Ultrasound-Assisted Neuraxial Anaesthesia for Caesarean Section

Neuraxial anaesthesia (spinal, epidural or combined spinal-epidural anaesthesia) is the gold standard technique for elective lower segment Caesarean section (LSCS) surgery. The traditional and accepted method of performing this anaesthetic procedure involves palpation of the patient’s spinous processes and iliac crests to identify the midline and intervertebral space to appropriately insert the needle and deliver the anaesthetic. The needle is then inserted through the skin, subcutaneous fat and ligaments until the epidural and spinal space is reached. Difficulties can be encountered during this procedure due to the misidentification of the appropriate level of insertion and midline of the spine and needle contact with vertebrae, nerves and blood vessels. Ultrasound images can help identify structures beneath the skin including bone, ligament anf muscle. This study aims to: * determine the accuracy of palpation-based identification of intervertebral level and midline of the spine compared with ultrasound, * assess the efficacy of ultrasound-assisted versus palpation-assisted neuraxial anaesthesia and identify the obstetric population, and * identify the obstetric population at higher risk of difficult neuraxial insertion. Full-term pregnant (>37 weeks gestation, adult patients undergoing elective LSCS surgery who are deemed appropriate to receive a neuraxial anaesthesia will be invited to participate in the study. Patients recruited to the study will be randomised to either the palpation-assisted (control) or ultrasound-assisted (intervention) group. Prior to the performance of a combined spinal-epidural anaesthetic, an anaesthetist will identify and mark the midline and “best” lumbar intervertebral space by palpating the patients hip bones and spine. An investigator will then perform an ultrasound of the patient’s lumbar spine to identify and mark the midline “best” intervertebral space. In the control group, the palpation-identified mark will be used as the needle insertion point. In the intervention group, the ultrasound-identified mark will be used as the needle insertion point. The combined spinal-epidural anaesthetic will be performed using the same standard technique in both groups.