Flank Pain

A kidney stone Stones in the Urinary Tract Stones (calculi) are hard masses that form in the urinary tract and may cause pain, bleeding, or an infection or block of the flow of urine. Tiny stones may cause no symptoms, but larger stones... read more causes excruciating pain when it enters a ureter. The ureter contracts in response to the stone, causing severe, crampy pain (renal or ureteral colic) in the flank or lower back that often extends to the groin or, in men, to a testis. The pain typically comes in waves. A wave may last 20 to 60 minutes and then stop. The pain stops without resuming again when the ureter relaxes or the stone passes into the bladder.

A kidney infection (pyelonephritis Kidney Infection Pyelonephritis is a bacterial infection of one or both kidneys. Infection can spread up the urinary tract to the kidneys, or uncommonly the kidneys may become infected through bacteria in the... read more ) causes swelling of the kidney tissue, which stretches the renal capsule, causing steady, aching pain. Kidney tumors Kidney Cancer Most solid kidney tumors are cancerous, but purely fluid-filled tumors (cysts) generally are not. Almost all kidney cancer is renal cell carcinoma. Another kind of kidney cancer, Wilms tumor... read more do not usually cause pain until they have become very large.

Other disorders that cause pain in the flank include sudden blockage of blood flow to a kidney or the intestine, ruptured and occasionally unruptured abdominal aortic aneurysms Abdominal Aortic Branch Occlusion Abdominal aortic branch occlusion is blockage or narrowing of one of the large arteries in the abdomen that come off of the aorta. Branches of the aorta can be blocked (occluded) due to atherosclerosis... read more , problems with the spine or spinal nerves, musculoskeletal injuries, and tumors that involve the back of the abdomen (retroperitoneum).

After noting symptoms, the doctor examines the person and usually does a urinalysis Urinalysis and Urine Culture Urinalysis, the testing of urine, may be necessary in the evaluation of kidney and urinary tract disorders and can also help evaluate bodywide disorders such as diabetes or liver problems. A... read more to check for red blood cells or excess white blood cells. White blood cells in the urine suggest an infection. If an infection is suspected, a urine culture Urinalysis and Urine Culture Urinalysis, the testing of urine, may be necessary in the evaluation of kidney and urinary tract disorders and can also help evaluate bodywide disorders such as diabetes or liver problems. A... read more is usually done. A person with very severe, cramping pain and blood in the urine is very likely to have a kidney stone Stones in the Urinary Tract Stones (calculi) are hard masses that form in the urinary tract and may cause pain, bleeding, or an infection or block of the flow of urine. Tiny stones may cause no symptoms, but larger stones... read more . A person with milder, steady pain, tenderness when the doctor taps over one kidney, fever, and excess white blood cells in the urine is likely to have a kidney infection Kidney Infection Pyelonephritis is a bacterial infection of one or both kidneys. Infection can spread up the urinary tract to the kidneys, or uncommonly the kidneys may become infected through bacteria in the... read more .

If a kidney stone is suspected, the doctor often does computed tomography Computed tomography There are a variety of tests that can be used in the evaluation of a suspected kidney or urinary tract disorder. (See also Overview of the Urinary Tract.) X-rays are usually not helpful in evaluating... read more (CT) or ultrasonography Ultrasonography There are a variety of tests that can be used in the evaluation of a suspected kidney or urinary tract disorder. (See also Overview of the Urinary Tract.) X-rays are usually not helpful in evaluating... read more to determine whether a stone is the cause, the size and location of the stone, and whether it significantly blocks urine flow. An intravenous contrast agent is not used for the CT scan. If the doctor is not sure of the cause of pain, often CT that uses an intravenous contrast agent or another imaging test is done.

The underlying disorder is treated. Mild pain can be relieved by taking acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs). Pain from kidney stones may be severe and may require use of intravenous or oral opioids.