Study Type – Prognosis (case series)
Level of Evidence 4
What'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.