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STONE
DISEASE
Use
of renal ultrasound to detect hydronephrosis after ureteroscopy
Manger JP, Mendoza PJ, Babayan RK, Wang DS
Department of Urology, Boston University School of Medicine, Boston, Massachusetts,
USA
J Endourol. 2009; 23: 1399-402
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Introduction:
Ureteral obstruction is a potentially serious complication after ureteroscopy.
Postoperative imaging with intravenous urogram and CT has been described
as a means to detect asymptomatic or “silent” obstruction.
We sought to evaluate the use of renal ultrasound to diagnose hydronephrosis
after ureteroscopy in a large, contemporary series.
Materials and Methods: Of the 438 ureteroscopies performed by one
staff surgeon at our institution from August 2003 to June 2008, 289
underwent a strict follow-up protocol that included renal ultrasound
at approximately 1 month from the date of operation in patients without
a stent or 1 month from the date of stent removal in patients with
a stent.
Results: Of the 289 patients with proper follow-up, 27 (9.3%) had
sonographic evidence of hydronephrosis. Fourteen patients were asymptomatic,
and 13 patients experienced ipsilateral flank pain. A total of 4.8%
of the patients (14/289) had silent hydronephrosis. The negative predictive
value and positive predictive value of ipsilateral flank pain for
hydronephrosis were 94% and 35%, respectively. There was no difference
between the symptomatic and asymptomatic groups with respect to need
for further surgery (38% vs. 21%, p = 0.42). The number of asymptomatic
patients after ureteroscopy needing renal ultrasound to diagnose one
case of hydronephrosis was 18.
Conclusions: This study demonstrates that hydronephrosis is present
in a small percentage of patients after ureteroscopy. Hydronephrosis
can be present in both symptomatic and asymptomatic patients and may
warrant further surgery. Renal ultrasonography at 1 month after ureteroscopy
permits appropriate detection of hydronephrosis and should be considered
as an imaging option.
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Editorial
Comment
The authors excluded patients who underwent alternative postoperative
imaging (CT scan, antegrade nephrostogram) - it would have been useful
to report why these patients underwent imaging (ex. symptoms) and
what the findings were. The authors did not evaluate intraoperative
factors that could help predict those who may benefit from postoperative
imaging (ex. impacted stones, ureteral perforation, need for balloon
dilation). It is possible that a more selective approach to postoperative
imaging could be considered. As one-third of patients with hydronephrosis
had subsequent spontaneous resolution, it is possible that delaying
ultrasonography to 6-8 weeks is warranted. The degree and chronicity
of preoperative hydronephrosis might guide the need for nuclear renography
instead of ultrasonography to define obstruction as opposed to calyectasis.
This issue is not addressed by the authors, though they note that
15% of patients with hydronephrosis on ultrasonography were determined
on follow-up to have chronic dilation as opposed to obstruction.
Dr.
Manoj Monga
Professor, Department of Urology
University of Minnesota
Edina, Minnesota, USA
E-mail: endourol@yahoo.com
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