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Urinary calculi patients with abnormal imaging results following ureteroscopy should continue to be monitored with routine imaging.
The researchers reviewed records of a contemporary group of 478 consecutive patients who underwent URS for renal or ureteral calculi between 2007 and 2009 at one of two academic medical centers: Penn State University's Milton S. Hershey Medical Center, Hershey, PA, or the University of Texas Southwestern Medical Center, Dallas. Of the entire cohort, 332 patients (70%) had undergone imaging 1 to 4 months after stent removal using a variety of techniques, which included computed tomography (186), intravenous pyelography (84), renal ultrasound (58), and nuclear study (four).
An imaging abnormality, defined as ipsilateral hydronephrosis or delayed renal excretion, was identified in 56 (17%) of the 332 patients. The 56 abnormal images represented ureteral stricture disease in 10 patients, 16 obstructing retained stone fragments, and 30 cases of delayed excretion and no evidence of an obstructing stone or stricture. Half of the patients diagnosed with an imaging abnormality were asymptomatic, reported first author William Caraway, MD, a former urology resident at Penn State who worked on the study with Jay Raman, MD, of Penn State, Yair Lotan, MD, of UT Southwestern, and co-authors.
"Our data show that a significant proportion of patients may have a clinically significant issue. Therefore, we believe it is prudent to routinely image patients following URS."
Two predictive factors found
The data were also analyzed to determine whether any patient, stone, or operative factors were predictive of an imaging abnormality. Only prior URS and inability to completely retrieve the stone were independently associated with an increased risk of having an abnormal image (OR=3.0 and 3.4, respectively; p≤.013 for both). Patient demographic features (age, gender, body mass index), stone variables (location, composition, size), preoperative hydronephrosis, operative time, need for dilation or access sheaths, and duration of postoperative stenting were also investigated but found to have no association with the finding of abnormal imaging.
Questions and comments made during the discussion of the paper at the AUA annual meeting in San Francisco reflected opposing opinions on whether routine imaging after uncomplicated URS represents "overkill," often identifying features with no clinical relevance, or is worthwhile, considering the potential deleterious consequences of an undiagnosed abnormality. Audience members also questioned whether there are any clinical characteristics that might help better define an at-risk population for which routine imaging should be performed.
Dr. Caraway was asked about the outcome of the 30 patients with delayed excretion and no other evidence of an abnormality. He reported they had no clinical sequelae, but noted the follow-up was only 12 months and suggested problems might emerge given more time or a larger patient population.
Co-author Dr. Raman noted that optimally, a refined algorithm reflecting a risk adoptive approach might be developed. Based on the data collected, distinguishing patients who had undergone a complicated versus uncomplicated URS would appear to have limited value in distinguishing a subgroup that should undergo routine imaging. Dr. Caraway reported that among the 10 patients found to have strictures, an intraoperative complication occurred in two, but the URS was completed as a straightforward procedure in the remaining eight.