Side Effects and Efficacy of Neuraxial Opioids in Pregnant Patients at Delivery: A Comprehensive Review.

Neuraxial opioids are an integral part of obstetric anaesthesia and have contributed to greatly improved analgesia for labour and caesarean delivery, both intraoperatively and postoperatively. Despite these advantages, neuraxial opioids may be associated with a number of side effects, some of which (such as respiratory depression), although rare, may be associated with significant morbidity and mortality. The risk of respiratory depression appears to be increased with less lipophilic opioids such as morphine but can be reduced with careful patient selection and monitoring. Other side effects such as pruritus and nausea and vomiting appear to be dose-related and so can be limited by choosing the appropriate dose to optimise analgesia whilst limiting the adverse effects. Urinary retention, the potential neurotoxic effects of neuraxial opioids and the postulated effects on the foetus are also considered but currently it is felt there is not enough evidence to make strong recommendations with regard to specific drugs or dosage. This review aims to discuss the mechanism and incidence of these side effects as well as, where possible, their prevention.