A 42 year old man presented with severe pain in the lower back radiating to the pubic symphysis. Ultrasonography revealed a stone in the left ureter, measuring 3mm in size. The stone is most likely to be lodged in which of the following sites?

Vesicoureteric junction is the narrowest pa of the uterus. This is the reason why stones as small as 2 to 3 mm get arrested in the vesicoureteric junction. The ureter is constricted at 5 places: At the pelvi-ureteric junction At the brim of the lesser pelvis (as it crosses the common iliac aery) At the site of crossing of the ureter by ductus deferens or broad ligament of the uterus. Vesico-ureteric junction. At its opening in the lateral angle of the trigone. These are regarded as surgical constriction of the ureter. However, the anatomical constriction are only 3 of them (1,2 and 4) Ref: Gray&;s Anatomy 41st edition Pgno: 1253