Placenta Previa: Definition, Diagnosis, Management, and Precautions
1. Definition:
Placenta previa (PP) is a condition in which the placenta attaches to the lower segment of the uterus, covering all or part of the cervix.
2. Reasons for diagnosing PP only in the last trimester:
- Cervical structure: The normal cervical os is only about 0.5-1cm in diameter. During the late pregnancy, the lower uterine segment stretches, the cervical os widens, creating a favorable environment for ultrasound to detect placenta attachment in this location.
- Fetal development: The fetus grows larger, and the placenta follows suit, increasing in size and putting pressure on the cervix, which is easily recognizable through ultrasound.
3. Mechanism of bleeding in PP:
- Stretching of the lower uterine segment: When the uterine segment is stretched due to fetal size, the placenta, which lacks the ability to stretch, can detach from the uterine wall, causing bleeding.
- Bright red blood mixed with clots: The blood flows from the uterine artery, typically bright red, sometimes mixed with clots.
4. Clinical features of PP:
- Vaginal bleeding: Recurring bleeding, in episodes, self-stopping, usually without abdominal pain.
- No labor: PP usually does not cause abdominal pain, and is not accompanied by labor.
- Fetal heart rate is almost normal: Fetal heart rate changes only when central PP causes excessive bleeding and shock.
5. Diagnosing PP:
Ultrasound: This is the most accurate diagnostic method, which helps to determine the placenta location and the degree of cervical coverage.
6. Differentiating PP from Placental abruption (PA):
Feature | Placenta Previa | Placental Abruption |
---|---|---|
Blood color | Bright red, with clots | Dark red |
Blood loss | Measurable blood loss | Unmeasurable blood loss |
Patient’s condition | Usually no shock | Quick shock if not intervened promptly |
Fetal heart rate | Only changes with excessive bleeding | Changes significantly with placental abruption |
Management | Medical management | Emergency treatment |
7. Reasons for different management of PP and PA:
- PA: Fetal heart rate changes significantly, and there is a hematoma, necessitating urgent intervention to save the fetus and mother.
- PP: Fetal heart rate only changes when bleeding is excessive, there is no hematoma, so medical treatment is possible.
8. Indications for termination of pregnancy with PP:
- Excessive bleeding: Uncontrolled bleeding, endangering the mother’s life.
- Severe fetal distress: Abnormal fetal heart rate, fetal growth restriction.
9. Management of PP:
- Tocolysis: Using medications to reduce uterine contractions, minimizing the risk of bleeding.
- Lung maturation: Using corticosteroids to help the fetus mature its lungs, reducing the risk of respiratory complications after birth.
- Birth plan: Choosing a suitable birth method, planning for emergency intervention.
10. Termination of pregnancy with a previous cesarean section:
- Week 38: This is the ideal time, reducing the risk of complications.
- After 39 weeks: If there are abnormalities, termination of pregnancy can be performed.
11. Amniotomy:
- Nature: Amniotomy is not a trigger for labor, but a way to induce effective contractions in cases of polyhydramnios.
- Classification:
- Bulging membranes: Amniotomy outside of contractions.
- Flat membranes: Amniotomy during contractions.
- Note: After amniotomy, do not rupture the membranes immediately, but wait for the baby’s head to touch the hand before rupturing the membranes.
12. Placenta accreta index on ultrasound:
- >12: Very high risk of PP.
- 8-12: High risk of PP.
Note:
- Early diagnosis of PP: Helps to monitor pregnancy and manage it promptly, reducing the risk of complications.
- Comprehensive counseling: Doctors need to clearly explain to the pregnant woman about the condition, treatment methods, and the risks of complications.
- Close pregnancy monitoring: Health checks, regular ultrasound scans, monitoring blood loss, and fetal heart rate.
Contact information:
- Note: This article is only for informational purposes and does not replace professional advice from a doctor.
- If you have any health concerns: Please contact a specialist for advice and timely treatment.
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