Flank pain

[Dianne]

Pain caused by kidney disorders usually is felt in the side (flank) or small of the back. Occasionally, the pain extends to the center of the abdomen. Usually pain occurs because the kidney’s outer covering (renal capsule) is stretched by a disorder that causes rapid swelling of the kidney or because a stone has entered one of the ureters (tubes connecting the kidney to the bladder). Severe kidney pain is often accompanied by nausea and vomiting.
(See Overview of Urinary Tract Symptoms.)