Role of white blood cell and neutrophil counts in predicting spontaneous stone passage in patients with renal colic
Authors: Sfoungaristos Stavros , Kavouras Adamantios , Katafigiotis Ioannis , Perimenis Petros 
Published: February 2012

Study Type – Prognosis (case series)Level of Evidence 4What's known on the subject? and What does the study add?Parameters that predict spontaneous stone passage is a subject that has been widely studied. Several factors have been proposed as potential predictors, however mainly stone size and location are the only ones that are consider in the clinical practice.So far, it is well known that stone size is the most significant parameter. Actually, based on the latest guidelines, stones sized <4 mm have a great likehood to pass spontaneously a waiting period of 4–6 months should be proposed to the patient. On the other hand, stones >7 mm have minimum possibilities to pass spontaneously and immediate intervention might be the optimal management.Another significant factor is stone location. Patients with stones placed in the distal ureter seem to have greater opportunities to be stone‐free than those patients with calculi in the proximal or mid‐ureter.Even by considering size and location of a ureteral stone, a significant number of patients with favorable characteristics stones are not stone‐free by surveillance and either ESWL or ureteroscopy is needed for definitive therapy. On the other hand, large stones in the proximal ureter are passing spontaneously and no intervention is needed. Based on the above, someone can consider that there are other parameters that enhance or not stones passage. The results of our study showed that increased WBC and neutrophils counts in blood serum can significantly contribute to the prediction of stone spontaneous passage. Using the present results in combination with the present knowledge (size and location) might help us to better define the best treatment protocol for each individual. Furthermore, both parameters can be easily, quickly and without significant cost assessed for every patient in the emergency department.OBJECTIVE
To determine the clinical, imaging and laboratory variables that can predict spontaneous passage of ureteral stones causing renal colic and the role of white blood cell (WBC) and neutrophil counts for the prediction of spontaneous calculi passage.
PATIENTS AND METHODS
A total of 156 patients who were referred to the emergency department complaining of renal colic due to a ureteral stone entered the analysis. Several clinical, laboratory and imaging parameters were evaluated for their potential ability to predict stone passage in a time interval of 1 month.
The study design had two objectives. Primarily we analyzed all patients irrespective of stone size and secondly we analyzed patients with calculi of 10 mm maximum length.
RESULTS
Spontaneous stone passage was observed in 96 (61.5%) patients in the overall population and in 84 (65.1%) of 129 patients with calculi <10 mm.
Increased concentrations of serum WBCs and neutrophils at the time of the acute phase of a renal colic were associated with increased likelihood of spontaneous passage.
In the multivariate analyses we found that WBC and neutrophil counts were the most important predictors of stone elimination.
CONCLUSIONS
Active surveillance of patients suffering from ureteral lithiasis is an acceptable option. Identifying the parameters which can predict those patients who will mostly benefit from this is of great importance.
Based on our results, WBC and neutrophil counts should be considered when patients with renal colic secondary to ureteral calculi are evaluated since they can significantly add to spontaneous elimination prediction.
Their consideration in addition to other important factors, like stone size and location, would maximize their predictive ability.