Lima 2014.

Study characteristics
Methods	Randomised controlled single‐blind study, Brazil.
Participants	34 women undergoing caesarean delivery (primiparous or multiparous), aged more than 18 years (18 to 42 years), with pain greater than 3, undergoing spinal anaesthesia and incision P‐fannestiel, literate, oriented and absence of pathology genitourinary. There were three treatment groups: TENS High frequency (n: 13), TENS low frequency (n: 12), and one placebo group (n: 9).
Interventions	13 women received TENS high frequency 100 Hz (G100), 12 women in the TENS low frequency 4 Hz (G4) and 9 women in the placebo group (GP) (appliance off), the pulse duration of 100 μs with a current intensity of according to the threshold of each participant. The TENS device was continuously used for 30 minutes in each participant, only 1 section, 8 hours after the CS. Participants who received drug prescription inflammatory or analgesic were submitted to the assessment and intervention after 6 and 8 hours, respectively, to minimise possible interactions between effects of drugs and TENS.
Outcomes	Pain score and adverse effect were evaluated immediately after, 20, 40 and 60 minutes after finalised treatment, using numerical rating scale (0‐10).
Notes	Funding sources: not mentioned. Setting: Santa Casa de Misericórdia and Hospital Estadual Dirceu Arcoverde (HEDA), Brazil. Conflicts of interest: not mentioned. Dates of trial: not mentioned, published 2014.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The participants were randomly allocated into 3 groups according to software.
Allocation concealment (selection bias)	Low risk	The randomisation and allocation, hidden in opaque envelopes and numbered, were performed by a researcher no research participant.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	The participants were unaware of the treatment protocol to which each participant was allocated.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	The assessor was unaware in treatment protocol to which each participant was allocated.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	There were losses which were not described. We contacted the author in 24 June 2015 with no response.
Selective reporting (reporting bias)	Low risk	Presents the results of the analysis proposed in the methods.
Other bias	Low risk	We do not suspect any other bias related to this study.