Nelson 2013.

Methods	Location: Los Angeles, CA, USA Recruitment time: from June 2008 to December 2008 Sample size calculation: Sample size arbitrarily selected for convenience to meet time and financial constraints in this investigator‐funded study.
Participants	General with N: 40 women Source: Women's Health Care Clinic (WHCC) at the Los Angeles Biomedical Research Institute at Harbor‐UCLA Medical Center Inclusion criteria: women identified as candidates for IUD use following clinic protocols, had given consent for IUD insertion and expressed interest in participating Exclusion criteria: not reported
Interventions	1) 2% lidocaine (1.2 mL) infused into endometrial cavity (lower third, middle, and top of cavity) 2) Saline (1.2 mL) Timing: 3 min before IUD was inserted
Outcomes	Primary: pain score after tenaculum placement, after liquid infusion and IUD insertion, pain score of overall procedure (0 to 9 scale) Secondary: pain score comparisons by IUD types, prior IUD use, NSAID use, and by timing of placement during menses or not
Notes	IUC used: CuT 380A or LNG‐IUS 11 women took NSAIDs 15 min to 2 h prior to IUD insertion
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomization was done in a 1:1 ratio using a random number generator.
Allocation concealment (selection bias)	Low risk	Sequentially numbered and sealed envelopes
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Double‐blinded" 2 clinicians who inserted IUDs were blinded to study group; participants apparently blinded. Research nurse placed study medication into tubing out of sight of provider and participant.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Loss to follow‐up: none