Fifteen RCTs were included (one trial included two types of comparison and was counted as two trials in the review). The number of patients was unclear; it appeared to be approximately 1,117. Eleven trials met all the quality criteria (adequate methods of randomisation, allocation concealment, blinding and completeness of follow-up). The other five trials were considered to be at moderate risk of bias.
Unilateral position during spinal anaesthesia (four RCTs): Studies using the same bupivacaine dose reported varying times to recovery. Results on time to home discharge were inconsistent. Failure rates were low (0% in 3 studies and 1.9% and 6.2% in one study).
Supine position during spinal anaesthesia (one RCT): Higher bupivacaine doses (10 and 15 mg) were associated with a significantly increased time to voiding and discharge compared to lower doses (5 and 7.5 mg); the 5 mg dose was associated with higher failure rate (26%).
Opioid adjuvants (fentanyl and morphine) (four RCTs, n=260 patients): There was no statistically significant difference in time to discharge for adjunctive fentanyl compared with no fentanyl (three studies, n=190 patients). Adding morphine increased recovery time compared with adjunctive fentanyl or no adjunctive agents. The authors stated that adding opioids was associated with reduced pain scores and decreased requirement for analgesia, but no supporting data were presented. All studies reported increased side effects associated with adjunctive fentanyl. The most common side effect was pruritus (in 48% to 75% of patients in the fentanyl group).
Bupivacaine versus ropivacaine (five RCTs): Studies reported no significant difference between bupivacaine or levobupivacaine plus ropivacaine for time to voiding, discharge and side effects.
Unilateral and bilateral spinal anaesthesia (two RCTs): The authors stated that unilateral spinal anaesthesia was associated with a reduced time to discharge, but it was not clear from tables which group in one study received the unilateral anaesthesia. Both studies reported that unilateral spinal anaesthesia was associated with a significant reduction in side effects and bradycardia; there was no significant difference in the risk of urinary retention.