Hampl 1995a.

Methods	Randomization: yes Participant blinding: yes Provider blinding: yes Assessor blinding: yes Dropouts: 0
Participants	Country: Switzerland ASA: I and II Gender: women Age range: 19–81 years Procedures: gynaecological Ambulatory surgery: no Surgical positioning: lithotomy Number of participants: 44
Interventions	Drug 1: 5% lido, hyperbaric, fixed dose (1.5 mL) Drug 2: 0.5% bupi, hyperbaric, fixed dose (1.5 mL) Needle: 25 G, pencil‐point
Outcomes	TNS at 1 day Back pain
Notes	Follow‐up duration: 1–4 days Follow‐up method: direct contact TNS therapy: unclear TNS resolution: all recovered
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "patients were randomly assigned to receive one of the following three local anesthetic solutions…" Comment: did not specify the method of randomization (referring to a random number table, computer‐generated random number sequence, tossing coin, etc.).
Allocation concealment (selection bias)	Unclear risk	No mention of the method of allocation concealment (central allocation, sequentially numbered, sealed, opaque envelopes, or sequentially numbered drug containers of identical appearance).
Participant blinding (performance bias and detection bias)	Low risk	Quote: "…the aim of this prospective double‐blinded study was…"
Provider blinding (performance bias)	Low risk	Quote: "the drugs were delivered by the pharmacy in blinded vials each containing 2 ml local anesthetic solution."
Assessor blinding (detection bias)	Low risk	Quote: "on post‐operative day 1, all patients were evaluated for TRI by oral interrogation by one anesthesiologist who was unaware of details of the anesthesia procedure."
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote "… we studied 44 ASA class I and II patients…" Comment: results reported for 44 participants.
Selective reporting (reporting bias)	Unclear risk	Study protocol not available.