Pruritus and postoperative nausea and vomiting after intrathecal morphine in spinal anaesthesia for caesarean section: Prospective cohort study

Background: Spinal anaesthesia is a common anaesthetic technique for caesarean sections. Neuraxial opioids such as intrathecal morphine may cause common adverse effects (pruritus, post-operative nausea and vomiting). Objectives: We investigated the incidence, severity and need for treatment of pruritus and post-operative nausea and vomiting following administration of intrathecal morphine in spinal anaesthesia for caesarean section at KK Women’s and Children’s Hospital, Singapore. Methods: We conducted a prospective study involving 124 parturients who received intrathecal morphine in spinal anaesthesia for caesarean section from October 2012 to October 2014. Results: Seventy patients (56.5%) had moderate or severe pruritus (score 4–10), while 54 patients (43.5%) had no or mild pruritus (score 0–3). Mean (SD) value of the worst pruritus score reported on a scale of 0–10 was 4 (2.59). Only seven out of the 124 patients (5.6%) required treatment for pruritus. With respect to distress and bother from itching in the past 24 hours on a score of 0–4, the mean score reported was 1.7 (1.23). Fourteen (11.2%) patients reported vomiting, dry-retching and nausea. Six (4.8%) patients had nausea that interfered with activities of daily living. Four (3.2%) patients had clinically significant post-operative nausea and vomiting. Seven (5.6%) patients received anti-emetics. The average Overall Benefit of Analgesia Score was 3.8 (SD 2.6, min–max: 0–15). The average (SD) maternal satisfaction with pain relief and side effects was 84.9% (9.9%). Conclusion: There is a high incidence of pruritus, with most women reporting moderate to severe pruritus. The incidence of post-operative nausea and vomiting is low, and women reported good maternal satisfaction