Contents
Implantation of placenta near the internal os.
Etiology
Risk factors:
- Defective endometrial vasculature & scarringĀ (leading to compensatory placental hypertrophy):
- Advancing maternal age
- Multiparity
- Previous LSCS
- Maternal cigarette smoking
- Big placenta:
- Multiple pregnancies
- Placenta succenturiata
- Placenta membranacea (compensatory mechanism in anaemia)
- Defective uterine development:
- Uterine anomalies
- Idiopathic:
- Fetal malpresentation
- Maternal serum-AFP
Classification

Minor degree:
- Type I: Low-lying placenta
- Lower placental margin within 2 cm of internal os
- Type II: Marginal placenta previa
- Anterior
Major degree:
- Type II: Marginal placenta previa
- Posterior “Dangerous placenta previa”
- Due to underlying sacral promontory
- Posterior “Dangerous placenta previa”
- Type III: Partial placenta praevia
- Lower placental edge covers internal os
- Type IV: Central placenta praevia “Complete placena praevia”
- M/dangerous
Presentation
Painless, recurrent vaginal bleeding
Only symptom
- Sentinel bleed: Warning haemorrhage that first occurs in late 2nd or 3rd trimester
- Stallworthy sign: Slowing of fetal heart rate on pressing the head down into the pelvis and prompt recovery on release of pressure (d/t posterior placenta previa)

Complications
Maternal complications:
- Antepartum complications:
- Antepartum haemorrhage (APH)
- Malpresentation
- Preterm labour
- Associated abruptio (10% cases)
- Complications during labour:
- Cord prolapse
- Intrapartum haemorrhage
- Premature rupture of membranes (PROM)
- Postpartum complications:
- Postpartum haemorrhage (PPH)
- Retained placenta
- Puerperal complications:
- Puerperal sepsis
Fetal complications:
- Low birthweight (M/C complication, 15% cases)
- Birth asphyxia
- Respiratory distress syndrome
- Birth injuries
- Congenital malformations (3x risk)
Diagnosis
Lab investigations:
- Haemoglobin, hematocrit
- ABO/Rh typing
- Coagulation studies
- Bleeding time, PT, APTT, etc
- Renal function test (RFT)
- Urine output
- Urea
- Creatinine
Fetal surveillance tests:
- Fetal movement counts
- Non-stress test (NST)
- Biophysical profile score
Imaging:
- USG ± Doppler
- 18-22 weeks (repeat after 2 months if low lying placenta seen)
- MRI
- Reserved for placenta praevia accreta


Differential diagnosis:
- Accidental hemorrhage “Abruptio placentae”
- Placenta accreta
Management
Mcafee and Johnson regimen:
Expectant management preferred before term which aims to continue pregnancy for fetal maturity without compromising maternal health
- Continue pregnancy till 37 weeks
- Avoid cervical stimulation
- No vaginal examination
- Abstinence
- No constipation
- Drugs:
- Steroids (< 34 weeks): Enhance fetal lung maturity
- Tocolysis: Suppress premature labour
- Antimicrobials
- Stool softeners
- Anti-Rh immunoglobulin
Definitive management:
- Minor degree placenta praevia: Vaginal delivery
- Major degree placenta praevia: Cesarean section