NCLEX Placenta Previa

NCLEX Placenta Previa

Placenta Previa Pathophysiology

Placenta previa is obstetric complication in which the placenta is inserted partially or wholly in the lower uterine segment.  It is a leading cause of antepartum hemorrhage.  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.  If the placenta does overlie the lower segment, as is the case with placenta previa, it may shear off and a small section may bleed.

Signs and Symptoms

Women with placenta previa often present with painless, bright red vaginal bleeding.  This common occurs around 32 weeks of gestation, but can be as early as late mid trimester.  This bleeding often starts mildly and may increase as the area of placental separation increases.  Previa should be suspected if there is bleeding after 24 weeks of gestation.

Causes

Exact cause of placenta previa is unknown.  It is hypothesized to be related to abnormal vascularisation of the endometrium caused by scarring or atrophy from previous trauma, surgery, or infection.  These factors may reduce differential growth of lower segment, resulting in less upward shift in placental position as pregnancy advances.

Risk Factors

• Maternal age >40
• Illicit drugs and alcohol
• Previous C-section
• Parity > 5
• Prior abortion
• Smoking
• Congenital anomalies
• Male fetus
• Pregnancy induced hypertension

Diagnosis

History may reveal antepartum hemorrhage.  Abdominal exam usually finds the uterus non-tender, soft 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.  Malpresentation is found in about 35% cases.  Vaginal examination is avoided in known cases of placenta previa.

Management

Treatment for placenta previa depends on various factors.  For little or no bleeding, bed rest at home is recommended.  For heavy bleeding, bed rest in a hospital is recommended, as well as, a blood transfusion and medications to prevent premature labor.

Complications

Maternal

• Antepartum hemorrhage
• Malpresentation
• Abnormal placentation
• Postpartum hemorrhage

Fetal

• Premature delivery
• Death