Nomogram Developed to Predict Ureteral Stone Passage
Likelihood of stone passage in patients on medical expulsive therapy is based on variables such as stone size and location and white blood cell count.
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BOSTON—Researchers have developed a nomogram for predicting ureteral stone passage in patients on medical expulsive therapy, according to a presentation at the American Urological Association 2017 annual meeting.
“This tool may be used for patient counseling, shared decision making, and to help identify patients who could benefit from early intervention,” lead author Vishnu Ganesan, MD, of the Cleveland Clinic Lerner College of Medicine in Ohio, told Renal & Urology News.
In a study of 1146 emergency department visits for ureteral stones confirmed by computed tomography, Dr Ganesan and his colleagues found that each 1 mm increase in stone size is associated with 50% decreased odds of stone passage. Compared with patients who had proximal ureteral stones, those with middle and distal stones had 1.6 and 3.1 times increased odds of stone passage. A history of stone passage was associated with 1.7 times increased odds of passage. Each 1000-cell increase in WBC count was associated with 10% increased odds of passage.
The nomogram assigns points to each of these variables, and these points are added to come up with a score (on a scale of 1 to 100). Higher scores indicated a greater probability of stone passage.
Age, gender, serum creatinine level, and hydronephrosis had no significant effect on stone passage.
Of the 1146 patients, 48% were lost to follow-up, 31% had spontaneous stone passage, and 20% underwent a procedure to remove the stone.
Ganesan V, Kattan M, Loftus C, et al. A predictive model for ureteral stone passage. [abstract] J Urol 2017;197(4S):e1. Poster presented at the American Urological Association 2017 annual meeting in Boston on May 12, 2017. Poster MP01-02.