Fetal presentation

Core Concepts

• Lie: Fetal long axis relative to mother’s.
  • Longitudinal: Parallel (normal).
  • Transverse: Perpendicular.
• Presentation: Part entering the pelvic inlet.
  • Cephalic (Vertex): Head first, chin tucked. Normal and most common.
• Malpresentation: Any presentation other than vertex.
• Position: Fetal presenting part relative to maternal pelvis.
  • Occiput Anterior (OA): Ideal for delivery.
  • Occiput Posterior (OP): “Sunny-side up”; associated with difficult, prolonged labor.

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High-Yield Malpresentations

• Breech Presentation
  • What: Buttocks/feet first. Most common malpresentation (~3-4% at term).
  • Risk Factors: Prematurity, multiple gestation, uterine anomalies (fibroids), polyhydramnios, placenta previa.
  • Dx: Leopold maneuvers (head in fundus), confirmed with ultrasound.
  • Management:
    • External Cephalic Version (ECV): Attempted at ≥37 wks to manually rotate fetus.
    • C-section: Indicated if ECV fails or is contraindicated.
• Transverse Lie (Shoulder Presentation)
  • What: Fetus is horizontal; shoulder presents.
  • Complication: High risk of umbilical cord prolapse with rupture of membranes (ROM).
  • Management:
    • Preterm (< 37 wks GA):
      • Expectant management: High likelihood of spontaneous conversion to longitudinal lie. c
    • Term (≥ 37 wks GA) & Intact Membranes:
      • External Cephalic Version (ECV): First-line intervention if no contraindications (e.g., no placenta previa, prior classical C-section, or oligohydramnios).
      • Elective Cesarean Section (C-section): Indicated if ECV fails, is contraindicated, or patient declines.
• Face & Brow Presentations
  • What: Due to fetal head extension instead of flexion.
  • Management:
    • Face: Vaginal delivery is possible only if chin is anterior (mento-anterior). If mento-posterior, C-section is required.
    • Brow: Largest presenting diameter. If persistent, C-section is required.