Wellcome to HCM There s most probably a stone (calculus) of 2 mm in the right kidney. The echogenic focus suggest that most probably its small stone. Hydronephrosis suggest that there was some kind of obstruction in the path of urine for e.g. a stone in the ureter and this leads to dilatation of the pelvicalyx of the kidney. The oedematous urethro-vescical (UV) junction further favours that a stone or fragment of stone which might have developed in your kidney has recently passes out. When this stone passes through the ureters and specially at UV junction, it causes severe pain. There is nothing to worry in it as such. Show this report to your urologist for further evaluation.