Presentation Authors: Ryan Chandhoke*, Jacob Bamberger, Blair Gallante, William Atallah, Mantu Gupta, New York, NY
Introduction: Impacted ureteral stones are associated with edema and hypertrophy of the ureteral mucosa, which often makes endoscopic ureteral stone surgery more challenging. If an easily measured parameter on preoperative CT scan could predict significant ureteral stone impaction, a urologist would be better prepared for patient counseling of associated risks and outcomes of surgery.
Methods: After IRB approval, we prospectively collected intraoperative data on 34 patients who had a preoperative CT scan and underwent ureteroscopy (URS) for ureteral stones. Surgeons were blinded to preoperative CT parameters except for stone size, location, and degree of hydronephrosis. Stones were considered impacted at surgery if contrast had difficulty passing proximal to the stone, or if a guidewire could not pass, and the stone was visually impacted >5 on a Likert scale. We correlated intra-operative findings to preoperative CT measurements of ureteral thickness on a coronal series directly above, around (ie P-CUT), and below the calculus. Other variables measured included hydronephrosis, stone volume, longest dimension, and stone location (Table 1). Chi-square, ANOVA, and logistic regression analyses were conducted.
Results: Of the 34 patients, 13 were found to have an impacted ureteral stone at the time of surgery. Patients with an intra-operative finding of an impacted stone had significantly higher ureteral thickness above, around (P-CUT), and below the calculus (all three p-values < 0.001) compared to non-impacted ureteral stones. Multivariate analysis revealed that only P-CUT was independently predictive of impaction at the time of surgery. A mean P-CUT of 5.3mm and 1.7mm was noted for the impacted and non-impacted stone groups, respectively.
Conclusions: Increased ureteral thickness as measured on CT coronal imaging above, around (P-CUT), and below the calculus is predictive of impacted stones at the time of surgery. This information is valuable for surgical planning and patient counseling of risks and outcomes expectations pre-operatively.