A 27-year-old woman with severe rheumatic mitral stenosis (valve area 0.9 cm2) reaches spontaneous labour at 37 weeks. She is haemodynamically stable. How should the second stage of labour be managed?

• A Allow prolonged spontaneous pushing until the head crowns
• B Proceed directly to caesarean section at onset of labour
• C Perform an elective instrumental delivery to shorten the second stage and avoid Valsalva straining ✓
• D Withhold all analgesia to preserve maternal effort

Explanation

Valsalva straining during pushing causes cyclical falls in venous return followed by sudden surges in cardiac output and left atrial pressure, which a stenotic mitral valve cannot accommodate. Shortening the second stage with forceps or vacuum delivery is standard practice in significant cardiac disease. Caesarean section is reserved for obstetric indications or unstable patients, since it carries greater haemodynamic and thrombotic stress than a well-conducted vaginal birth. Withholding analgesia worsens the tachycardic stress response.

Reference: Williams Obstetrics, 26th ed.

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Written and medically reviewed by the StethoPrep medical team.