BACKGROUND:Although the application of ureteroscopy in the treatment of ureteral calculi during pregnancy has been on the rise, for persistent renal colic patients without ultrasound-detected ureteral calculi, it may represent a clinical dilemma due to the potential risks for both mother and fetus. OBJECTIVE:The aim of the present study is to present our experience with the application of the ureteroscope in the emergency treatment of persistent renal colic patients during pregnancy. METHODS:From March 2009 to September 2014, a total of 117 pregnant women who received ureteroscopy for persistent renal colic were retrospectively analyzed. Patients were divided into three groups according to duration of the persistent renal colic: Group A (within 12 hours; 24 cases); Group B (12 to 24 hours; 76 cases); and Group C (more than 24 hours; 17 cases). The stone-free rate, complications, and other qualitative data were analyzed. RESULTS:Of the 117 patients, 31 patients who were found not to have renal or ureteral calculi received ureteroscopic double-J (DJ) stent insertion, whereas 86 patients who were found with ureteral calculi received ureteroscopic lithotripsy (URSL) and DJ stent insertion. Among them, 24 patients (27.9%) were found with ureteral calculi by ureteroscopy rather than ultrasound. In addition, 73 patients (84.9%) had complete fragmentation of calculi; 12 patients (10.3%) had a threatened abortion (the rates of threatened abortion in Groups A, B and C were 8.3% vs. 6.5% vs. 29.4%; Group C compared with Groups A and B, p