Abstract Textbooks describe three narrowest anatomic
sites in the ureter as the most likely places for ureteral
calculi to lodge, these are: the pelvi-ureteric junction
(PUJ), the point where the ureters cross over the iliac
vessels and the ureterovesical junction (UVJ). The purpose
of this study is to determine whether calculi causing ureteric
obstruction and requiring surgical treatment are found
mostly at these three narrowest anatomic points of the
ureter. Three hundred consecutive patients with impacted
ureteric calculi who required surgical intervention were
studied. The location of the impacted calculus on the day of
surgical intervention was categorized according to nine
predetermined levels outlined in a designed diagram based
on findings on non-contrast CT of kidneys, ureters and
bladder. Two peaks in stone distribution in the ureters were
encountered; the first was above the ischial spine in the
proximal part of the lower third ureter (84 patients, 28 %),
while the second was at the level between L3 and L4
lumbar vertebrae (66 patients, 22 %). Overall, the location
of impacted calculi was as follows, 53, 34, 10 and 3 % in
the lower third ureter, upper third ureter, PUJ and mid
ureter, respectively. This study demonstrates two peaks of
calculi distribution in the ureter where ureteric calculi
become impacted: the upper ureter below the PUJ and a
second in the lower ureter, more proximal than the UVJ.
There was an absence of the peak in stone location over the
iliac vessels, that is, the mid ureter.