To evaluate the effect of Hounsfield unit(Hu) value to the efficiency of flexible ureteroscopy (FURS) for the upper ureteral calculi.

The data of patients with upper ureteral calculi who were treated by FURS with holmium laser lithotripsy between June 2017 and June 2018, with calculi size <20 mm, at Wenzhou Central Hospital were retrospectively evaluated. Patients were divided into two groups according to the CT value(above 800 Hu or below 800 Hu), the high CT value group included 91 patients and the Low CT group included 88 patients. Then compared the operative time, stone-free(SF), and the complications status between the two groups.

The age, male-female ratio, the stone size or the accompanying diseases between the low CT group and the high Hu group had no statistical difference (P>0.05).The average operative time of the two groups was (43±23) min and (50±25) min, respectively, which had statistical difference respectively (P<0.05); the incidence of complications was 3.3% and 6.8%, respectively, which had no statistical difference (P<0.05); the SF was 94.6% and 93.2%, respectively, which had no statistical difference (P>0.05).

FURS for the upper ureteral calculi, with calculi size <20 mm, was safe and effective; the Hu of calculi above 800 Hu could extend operative time and reduce lithotripsy efficiency. Preoperative evaluation of Hu value of patients, to a certain extent,could help the urologists to evaluate incidence of postoperative complications and grasp the difficulty and the risk of surgery.