Placenta Previa

Introduction:

The placenta is implanted in the lower uterine segment near or over the internal cervical os. The degree to which the internalcervical os is covered by the placenta has been used to classify four types of placenta previa; total, partial , marginal and low–lying. In total previa the internal os is entirely covered by the placenta.Partial placenta previa implies incomplete coverage of the internal os. Marginal placenta previa indicates that only an edge of the placenta extends to the margin of the internal os. And the last is the low – lying placenta has been used when the placenta is implanted in the lower uterine segment but not reach the os. The more descriptive classification that includes placenta previa is in the third trimester.

The incidence of placenta previa is approximately 0.5% of births. The most important risk factors are previous placenta previa, previous cesarean birth, and suction curettage for miscarriage or induced abortion, possible related to endometrial scarring. The risk also increases with multiple gestations because of the larger placental area, closely spaced pregnancies, advanced maternal age older than 34 years, African or Asian ethnicity, male fetal sex, smoking, cocaine use, multiparity, and tobacco use.

Classification of Placenta Previa:

1. Total Previa- the placenta completely covers the internalcervical os.
2. Partial Previa- the placenta covers a part of the internalcervical os.
3. Marginal Previa- the edge of the placenta lies at the margin of the internal cervical os and may be exposed during dilatation.
4. Low-lying placenta- the placenta is implanted in the lower uterine segment but does not reach to the internal os of the cervix.

Predisposing Factors:

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

Complications for the baby include:

• Problems for the baby, secondary to acute blood loss
• Intrauterine growth retardation due to poor placental perfusion
• Increased incidence of congenital anomalies

Clinical Manifestations:

• Painless vaginal bleeding > occurs after 20 weeks of gestation, bright red in color associated with the stretching and thinning of the lower uterine segment that occurs in third trimester.
• Adequately contract and stop blood flow from open vessels.
• Stop blood flow from open vessels
• Decreasing urinary output

Normal Placenta During Childbirth

Process of placental growth and uterine wall changes during pregnancy

1. The placenta grows with the placental site during pregnancy.
2. During pregnancy and early labor the area of the placental site probably changes little, even during uterine contractions.
3. The semirigid, noncontractile placenta cannot alter its surface area.

Anatomy of the uterine/placental compartment at the time of birth

1. The cotyledons of the maternal surface of the placenta extend into the decidua basalis, which forms a natural cleavage plane between the placenta and the uterine wall.
2. There are interlacing uterine muscle bundles, consisting of tiny myofibrils, around the branches of the uterine arteries that run through the wall of the uterus to the placental area.
3. The placental site is usually located on either the anterior or the posterior uterine wall.
4. The amniotic membranes are adhered to the inner wall of the uterus except where the placenta is located

Anatomy of Female Reproductive System
Physiology of Female Reproductive System
Anatomy and Physiology of Male Reproductive System

Pathophysiology

No specific cause of placenta previa has yet been found but it is hypothesized to be related to abnormal vascularisation of the endometrium caused by scarring or atrophy from previous trauma, surgery, or infection.

In the last trimester of pregnancy the isthmus of the uterus unfolds and forms the lower segment. In a normal pregnancy the placenta does not overlie it, so there is no bleeding. If the placenta does overlie the lower segment, it may shear off and a small section may bleed.

Women with placenta previa often present with painless, bright red vaginal bleeding. This bleeding often starts mildly and may increase as the area of placental separation increases. Praevia should be suspected if there is bleeding after 24 weeks of gestation. Abdominal examination usually finds the uterus non-tender and relaxed. Leopold’s Maneuvers may find the fetus in an oblique or breech position or lying transverse as a result of the abnormal position of the placenta. Praevia can be confirmed with an ultrasound.[3] In parts of the world where ultrasound is unavailable, it is not uncommon to confirm the diagnosis with an examination in the surgical theatre.

The proper timing of an examination in theatre is important. If the woman is not bleeding severely she can be managed non-operatively until the 36th week. By this time the baby’s chance of survival is as good as at full term.

Diagnostic Evaluation:

Placenta previa is diagnosed using transabdominal ultrasound.
-    transabdominal scans with fewer false positive results

Transvaginal ultrasound

• If a woman is bleeding she is usually placed in the labor and birth unit or for cesarean birth because profound hemorrhage can occur during the examination. This type of vaginal examination knows as the double- setup procedure

Ultrasonographic scan

• If ultrasonographic scanning reveals a normally implanted placenta, an examination may be performed to rule out local causes of bleeding and a coagulation profile is obtained to rule out other causes of bleeding management of placenta previa depends of the gestational age and condition of the fetus and the amount and cesarean birth.

Complete blood count (CBC)

• To monitor mother’s blood volume

Fetoscope

• To monitor fetal heart rate and conditions

Medical Management:

• Maternal stabilization and fetal monitoring
• Control of blood loss, blood replacement
• Delivery of viable neonate
• With fetus of less than 36 weeks gestation, careful observation to determine safety of continuing pregnancy or need for preterm delivery
• Hospitalization with complete bed rest until 36 weeks gestation with complete placenta previa
• Possible vaginal delivery with minimal bleeding or rapidly progressing labor

Nursing Interventions:

1. If continuation of the pregnancy is deemed safe for patient and fetus administer magnesium sulfate as ordered for premature labor
2. Obtain blood samples for complete blood count and blood type and cross matching
3. Institute complete bed rest
4. If the patient and placenta previa is experiencing active bleeding, continuously monitor her blood pressure, pulse rate, respiration, central venous pressure, intake and output, and amount of vaginal bleeding as well as the fetal heart rate and rhythm
5. Assist with application of intermittent or continuous electronic fetal monitoring as indicated by maternal and fetal status.
6. Have oxygen readily available for use should fetal distress occur, as indicated by bradycardia, tachycardia, late or available decelerations, pathologic sinusoidal pattern, unstable baseline, or loss of variability.
7. If the patient is Rh-negative and not sensitized, administer Rh (D) immune globulin (RhoGAM) after every bleeding episode.
8. Administer prescribed IV fluids and blood products.
9. Provide information about labor progress and the condition of the fetus.
10. Prepare the patient and her family for a possible caesarian delivery and the birth of a preterm neonate, and provide thorough instructions for postpartum care.
11. If the fetus less than 36 weeks gestation expect to administer an initial dose of betamethasone: explain that additional doses may be given again in 24 hours and possibly for the next 2 weeks to help mature the neonates lungs.
12. Explain that the fetus survival depends on gestational age and amount of maternal blood loss. Request consultation with a neontologist or pediatrician to discuss a treatment plan with the patient and her family.
13. Assure the patient that frequent monitoring and prompt management greatly reduce the risk of neonatal death.
14. Encourage the patient and her family to verbalize their feelings helps them to develop effective coping strategies, and refer them for counseling, if necessary.
15. Anticipate the need for a referral for home care if the patient bleeding ceases and she’s to return home in bed rest.
16. During the postpartum period, monitor the patient for signs of early and late postpartum hemorrhage and shock.
17. Monitor VS for elevated temperature, pulse, and blood pressure, monitor laboratory results for elevated WBC count, differential shift; check for urine tenderness and malodorous vaginal discharge to detect early signs of infection resulting from exposure of placental tissue.
18. Provide or teach perineal hygiene to decrease the risk of ascending infection.
19. Observe for abnormal fetal heart rate patterns such as loss of variability, decelerations tachycardia to identify fetal distress.
20. Position the patient in side lying position and wedge for support to maximize placental perfusion.
21. Assess fetal movement to evaluate for possible fetal hypoxia.
22. Teach woman to monitor fetal movement to evaluate well being
23. Administer oxygen as ordered to increase oxygenation to mother and fetus.

Discharge Plan:

Medication

• Betamethasone (Celestone) is a corticosteroid that acts as an anti-inflammatory and immunosuppressive agent.
• Assess for contraindications of Betamethasone administration. Obtain reports of urine and cervical cultures and fibronectin.

Exercise

• Needs to adequate her time with her child to be certain he or she is all right, and nurse can states hearing fetal heart beat helps to reassure her about baby’s health.
• Attach contraction and fetal heart rate monitoring for continuous evaluation of contractions of fetal response.

Treatment

• Used of drugs
• Catheterization

Health Teaching

• Maintain a bed rest
• Maintain a 8 glasses of water

Ongoing Assessment

• Assess client’s home surrounding to determine whether they are appropriate for bed rest and continuing monitoring at home. Administer oral dose and home monitoring requires professional supervision.

Diet

• She might to begin to neglect her diet or her supplementary vitamins because “It doesn’t matter anymore”.

Spiritual

• Assess anxiety level of client over preterm labor possible feelings.
• Determine whether client wants a support person to be wit her, to the presence of a support person can offer additional comfort to a client.

Possible Nursing Diagnosis for Placenta Previa:

• Risk for Impaired Fetal Gas Exchange r/t Disruption of Placental Implantation
• Fluid Volume Deficit r/t Active Blood Loss Secondary to Disrupted Placental Implantation
• Active Blood Loss (Hemorrhage) r/t Disrupted Placental Implantation
• Fear r/t Threat to Maternal and Fetal Survival Secondary to Excessive Blood Loss
• Activity Intolerance r/t Enforced Bed Rest During Pregnancy Secondary to Potential for Hemorrhage
• Altered Diversional Activity r/t Inability to Engage in Usual Activities Secondary to Enforced Bed Rest and Inactivity During Pregnancy
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References:

• Maternal & Child Nursing Seventh Edition Vol.1 page 413.
• Maternity nursing, Lowdermilk Perry, seventh edition, chapter 23, page 751.
• Maternal Neonatial Nursing Lippincott manual of Nursing Practice
• http://wikipedia.org