References. 1  Shmerling RH. Approach to the patient with myalgia. http://www.uptodate.com/home. 2  LeBlond RF, et al., eds. The spine, pelvis and extremities. 3  Muscle cramps. Merck Manual Professional Version. 4  Sprains, strains and other soft tissue injuries. American Academy of Orthopaedic Surgeons.
Freebase(0.00 / 0 votes)Rate this definition: Hydronephrosis â literally water inside the kidney â refers to distension and dilation of the renal pelvis and calyces, usually caused by obstruction of the free flow of urine from the kidney. Untreated, it leads to progressive atrophy of the kidney.
1 The obstruction may occur at any level in the urinary collecting system from the kidney to the ureter to the bladder to the urethra.  Depending on the level of the cause, hydronephrosis may be unilateral involving one kidney or bilateral involving both.