This is a rare condition where the uppermost renal calyces in the kidney, which are part of the central region where urine collects before passing out of the kidney, become compressed. The compression is often caused by certain blood vessels that supply the area. The main symptoms typically include abdominal pain, back pain in the kidney area, and the presence of blood in the urine. Complications that may arise from this syndrome include recurrent urinary tract infections and the formation of kidney stones.