Predictive factors for difficult ureter in primary kidney stone patients before retrograde intrarenal surgery.

Introduction: Ureter may be resistant to insertion of ureteral access sheath (UAS) and/or semi-rigid ureterorenoscope because of the narrow ureter, 'difficult ureter' especially in primary retrograde intrarenal surgery (RIRS) cases. We aimed to delineate the parameters that affect significantly the accessibility of the ipsilateral ureter of the stone-bearing patient side. Material and methods: The data of age, gender, body mass index, comorbidities, prior urinary tract infection, prior stone passage, stone burden, stone density, number of stones, stone localization, surgery side, the presence of hydronephrosis and need for double J (DJ) stent due to difficult ureter for all patients were reviewed. Difficult ureter was defined as the insertion inability of a semi-rigid ureterorenoscope or UAS into the ureter at the surgery side. All patients were divided into two groups as difficult ureter group and non-difficult ureter group. Results: A total of 454 patients who underwent RIRS for primary kidney stones were included. The incidence of difficult ureter was 7.5% (34/454). The patients in the difficult ureter group were younger. Female gender and prior urinary tract infection rates were higher in the difficult ureter group. Multivariate logistic regression analysis indicated that the factors significantly associated with higher odds of having a difficult ureter in primary RIRS patients were younger age (OR 1.040; 95% CI 1.010-1.070; p = 0.008), female gender (OR 2.859; 95% Cl 1.383-5.908; p = 0.005) and prior urinary tract infection (OR 3.327; 95% CI 1.230-8.999; p = 0.018). Conclusions: Difficult ureter was associated with younger age at the time of RIRS, female gender and the manifestation of urinary infections in the patient's medical history.