Presentation
Severe left sided flank pain. History of calculus in the left kidney having undergone extracorporeal shock wave lithotripsy (ESWL). Microscopic hematuria on routine urine examination.
Patient Data
Right kidney is normal in size, position and outline. No calculus seen in the right pelvicalyceal system or ureter.
Left kidney is normal in size, position and outline. However, there is left perinephric fat stranding. There is a column of 3 calculi in the left distal ureter, the most distal one lying approximately 2 cm above the left vesicoureteric junction causing mild dilation of the left upstream ureter and the left pelvicalyceal system. The calculi measure approximately 8.6 x 4.8mm, 4.5 x 3.5mm, and 4.7 x 3.9mm in size with attenuation values of +1196 HU, +843 HU and +915 HU respectively.
Case Discussion
Sequence of event during the urinary obstruction:
Ureteric peristalsis causes urine to propel from renal pelvis to the bladder. Any obstruction or stasis of the column of urine in the ureter generates high pressure to the renal pelvis.
Acute obstruction 1:
<3 h - Obstructed kidney response with paradoxical increase in renal blood flow by release of prostaglandin which causes afferent arteriolar dilatation.
3-5h - Vasoconstriction of afferent arterioles resulting in increased intrarenal resistance and reduced renal blood flow.
18-24 h - Marked intrarenal vasoconstriction leads to further reduction in renal blood flow.
4-7 days - Complete obstruction causes permanent damage which is unrecoverable by 6 weeks.
Steinstrasse usually develops 1 day to 3 months after stone fragmentation by extracorporal shock wave lithotripsy (ESWL). The most common site of the column of stone fragment obstruction is the distal ureter (64%) followed by the proximal (29%) and mid ureter (8%) 2.
Refined technique in ESWL these days has reduced the incidence of steinstrasse from 20% to 6%.
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