Women require routine opioids to prevent painful colonoscopies: a randomised controlled trial.

Fentanyl prior to colonoscopy provided better pain control than fentanyl or alfentanil on-demand. Fentanyl before colonoscopy should be recommended to all women at screening age. Trial registration: Clinicaltrials.gov (NCT01538550). Norwegian Medicines Agency (16/16266-13). EU Clinical Trials Register (EUDRACTNR. 2016-005090-13).