Ureteric entrapment in sacroiliac joint causing hydroureter and ipsilateral kidney hypertrophy

A unilateral megaureter was found in an elderly female cadaver during routine dissection. The left proximal ureter, which was thick and convolute, descended and entered into the pelvic cavity, where the distal ureter was attached to the posterior pelvic wall at the inlet level. Removal of connective tissue surrounding the attached region revealed ureteric entrapment in the sacroiliac joint. The ipsilateral kidney, from which the megaureter originated, showed no pelvicalyceal dilatation. In contrast, the left kidney was enlarged, weighing 24% more than the right kidney. Differences in the upper urinary system between the obstructed and normal sides were examined in terms of gross anatomy, measurements, and histology. Although ureteric obstruction frequently causes hydroureter and hydronephrosis, the present case is very rare as the incomplete obstruction may have stimulated ipsilateral kidney growth, instead of contralateral compensatory augmentation.