is often accompanied with a non reassuring fhr tracing
41 Fetal/Uterine Monitor in an Abruption If no reassuring- emergent cesarean delivery should occur, since a significant number will end in fetal demise even in patient’s who present to the hospital with a live fetus.
42 Ultrasound Abruption Abruption is a clinical diagnosis!* Placental location and appearanceRetroplacental echolucencyAbnormal thickening of placenta“Torn” edge of placentaFetal lieEstimated fetal weight
43 Placental Abruption Hemorrhage isoechoic with placenta Placental abruption with isoechoic hematoma. This hematoma has no distinct margin with the placenta. The straight arrows delineate the anterior margin of the placenta, curved arrows mark the posterior aspect of the hematoma at the myometriumThe right image reveals a large retroplacental hematoma. A large heterogeneous echotexture (asterisk) is seen behind a posterior placenta. This hematoma could be easily mistaken for a myofibroma or contractionHemorrhage isoechoic with placentaHematoma retroplacental
44 Abruption - Retroplacental Hematoma Retroplacental hematoma initial sonogram at 25 weeks gestation is large hyperechoic arrowhead in the placentaRepeat sonogram 1 week later shows that the hemotoma has become hypoechoic relative to the placenta. There was subsequent fetal death.Retro placental hematoma day17 days later
45 False Abruption? Contraction Mimicking Abruption These subsegmental contractions can last a few to many minutesNo Contraction30 minutes later
46 Placenta Lakes Subchorionic Placental Lake Placenta lake are subchoironic, yet can be marginalDoppler can help differentiate it from a clotDoppler revealing flow through the lake
47 Laboratory-Abruption Complete blood countType and RhCoagulation tests + “Clot test”Kleihauer-Betke test not diagnostic, but useful to determine Rhogam dosePre-eclampsia labs, if indicatedConsider urine drug screenTape additional sample to wall in red top tube - check in 7-10 minutesPre-eclampsia labs - Fibrinogen levels <250mg/dl are abnormal and those <150 are diagnostic for coagulopathyPT/PTT may be abnormalFDP may be abnormal yet presence of D-dimer is poorly correlated with the diagnosis of abruption.Fibrin D Dimer is poorly correlated with the diagnosis of abruptionA new marker - thrombomodulin, has been utilized in confirming placental abruption in some studies yet not widely available
48 Sher’s Classification Grade IMild, often retroplacental clot identified at deliveryGrade IITense, tender abdomen and live fetusGrade III-IIIA-IIIBWith fetal demise-without coagulopathy (2/3)-with coagulopathy (1/3)Expeditious vaginal delivery is indicated for patients presenting with both a live fetus (grade II) and a dead fetus (grade III)
49 Treatment-Grade II Abruption Assess fetal and maternal stabilityAmniotomyIUPC to detect elevated uterine toneExpeditious operative or vaginal deliveryMaintain urine output > 30 cc/hr and hemotocrit > 30%Prepare for neonatal resuscitationCategory CIf the patient has a reassuring fetal heart rate tracing and is in active labor, vaginal delivery can be permittedThe threshold for operative delivery should include any demonstration of fetal intolerance of labor in a patient where vaginal delivery is not imminent.If labor is continuing, an amniotomy should be done to accelerate the processAnd may reduce the incidence of amniotic fluid embolus.If labor not progressing rapidly to a vaginal delivery then a cesarean delivery should be performed because of the high risk to the fetus.
50 Treatment - Grade III Abruption Assess mother for hemodynamic and coagulation statusVigorous replacement of fluid and blood productsVaginal delivery preferred, unless severe hemorrhageOxytocin administration is not contraindicated if labor hypotonic but should be used judicious with the aid of an IUPCIndications for cesarean delivery include failure of labor progression, brisk hemorrhage that cannot be compensated by a transfusion.Category C
51 Coagulopathy with Abruption Occurs in 1/3 of Grade III abruptionsUsually not seen if live fetusEtiologies: consumption, DICAdminister platelets, FFPGive Factor VIII if severeEtiologiesConsumption and DICAdmin platelets and FFP prior to operative delivery, cryoprecipitate or Factor VIII may be of specific benefit in severe coagulopathy.
52 Epidemiology of Uterine Rupture* Occult dehiscence vs.. symptomatic rupture.03%-.08% of all women.03%-1.7% of all women with uterine scarPrevious cesarean incision most common reason for scar disruptionOther causes: previous uterine curettage or perforation, inappropriate oxytocin usage, trauma, drugs*Rupture of 2.6% for inducted VBAC’s
53 Risk Factors - Uterine Rupture* Previous Uterine Surgery*Congenital Uterine AnomaliesUterine Overdistension*Gestational Trophoblastic DiseaseAdenomyosisFetal AnomalyVigorous Uterine PressureDifficult Placental RemovalPlacenta Increta or Percreta (US/MRI)During labor or deliveryConditions present during index pregnancyConditions during labor and delivery
54 Uterine Scar Disruption Can be an occult separation, thinning or dehiscence that is discovered at repeat cesarean section. Complete rupture as in these examples requires emergency laparotomy and may include fetal extrusion and/or demiseExtension ofTransverseScarMidlineClassicalRuptureCatastrophicRupture
55 Morbidity with Uterine Rupture MaternalHemorrhage with anemiaBladder ruptureHysterectomyMaternal DeathFetalRespiratory distressHypoxiaAcidemiaNeonatal deathBladder rupture .05%Hysterectomy .1 %Maternal death rareFetal morbidity is more common
56 Patient History -Uterine Rupture* Vaginal BleedingPainCessation of contractions*Absences FHRLoss of StationPalpable fetal parts through maternal abdomenProfound maternal tachycardia and hypotension13% of uterine ruptures occur outside of the hospital. Patient’s with a previous uterine scar should be advised to come to the hospital for evaluation upon the onset of contractions, abd pain or vaginal bleeding asap
57 Uterine Rupture Category C Sudden deterioration of FHR pattern is a most frequent findingPlacenta may play a role in uterine ruptureTransvaginal ultrasound to evaluate uterine wallMRI to confirm possible placenta accretaTreatmentAsymptomatic scar disruption* - expectant managementSymptomatic rupture - emergent cesarean deliveryCategory CInstitute intrauterine resuscitation while waiting for cesareanmaternal position changes, iv fluids, d/c pit, o2 administration, sq terbA small false negative rate of cesarean deliveries may be acceptable in the clinical setting of an abrupt change in fetal hr in a previous scarred uterus.Uterine rupture is not always associated with the prior uterine incision. Of those patients who experienced a uterine rupture, the placenta was found at the uterine rupture site and was partially or completely abrupted.Transvaginal ultrasonography may be useful for measurement of the uterine wall after previous cesarean delivery.MRI may be helpful for confirmation of a possible placenta accreta
58 Vasa PreviaFetal blood vessels transversing presenting membranes and is associated with abnormal insertion of fetal membranes into the membranes rather than the placenta.(velamentous insertion)Bridging vessels
59 Vasa Previa Category C Rarest cause of hemorrhage Onset with membrane ruptureBlood Loss is fetal, with 56% mortality (3%)Associated with placenta previa, velamentous insertion of the cord, bilobed/succenturiate lobe, or IVFAntepartum diagnosisAmnioscopyColor doppler ultrasoundPalpate vessels during vaginal examinationRarest cause of obstetrical hemorrhageoccurs in placentas that are low-lying and with a velamentous insertion or a placenta with a succenturiate lobe. This is the only cause of major blood loss in pregnancy where blood loss in mainly fetal. Fetal mortality is high as much as 50%.In a review of cases - 18 cases of vasa previa were diagnosed. 8 developed in setting where a previous placenta previa receded. 6 had vaginal 31 weeks mean, 3 had normal 3rd trimester u/s and subsequent vaginal deliveries. The remaining had cesareansColor flow doppler may be a useful modality in the evaluation of patients suspected to have a vasa previa. Digital palpation of the membranes prior to artificial rupture is wizeCategory C
60 Diagnostic Tests - Vasa Previa Apt test - based on colorimetric response of fetal hemoglobinWright stain of vaginal blood - for nucleated RBCsKleihauer-Betke test - 2 hour delay prohibits its useApt test -Modified Apt TestSeveral cc’s of blood from vaginaMix with Tap waterCentrifugeMix supernatant with NaOHRead Color in Two minutesFetal = pinkAdult = brown
61 Modified Apt Test Several cc’s of blood from vagina Mix with Tap water CentrifugeMix supernatant with NaOHRead Color in Two minutesFetal = pinkAdult = brown-Several cc’s of blood from vagina, mix with small amount of tap water, hemolysis occurs. Centrifuge for several minutes. Mix the pink supernatant with 1cc 1% NaOH (.25 normal) for every 5 cc supernatant, read the color in two minutes. Fetal: PINK!!! Adult stays brownOr simply do a Wright’s Stain on the vaginal blood smear, look for nucleated rbc’s – if present = fetal blood = vasa previa
62 Management Vasa Previa Immediate Cesarean Delivery if fetal heart non-reassuringAdminister normal saline cc/kg bolus to newborn, if found to be in shock after deliveryFetal exsanguinations is the cause of mortality in this disorder, preparation for resuscitation at the delivery includes availability of normal saline at 102/ cc/kg bolus to administer if the newborn is in shock.
63 SummaryLate pregnancy bleeding may herald diagnoses with significant morbidity/mortalityDetermining diagnosis important as treatment dependent on causeAvoid vaginal exam when placental location not known!
64 Transvaginal Predictive Value TVS Overlap of 10 mm or weeks predictive 100% previa at termLauria US ObGyn Nov 1996TVS Overlap of weeks predictive at birth 5.1 %Taipale ObGyn 1997
65 Risk factors for Abruptions Younger Women RR 1.4Parity > 3 RR 10May reflect effects of close pregnancy spacingPrevious Abruption RR 10Chronic HypertensionPreeclampsia RR 1.7PROM RR 3.0
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