Placenta Previa: Types, Causes, Symptoms, Diagnosis & Management


Placenta Previa 

Definition

Placenta previa is a placental implantation abnormality in which the placenta is partially or completely implanted in the lower uterine segment, thereby covering the internal os of the cervix.

Classification / Types

Placenta previa is classified into four main types based on the degree of coverage of the cervical os:

  1. Type I (Minor): Low-Lying Placenta

    • Placenta is implanted in the lower uterine segment but does not reach the internal os.

  2. Type II (Marginal)

    • The lower edge of the placenta reaches the internal os but does not cover it.

  3. Type III (Partial)

    • The placenta partially covers the internal os.

  4. Type IV (Major/Complete)

    • The placenta completely covers the internal os.

🔴 Types III and IV are considered major placenta previa and are more likely to require cesarean delivery.

Incidence

  • Occurs in approximately 0.3–0.5% of all pregnancies.

  • More common with:

    • Multiparity

    • Advanced maternal age (>35 years)

    • Previous cesarean section

    • Uterine surgery

    • Multiple pregnancies

Etiology / Risk Factors

Factor Description
Previous uterine surgery Scarring from C-section or D&C may interfere with normal implantation
Multiparity Repeated pregnancies can increase risk
Advanced maternal age Women over 35 are at higher risk
Smoking Reduces oxygenation and affects placental placement
Assisted reproductive technologies (IVF) Increase likelihood of abnormal implantation
Previous placenta previa Recurrence rate is 4–8%

Pathophysiology

  • Normally, the placenta implants in the upper uterine segment.

  • In placenta previa, implantation occurs in the lower uterine segment, where the placenta may cover or encroach on the cervical os.

  • As the lower segment thins and dilates in the third trimester, the placenta may shear off, causing painless vaginal bleeding.

Clinical Features

Main Symptom

  • Painless, bright red vaginal bleeding in the third trimester

Other Symptoms

  • Bleeding may be recurrent and variable in amount

  • No uterine tenderness or contractions

  • Malpresentation (e.g., breech or transverse lie)

  • High presenting part or floating fetal head

Diagnosis

History

  • Painless, bright red bleeding

  • History of risk factors (previous C-section, multiparity)

Physical Examination

  • DO NOT perform digital vaginal examination (DVE) unless placenta previa is ruled out → may trigger massive hemorrhage.

Investigations

  1. Ultrasound (Primary Diagnostic Tool)

    • Transabdominal USG: Initial screening

    • Transvaginal USG: Gold standard for diagnosis

    • Placenta location, fetal growth, and cervical length are evaluated

  2. MRI (in selected cases)

    • For better imaging in complex cases (e.g., suspected placenta accreta)

  3. Hemoglobin & Hematocrit

    • To assess blood loss and anemia

Complications

Maternal

  • Hemorrhage → hypovolemic shock

  • Anemia

  • Placenta accreta spectrum (in cases with scarring)

  • Infection

  • Emergency C-section

  • Postpartum hemorrhage (PPH)

Fetal

  • Preterm birth

  • Low birth weight

  • Hypoxia or stillbirth (due to placental insufficiency or bleeding)

  • Fetal malpresentation

Management

Initial Management

  • Stabilize the patient

    • IV fluids, blood transfusion if needed

    • Continuous monitoring of fetal heart rate (FHR)

    • Strict bed rest in minor cases

Expectant (Conservative) Management

  • Indicated if:

    • Gestational age <37 weeks

    • Bleeding is mild and controlled

    • Fetus is alive and not in distress

  • Components:

    • Hospitalization or close monitoring at home

    • Corticosteroids (e.g., Betamethasone) for fetal lung maturity

    • Rh immunoglobulin for Rh-negative mothers

    • Serial ultrasound monitoring

Definitive Management

  • Planned cesarean section at 37–38 weeks for complete or partial previa

  • Emergency cesarean if:

    • Heavy bleeding

    • Fetal distress

    • Labor starts

  • Vaginal delivery may be possible in minor (type I) placenta previa with no active bleeding and engaged head under close monitoring.

Nursing Management

Task Description
Monitor VS & FHR Every 15–30 minutes during active bleeding
IV access For fluids, medications, and blood transfusion
Avoid vaginal exams Unless placenta previa is excluded
Prepare for emergency C-section In case of heavy bleeding
Administer medications Corticosteroids, tocolytics if needed
Emotional support Address anxiety, provide education

Patient Education

  • Avoid intercourse and strenuous activity

  • Report any vaginal bleeding immediately

  • Importance of follow-up scans

  • Early hospitalization when near term

  • Prepare mentally for possible cesarean delivery

Mnemonic: PREVIA

To remember key features of Placenta PREVIA:

P – Painless bleeding
R – Relaxed uterus, non-tender
E – Episodes of bleeding, bright red
V – Visible placenta on ultrasound
I – Intercourse or exam may trigger bleeding
A – Avoid vaginal exams!

Differential Diagnosis

Condition Differentiating Features
Abruptio placentae Painful bleeding, tender uterus, hard abdomen, fetal distress common
Vasa previa Fetal vessels crossing cervix, sudden bleeding with rupture of membranes, fetal bradycardia
Cervical polyps or carcinoma Vaginal bleeding, diagnosed on speculum exam and biopsy

Summary Table

Feature Placenta Previa
Pain Absent (painless)
Bleeding Bright red
Uterus Soft, non-tender
Fetal Heart Rate Usually normal unless massive hemorrhage
Management Conservative or Cesarean
Digital Exam Contraindicated

 

Comments

Post a Comment

Popular posts from this blog

Clinical Pathology Notes || Various blood and bone marrow tests in assessment and monitoring of disease conditions || Hemoglobin || RBC, White cell & platelet counts || Bleeding time, clotting time and prothrombine time || Blood grouping and cross matching || Blood chemistry || Blood culture || Serological and immunoligical tests || Other blood tests - Examination of Bone marrow || Methods of collection of blood specimen for various clinical pathology, biochemistry, microbiology tests, inference and normal value

Image
Clinical Pathology  Various blood and bone marrow tests in assessment and monitoring of disease conditions Clinical pathology involves a variety of blood and bone marrow tests that are crucial for assessing and monitoring disease conditions. Here are some common tests: Blood Tests Complete Blood Count (CBC) : Measures red blood cells, white blood cells, hemoglobin, and platelets to detect conditions like anemia, infections, and leukemia. Liver Function Tests (LFTs) : Assesses liver health by measuring enzymes and proteins produced by the liver. Urinalysis : Examines urine for glucose, proteins, pH levels, and infections to diagnose conditions like diabetes and kidney disease. Bone Marrow Tests Bone Marrow Aspiration/Biopsy : Involves taking a sample of bone marrow to examine blood cell production and diagnose conditions like leukemia, anemia, and infections. Flow Cytometry : Analyzes surface markers on cells to identify specific types of blood cells. Cytogenetics/Fluorescence In S...
Read more

50 Most Important Questions and Answers for NORCET 2025 | Staff Nurse Exam Preparation

Image
🧠 Section A: Fundamentals of Nursing (1–10) Q: What are the 10 Rights of Medication Administration? A: Right patient, drug, dose, time, route, documentation, reason, response, education, and right to refuse. Q: Define nursing process. A: A systematic method including Assessment, Diagnosis, Planning, Implementation, and Evaluation (ADPIE). Q: What is the difference between medical and surgical asepsis? A: Medical asepsis reduces pathogens (clean technique); surgical asepsis eliminates all pathogens (sterile technique). Q: What are the normal vital sign ranges for adults? Temp: 97–99°F Pulse: 60–100 bpm Resp: 12–20/min BP: 90/60–120/80 mmHg SpO₂: > 95% Q: What is the purpose of back care in bedridden patients? A: Prevent pressure sores and promote circulation. Q: How do you confirm NG tube placement? A: X-ray is the gold standard. Also: pH of aspirate (<5), auscultation, and aspiration. Q: What is the purpose of Trendelenburg posit...
Read more

Medical Instruments: Comprehensive Guide for Healthcare Professionals || Medical Instruments and Their Uses || Essential Medical Instrument Handbook

Image
The Definitive Guide to Medical Devices Medical instruments, also known as medical devices, are tools designed to diagnose, monitor, and treat diseases and medical conditions. They range from simple tools like thermometers to complex machines like MRI scanners. Here are descriptions of some commonly used medical instruments: 1. Stethoscope Function : Used to listen to internal sounds of the body, such as the heartbeat, lung sounds, and bowel sounds. Components : Consists of a diaphragm and bell connected to earpieces via a flexible tube. Usage : Essential for auscultation in physical examinations. 2. Blood Pressure Monitor (Sphygmomanometer) Function : Measures blood pressure. Components : Includes a cuff that inflates, a measuring unit (dial or digital screen), and a bulb or automated pump. Usage : Wrapped around the upper arm to gauge systolic and diastolic pressure. 3. Thermometer Function : Measures body temperature. Types : Mercury thermometers, digital thermometers, infrared ther...
Read more