Obstetrics & Gynecology
Placenta Previa
전치태반
Placenta partially or fully covers internal cervical os, causing painless bleeding
- How common
- 0.3–0.5% of late pregnancies
- Typical age
- Higher risk >35, multiparous
What is it?
Abnormal placental implantation in lower uterine segment → as segment stretches, villi shear from decidua → painless bleeding.
Commonly affected: Lower uterine segment and placental bed
How it develops
- Lower segment implantationRisk factors: prior cesarean scar, multiparity
- Cervical relationshipComplete · marginal · low-lying
- Segment changesLate pregnancy effacement of segment
- Villous shearingPainless, spontaneous hemorrhage
Symptoms
- Painless vaginal bleedingBright red, common after 28 wk
- Hemorrhagic shockWith heavy bleeding
- MalpresentationHigher rates of transverse/breech
- No abdominal painDistinguishes from abruption
How it is examined
- NO digital examNever do digital exam — can precipitate hemorrhage
- TAUS + TVUSTVUS most accurate for distance to internal os
- LabsCBC, coagulation, type and cross
Imaging
X-ray not used.
- Not applicable
TVUS: placental edge covers internal os. MRI to evaluate accreta spectrum.
- Placenta over os
- Accreta evaluation
- Low-lying placenta
Non-surgical care
- Inpatient observationAdmit for active bleeding; bed rest
- Antenatal corticosteroidsBetamethasone 12 mg IM × 2 (24–34 wk)
- Type and cross/transfusion prepCross-match ≥2 units PRBC
- Pelvic restNo intercourse/exam after diagnosis
- Anti-D immunoglobulinFor Rh-negative mothers
Conservative options are generally tried first. Medications listed here can have side effects — discuss them with your prescriber.
When surgery is considered
Planned cesarean at 36–37 wk for all complete previa
Procedures that may be discussed
- Scheduled cesarean (36–37 wk)
- Emergency cesarean for massive bleed
- Consent for hysterectomy if accreta suspected
Outlook
Good with planned cesarean; risk increases if placenta accreta coexists.