Evaluation of the patient and stone related parameters on the likelihood of spontaneous ureteral stone passage: A critical evaluation focusing on the urinary tract infection without pyuria due to luminal obstruction.

Introduction: This study aimed to investigate the patient-, stone-, and laboratory-related parameters to predict the likelihood of spontaneous stone passage (SSP) in uncomplicated 5-10 mm ureteral stones.

Methods: Between August 2020 and April 2024, 421 patients presenting with 5-10 mm ureteral stones were included in the study program. Patients were divided into two groups based on the spontaneous passage status of the stones during the 4-week close follow-up period. Group 1 [n: 252 (%59.8)] patients passing the stones during this period, Group 2 [n: 169 (%40.2)] patients who could not pass the stones. In addition to the stone (size and location), patient (associated co-morbidities, presence of UTI) and degree of hydronephrosis were assessed in all patients. Urinary tract infection (UTI) without pyuria was defined as the absence of pyuria in urinalysis due to ureteral obstruction despite the presence of an elevated blood level of white blood cells or C-reactive protein. UTI without pyuria patients were tested by a mid-stream urine sample for culture and were defined as no bacterial growth (<105 cfu/mL) in the urine culture.

Results: The presence of comorbidities (p=0.006), degree of hydronephrosis (grade 3 vs. grade 2, p=0.011 and grade 3 vs. grade 1, p=0.008), transverse stone size (p=0.004), ureteral stone location (proximal vs. distal, p=0.010), and UTI without pyuria (p<0.001) were found to be independent predictors for SSP. Spontaneous passage of ureteral stones could be predicted with the help of some patient and stone related parameters.

Conclusions: Associated co-morbidities and, most importantly, the presence of UTI without pyuria (due to luminal obstruction) were the most important independent predictors that decreased SSP in ureteral stones.