Radiological and Inflammatory Markers Predicting the Spontaneous Transit of Mid and Lower Ureteric Stones: A Prospective Observational Study

Introduction: Almost 75-90% of ureteric stones pass out spontaneously without any active intervention. Stones that do not pass out can be treated with Extracorporeal Shock Wave Lithotripsy (ESWL) or Ureteroscopic Lithotripsy (URSL). Certain radiological and inflammatory factors can be used to foresee the spontaneous passage of stones. Aim: To determine the factors predicting the spontaneous transit of mid and lower ureteric stones and to assess the outcome of expectant management of stones. Materials and Methods: A prospective observational study was carried out in the Department of Urology, IPGMER and SSKM Hospital, Kolkata, West Bengal, India, from December 2022 to November 2023. All patients attending Urology Outpatient Department (OPD) and Emergency Department of a tertiary care hospital with ureteric colic due to mid and lower ureteric stones were considered for the study. A total of 108 patients meeting inclusion criteria were included in the study. Among them, four patients were lost to follow-up and another two patients had to be excluded as they developed urosepsis with acute pyelonephritis. Hence, data was collected from 102 patients. Stone identification was done using X-ray Kidney Ureter Bladder (KUB), Ultrasonography (USG) KUB and Non Contrast Computed Tomography (NCCT) KUB. Patients were followed-up after every two weeks with repeat reports. The patients were followed-up till they spontaneously passed the stone or till four weeks. Confirmation of stone passage was done with NCCT KUB. The radiological factors that were taken into consideration were included stone volume, stone position, stone density, side of presentation, proximal ureteral diameter, Ureteral Wall Thickness (UWT), Tissue Rim Sign (TRS), Perinephric Fat Stranding (PFS) and degree of hydronephrosis. The inflammatory factors studied included C-reactive Protein (CRP), White Blood Cell (WBC)/Total Leucocyte Count (TLC), Neutrophil Percentage (NP) and procalcitonin. The patients were divided into two groups: those who spontaneously passed the stone (SP) and those who did not (SNP). The non parametric Mann-Whitney U test and independent t-test were used to compare continuous variables, while Fisher’s exact test or the Chi-square test was used to compare categorical variables. Univariate and multivariate analyses were performed to identify predictors for stone passage. Results: Of the 102 participating patients, 67 (65.7%) passed the stone spontaneously. The mean age of the total population was 34.9±9.7 years. The presence of hydronephrosis, PFS and TRS were all found to be associated with failure of spontaneous passage of ureteric calculi (p-value<0.001). High CRP, leucocyte count and procalcitonin were associated with a lower spontaneous passage of stones. Increased CRP (SP 3.13±1.76 vs SNP 8.56±7.02, p-value <0.0001) and procalcitonin (SP 0.13±0.02 ng/mL vs SNP 0.22±0.14 ng/mL, p-value=0.001) were significantly associated with non passage of ureteric stones. On multivariate analysis, only stone size (p-value=0.028), procalcitonin (p-value=0.003) and stone level (p-value=0.026) were found to be significantly related to spontaneous stone passage. Conclusion: Inflammatory markers and radiological variables were found to predict the spontaneous transit of mid and lower ureteric stones.