A 28-year-old female at 38 weeks gestation is undergoing emergency caesarean section under general anaesthesia. Rapid sequence induction is performed with cricoid pressure. After intubation, the anaesthetist notes that the endotracheal tube size selected should be:

• A 6.5 mm ID, only if the patient weighs less than 60 kg
• B 7.0 mm ID, as in non-pregnant females of similar size
• C 8.0 mm ID, to allow larger suction catheters for the increased secretions of pregnancy
• D 6.0 mm ID, because pregnancy causes airway oedema and smaller tubes are easier to insert ✓

Explanation

During pregnancy, capillary engorgement and oedema of the upper airway increase the risk of trauma and post-extubation stridor. Current obstetric anaesthetic practice recommends using a smaller endotracheal tube (6.0 to 6.5 mm ID) compared to the standard 7.0 to 7.5 mm used in non-pregnant females. D 6.0 mm tube is commonly chosen to minimise airway trauma while still permitting adequate ventilation and suctioning.

Reference: Chestnut's Obstetric Anesthesia, 5th ed.

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Written and medically reviewed by the StethoPrep medical team.