Forty-two RCTs were included: of these, 8 RCTs assessed NSAIDs, 13 assessed intraperitoneal local anaesthetics, 3 assessed local anaesthetics injected into the wound, 3 assessed intraperitoneal saline, 4 assessed the removal of insufflation gas, and 6 assessed characteristics of the insufflation gas. The total number of participants was not stated.
None of the included studies complied fully with the CONSORT guidelines. The deficiencies in the methodology included: inadequate description of randomisation methods (5 RCTs); failure to report inclusion and exclusion criteria (4 RCTs); non-blinded evaluation of outcomes (3 RCTs); lack of power calculations (5 RCTs); inadequate description of the methods used to evaluate pain (1 RCT); follow-up limited to short post-operative period (3 RCTs); and failure to mention methods of restriction of randomisation (3 RCTs).
NSAIDs (8 RCTs, 472 patients).
All trials demonstrated a statistically-significant reduction in some aspect of post-operative pain. The reduction was usually short-lived (first 24 hours).
Intraperitoneal local anaesthetic (13 RCTs, 1,136 patients).
Conflicting results were reported with only 8 of the 13 RCTs demonstrating some reduction in pain for the intervention. No benefit was found in earlier discharge or earlier return to normal activity. The dose and concentration of bupivacaine, the local anaesthetic used, varied considerably between trials. Wound local anaesthetic (3 RCTs, 200 patients).
Two of the 3 RCTs reported reduced pain after wound local anaesthetic.
Intraperitoneal saline (2 RCTs, 110 patients allocated to 11 treatment arms).
Groups receiving instilled saline or saline plus bupivacaine were less likely to report pain than the control groups.
Removal of insufflation gas (4 RCTs, 294 patients).
Two of the four RCTs reported a reduction in pain after removal of the gas.
Insufflated gases (6 RCTs, 285 patients).
Three RCTs compared different gases and found benefit for heated and humidified carbon dioxide over carbon dioxide, gasless abdominal wall lift over standard carbon dioxide pressure, and nitrous oxide over carbon dioxide. Two RCTs found less pain with low-pressure (7.5 to 10 mmHg) insufflation than with high-pressure (14 to 16 mmHg) insufflation. One RCT found less pain with a lower gas flow (2.5 l/minute) than with a higher gas flow (7.5 l/minute).
Size and number of ports: 1 RCT compared 5 and 10 mm epigastric ports and found no difference in post-operative pain.