McKeen 2014.

Methods	Double‐blinded (participant, outcome assessor) randomized placebo‐controlled clinical trial Sequence generation by computer‐generated random numbers Follow‐up: 6 months
Participants	Participants: 74 pregnant women from university hospital in Halifax, Canada Operation: scheduled caesarean delivery (planned SA) 2 groups, size: 35/39 (completed) Age (± SD), group 1, 2: 32.1 (± 5.3), 31.4 (± 5.8) All female participants Comorbidities: gravidity (n) 1/2/3/4/5, group 1, 2: 1/1/11/16/5, 2/1/12/15/9; parity (n) 0/1/2/3, group 1, 2: 7/21/7/0, 10/18/10/1
Interventions	Group 1 (ropivacaine): at conclusion of surgery, 20 mL 0.25% ropivacaine injected deep to tissue fascial plane between interior oblique and transversus abdominis Group 2 (placebo): at conclusion of surgery, 20 mL 0.9% saline injected deep to tissue fascial plane between interior oblique and transversus abdominis. All participants received antacid prophylaxis. Standardized spinal anaesthetic technique hyperbaric bupivacaine, fentanyl, morphine. At conclusion of procedure, ketorolac, ondansetron, paracetamol and bilateral TAP blocks under ultrasound. Post‐op pain control with naproxen 250 mg every 8 h, paracetamol 1 g every 6 h, and oxycodone 2.5 mg‐5mg every 6 h as needed. Adjuvants: none Immediate post‐op pain control: no significant decrease in pain or morphine consumption
Outcomes	Dichotomous: none Continuous: SF‐36 Other: adverse effects reported on include nausea, vomiting, pruritus, urine retention
Notes	We acknowledge the study author's response that no dichotomous pain data were collected at 6 months, only SF‐36 Funding sources: "Dr McKeen acknowledges the support of the Canadian Anesthesiologists’ Society (CAS) GE Healthcare Canada Research Award in Perioperative Imaging Operating Grant. Dr George held an IWK Recruitment & Establishment Grant and acknowledges the support of a CAS Career Scientist Award. Dr Allen held a Canadian Institutes of Health Research New Investigator Award and a Dalhousie University Clinical Research Scholar Award. Dr Pink acknowledges Dalhousie University Medical Research Foundation Summer Research Studentship Funding." Conflicts of interest: "none declared"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "computer‐generated block randomized table. Blocks were permuted at ten patients per block with equal allocation of patients between the two groups"
Allocation concealment (selection bias)	Low risk	Quote: "sealed opaque envelopes" labelled with a study number based on order of recruitment with randomization to 1 of two groups (A or B) inside envelope. The pharmacy supplied sterile blinded study drug syringes labelled TAP Block Study Drug ‘‘A’’ or ‘‘B’’
Blinding of participants and personnel (performance bias) All outcomes	Low risk	The pharmacy supplied sterile blinded study drug syringes labelled TAP Block Study Drug ‘‘A’’ or ‘‘B’’. Quote: "prior to each patient’s discharge from the PACU (once spinal motor block had regressed), one of the investigators (D.M. or R.G.) assessed the adequacy of the TAP." This was only known after the participant had left the PACU and was receiving the same ward orders no matter what group.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "research personnel unaware of the patients’ randomization or adequacy of block assessment collected data until the patients left the PACU (minimum two hours), then 24 h and 48 h postoperatively via a ward visit... research personnel contacted patients via telephone at 30 days and six months to complete a five minute Short Form‐36 Health Survey (SF‐36)"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Balanced, low rates of attrition between groups. Reasons for exclusion/missing data are listed for each group.
Selective reporting (reporting bias)	Low risk	Quote: "trial registration was not congruent with the final study protocol and did not include cumulative opioid consumption at 24 h postoperatively as a primary outcome". However, this value was not statistically significant and did not add effect to their results, thus low risk of reporting bias.
Null bias	High risk	Quote: "pain scores at 24 hr were slightly higher in the TAP 0.25% ropivacaine group. These differences were not statistically significant"