Placenta previa

WARNING!

Pelvic examination is contraindicated until placenta previa is ruled out as cause of bleeding because it increases maternal bleeding and can dislodge more of the placenta. Because of possible fetal blood loss through the placenta, an intensive care pediatric team should be on hand during delivery to immediately assess and treat neonatal shock, blood loss, and hypoxia.

Three types of placenta previa

The degree of placenta previa depends largely on the extent of cervical dilation at the time of examination, because the dilating cervix gradually uncovers the placenta, as shown below. MARGINAL PLACENTA PREVIA If the placenta covers just a fraction of the internal cervical os or approaches the border of the os, the patient has marginal, or low-lying, placenta previa. PARTIAL PLACENTA PREVIA The patient has the partial, or incomplete, form of the disorder if the placenta caps a larger part of the internal os. COMPLETE PLACENTA PREVIA If the placenta covers all of the internal os, the patient has complete placenta previa, also called central placenta previa.

risk factors

•Advanced maternal age (over age 35)* •Defective vascularization of the decidua •Endometriosis ~DM* ~HTN* •Multiparity* •Infertility treatments* •Multiple gestation* •Previous uterine surgery, injury, abortion, or cesarean birth* •Smoking •Male fetus •Cocaine use* •Low socioeconomic status* •History of placenta previa* •High altitudes •Uterine abnormalities inhibiting normal embryonic implantation (such as prior curettage or the presence of uterine fibroids)

treatment

•Expectant management (observation and bed rest) unless bleeding or contractions occur •Cervical length surveillance to assess for increased risk of hemorrhage •Control of blood loss and blood replacement; fresh frozen plasma and platelets, as necessary, for coagulation problems •Delivery of a viable neonate •Prevention of coagulation disorders •With a premature fetus, careful observation to give the fetus more time to mature •With complete placenta previa, hospitalization •Possible vaginal delivery if bleeding is minimal and placenta previa is marginal or when labor is rapid; cesarean birth (preferred) •Venous thromboembolism (VTE) prophylaxis Bedrest with limited activity No douching or intercourse Monitor and record fetal movement Seek care immediately if active bleeding or decrease/absence of fetal movement

medications

•IV fluids, such as lactated Ringer solution or normal saline solution, using a large-bore catheter •Oxygen therapy •Tocolytics, such as terbutaline sulfate, calcium channel blockers, or magnesium sulfate short-term to halt preterm labor and to allow time for doses of betamethasone dipropionate (Diprolene) •Betamethasone dipropionate to enhance fetal lung maturity if less than 34 weeks' gestation •Uterotonics, such as methylergonovine maleate (Methergine) or oxytocin, may be administered postdelivery to treat uterine atony

labs/ DI

•Maternal hemoglobin level is decreased. •Transvaginal ultrasonography determines placental position. •Fetal ultrasonography evaluation identifies gestational age and weight as well as possible malpresentation.

interventions

•Obtain blood samples for complete blood count and blood type and crossmatch. •Initiate external electronic fetal monitoring; auscultate fetal heart tones; palpate the uterus for contractions; and determine contraction frequency, intensity, and duration. •Administer tocolytic agents, if ordered, and determine the effectiveness of tocolytic therapy, if indicated. •Administer supplemental oxygen, as ordered; check oxygen saturation levels. •Encourage the patient to remain in a side-lying position to reduce the risk of supine hypotension syndrome. •Apply antiembolism stockings or sequential compression stockings to prevent VTE. •Give prescribed IV fluids and blood products; ensure IV patency. Provide IV site care according to facility policy. •Assess the perineal area for bleeding and evidence of ruptured membranes; check vaginal discharge with nitrazine paper to determine whether membranes have ruptured. •If the patient is Rh-negative, give Rho(D) immune globulin (RhoGAM) after every bleeding episode, as ordered. •Offer emotional support to the patient and family. •Provide information about the progress of labor and the condition of the fetus. •Encourage the patient to express fears and concerns and give clear explanations of what is happening as well as the status of the fetus. •Model appropriate and effective coping strategies. •Prepare the patient and the family for possible emergency delivery, if indicated.

assessment history

•Onset of painless bright red vaginal bleeding most commonly after 30 weeks' gestation, although the first episode may occur before 30 weeks •Vaginal bleeding before labor onset, typically episodic and stopping spontaneously •Possibly no symptoms

Sx

•Oversewing the placental implantation site to control bleeding •Immediate cesarean delivery in case of severe hemorrhage or as soon as the fetus is sufficiently mature

overview

•Placental implantation in the lower uterine segment, encroaching on the internal cervical os •Three types: Marginal, partial, and complete •Common cause of painless bleeding (hemorrhage) during the third trimester of pregnancy (Among patients who develop placenta previa during the second trimester, fewer than 15% have persistent previa at term.) •Good maternal prognosis if hemorrhage can be controlled •Usually necessitates pregnancy termination if bleeding is heavy •Fetal prognosis dependent on gestational age and amount of blood lost; risk of death greatly reduced by frequent monitoring and prompt management •Placenta previa occurs in about 1 of 200 pregnancies at term. •It is a complication in approximately 0.5% of pregnancies. •The disorder is more common in multigravidas than primigravidas. •It's more common after age 35. ~First episode on average occurs between 27-32 weeks of pregnancy

complications

•Preterm delivery/low birth weight •Dystocia •Anemia •Hemorrhage* •Abruptio placentae •Disseminated intravascular coagulation •Shock* •Placenta accreta, increta, percreta •Intrauterine growth restriction •Abnormal fetal presentation •Kidney damage •Cerebral ischemia •Congenital malformation •Neonatal respiratory distress

Placenta previa

•The placenta attaches and grows in the lower uterine segment, possibly covering the cervical os. (It's believed that vascularization of the decidua is defective because of inflammatory or atrophic changes.) •The placenta covers all or part of the internal cervical os. (See Three types of placenta previa.) •With development of the lower uterine segment and gradual changes in the cervix during the third trimester, shearing forces at the attachment site lead to partial detachment and bleeding.

physical findings

•Vaginal bleeding (may be profuse) •Hypotension •Tachycardia •Soft, nontender uterus •Fetal malpresentation •Minimal descent of fetal presenting part •Good fetal heart tones •Possible contractions

monitor

•Vital signs •Pain level and effectiveness of interventions •Vaginal bleeding, including characteristics of blood loss •Pad count •Intake and output •Fetal heart tones •Uterine contractions •Signs and symptoms of hemorrhage and shock •Coping strategies •Effectiveness of drug therapy