Placenta Previa

Placenta previa is the development of placenta in the lower uterine segment, partially or completely covering the internal cervical os. The cause is unknown, but a possible theory states that the embryo will implant in the lower uterine segment if the deciduas in the uterine fundus is not favorable. Complications are immediate hemorrhage, shock, and maternal death; fetal mortality; and post partum hemorrhage. Predisposing Factors: 1. 2. 3. 4. 5. 6.

Multiparity (80% of affected clients are multiparous) Advanced maternal age (older than 35 years old in 33% of cases Multiple gestation Previous Cesarean birth Uterine Incisions Prior placenta previa ( incidence is 12 times greater in women with previous placenta previa)

Nursing Management 1. Ensure the physiologic well-being of the client and fetus a. Take and record vital signs, assess bleeding, and maintain a perineal pad count. Weigh perineal pads before and after use to estimate blood loss. b. Observe for shock, which is characterized by a rapid pulse, pallor, cold moist skin and a drop in blood pressure c. Monitor the FHR d. Enforce strict bed rest to minimize risk to the fetus e. Observe for additional bleeding episodes. 2. Provide client and family teaching a. Explain the condition and management options. To ensure an adequate blood supply to the mother and fetus, place the woman at bed rest in a side-lying position. Anticipate the order for a sonogram to localize the placenta. If the condition of mother or fetus deteriorates, a cesarean birth will be required. b. Prepare the client for ambulation and discharge ( may be within 48 hours of last bleeding episode) c. Discuss the need to have transportation to the hospital available at all times. d. Instruct the client to return to the hospital if bleeding recurs and to avoid intercourse until after the birth. e. Instruct the client on proper handwashing and toileting to prevent infection. 3. Address emotional and psychosocial needs

a. Offer emotional support to facilitate the grieving process, if needed b. After birth of the newborn, provide frequent visits with the newborn so that the mother can be certain of the infant’s condition NCP – Placenta Previa lower uterine segment n. The isthmus of the uterus, the lower extremity of which joins with the cervical canal and during pregnancy expands to become the lower part of the uterine cavity.

Placenta Previa Author: Patrick Ko, MD, Clinical Assistant Professor, Department of Emergency Medicine, New York University Medical School; Assistant Program Director, Department of Emergency Medicine, North Shore University Hospital Coauthor(s): Young Yoon, MD, Associate Director, Assistant Professor, Department of Emergency Medicine, Mount Sinai Medical Center Contributor Information and Disclosures Updated: Aug 10, 2009

• • • • • • •

Overview Differential Diagnoses & Workup Treatment & Medication Follow-up Multimedia

• •

References Keywords

Print This Email This

Introduction Background Placenta previa is an obstetric complication that occurs in the second and third trimesters of pregnancy. It may cause serious morbidity and mortality to both the fetus and the mother. It is one of the leading causes of vaginal bleeding in the second and third trimesters.

Placenta previa.

Placenta previa is generally defined as the implantation of the placenta over or near the internal os of the cervix.

•

Total placenta previa occurs when the internal cervical os is completely covered by the

• • •

placenta. Partial placenta previa occurs when the internal os is partially covered by the placenta. Marginal placenta previa occurs when the placenta is at the margin of the internal os. Low-lying placenta previa occurs when the placenta is implanted in the lower uterine

•

segment. In this variation, the edge of the placenta is near the internal os but does not reach it. A recent study concluded that more than two thirds of women with a distance of more than 10 mm from the placental edge to cervical os have vaginal delivery without an increased risk of hemorrhage.1

Pathophysiology The exact etiology of placenta previa is unknown. The condition may be multifactorial and is postulated to be related to multiparity, multiple gestations, advanced maternal age, previous cesarean delivery,2 previous abortion, and possibly, smoking. Unlike first trimester bleeding, second and third trimester bleeding is usually secondary to abnormal placental implantation.

Frequency United States

Placenta previa complicates approximately 5 of 1,000 deliveries and has a mortality rate of 0.03%. Data recorded from 1989-1997 indicated placenta previa occurs in 2.8 per 1000 live births in the United States.

Mortality/Morbidity The maternal mortality rate secondary to placenta previa is approximately 0.03%. Babies born to women with placenta previa tend to weigh less than babies born to women without placenta previa. The risk of neonatal mortality is higher for placenta previa babies compared with pregnancies without placenta previa. The great majority of deaths are related to uterine bleeding and the complication of disseminated intravascular coagulopathy. In early pregnancy, a partial previa can often self-correct as the uterus enlarges and the placental site moves cephalad.

Race Significance of race is somewhat controversial. Some studies suggest an increased risk of placenta previa among blacks and Asians, whereas other studies cite no difference.

Age Women older than 30 years are 3 times more likely to have placenta previa than women younger than 20 years.

Clinical History Placenta previa is one of the leading causes of vaginal bleeding.

•

Vaginal bleeding is apt to occur suddenly during the third trimester.

•

Bleeding is usually bright red and painless. Some degree of uterine irritability is present in

•

about 20% of the cases. Initial bleeding is not usually profuse enough to cause death; it spontaneously ceases,

• •

only to recur later. The first bleed occurs (on average) at 27-32 weeks' gestation. Contractions may or may not occur simultaneously with the bleeding.

Physical • • • • • •

Profuse hemorrhage Hypotension Tachycardia Soft and nontender uterus Normal fetal heart tones (usually) Vaginal and rectal examinations o Do not perform these examinations in the ED because they may provoke

o

uncontrollable bleeding. Perform examinations in the operating room under double set-up conditions (ie, ready for emergent cesarean delivery).

Causes • •

Prior uterine insult or injury Risk factors o Prior placenta previa (4-8%) o First subsequent pregnancy following a cesarean delivery o Multiparity (5% in grand multiparous patients) o Advanced maternal age o Multiple gestations o Prior induced abortion o Smoking

Understanding Placenta Previa - the Basics What Is Placenta Previa? The placenta is the organ created during pregnancy to nourish the fetus, remove its waste, and produce hormones to sustain the pregnancy. The placenta is attached to the wall of the uterus by blood vessels that supply the fetus with oxygen and nutrition, and which remove waste from the fetus and transfer it to the mother. The fetus is attached to the placenta by the umbilical cord. Through the cord, the fetus receives nourishment and oxygen and expels waste. On one side of the placenta, the mother's blood circulates, and on the other side, fetal blood circulates. The mother's blood and fetal blood usually don't mix in the placenta.

The placenta is usually attached to the upper part of the uterus, away from the cervix, the opening which the baby passes through during delivery. On rare occasions, the placenta lies low in the uterus, partly or completely blocking the cervix -- called a placenta previa. As many as 1 in every 3 to 5 pregnancies has some form of placenta previa before the 20th week of pregnancy. As the uterus grows, the placenta usually moves higher in the uterus, away from the cervix. But if it remains near the cervix as your due date nears -- which happens in about 1 in 200 pregnancies -- you're at risk for bleeding, especially during labor as the cervix thins (effaces) and opens (dilates). This can cause major blood loss in the mother. For this reason, women with a placenta previa are usually delivered by cesarean delivery. There are several types of placenta previa: • • •

A low-lying placenta is near the cervical opening but not covering it. It will often move upward in the uterus as your due date approaches. A partial placenta previa covers part of the cervical opening. A total placenta previa covers and blocks the cervical opening.

What Causes a Placenta Previa? The cause of placenta previa is usually unknown, although it occurs more commonly among women who are older, smoke, have had children before, have had a cesarean section or other surgery on the uterus, or have scars inside the uterus. Women with placenta previa -- specifically if they have a placenta previa after having delivered a previous baby by cesarean section -- are at increased risk of placenta accreta, placenta increta, or placenta percreta. In placenta accreta, the placenta is firmly attached to the uterus. In placenta increta, the placenta has grown into the uterus; and in placenta percreta, it has grown through the uterus. This condition is often first suspected because the woman has both a previa and a prior cesarean section. It can be confirmed by ultrasound, CT scan, or MRI, though those tests are not completely reliable. Women with one of these conditions usually require a hysterectomy after delivery of the baby, because the placenta does not separate from the uterus.

Definition By Mayo Clinic staff Placenta previa

Placenta previa is an uncommon pregnancy complication that can cause excessive bleeding before or during delivery. Soon after conception, the placenta begins to form. This oval, flat organ provides oxygen and nutrients to your growing baby and removes waste products from your baby's blood. It attaches to the wall of your uterus, and your baby's umbilical cord arises from it, forming a vital connection between you and your baby. Placenta previa occurs when the placenta attaches to the lower part of your uterine wall, partially or totally covering your cervix. When the cervix starts to open in preparation for labor, the placenta is detached, which can trigger severe vaginal bleeding. Thankfully, placenta previa is nearly always detected before a woman or her baby is in significant danger.

Causes By Mayo Clinic staff Early in pregnancy, the placenta may implant in the lower part of the uterus. As the uterus grows, the placenta usually moves up and away from the opening of the uterus (cervix). If it doesn't, the cervix may be blocked. This is placenta previa. Placenta previa is associated with:



Scars in the lining of the uterus (endometrium)



A large placenta, such as with a multiple pregnancy



An abnormally shaped uterus

Risk factors By Mayo Clinic staff Placenta previa is more common among women who:



Have already delivered at least one baby



Had a previous C-section



Had placenta previa with a previous pregnancy



Are age 35 or older



Are Asian



Smoke



Are carrying twins, triplets or other multiples



Have had a previous uterine surgery, such as myomectomy to remove uterine fibroids or dilation and curettage (D and C) to scrape the uterine lining

Complications By Mayo Clinic staff

If you have placenta previa, your health care provider will monitor you and your baby carefully to reduce the risk of these serious complications:



Bleeding. One of the biggest concerns with placenta previa is the risk of severe vaginal bleeding (hemorrhage) during labor, delivery or the first few hours after delivery. The bleeding can be heavy enough to cause maternal shock or even death.



Premature birth. Severe bleeding may prompt an emergency C-section before your baby is full term.



Placenta accreta. If the placenta implants too deeply and firmly into the uterine wall, the placenta may not spontaneously detach from the uterus after delivery — an uncommon condition known as placenta accreta. This can result in severe bleeding and, often, the need for surgical removal of the uterus (hysterectomy).

Preparing for your appointment By Mayo Clinic staff If you're pregnant beyond 12 to 13 weeks' gestation and develop any vaginal bleeding, call the doctor who is caring for you during pregnancy (obstetrical care provider). Depending on your symptoms, your personal health history and how far along you are in the pregnancy, your doctor may recommend immediate medical care. But don't panic. If you have placenta previa, it can be managed with a good outcome for both you and your baby 90 percent of the time. Here's some information to help you get ready for your appointment, and what to expect from your doctor. What you can do



Ask about pre-appointment restrictions. In most cases you'll be seen immediately. However, if your appointment will be delayed for a day or two, ask whether you should restrict your activity while you wait to come in.



Share your medical history. Depending on your prior care, your doctor likely will already know important medical details about this pregnancy and much of your reproductive history. But if you haven't yet told your doctor about previous uterine surgeries, including dilation and curettage (D and C) following a miscarriage or abortion, it's important for your health and your baby's health to share this information now.



Find a family member or friend who can join you for your appointment. The fear you may be feeling about bleeding during pregnancy can make it difficult to focus on what the doctor says. Take someone along who can help soak up all the information.



Write down questions to ask your doctor. Creating your list of questions in advance can help you make the most of your time with your doctor.

Tests and diagnosis

By Mayo Clinic staff Placenta previa is diagnosed through ultrasound, either during a routine prenatal appointment or after an episode of vaginal bleeding. Placenta previa is nearly always detected before a woman or her baby is in significant danger. Diagnosis before 20 weeks of pregnancy It's not unusual to detect a low-lying placenta or to see the placenta covering the cervix during a routine midpregnancy ultrasound. Most of these cases resolve on their own before delivery, as the uterus grows and the placenta migrates away from the cervix. You may need additional ultrasounds to track the position of your placenta. The longer placenta previa persists, the more likely it will be present at delivery. Diagnosis after 20 weeks of pregnancy Your health care provider may detect placenta previa later in pregnancy during an ultrasound for an unrelated reason. At this stage of pregnancy, however, vaginal bleeding is usually the tip-off. If you experience vaginal bleeding during the second or third trimester, call your health care provider right away. You'll likely need to go to your doctor's office or the hospital to determine the cause of the bleeding. In most cases, your health care provider can use an abdominal ultrasound to quickly confirm or rule out placenta previa. A definitive diagnosis may require a combination of abdominal ultrasound and transvaginal ultrasound, which is done through a wand-like device (transducer) placed inside your vagina. Your health care provider will closely monitor the location of the transducer in your vagina to prevent any bleeding. Rarely, magnetic resonance imaging (MRI) may be used to diagnose placenta previa. If your health care provider suspects that you may have placenta previa, he or she will avoid routine vaginal exams to reduce the risk of heavy bleeding. You may need additional ultrasounds or, rarely, an MRI to determine the exact location of your placenta before delivery. Your baby's heartbeat may be tracked as well. Related conditions Two uncommon conditions are often grouped with placenta previa because they can cause vaginal bleeding in the late second or third trimester. If you have vaginal bleeding late in your pregnancy, your health care provider will also consider these conditions before making a diagnosis:



Placental abruption. Rarely, the placenta separates from the uterus before birth. This can deprive the baby of oxygen and nutrients and cause heavy bleeding that may be dangerous for both mother and baby.



Vasa previa. The umbilical cord usually develops in the center of the placenta. If the umbilical cord attaches to the placenta in an unusual way, a portion of the blood vessels normally inside the umbilical cord may be left unprotected. If these unprotected blood vessels cross the cervix, it's known as vasa previa. If these blood vessels rupture, the baby faces life-threatening bleeding.

Treatments and drugs By Mayo Clinic staff Treatment for placenta previa depends on various factors, including:



The amount of vaginal bleeding



Whether the bleeding has stopped



Your baby's gestational age



Your health



Your baby's health



The position of the placenta and the baby For little or no bleeding If you have marginal placenta previa or another form of placenta previa but little or no bleeding, your health care provider may recommend bed rest at home. Depending on the circumstances, you may need to lie in bed most of the time —sitting and standing only when necessary. You'll need to avoid sex and vaginal exams, which can trigger bleeding. Exercise is usually off-limits, too. Discuss the do's and don'ts with your health care provider — and be prepared to seek emergency medical care if you begin to bleed. If your placenta doesn't cover your cervix, you may be allowed to attempt a vaginal delivery. If you begin to bleed heavily, you may need an emergency C-section. For heavy bleeding If you're bleeding, you may need bed rest in the hospital. If the bleeding is severe, you may need a blood transfusion to replace lost blood. You may also benefit from medications to prevent premature labor. Your health care provider will likely plan a C-section as soon as the baby can be safely delivered, ideally after 36 weeks of pregnancy. If it's not possible to wait, you will need an earlier C-section. In this case, you may be given corticosteroids to speed your baby's lung development. In as little as 48 hours, these potent medications can help your baby's lungs prepare for life outside the uterus. For bleeding that won't stop If your bleeding can't be controlled or your baby is in distress, you may need an emergency C-section — even if the baby is premature.

Coping and support By Mayo Clinic staff Pregnancy is supposed to be a time of awe and anticipation. If you're diagnosed with placenta previa, you're sure to be worried about how your condition will affect your baby. Some of these strategies may help:



Learn about placenta previa. Gathering information about your condition may help you feel less scared. Talk to your health care provider, do some research on your own and connect with other women who've had placenta previa.



Prepare for a C-section. Placenta previa may prevent you from delivering your baby vaginally. Ask your health care provider every C-section question that comes to mind. If you're disappointed that you may not have a vaginal birth, remind yourself that your baby's health and your health are more important than the method of delivery.



Make the best of bed rest. If your health care provider recommends bed rest, fill your days by planning for your baby's arrival. Read about newborn care or purchase newborn necessities, either online or from catalogs. Or use the time to balance your checkbook, organize old photo albums or catch up on thank-you notes.



Take care of yourself. Surround yourself with things that bring you comfort, such as a good book or a favorite pair of pajamas. Give your partner, friends and loved ones concrete suggestions for ways to help, such as bringing a favorite food or simply stopping by for a visit. A condition that could cause excessive bleeding before or during delivery isn't part of any mother's vision of the perfect pregnancy. Yet most women who have placenta previa go on to deliver a healthy baby — which is far better than a perfect pregnancy.