5: Antepartum hemorrhage Flashcards
if part of the placental atrophies and is discrete from the rest of the placenta
succenturiate lobe
Placenta previa
abnormal implantation of the placenta over the internal cervical os
complete, partial, and marginal
vasa previa
Occurs when a velamentous cord insertion causes the fetal vessels to pass over the internal cervical os
Also seen with velamentous and succenturiate placentas
placenta accreta, increta, percreta
accreta: superficial attachment of the placenta to the uterine myometrium.
increta: placenta invades the myometrium.
percreta: placenta invades through the myometrium to the uterine serosa. this may lead to invasion of other organs such as the bladder anteriorly or the rectum posteriorly.
placenta previa may result in
preterm delivery, PPROM, IUGR, malpresentation, vasa previa, congenital abnormalities, profuse hemorrhage and shock
placenta accreta causes inability of placenta to separate properly from uterine wall, can result in
profuse hemorrhage and shock with substantial maternal morbidity and mortality, such as need for hysterectomy, surgical injury to the ureters, bladder, and other viscera, adult respiratory distress syndrome, renal failure, coagulopathy, and death.
EBL is 3,000 to 5,000 mL
most frequent indication for a peripartum (during C section) hysterectomy
uterine atony
abnormal placentation is becoming more common
major causes of antepartum hemorrhage include
placenta previa (20%) and placental abruption (30%).
placenta previa presentation
sudden and profuse PAINLESS vaginal bleeding
the “sentinel” (first) bleed—usually occurs after 28 weeks of gestation
digital exam is CONTRAINDICATED
Placenta accreta (and increta) presentation
usually asymptomatic. On rare occasions, however, a patient with a percreta into the bladder or rectum may present with hematuria or rectal bleeding.
Circumvallate placenta
Occurs when the membranes double back over the edge of the placenta, forming a dense ring around the periphery of the placenta. Often considered a variant of placental abruption, it is a major cause of second-trimester hemorrhage
Velamentous placenta
Occurs when blood vessels insert between the amnion and the chorion, away from the margin of the placenta, leaving the vessels largely unprotected and vulnerable to compression or injury
Succenturiate placenta
An extra lobe of the placenta that is implanted at some distance away from the rest of the placenta
Fetal vessels may course between the two lobes, possibly over the cervix, leaving these blood vessels unprotected and at risk for rupture
predisposing factors for placenta previa
Prior cesarean section and uterine surgery (e.g., myomectomy) Multiparity Multiple gestation Erythroblastosis Smoking History of placenta previa Increasing maternal age
diagnosing placenta previa
transvaginal US»transabdominal US
deliver placenta previa pts via C section if ?
placenta edge is less than 2cm from internal os
management of placenta previa
strict pelvic rest, modified bed rest
immediate C section if unstoppable labor, fetal distress, and life-threatening hemorrhage
70% of patients with placenta previa have a recurring bleeding episode and will require delivery before
36 weeks
if make it to week 36: amniocentesis to determine fetal lung maturity and delivery by c section between 36 and 37 weeks after confirmation of fetal lung maturity. If not mature, elective cesarean at 38 weeks, without repeating the amniocentesis or earlier if bleeding occurs or the patient goes into labor
now research shows patients with suspected placenta previa and/or accreta should be delivered between
34 and 37 weeks with minimal benefit gained by confirming fetal lung maturity.
course of action in the case of vaginal bleeding and suspected placenta previa and/or placenta accreta:
- stabilize
- prepare for hemorrhage: transfusions to maintain HCT >25%
- prepare for preterm delivery: steroids, tocolytics to prolong pregnancy up to 34 weeks
considerations for suspected placenta accreta/increta/percreta:
- Plan for total abdominal hysterectomy at the time of cesarean section; attempts at detachment causes hemorrhage
- Schedule delivery at 34 to 37 weeks of gestation
- Plan ahead and have back-up available.
Placental abruption (abruptio placentae)
premature separation of the normally implanted placenta from the uterine wall, resulting in hemorrhage between the uterine wall and the placenta. 50% occur before labor and after 30 weeks, 15% occur during labor, and 30% are identified only on placental inspection after delivery.
placental abruption may result in
premature delivery, uterine tetany, disseminated intravascular coagulation (DIC), and hypovolemic shock.
Predisposing factors for placenta abruption
*Hypertension* most common, preeclamspsia, HTN secondary to Cocaine or Methamphetamine use Previous placental abruption Advanced maternal age Multiparity Uterine distension Multiple pregnancy Polyhydramnios Vascular deficiency Diabetes mellitus Collagen vascular disease Cigarette smoking Alcohol use (>14 drinks/wk) Circumvallate placenta Short umbilical cord
Precipitating factors for placental abruption
Trauma External/internal version Motor vehicle accident Abdominal trauma Sudden uterine volume loss Delivery of first twin Rupture of membranes with polyhydramnios Preterm premature rupture of membranes
mortality from placental abruption
maternal: hemorrhage, cardiac failure, renal failure
fetal: preterm birth, hypoxia resulting from decreased placental surface area and maternal hemorrhage
placental abruption presentation
PAINFUL bleeding (vs previa) third-trimester vaginal bleeding associated with severe abdominal pain and/or frequent, strong contractions. However, about 30% of placental separations are small with few or no symptoms and are identified only after inspection of the placenta at delivery
Couvelaire uterus
a life-threatening condition and occurs when there is enough blood from the abruption that markedly infiltrates the myometrium to reach the serosa, especially at the cornua, that it gives the myometrium a bluish purple tone that can be seen on the surface of the uterus.
CANNOT rule out abruption if
negative US findings
placental abruption confirmed at delivery with
presence of a retroplacental clot with overlying placental destruction confirms the diagnosis
severe placental abruption results in consumptive coagulopathy
levels?
-hypofibrinogenemia (i.e., plasma levels less than 150)
mechanism of coagulopathy in abruption
activation of intravascular coagulation with varying degrees of defibrination.
Procoagulants are also consumed in the retroplacental clots
activation of plasminogen to plasmin, which lyses fibrin microemboli to maintain microcirculatory patency
may result in overt thrombocytopenia
suspected placental abruption management
- stabilize the patient:CBC, type and cross, PT/PTT, fibrinogen, and D-dimer or fibrin split products. For an Rh- woman, RhoGAM, prepare for emergent c sx (anesthesia)
- Prepare for the possibility of future hemorrhage: IVF, blood, FFP, cryoprecipitate
- Prepare for preterm delivery
- Deliver if bleeding is life threatening or fetal testing is nonreassuring
More than 90% of all uterine ruptures are associated with ?
a prior uterine scar either from cesarean section or other uterine surgery
others: abdominal trauma, L&D probs (i.e. improper oxytocin use, manual pressure), spontaneous (i.e. placenta percreta, multiple gestation, grand multiparity, invasive mole, or choriocarcinoma).
Risk Factors for Uterine Rupture
Prior uterine surgery/uterine scar Injudicious use of oxytocin Grand multiparity Marked uterine distension Abnormal fetal lie Large fetus External version Trauma
presentation of uterine rupture
sudden onset of intense abdominal pain +/- vaginal bleeding.
other signs: nonreassuring fetal testing, abnormal abdominal contour, cessation of uterine contractions, absent FHTs, and regression of the presenting fetal part
Management of uterine rupture
immediate laparotomy and delivery, repair rupture site and maintain hemostasis
may require a hysterectomy, discouraged to attempt future pregnancies due to recurrence
Most pregnancies complicated by rupture of a fetal vessel are due to ?
velamentous cord insertion, the blood vessels insert between the amnion and chorion away from the placenta instead of inserting directly into the chorionic plate
-may have additional vasa previa
complications of vasa previa
fetal exsanguination/death: the fetal blood volume is only about 80 to 100 mL/kg, loss of even small amounts of blood could prove disastrous to the fetus. Additionally, pressure on the unprotected vessels by the presenting fetal part could lead to fetal asphyxia and death.
risk factors for fetal vessel rupture
abnormal placentation leading to a succenturiate lobe as well as multiple gestations that increase the risk of velamentous insertion
have a high index of suspicion for a ruptured vasa previa if
bleeding accompanies ROM in labor, especially if there are associated FHR decelerations, fetal bradycardia, or a sinusoidal FHR pattern (indicates anemia)
Apt test to examine vaginal bleeding
examination of the blood for nucleated (fetal) RBCs
-dilute the blood with water, collecting the supernatant, and combining it with 1% NaOH. If the resulting mixture is pink, it indicates fetal blood; a yellow-brown color is seen with maternal blood
treatment of a ruptured fetal vessel
emergent cesarean delivery, elective at 35 weeks if dx in antepartum period
if choose to under go TOLAC, AROM is contraindicated
what is the imaging modality of choice to evaluate for the myometrial and/or bladder invasion of the placenta, particularly when it is not clear on ultrasound?
MRI of abdomen/pelvis without contrast
