Placenta previa : definition , clinical feature ,management

PLACENTA PREVIA

“When placenta is implanted partially or completely over the lower uterine segment (over and adjacent to the internal os ) is called placenta previa”

• about one third  of antepartum hemorrhage belongs to placenta previa.
• the incidence of placenta previa ranges from 0.5 to 1% among hospital deliveries.
• in 80% cases, it is found in multiparous women.
• the incidence is increased beyond the age of 35 years, with high birth order pregnancies and in multiple pregnancy

High risk factors for placenta previa

• Multiparity
• Maternal age >35 years
• Race : Asian women
• Maternal factors : infertility treatment
• Presence of uterine scar
• Prior curettage
• Prior placenta previa
• Multiple pregnancy
• Placenta size and abnormality : succenturiate lobes , big placenta
• Smoking : causes placenta hypertrophy to composite CO-induced hypoxemia

Type or degree of placenta previa

There are four type of placenta previa depending upon the degree of extension of placenta to the lower segment

1. Type 1 (LOW LYING) : The major part of placenta is attached to the upper segment and only the lower margin encroaches  onto the lower segment but not up to the os.
2. Type 2 (MARGINAL) : The placenta is reaches the margin of the internal os but does not cover it.
3. Type 3(INCOMPLETE OR PARTIAL CENTRAL): The placenta covers the internal os partially ( covers the internal os when closed but does not entirely do so when fully dilated)
4. Type 4 ( CENTRAL OR COMPLETE) : The placenta is completely covers the internal os even after it is fully dilated .

SYMPTOMS:  The only symptom of placenta previa is vaginal bleeding

• sudden onset, painless , apparently causeless and recurrent bleeding

SIGN :

• Anemia is proportionate to the visible blood loss
• head is floating in contrast to the period of gestation

COMPLICATION OF PLACENTA PREVIA :

1. Antepartum hemorrhage
2. malpresentation
3. early rupture of membrane
4. cord prolapse
5. slow dilatation of cervix
6. intrapartum hemorrhage
7. increase incidence of operative interferance
8. postpartum hemorrhage
9. death due to massive hemorrhage
10. trauma to the cervix and lower segment
11. placenta previa accreta is serious complication
12. atonic uterus
13. imperfect retraction
14. sepsis
15. subinvolution
16. embolism

FETAL COMPLICATION :

1. low birth weight
2. fetal growth restriction
3. asphyxia
4. intrauterine death
5. birth injuries
6. congenital malformation

MANAGEMENT OF PLACENTA PREVIA : 

PREVENTION : Thus to minimize the risks , the following guidelines are useful

• Regular antenatal care : to improve the health status of women and correction of anemia.
• Antenatal diagnosis : of low lying placenta at 20 weeks with routine ultrasound needs repeat ultrasound examination at 34 weeks to confirm the diagnosis
• significance of ‘warning hemorrhage ‘: should not be ignored
• color flow doppler USG : in placenta previa is indicated to detect any placenta accreta

AT HOME : 

1. The patient is immediately put to bed.
2. to assess the blood loss
3. quick but gentle abdominal examination to mark the height of the uterus
4. vaginal examination must be avoid

TRANSFER TO HOSPITAL

1. Amount of blood loss : by noting the general condition ,pallor , pulse rate and blood pressure
2. Blood sample are taken for groups, cross matching and estimation of hemoglobin.
3. A large bore iv canula is inserted and infusion of normal saline is started
4. Gentle abdominal palpation to as to ascertain any uterine tenderness and auscultation to note the fetal heart rate
5. inspection of vulva to note the presence of any active bleeding