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Placenta Previa: Causes, Symptoms, Diagnosis and Nursing Management

OBSTETRICS / NURSING EDUCATION · MINI NURSES

PLACENTA PREVIA

Definition

  • Placental tissue reaches or covers the internal cervical opening (internal os).
  • An important cause of bleeding in the second half of pregnancy.

Classification

  • Placenta previa: placenta reaches or covers the internal os.
  • Low-lying placenta: edge less than 20 mm from the os, without covering it.
  • Modern ultrasound terminology replaces the older Type I–IV classification. [1]

Pathophysiology / Mechanism

  • Implantation occurs in the lower uterine segment.
  • Stretching of the lower segment and cervical changes may disrupt placental attachment, causing bleeding.

Clinical Presentation

  • Classically painless vaginal bleeding, which may be sudden or recurrent.
  • Pain or contractions may coexist; their presence does not exclude previa.
  • Heavy blood loss can cause maternal compromise. [2]

Investigations

  • Ultrasound establishes placental location; transvaginal ultrasound by a trained clinician is safe and precise.
  • Follow-up commonly occurs around 32 weeks and again around 36 weeks if the placenta remains low.
  • During bleeding: maternal assessment, appropriate fetal monitoring and blood tests, including full blood count and crossmatching.

Management

  • Immediate: urgent obstetric review; activate the haemorrhage pathway for significant bleeding.
  • Stabilisation: monitor vital signs and blood loss; prepare IV access, prescribed fluids and blood products.
  • Ongoing care: individualise admission, surveillance, iron treatment, antenatal corticosteroids and eligible anti-D prophylaxis.
  • Birth: persistent previa generally requires caesarean delivery; timing depends on bleeding, gestation and maternal–fetal condition.
  • Selected asymptomatic low-lying placentas 11–20 mm from the os after 36 weeks may be considered for a trial of labour after specialist discussion. [1]
A pregnant woman attending a consultation with a healthcare professional
Illustrative antenatal consultation photograph by MART PRODUCTION / Pexels. Models shown; the image does not depict a diagnosed case.

Common Risk Factors

  • Previous caesarean birth or uterine surgery.
  • Previous placenta previa.
  • Fertility treatment and smoking.

Complications

  • Severe maternal haemorrhage and anaemia.
  • Emergency delivery and preterm birth.
  • Placenta accreta spectrum, particularly with previa over a previous caesarean scar. [3]

Contraindications / Precautions

  • Avoid digital vaginal examination when previa is suspected; it may provoke severe bleeding.
  • Transvaginal ultrasound is different from a digital examination. A clinician may use a careful speculum examination when indicated.
  • Sex and activity advice should follow the treating team’s assessment; routine strict bed rest is not a proven treatment.

Nursing Responsibilities

  • Escalate bleeding promptly and monitor the mother and fetus.
  • Prepare for resuscitation or urgent delivery as directed.
  • Explain care, preserve dignity and document assessments and actions.
  • Teach warning signs, follow-up arrangements and how to obtain urgent maternity care. [4]
☀ Key PointPainless bleeding is the classic presentation. Confirm placental location with ultrasound, avoid digital examination and escalate promptly. Heavy bleeding, faintness or collapse is an emergency.
MINI NURSES · Obstetrics & Midwifery
Educational summary · Updated 16 October 2026 · Sources linked above. Follow local protocols and specialist instructions.